Vurdering og sammenligning av brukonsepter for kryssing av Bjørnafjorden: Oppetid

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1 Vurdering og sammenligning av brukonsepter for kryssing av Bjørnafjorden: Oppetid Foto: Statens Vegvesen Versjon Sammenfattet av: Inger Lise Johansen

2 Forord Denne rapporten utgjør fjordkryssingsprosjektets leveranse nr. 7 til bestilling av dokumentasjon for «Bjørnafjorden bru» til planarbeidet for KDP Stord-Os. Rapporten gir en overordnet vurdering og sammenligning av de aktuelle brukonseptene i forhold til oppetid. Dette omfatter både nedetid som følge av planlagt stengning grunnet inspeksjon, drift og preventivt vedlikehold, og ikke-planlagt stenging grunnet ulykker og vær-relaterte forhold. Vurderingene er basert på konseptvise oppetidsanalyser utført av de respektive konsulentfirmaene på bestilling fra fjordkryssingsprosjektet. Arbeidet med de ulike konseptene har ulik fremdrift og samtlige resultater er midlertidige. Denne rapporten gir derfor kun en grov vurdering av konseptene på overordnet nivå, og bør revurderes når endelige resultater foreligger.

3 Innhold Innhold Forord... 2 Innhold... 3 Sammendrag Innledning Metode... 9 RAMS... 9 Metodikk og omfang... 9 Forutsetninger Begrensninger Resultater K1-2: Multispenn hengebru på flytende fundament (TLP) Grunnlag og status Planlagt nedetid: Inspeksjon, drift og preventivt vedlikehold Ikke-planlagt nedetid: Vær-relaterte forhold Ikke-planlagt nedetid: Ulykker og korrektivt vedlikehold Samlet vurdering K3+K4: Rørbru Grunnlag og status Planlagt nedetid: Inspeksjon, drift og preventivt vedlikehold Ikke-planlagt nedetid: Vær-relaterte forhold Ikke-planlagt nedetid: Ulykker og korrektivt vedlikehold Samlet vurdering K7-K8: Flytebru Grunnlag og status Planlagt nedetid: Inspeksjon, drift og preventivt vedlikehold Ikke-planlagt nedetid: Vær-relaterte forhold Ikke-planlagt nedetid: Ulykker og korrektivt vedlikehold Samlet vurdering Sammenligning Planlagt nedetid Ikke-planlagt nedetid... 26

4 Konklusjon Vedlegg... 28

5 Sammendrag Denne rapporten utgjør del av dokumentasjonen for «Bjørnafjorden bru» til planarbeidet for KDP Stord-Os. Rapporten gir en overordnet vurdering og sammenligning av de aktuelle brukonseptene i forhold til oppetid. De aktuelle konseptene er: K1: Multispenn hengebru med tårn på stålflytere K2: Multispenn hengebru med tårn på betongflytere K3: Pongtongforankret rørbru K4: Strekkstagforankret rørbru K7: Endeforankra flytebru m/seilingsled i sør K8: Sideforankra flytebru m/seilingsled i sør Oppetidsvurderingen omfatter både nedetid som følge av planlagt stengning grunnet inspeksjon, drift og preventivt vedlikehold, og ikke-planlagt stenging grunnet ulykker og vær-relaterte forhold. Vurderingene er basert på konseptvise oppetidsanalyser utført av de respektive konsulentfirmaene på bestilling fra fjordkryssingsprosjektet. Resultatene fra disse er sammenfattet i tabell 1. Tabell 1 Planlagt og ikke-planlagt nedetid for brukonsepter for kryssing av Bjørnafjorden Planlagt nedetid grunnet K1 K2 K3 K4 K7 K8 inspeksjon, drift og vedlikehold Full nedetid 0t (0%) 0t (0%) 0t (0%) 0t (0%) 0t (0%) 0t (0%) Stengning av én kjørebane 14, 2t (0,62%) 14, 2t (0,62%) - - 7,1 t (0,08%) 14, 2t (0,62%) Stengning av ett felt 25,2t (0,29%) 25,2t (0,29%) , 0t (0,34%) 6,4 t (0,07%) Ikke-planlagt nedetid grunnet hendelser og værrelaterte forhold Vær-relaterte forhold 18, 35t (0,21%) 18, 35t (0,21%) Hendelser 0.4t 0.4t (0,0004 (0,0004 %) %) 0t (0%) 0t (0%) 16,8t (0,19%) 16,8t (0,19%) 20,19 20,19 12,3t 14,5t timer timer (0,14%) (0,17%) (0,23%) (0,23%) Total oppetid (hel og delvis åpning) 99,79% 99,79% 99,77% 99,77% 99,70% 99,68% Konsulentene har vært frie til å velge metodikk, grunnlagsdata og antagelser under visse forutsetninger og tett oppfølging fra Statens Vegvesen, og resultatene er derfor ikke direkte sammenlignbare. Arbeidet med de ulike konseptene har videre ulik fremdrift og samtlige resultater er midlertidige. Denne rapporten gir derfor kun en grov vurdering av konseptene på overordnet nivå, med fokus på å fremheve fordeler og ulemper, potensiale og usikkerheter. Oppetidsvurderingene skiller konseptene hovedsakelig på hovedkonseptnivå, men der det er forskjeller mellom ulike underkonsepter er disse fremhevet.

6 Som grunnlag for å vurdere behov nedetidsreduserende tiltak har fjordkryssingsprosjektet nedsatt et tentativt oppetidskriterium på 99,5%. Kriteriet forstås som prosentvis andel tid per år brua skal være åpen for trafikk. Dette innebefatter hel og delvis åpning (ved nedstengning av én eller flere kjørebaner/felt), slik at nedetid kun innebefatter full stengning. Samtlige konsepter har akseptabel oppetid ifølge dette kriteriet, med multispenn hengebru (K1 og K2) som tilsynelatende beste konsept. Forskjellene er imidlertid for små og usikkerhetene for store til at dette kan tillegges betydning. I denne vurdering er det derfor heller blitt lagt vekt på konseptenes «iboende» godhet eller potensiale med tanke på oppetid, og i så måte skiller rørbru (K3 og K4) seg positivt ut ved å unnslippe problematikk relatert til vind og ising. Det bør understrekes at oppetidsanalysen for multispenn hengebru er mindre komplett enn for de andre konseptene, og at oppdaterte analyser kan påvirke rangeringen i begge retninger. Samtlige konsepter har estimert full, planlagt nedetid grunnet inspeksjon, drift og preventivt vedlikehold til 0 timer per år. Andel tid brua er delvis stengt grunnet er også en viktig parameter. Her skiller rørbru seg ut i negativ forstand grunnet høy frekvens av planlagte innvendige vedlikeholdsoppgaver, mens endeforankret flytebru kommer best ut dersom nedstengning av én kjørebane med toveistrafikk i den andre straffes hardere enn stengning ett felt. Oppetidsanalysene bygger på- og fordrer- valg og antagelser som er gjort for de respektive konseptene med hensyn til design, inspeksjon, vedlikehold og drift, og er således en integrert del av konseptutviklingen. Foruten å inngå som grunnlag for valg av konsept for kryssing av Bjørnafjorden, har analysene derfor verdi i å gjøre oppetid til premiss for konseptutvikling i tidligfase, ved å synliggjøre konsekvenser og avveininger ved de valgene som tas. Vurderingen av hva som er akseptabel oppetid bør til slutt ses i et ALARPperspektiv, der tiltak for å øke oppetida avveies mot andre grunnleggende mål som sikkerhet, kostnad og effektivitet.

7 1 Innledning Tilgjengelighet er et av flere prosjektmål som ligger til grunn for planlegginga av den nye strekningen E39 Stord-Os. Som grunnlag for valg av brukonsept for kryssing av Bjørnafjorden på denne strekningen skal derfor konseptene derfor vurderes i forhold til brusystemets tilgjengelighet, operasjonalisert som oppetid. Formålet med denne rapporten er å vurdere og sammenligne resultatene fra oppetidsanalysene som er gjort for de respektive brukonseptene, og fremheve konseptenes relative fordeler og ulemper med oppetid som mål. Rapporten inngår som del av dokumentasjonen for «Bjørnafjorden bru» til planarbeidet for KDP E39 Stord-Os. Rapporten omfatter både nedetid som følge av planlagt stengning grunnet inspeksjon, drift og preventivt vedlikehold, og ikke-planlagt stenging grunnet ulykker og vær-relaterte forhold. Vurderingene er basert på oppetidsanalysene som er gjort som del av arbeidet med RAMS (akronym for pålitelighet, tilgjengelighet, vedlikeholdbarhet og sikkerhet) for de ulike konseptene, utført av de respektive konsulentfirmaene på bestilling fra fjordkryssingsprosjektet. Konsulentene har vært frie til å velge metodikk, grunnlagsdata og antagelser under visse forutsetninger og tett oppfølging fra Statens Vegvesen. Konseptene har videre ulik fremdrift og samtlige resultater er midlertidige. Denne rapporten gir derfor kun en grov vurdering av konseptene på overordnet nivå, med fokus på å fremheve fordeler og ulemper, potensiale og usikkerheter. De aktuelle konseptene er: K1: Multispenn hengebru med tårn på stålflytere K2: Multispenn hengebru med tårn på betongflytere K3: Pongtongforankret rørbru K4: Strekkstagforankret rørbru K7: Endeforankra flytebru m/seilingsled i sør K8: Sideforankra flytebru m/seilingsled i sør Konseptene er beskrevet i fjordkryssingsprosjektets øvrige leveranser til planararbeidet for KDP. Tilgjengelighet er et grunnleggende mål i seg selv, men har også har indirekte samfunnsøkonomiske og samfunnssikkerhetsmessige konsekvenser avhengig av mulighetene for omkjøring. Samtidig er det ofte et direkte motsetningsforhold mellom oppetid og sikkerhet, ved at oppetida kan økes på bekostning av sikkerhetsmessige forhold eller omvendt. Oppetidsvurderingene må derfor ses i lys av kostnadene og konsekvensene av nedetida i seg selv så vel som reduserende tiltak. De må videre forstås som et resultat av de valg og avveininger som er gjort med hensyn til design, inspeksjon, vedlikehold og drift. Tilgjengelighet bør derfor bli premissgivene tidlig i konseptutviklingen, både i forhold til å velge det konseptet som har best forutsetninger og potensiale for å oppnå høy oppetid i avveining mot andre mål, samt å stimulere gode løsninger i videre utvikling av valgt(e) konsept(er).

8 Rapporten er lagt opp som følger: Kapittel 2 gir oversikt over metode og forutsetninger, mens kapittel 3 sammenfatter resultatene for henholdsvis multispenn hengebru, rørbru og flytebru, alle med ulike underkonsepter. Kapittel 4 sammenligner de ulike konseptene og gir i en overordnet konklusjon med tanke på oppetid. De foreliggende konseptvise oppetidsanalysene er vedlagt i vedlegg 1-4.

9 2 Metode RAMS Oppetidsvurderingene er gjort som del av arbeidet med RAMS (pålitelighet, tilgjengelighet, vedlikeholdbarhet og sikkerhet) i utviklingen av brukonsept for kryssing av Bjørnafjorden. Figur 1 illustrerer sammenhengen mellom de fire begrepene, der sikkerhet og tilgjengelighet er overordnede systemegenskaper (mål) som avhenger av delsystemenes pålitelighet og vedlikeholdbarhet. Figur 1 Begrepsstruktur RAMS RAMS dekker en rekke disipliner relatert til risikohåndtering av teknologiske systemer, men kan generelt forstås som en systematisk prosess for å sikre et pålitelig, tilgjengelig, vedlikeholdsvennlig og sikkert system i et livssyklusperspektiv. Fjordkryssingsprosjektet har et uttalt mål om å innføre systematikk for RAMS, nettopp på grunn av de spesielle kravene og utfordringene knyttet til sikkerhet og tilgjengelighet i prosjektet. Statens vegvesen har imidlertid begrenset erfaring med bruk av RAMS-systematikk i vegprosjekter, og det finnes ikke noe veletablert RAMS-metodikk i etaten 1. Metodikk og omfang Tradisjonell metodikk for oppetidsanalyse er typisk rettet mot produksjonssystemer hvis tilgjengelighet avhenger av delsystemers pålitelighet, gitt av detaljert design og planer for drift og vedlikehold, interne feilmoder og eksterne påvirkninger. En oppetidsanalyse for et brusystem i tidligfase krever en videre tilnærming, da oppetida primært er en funksjon av eksterne forhold og farer i kombinasjon med grove forutsetninger for design og drift. I fjordkryssingsprosjektets bestilling til konseptgruppene er derfor konsulentene gitt stor frihet i valg av metodikk, gitt at følgende bidrag er dekket: Gjennomsnittlig planlagt nedetid (%) per år grunnet preventivt vedlikehold Gjennomsnittlig ikke-planlagt nedetid (%) per år grunnet uønskede hendelser (inkl. korrektivt vedlikehold) og vær-relaterte forhold 1 Utkastet til veilederen «VegRAMS Drift og vedlikehold av vegtunneler. Premisser for planlegging, prosjektering, bygging og rehabilitering» er et første initiativ til å etablere prosesser for RAMS i Statens Vegvesen.

10 Konsulentene har i sine analyser hovedsakelig basert seg på erfaringstall for sammenlignbare konstruksjoner. Bidrag fra ikke-planlagt nedetid er representert ved forventningsverdien som et produkt av frekvens og konsekvens (nedetid) for de ulike hendelsene. I praksis vil derfor sjeldne, men langvarige nedstengninger kunne gi samme bidrag som hyppige, men mindre langvarige nedstengninger. Forutsetninger Oppetidsanalysene er basert på - og har bidratt til å definere- forutsetninger, antagelser og strategier for design, drift og vedlikehold. Noen av disse er like for samtlige konsepter, slik som værdata, akseptkriterier for kjørekomfort, og til en viss grad kriterier for nedstengning ved høy vind (her har både flytebru og TLP forutsatt stengning ved gjennomsnittlig vindhastighet på 25 m/s). Andre er spesifikke for det enkelte konsept, slik som preventiv vedlikeholdsfilosofi og prosedyrer for nedstengning og gjenåpning etter en uønsket hendelse. Som del av bestillingen er konsulentene bedt om å synliggjøre slike forutsetninger/antagelser og vurdere aktuelle tiltak. Vi skiller hovedsakelig mellom 4 kategorier av nedetid: 1. Hel stengning: Stengning av to kjørebaner 2. Delvis stengning: Stengning av én kjørebane, toveis trafikk i den andre kjørebanen eventuelt med fartsbegrensninger 3. Delvis stengning: Stengning av ett felt, enveis trafikk i to kjørebaner, eventuelt med fartsbegrensninger 4. Delvis stengning: Stengning av veiskulder eller gang/sykkelfelt, eventuelt med fartsbegrensninger Som grunnlag for å vurdere behov for ytterligere tiltak er konsulentene bedt om å vurdere resultatene i lys av et oppetidskriterium på 99,5%. Kriteriet forstås som prosentvis andel tid per år brua er åpen for trafikk. Oppetid innebefatter her både full og delvis åpning som muliggjør trafikk i begge retninger, slik at nedetid kun betyr full stengning (punkt 1 over). Konsulentene er imidlertid også oppfordret til å synliggjøre andel tid brua er delvis åpen (punkt 2-3). Oppetidskriteriet er kun et tentativt kriterium fjordkryssingsprosjektet har nedsatt for å indikere oppetidsnivået som bør tilstrebes. Som for sikkerhet oppfordres enn ALARPtankegang (as low as reasonably practicable), der tiltak for å øke oppetida bør iverksettes så lenge de er innen rimelighetens grenser og ikke er i konflikt med andre mål (sikkerhet). Begrensninger En konsekvens av at konsulentene er gitt stor frihet i valg av metodikk og forutsetninger er at resultatene fra de respektive oppetidsanalysene ikke er direkte sammenlignbare. En annen begrensning er at de ulike konsulentgrupperingene har hatt ulik progresjon i arbeidet (som fortsatt er pågående), der sluttrapporten for multispenn hengebru ikke er ferdig før Juni Det er fortsatt meningsfylt å vurdere resultatene mot hverandre og oppetidskriteriet

11 på 99,5%, men ikke å tillegge promillevise forskjeller avgjørende betydning. Den største verdien av de foreliggende vurderingene er derfor å synliggjøre relative fordeler og ulemper, samt usikkerheter og potensiale for videre utvikling. En begrensning er at langvarig nedetid grunnet kollaps eller annen alvorlig skade som følge av ulykkeslaster større enn dimensjonerende laster ikke er inkludert i konsulentenes analyser. Slike hendelser vil gi et svært lite bidrag til den forventede nedetida grunnet den lave returperioden, bestemt ved kriteriet i N400 som sier at man kan se bort fra hendelser med frekvens mindre enn Dette kriteriet vil imidlertid bli supplert med andre risikoakseptkriterier for langvarig nedetid, slik at problemstillingen blir adressert i senere risikoanalyser. De foreliggende oppetidsanalysene har således et operativt fokus på hendelser og forhold som kan oppstå med en rimelig sannsynlighet i løpet av levetiden. De ulike konsulentgruppene har valgt ulike grenser for hva som skal inkluderes basert på hendelsenes konsekvenser for det spesifikke systemet. I en tidligfase er detaljnivået så lavt at oppetidsanalysene i liten grad viser ulikheter mellom underkonseptene av rørbru, flytebru og multispenn hengebru. Vurderingene skiller derfor konseptene hovedsakelig på hovedkonseptnivå, men der det er forskjeller mellom underkonseptene er disse fremhevet.

12 Resultater K1-2: Multispenn hengebru på flytende fundament (TLP) Dette delkapitlet sammenfatter resultatene fra oppetidsanalysene for multispenn hengebru på flytene fundament (populært kalt TLP), med underkonseptene flyter i stål (K1) og flyter i betong (K2). Grunnlag og status Oppetidsanalysene av multispenn hengebru er utført av Cowi Danmark og Aas Jacobsen med innspill fra øvrige samarbeidspartnere. Rapporten kan leses i sin helhet i Vedlegg 1. De endelige resultatene fra oppetidsanalysen for multispenn hengebru foreligger ikke før Juni Dette skyldes at fase 2 i arbeidet med multispenn hengebru ble senere igangsatt enn for de øvrige brukonseptene, slik at man for oppetidsanalysene må avvente grunnleggende beslutninger relatert til design, drift og vedlikehold. Som grunnlag for midtveis konseptevaluering er det allikevel blitt utført et preliminær analyse. De foreliggende resultatene bygger på erfaringstall fra sammenlignbare bruer (hovedsakelig Storebælt og flytebrukonseptene K7 og K8), vurdert i lys av forenklede antagelser om inspeksjon, drift og vedlikehold og tidlige designløsninger som forventes oppdatert i senere faser. På dette stadiet dekker den kvantitative oppetidsanalysen kun noen få, essensielle bidrag. Analysene skiller ikke mellom multispenn hengebru med flyter i stål (K1) og betong (K2), slik at oppetida for de to underkonseptene er antatt å være den samme. Planlagt nedetid: Inspeksjon, drift og preventivt vedlikehold Planlagt (full) nedetid som følge av inspeksjon, drift og preventivt vedlikehold av elementer under vann er satt til 0 timer per år. Dette bygger på antagelsen om at all inspeksjon og vedlikehold kan utføres ved hjelp av båter og fjernstyrte kjøretøy (ROV) fra sjøen, slik at det ikke er behov for å beslaglegge areal på brua/veibanen. Det er imidlertid usikkerhet relatert til hvorvidt det er mulig å designe strekkstag med 100 års levetid eller om man må legge til rette for utskifting av disse. Dette kan også gjøres fra sjøen med hjelp av båter og ROV, men brua vil da være mer sensitiv til bølger og vind. Det er usikkert hvilke krav som skal stilles til sikkerhet og komfort under slike operasjoner, men det er antatt at disse kan planlegges til rolige perioder slik at oppetida ikke vil bli påvirket. Planlagt (full) nedetid som følge av inspeksjon, drift og preventivt vedlikehold av elementer over vann er satt til 0 timer per år. Dette bygger på antagelsen om at hensyn til inspeksjon og vedlikehold vil bli tilstrekkelig ivaretatt i designet, bygging og drift. Planlagt nedetid for én kjørebane er antatt å være på samme nivå som for sideforankret flytebru (K8). Begrunnelsen er at det er inspeksjon og vedlikehold av brubelegningen, hvis form og lengde er tilnærmet lik for de to konseptene, som utgjør det største bidraget for lukking av en hel kjørebane. Dette utgjør 14,2 timer per år (0,162%).

13 Det er forventet at større og mindre vedlikeholdsarbeider av kabler og hengere vil bidra til stengning av ett felt i 25.2 timer per år (0.29 %). I tillegg kommer inspeksjon og vedlikehold av andre komponenter som ikke er inkludert i analysen, deriblant interne rom i flyterne som fører til stengning av ett felt. Ikke-planlagt nedetid: Vær-relaterte forhold Ikke-planlagt nedetid som følge av vær-relaterte forhold er beregnet ut fra tilgjengelig værdata fra Norsk meteorologisk institutt, gjeldende komfortkriterier og antagelsen om at brua stenges ved en vindhastighet på 25 m/s, målt ved 10 min gjennomsnittlig sidevind. Sistnevnte kriterium er adoptert fra Storebælt, men reflekterer også norske stengningsrutiner. Beregningene inkluder kun vind fra østlig (60-120) og vestlig sektor ( ). Ikke-planlagt nedetid grunnet stengning ved vind over 25 m/s er beregnet til 15,6 timer per år (0,18%). I tillegg kommer bidrag fra is og snø som kan falle fra kabler og tårn, som er anslått til 2,75 timer per år (0,03%). Dette er basert på erfaringsdata fra Storebælt, der man antar at de negative forskjellene ved klimaet i Bjørnafjorden og de positive forskjellene ved atmosfærisk ising grunnet høyde veier opp for hverandre. Bidrag fra nedstengning grunnet akselerasjoner fra vind og bølger er ikke inkludert i analysen. Delvis stenging er ikke aktuelt i forbindelse med vær-relaterte forhold, men aktuelle tiltak som reduserer fremkommeligheten på tilsvarende vis er reduserte hastighetsgrenser og differensierte regler for kjøretøy av en viss størrelse. Slike prosedyrer er ennå ikke utarbeidet for konseptet, og man har i stedet konservativt antatt full oppetid frem til 25 m/s. Et mer omfattende tiltak er vindskjerming, som kan være global eller lokal i relasjon til spesielle hotspots ved tårnene. Dette er ikke vurdert som nødvendig i lys av oppetidskriteriet, men bør undersøkes videre fra et ALARP-perspektiv og i lys av en eventuell skjerping av oppetidskravet fra Statens Vegvesen. En slik vurdering må se de positive konsekvensene av vindskjerming i forhold til oppetid og trafikksikkerhet i lys av vindskjermens påvirkning på konstruksjonens stabilitet. Dagens vurdering er at en vindskjerm vil medføre større kostnader og utfordringer enn gevinster i så måte. Ikke-planlagt nedetid: Ulykker og korrektivt vedlikehold Ikke-planlagt nedetid som følge av uønskede hendelser og korrektivt vedlikehold er kun vurdert for to typer hendelser: brann og skipstøt. Uforutsett nedetid relatert til funn fra inspeksjoner er heller ikke inkludert. Den estimerte nedetida kan derfor forventes å øke når flere hendelser blir inkludert i den endelige oppetidsrapporten. Brann-relaterte hendelser er vurdert å gi et neglisjerbart bidrag til nedetida, basert på risikoanalyser for Lillebælt bru i Danmark i 2013.

14 Bidraget til nedetid fra skipskollisjonshendelser er grovt estimert til 0.4t (0, 0004%). Dette er basert på erfaringsdata fra Storebælt bru, og er ansatt som svært konservativt grunnet forskjellene i skipstrafikkens størrelse og art. Bidraget fra både brann og skipstrafikk vil blir nærmere analysert i den endelige oppetidsanalysen. Et mulig tiltak for å øke sikkerheten til trafikanter på brua i forhold til skipskollisjon er varsling og påfølgende nedstengning hvis skip av kritisk størrelse er på kollisjonskurs. Dette vil gå på bekostning av bruas oppetid, men er en avveining som bør vurderes når system og prosedyrer for overvåkning og kontroll av skipstrafikken skal bestemmes. Samlet vurdering Tabell 2 oppsummerer estimert planlagt og ikke-planlagt nedetid for multispenn hengebru på flytende fundamenter. Resultatene er kun foreløpige og er like for underkonseptene flyter i stål (K1) og flyter i betong (K2). Tabell 2 Planlagt og ikke-planlagt nedetid for multispenn hengebru Planlagt nedetid grunnet inspeksjon, drift og vedlikehold K1 Multispenn hengebru på stålflyter K2 Multispenn hengebru på betongflyter Full nedetid 0t (0%) 0t (0%) Stengning av én kjørebane 14, 2t (0,62) 14, 2t (0,62) Stengning av ett felt 25,2t (0,29%) 25,2t (0,29%) Ikke-planlagt nedetid grunnet hendelser og værrelaterte forhold Vær-relaterte forhold 18, 35t (0,21%) 18, 35t (0,21%) Hendelser 0.4t (0,0004%) 0.4t (0,0004%) Total oppetid (hel eller delvis åpent) 99,79% 99,79% Generelle fordeler ved multispenn hengebru (K1+K2): Aldri behov for nedstengning av to kjørebaner ved vedlikehold, sjelden behov for nedstengning av én kjørebane eller ett felt Lav kollisjonsfrekvens for skipsstøt, både for flytere og brubane Generelle ulemper ved multispenn hengebru (K1+K2): Høyden over vannet gjør det til det mest utfordrende konsept i forhold til vind og atmosfærisk ising Behov for fartsreduksjoner og differensierte regler for visse kjøretøy ved høy vind eller vanskelige kjøreforhold Usikkerheter ved komfortkriterier og akselerasjoner som følge av lastvirkninger på hengebru på flytende fundament Eventuell (lokal) vindskjerming vil påvirke konstruksjonens stabilitet Spesielle fordeler ved multispenn hengebru på stålflytere (K1):

15 Ingen spesielle Spesielle ulemper ved multispenn hengebru på stålflytere (K1): Ingen spesielle Spesielle fordeler ved multispenn hengebru på betongflytere (K2): Ingen spesielle Spesielle ulemper ved multispenn hengebru på betongflytere (K2): Ingen spesielle Det må understrekes at oppetidsvurderingene for multispenn hengebru på flytende fundamenter er mindre komplette og heftet med mer usikkerhet enn for de øvrige konseptene. Dette skyldes ene og alene at oppetidsanalysene ble igangsatt på et senere tidspunkt og resultatene kun er basert på preliminære analyser. Usikkerheten kan imidlertid ikke blir brukt som et argument mot dette konseptet, da den kan effektivt reduseres ved mer detaljerte analyser og mer gjennomarbeidede forutsetninger om design, drift og vedlikehold. Det er lite som tyder på at multispenn hengebru er beheftet med større epistemisk eller stokastisk usikkerhet enn de øvrige konseptene, selv om kombinasjonen hengebru på flytende fundamenter innebærer spesielle usikkerheter relatert til kjørekomfort. Opprettholdelse eller økning av den beregnede oppetida forutsetter at hensynet til oppetidsvurderinger blir en sentral og integrert del av den videre konseptutviklingen.

16 K3+K4: Rørbru Dette delkapitlet sammenfatter resultatene fra oppetidsanalysene for rørbru, med underkonseptene pongtongforankret rørbru (K3) og strekkstagforankret rørbru (K4). Grunnlag og status Oppetidsanalysene for rørbru er utført av Dr.ing. Olav Olsen med innspill fra samarbeidspartene. Første utkast av oppetidsanalysene for rørbrukonseptene K3 og K4 forelå i februar 2016 og har blitt oppdatert i April Resultatene anses imidlertid ikke som endelige, og vil bli videre oppdatert i mai Den foreliggende rapporten kan leses i sin helhet i Vedlegg 2. Rørbrua er 5,5km lang og går over i henholdsvis 2,5km og 8km lang fjelltunnel på begge sider, slik at total tunnellengde blir 15km. En viktig avgrensning er at grensesnittet for analysen er satt ved inngangen til fjelltunnelen, slik at vedlikeholdsarbeid og hendelser som fører til nedetid i fjelltunnelen er ekskludert og antatt dekket i en annen oppetidsanalyse. Oppetidsanalysene er hovedsakelig basert på erfaringstall fra norske tunneler. Offentlig tilgjengelig statistikk for hendelser i norske tunneler er imidlertid mangelfulle, og analysene har der for blitt supplert med Vegtrafikksentralenes «Veglog» for fem lignende tunneler. Analysene skiller ikke mellom underkonseptene forankring med pongtong (K3) og strekkstag (K4), med unntak av bidrag fra skipsstøt mot pongtong. Planlagt nedetid: Inspeksjon, drift og preventivt vedlikehold Vurderingene av planlagt nedetid grunnet inspeksjon, drift og preventivt vedlikehold er basert på en rapport fra April 2015 som beskriver drifts- og vedlikeholdsfilosofi for rørbrukonseptene. Forventet frekvens og varighet av innvendige vedlikeholdsaktiviteter er basert på erfaringsdata fra tunneler, mens for utvendige aktiviteter under vann og i skvalpesonen er baser på erfaringer fra flytebruer og offshore-konstruksjoner. Planlagt (full) nedetid som følge av inspeksjon, drift og preventivt vedlikehold for begge rørbrukonseptene er satt til å 0 timer per år. Innvendig inspeksjon, drift og vedlikehold forutsettes utført med maksimum ett løp stengt og det andre åpent for toveis trafikk. Stengning av ett løp er nødvendig for følgende aktiviteter: Rensing (1 gang hvert 5 år) Rengjøring (2 ganger i året) Delvis rengjøring (3 ganger i året) Stengning av ett felt er nødvendig for følgende aktiviteter: Enkel inspeksjon (1 gang per år) Hovedinspeksjon (1 gang hvert 5 år)

17 Inspeksjon av elektro (2 ganger per år) Inspeksjon av installasjon (2 ganger per år) Teknisk rengjøring (5 ganger per år) Estimater for varigheten av de ulike aktivitetene avventes og med det også forventet delvis nedetid for henholdsvis ett løp og ett felt. Endelige resultater for dette vil foreligge i Mai Omfanget av aktiviteter som krever delvis nedstengning forventes å være betydelig i forhold til de øvrige brukonseptene, og vil i en større grad forutsette tilrettelegging i design og drift i forhold til vedlikeholdbarhet og sikkerhet for vedlikeholdspersonell og brukere. Det forutsettes at utvendig vedlikehold kan utføres uten å påvirke trafikken. Stålelementer vil ha katodisk beskyttelse med offeranoder som kan utskiftes ved hjelp av ROV under normal drift. Det er ikke forventet behov for utskifting av strekkstag (K4) i løpet av levetiden, noe som er heftet ved mindre usikkerhet enn for multispenn hengebru (K1 og K2) grunnet svært lave stressvariasjoner fra sykliske laster. Rehabilitering av betongelementene (rør for begge konseptene og pongtonger for K3) er ikke ansett som nødvendig i løpet av 100 års levetid. Ikke-planlagt nedetid: Vær-relaterte forhold Ikke-planlagt nedetid som følge av vind eller ising på kjørebanen er ikke relevant for noen av rørbrukonseptene, da trafikantene er beskyttet i tunnel. Nedetid som følge av uakseptable akselerasjoner for kjørekomfort er relevant, men har blitt vurdert som marginal med gitte komfortgrenser. De forventede akselerasjonene for storm med 1 års returperiode er betydelig mindre enn for de øvrige brukonseptene. Totalt bidrar derfor vær-relaterte forhold til 0 timer per år. Ikke-planlagt nedetid: Ulykker og korrektivt vedlikehold Ikke-planlagt nedetid som følge av uønskede hendelser og korrektivt vedlikehold er basert på identifikasjon av potensielle farer og hendelser (HAZID og FMECA) kombinert med erfaringstall fra norske tunneler. Analysene bygger videre på antagelser om prosedyrer for nedstengning ved inspeksjon etter ulike hendelser, samt påfølgende tid for korrektivt vedlikehold. Både inspeksjons- og reparasjonstida avhenger av hendelsens konsekvenser lokalt og globalt, som igjen avhenger av strategi og design for redundans/robusthet og mulighet for følge- eller fellesfeil. Ikke-planlagt nedetid som følge av uønskede hendelser og korrektivt vedlikehold er estimert til 20,19 timer (0,23%) for pongtongforankret rørbru og 0,15 timer (0,23%) for strekkstagforankret rørbru. Den lille forskjellen mellom konseptene skyldes at bidraget fra skipsstøt er aktuelt kun for pongtongforankret rørbru. Det er her forutsatt at brua stenges for inspeksjon ved skipsstøt større enn 50 MJ, med varighet fra 8 til 336 timer avhengig av omfang. Brua er videre designet til å tåle tap av én pongtong, men langvarig nedetid grunnet strukturell kollaps er kun indirekte inkludert ved å anta en årlig kollapssannsynlighet på 10E-6 i henhold til Eurokode. Hvorvidt dette er en gyldig vurdering kan diskuteres, og bør undersøkes i videre robusthetsanalyser. En robusthetsanalyse bør også inkludere støt fra u-

18 båt, hvis bidrag i foreliggende analyse er konkludert neglisjerbart siden rørbrua er vurdert til å tåle støt fra en ULA-klasse ubåt. Det største bidraget til ikke-planlagt nedetid (og med det rørbruas totale nedetid) er fra teknisk systemfeil, som tilsvarer 17,4 timer. Dette viser at det er en stor utfordring, men også et stort potensiale i å forbedre tekniske systemers pålitelighet i henhold til metodikk for RAMS. Bidraget fra trafikkulykker er kun på 2,8 timer, da erfaringer fra sammenliknbare tunneler viser at vegtrafikksentralene er dyktige i å holde tunneler oppe i forbindelse med trafikkulykker. Dette inkluderer brann i kjøretøy og røykutvikling uten brann. I tillegg kommer branner som krever større reparasjonsarbeid, hvilket bidrar med 0,2t per år. En mer detaljert analyse med risikoanalyseprogrammet TRANSIT bør gjøres for å demonstrere rørbruas oppetid i forhold til sammenlignbare tunneler. Samlet vurdering Tabell 3 oppsummerer estimert planlagt og ikke-planlagt nedetid for pongtongforankret rørbru (K3) og strekkstagforankret rørbru (K4). Resultatene er midlertidige og vil bli oppdatert i Mai Tabell 3 Planlagt og ikke-planlagt nedetid for brukonsepter for rørbru Planlagt nedetid grunnet inspeksjon, drift og vedlikehold K3 Pongtongforankret rørbru K4 Strekkstagforankret rørbru Full nedetid 0t (0%) 0t (0%) Stengning av én kjørebane Avventer resultat Avventer resultat Stengning av ett felt Avventer resultat Avventer resultat Ikke-planlagt nedetid grunnet hendelser og værrelaterte forhold Vær-relaterte forhold 0t (0%) 0t (0%) Hendelser 20,19 timer (0,23%) 20,19 timer (0,23%) Total oppetid (hel eller delvis åpent) 99,77% 99,77% Generelle fordeler ved rørbru (K3+K4): Aldri behov for full nedstengning grunnet planlagt vedlikehold Aldri behov for nedstengning grunnet værrelaterte forhold Ikke behov for reduserte fartsgrenser eller differensiering grunnet værrelaterte forhold, e.g. nekt av høye kjøretøy Minst nedetid for gående og syklende grunnet vær-relaterte forhold og trolig også vedlikehold Generelle ulemper ved rørbru (K3+K4):

19 Trolig størst forventet delvis nedetid (ett løp/felt) grunnet planlagte drifts- og vedlikeholdsoppgaver sammenlignet med øvrige konsepter Potensielt alvorlige konsekvenser ved brann- og eksplosjonshendelser, fordrer hyppigere nedstenging ved enkelthendelser og kan gi varige skader på konstruksjon Grensesnittsutfordringer mot fjelltunneler på hver side, med potensielt forhøyet nedetid om man tar hensyn til vedlikeholdsarbeid og hendelser i de to fjelltunnelene. Rørbruas oppetid avhenger av påliteligheten til aktive sikkerhetsinstrumenterte systemer (pumper, viftesystem), som erfaringsmessig har vært en utfordring for sammenlignbare tunneler. Spesielle fordeler ved pongtongforankret rørbru (K3): Ingen nedetid eller usikkerhet som følge av (eventuelt) bytte av strekkstag eller hendelser knyttet til grunnforhold Spesielle ulemper ved pongtongforankret rørbru (K3): Nedetid som følge av skipsstøt, men denne er mindre sammenlignet med flytebrukonseptene på grunn av fri høyde over vann Spesielle fordeler ved strekkstagforankret rørbru (K4): Ikke nedetid som følge skipsstøt Spesielle ulemper ved strekkstagforankret rørbru (K4): Nedetid som følge av eventuelt bytte av strekkstag, men mindre usikkerhet sammenlignet med multispenn hengebru Det bør også her understrekes at analysen kun gir et grovt overslag av den totale oppetida, og at estimerte verdier kun bør leses som en indikasjon på positive/negative bidrag og størrelsesordenen av bidraget. En detaljert analyse med risikoanalysemodellen TRANSIT vil kunne demonstrere en høyere oppetid ved å inkludere spesielle betraktninger relatert til bruas stigning, lengde og standard. Grensesnittsbetraktninger rundt rørbruas tilknytning til fjelltunneler på begge sider vil imidlertid kunne vise seg å telle negativt for totalbildet forhold til de øvrige brukonseptene.

20 K7-K8: Flytebru Dette delkapitlet sammenfatter resultatene fra oppetidsanalysene for flytebru, med underkonseptene endeforankret flytebru (K7), også kalt «bøttehanken», og sideforankret flytebru (K8), også kalt «rett bru». Begge konseptene har seilingsled i sør. Grunnlag og status Oppetidsanalysene av flytebru er utført av Cowi og Global Maritime innspill fra øvrige samarbeidspartnere. Rapportene kan leses i sin helhet i Vedlegg 3 og 4. En komplett oppetidsanalyse for konseptene endeforankret flytebru (K5) og sideforankret flytebru (K5), begge med seilingsled midtfjords, ble utført februar Disse variantene med seilingsled midtfjords er imidlertid utgått til fordel for seilingsled i sør. De opprinnelige resultatene er derfor ikke direkte gyldige for de gjenværende flytebrukonseptene K7 og K8. Arbeidet med å oppdatere analysene er pågående og de endelige resultatene vil ikke foreligge før i mai En preliminær analyse er utført i april 2016 for å gi et grovt anslag av ikke-planlagt nedetid grunnet vær og uønskede hendelser, med påfølgende korrektivt vedlikehold. Analysen dekker et omfattende sett med hendelser og tilstander, men det understrekes at de estimerte verdiene kun bør leses som en indikasjon på positive/negative bidrag og størrelsesordenen av bidraget. For ikke-planlagt nedetid er det videre kun estimert full nedetid, slike at hendelser som påvirker kun én kjørebane eller ett felt ikke vil gi utslag. Planlagt nedetid: Inspeksjon, drift og preventivt vedlikehold Planlagt nedetid grunnet inspeksjon, drift og vedlikehold er antatt å være de samme for de respektive konseptene med skipsled midtfjords. Analysene er basert på tre rapporter fra Juni 2015 som beskriver drifts- og vedlikeholdsfilosofi for henholdsvis stålstrukturer, betongelementer og forankring for flytebrukonseptene. Planlagt (full) nedetid som følge av inspeksjon, drift og preventivt vedlikehold for begge flytebrukonseptene er satt til å 0 timer per år. Dette forutsetter at det blir tatt tilstrekkelig hensyn til drift og vedlikehold ved senere faser i konseptutviklingen. Det forutsettes videre at inspeksjon og vedlikehold av betongelementene (pongtongene) kan gjøres fra sjøen for ikke å forstyrre trafikken på brua. Også forankringssystemet kan inspiseres og vedlikeholds fra sjøen, men det fremheves at man av økonomiske hensyn kan utføre noen aktiviteter ved tilgang fra kjørebanen. Dette vil kreve stengning av ett kjørefelt i en kortere periode. Planlagt nedetid for én kjørebane er estimert til 14,2timer (0,162%) for sideforankret flytebru (K8) og 7,1 timer (0,08%) for endeforankret flytebru (K7). Planlagt nedetid for ett felt er estimert til 6, 4 timer (0,073%) for sideforankret flytebru (K8) og 30, 0t timer (0,34%) for endeforankret flytebru (K7).

21 Forskjellen mellom konseptene skyldes at utskifting av brubanens belegning krever nedstengning av én hel kjørebane for sideforankret flytebru, men kun ett felt for endeforankret flytebru. Dette er fordi sideforankret bru har singel brukuasse, mens endeforankret har dobbel brukasse med adskilte kjørebaner. Videre må den endeforankrede flytebrua stenges for et felt ved større vedlikeholdsarbeid på skråkabelsystemet, mens dette kun krever stengning av en skulder for den sideforankrede brua. Av samme grunn forventes større nedetid for gående og syklende grunnet planlagt vedlikehold for sideforankret flytebru (566 t/år) enn for endeforankret flytebru (329 timer per år.) Det må understrekes at resultatene er for flytebrukonseptene med seilingsled midtfjords, og at disse vil bli oppdatert for seilingsled i sør. Ikke-planlagt nedetid: Vær-relaterte forhold Ikke-planlagt nedetid som følge av vær-relaterte forhold er beregnet ut fra tilgjengelig værdata fra Norsk meteorologisk institutt, gjeldende komfortkriterier og antagelsen om at brua stenges ved en vindhastighet på 25 m/s, målt ved 10 min gj. Sidevind. Sistnevnte kriterium er adoptert fra Storebælt, men reflekterer også norske stengningsrutiner. Beregningene inkluder kun vind fra østlig (60-120) og vestlig sektor ( ), og er utført for to forskjellige høyder; 55m (høybru) og 17 (lavbru). De originale analysene har ikke blitt oppdatert for seilingsled i sør, da det er antatt at nedetida grunnet vind vil være relativt likt fordi høyeste nivå av kjørebanen er relativt lik for alle konseptene. Ikke-planlagt nedetid grunnet stengning ved vind over 25 m/s er beregnet til 14 timer per år (0,16%) for begge flytebrukonseptene. I tillegg kommer bidrag fra is og snø som kan falle fra kabler og tårn, som er anslått til 2,8 timer per år (0,03%) for flytebrukonseptene med seilingsled midtfjords, basert på erfaringsdata fra Storebælt. Det er imidlertid knyttet høy usikkerhet både til frekvensen for fallende is og effekten av færre kabler for konseptene med seilingsled i sør, slik at videre analyser bør gjøres. Bidrag fra nedstengning grunnet akselerasjoner fra vind og bølger er inkludert i analysen, men funnet å gi et neglisjerbart bidrag. En ikke-konservativ avgrensning er at vind-og bølgelaster er beregnet med en returperiode på kun ett år. En sensitivitetsanalyse vil kunne vise at forventet nedetid øker dersom vind- eller bølgelaster med returperioder på f.eks. 5 eller 10 år inkluderes i analysen. For seilingsled i sør vil høybrudelen ha mest vind, mens lavbrua midt i fjorden har størst akselerasjon, men en nærmere kvantifisering av effekten av akselerasjoner vil kreve dialog med spesialister på trafikksikkerhet. Som for multispenn hengebru er delvis stenging ikke aktuelt i forbindelse med vær-relaterte forhold, men aktuelle tiltak som reduserer fremkommeligheten på tilsvarende vis er reduserte hastighetsgrenser og differensiering for visse kjøretøy. Slike prosedyrer er ennå ikke utarbeidet for konseptet, og man har i stedet konservativt antatt full oppetid frem til 25 m/s.

22 Et mer omfattende tiltak er lokal eller global vindskjerming. Dette er ikke vurdert som nødvendig i lys av oppetidskriteriet, men bør undersøkes videre fra et ALARP-perspektiv og i lys av en eventuell skjerping av oppetidskravet fra Statens Vegvesen. En slik vurdering må se de positive konsekvensene av vindskjerming i forhold til oppetid og trafikksikkerhet i lys av vindskjermens påvirkning på konstruksjonens stabilitet. Dagens vurdering er at en vindskjerm vil medføre større kostnader og utfordringer enn gevinster i så måte. Ikke-planlagt nedetid: Ulykker og korrektivt vedlikehold Ikke-planlagt nedetid som følge av uønskede hendelser og korrektivt vedlikehold er basert på identifikasjon av potensielle farer og hendelser (HAZID og FMECA) kombinert med historisk data for hendelser på lignende konstruksjoner. Analysene bygger videre på antagelser om prosedyrer for nedstengning ved inspeksjon etter ulike hendelser, samt påfølgende tid for korrektivt vedlikehold. Både inspeksjons- og reparasjonstida avhenger av hendelsens konsekvenser lokalt og globalt, som igjen avhenger av strategi og design for redundans/robusthet og mulighet for følge- eller fellesfeil. Ikke-planlagt nedetid som følge av uønskede hendelser og korrektivt vedlikehold er estimert til 12,3timer (0,14%) for endeforankret flytebru, og 14,5timer (0,17%) for sideforankret flytebru. Forskjellen mellom konseptene skyldes hovedsakelig at hendelser og skader som berører forankringssystemet for sideforankret bru (2,19t) ikke er aktuelt for endeforankret bru. De største øvrige bidrag for begge konseptene er funn ved inspeksjon av brukabler (6,4timer) og skipstøt mot pongtonger (1,6 timer) og brokasse (1,75timer). Grensen for langvarig nedetid er satt ved 50 dager, det vil si at bidrag fra ekstreme hendelser som medfører langvarig vedlikeholdsarbeid eller i verste fall total gjenoppbygging ikke er inkludert i analysen. Denne begrensning skyldes delvis mangelen på analyser om konstruksjonens robusthet i møte med ekstreme laster, og delvis et operativt fokus på hendelser og forhold som kan oppstå med en rimelig sannsynlighet i løpet av levetiden. Det understrekes at den ikke-planlagte nedetida avhenger av omfang og utførelse av planlagte vedlikeholdsaktiviteter, og at den endelige planen for drift og vedlikehold må utformes med tanker på å redusere risiko, både for vedlikeholdspersonell, trafikanter og brustrukturen. Som for multispenn hengebru er et mulig tiltak for å øke sikkerheten til trafikanter på brua i forhold til skipskollisjon varsling og påfølgende nedstengning hvis et skip av kritisk størrelse er på kollisjonskurs. Dette vil gå på bekostning av bruas oppetid, men er en avveining som bør vurderes når system og prosedyrer for overvåkning og kontroll av skipstrafikken skal bestemmes. Samlet vurdering Tabell 4 oppsummerer estimert planlagt og ikke-planlagt nedetid for endeforankret flytebru (K7) og sideforankret flytebru (K8), begge med seilingsled i sør. Resultatene er midlertidige og vil bli oppdatert i Mai 2016.

23 Tabell 4 Planlagt og ikke-planlagt nedetid for flytebru Planlagt nedetid grunnet inspeksjon, drift og vedlikehold K7 Endeforankret flytebru K8 Sideforankret flytebru Full nedetid 0t (0%) 0t (0%) Stengning av én kjørebane 7,1 t (0,08%) 14, 2t (0,62%) Stengning av ett felt 30, 0t timer (0,34%) 6,4 t (0,073%) Ikke-planlagt nedetid grunnet hendelser og værrelaterte forhold Vær-relaterte forhold 16,8t (0,19%) 16,8t (0,19%) Hendelser 12,3t (0,14%) 14,5t (0,17%) Total oppetid (hel eller delvis åpent) 99,70% 99,68% Generelle fordeler ved flytebru (K7+K8): Aldri behov for full nedstengning grunnet planlagt vedlikehold, sjelden behov for nedstengning én kjørebane eller ett felt Lavere høyde enn multispenn hengebru i forhold til vind- og isingsproblematikk Generelle ulemper ved flytebru (K7+K8): Mest utsatt for skipsstøt både i pongtong og brubjelke Eventuell (lokal) vindskjerming vil påvirke konstruksjonens stabilitet Behov for fartsreduksjoner og differensiering av kjøretøy ved høy vind eller vanskelige kjøreforhold Spesielle fordeler ved endeforankret flytebru (K7): Utskifting av brubelegning kan gjøres ved å stenge kun ett kjørefelt Vedlikehold og hendelser relatert til forankring er ikke relevant Spesielle ulemper ved endeforankret flytebru (K7): Større vedlikeholdsarbeid på skråkabelsystemet krever nedstrengning av et kjørefelt Større nedetid for gående og syklende grunnet planlagt vedlikehold i gang/sykkelbane (566 t/år) Spesielle fordeler ved sideforankret flytebru (K8): Større vedlikeholdsarbeid på skråkabelsystemet krever kun nedstrengning av veiskulder. Mindre nedetid for gående og syklende grunnet planlagt vedlikehold i gang/sykkelbane (329 t/år) Spesielle ulemper ved sideforankret flytebru (K8): Utskifting av brubelegning krever stengning av én kjørebane

24 Vedlikehold og hendelser relatert til forankring har relativt stort bidrag til ikkeplanlagt nedetid, og er i tillegg heftet med usikkerhet. Det bør også her understrekes at analysen kun gir et grovt overslag av den totale oppetida, og at estimerte verdiene kun bør leses som en indikasjon på positive/negative bidrag og størrelsesordenen av bidraget. Dersom tilstrekkelig informasjon foreligger vil en oppdatert analyse inkludere en Monte Carlo-simulering for utforske usikkerheter og sensitiviteter i resultatene. Sentrale usikkerhetsmomenter er behov og metoder for utskifting av ankerliner, relevans av isingsproblematikk i Bjørnafjorden og kriterier og frekvens for nedstengning grunnet akselerasjoner fra vind og bølger.

25 Sammenligning Tabell 5 sammenstiller estimert planlagt og ikke-planlagt nedetid for de alternative brukonseptene for kryssing av Bjørnafjorden. Tabellen viser at det er forholdsvis små forskjeller mellom konseptene når det gjelder forventet timer med full nedstengning. Forskjellene er ikke signifikante nok til å tillegges avgjørende betydning, sett i lys at samtlige analyser er midlertidige og kun gir et grovt estimat av forventet nedetid. Resultatene gir imidlertid verdifullt oversikt over vesentlige bidrag for de ulike konseptene og den relative størrelsesorden på disse. Tabell 5 Planlagt og ikke-planlagt nedetid for brukonsepter for kryssing av Bjørnafjorden Planlagt nedetid grunnet K1 K2 K3 K4 K7 K8 inspeksjon, drift og vedlikehold Full nedetid 0t (0%) 0t (0%) 0t (0%) 0t (0%) 0t (0%) 0t (0%) Stengning av én kjørebane 14, 2t (0,62%) 14, 2t (0,62%) - - 7,1 t (0,08%) 14, 2t (0,62%) Stengning av ett felt 25,2t (0,29%) 25,2t (0,29%) , 0t (0,34%) 6,4 t (0,07%) Ikke-planlagt nedetid grunnet hendelser og værrelaterte forhold Vær-relaterte forhold 18, 35t (0,21%) 18, 35t (0,21%) Hendelser 0.4t 0.4t (0,0004 (0,0004 %) %) 0t (0%) 0t (0%) 16,8t (0,19%) 16,8t (0,19%) 20,19 20,19 12,3t 14,5t timer timer (0,14%) (0,17%) (0,23%) (0,23%) Total oppetid (hel og delvis åpning) 99,79% 99,79% 99,77% 99,77% 99,70% 99,68% Planlagt nedetid Planlagt full nedetid grunnet inspeksjon, drift og preventivt vedlikehold er for samtlige konsepter satt til 0 timer per år. Dette betinger a tilstrekkelig hensyn blir tatt til drift og vedlikehold i senere faser, fra detaljert design til konstruksjon og drift. Selv om det kan diskuteres om dette er realistisk over 100 års levetid, er det et ambisiøst mål som fordrer et proaktivt fokus på pålitelighet, tilgjengelighet, vedlikeholdsvennlighet, og sikkerhet (RAMS) i prosjektet. Selv om konseptene ikke kan skilles på full, planlagt nedetid, er det til dels vesentlige forskjeller ved behov for delvis stengning i form av kjørebane/felt. Her skiller endeforankret flytebru (K7) seg positivt ut med hensyn til stengning av én kjørebane, men kommer vesentlig dårligere ut enn sideforankret flytebru (K8), og noe dårligere enn multispenn hengebru (K1 og K2), med hensyn til stengning av ett felt. Stengning av kjørebane vurderes imidlertid som mer kritisk fra et effektivitets- og trafikksikkerhetsmessig perspektiv, da det fordrer reduserte hastigheter ved toveistrafikk i én bane. Beklageligvis avventes resultater for delvis, planlagt stengning av rørbru, men den høye frekvensen av tunnel-spesifikke

26 aktiviteter som rensing/rengjøring og inspeksjon av elektro indikerer at begge rørbrukonseptene (K3 og K4) vil ha høyest delvis nedetid både for kjørebane og felt. Disse konseptene forventes imidlertid å komme fordelaktig ut med tanke på planlagt nedstengning for gående og syklister. En grov, tentativ rangering av konseptene med tanke på planlagt nedetid er: 1. Endeforankret flytebru (K7) 2. Sideforankret flytebru (K8) 3. Multispenn hengebru (K1 og K2) 4. Strekkstagforankret rørbru (K4) 5. Pongtongforankret rørbru (K3) Ikke-planlagt nedetid Tabell 5 indikerer at multispenn hengebru (K1 og K2) kommer best ut når det gjelder ikkeplanlagt (full) nedetid, foran rørbru (K3 og K4), endeforankret (K7) og sideforankret flytebru (K8). Dette bør imidlertid ikke tillegges særlig vekt da oppetidsanalysen for multispenn hengebru også er den minst komplette, og bare dekker noen få, vesentlige bidrag basert på erfaringstall fra få sammenlignbare konstruksjoner. Inntil oppdaterte resultater foreligger i Juni 2016 vurderes derfor rørbrukonseptene som mest fordelaktige med tanke på ikkeplanlagt nedetid. Dette skyldes at rørbru fullstendig unnslipper vær-problematikken relatert til vind og ising, hvilket utgjør det desidert største bidraget for de øvrige konseptene. Her har flytebrukonseptene en liten fordel fremfor multispenn hengebru med tanke på at vind og atmosfærisk ising øker med høyde over vannet, men kommer på den annen side dårligst ut med tanke på uønskede hendelser (skipsstøt). Det må imidlertid understrekes at oppetidsanalysen relatert til uønskede hendelser er mindre komplette for multispenn hengebru enn for de øvrige konseptene. Selv om rørbru har en klar fordel med tanke på ikke-planlagt nedetid, er det langt fra et problemfritt konsept. To særegne utfordringer er sårbarheten for systemfeil av tekniske systemer og potensialet for katastrofale konsekvenser ved brann- eller eksplosjonshendelser. Dette er utfordringer som spesielt krever hensyn til systempålitelighet, tilgjengelighet, vedlikeholdbarhet og sikkerhet (RAMS). Det positive er at imidlertid muligheten for å kontrollere slike hendelser er desto større ved proaktiv bruk av RAMS-systematikk i et livssyklusperspektiv. Her ser vi ser et stort, nærmest uutnyttet potensiale i forhold til eksisterende erfaringstall og praksis i etaten. Til sammenligning er bidrag fra vær-relaterte forhold langt vanskeligere å kontrollere, og aktuelle tiltak som vindskjerming og fartsreduksjoner med differensiering mellom kjøretøy kan få negative konsekvenser for konstruksjonens stabilitet og regularitet. En grov, tentativ rangering av konseptene med tanke på ikke-planlagt nedetid er: 1. Strekkstagforankret rørbru (K4) 2. Pongtongforankret rørbru (K3) 3. Multispenn hengebru (K1 og K2) 4. Endeforankret flytebru (K7)

27 5. Sideforankret flytebru (K8) Konklusjon Samtlige brukonsepter tilfredsstiller det tentative oppetidskravet på 99,50% og gir i så måte en akseptabel oppetid. De alternative brukonseptene rangeres imidlertid ulikt avhengig om planlagt eller ikke-planlagt nedetid tillegges mest vekt. Det er bemerkelsesverdig at rørbru i så måte skiller seg mest ut i både negativ og positiv forstand. Den relative vektingen mellom planlagt eller ikke-planlagt nedetid er et verdispørsmål som må ses i lys av andre viktige mål for kryssingen. På bakgrunn av foreliggende analyser synes det imidlertid riktig å tillegge ikke-planlagt nedetid minst vekt grunnet mangelfullt grunnlag for samtlige konsepter, ikke minst fordi alle har en uttalt ambisjon om 0% bidrag i lys av det tentative oppetidskriteriet. Det kan imidlertid vise seg at planlagt, delvis nedetid grunnet inspeksjon, drift og preventivt vedlikehold står for de mest signifikante forskjeller mellom konseptene og dermed bør blir utslagsgivende. Et mer grunnleggende argument for å tillegge ikke-planlagt nedetid mest vekt er at mulighetene for kontroll og nedetidsreduserende tiltak er mindre, slik at man bør velge konseptet med mest «iboende» godhet eller potensiale i forhold til oppetid. Bidrag fra værrelaterte forhold er i så måte vanskeligst å kontrollere, i hvert fall uten å gå på bekostning av andre mål som sikkerhet, kostnad, og effektivitet. En samlet vurdering viser at rørbrukonseptene (K3 og K4) har størst potensiale til å oppnå høy oppetid, hovedsakelig fordi de unnslipper problematikken relatert til vind og ising. Dette forutsetter imidlertid et proaktivt og systematisk fokus på pålitelighet, tilgjengelighet, vedlikeholdsvennlighet og sikkerhet (RAMS) i videre design og drift, særlig med tanke på pålitelighet av tekniske systemer. Dette er også viktig for multispenn hengebru (K1 og K2) og flytebru (K7 og K8), som kommer forholdsvis likt ut om vær- og hendelsesproblematikk ses under ett. Analyse- og dokumentasjonsarbeid gjenstår for samtlige konsepter, og multispenn hengebru især. Samtlige analyser er basert på mer eller mindre utilstrekkelige erfaringstall og miljødata, og en utfordring er å gjøre oppetidsanalysene mest mulig spesifikke for den unike konstruksjon og de spesifikke forhold i Bjørnafjorden. Rangeringen må derfor revurderes når oppdaterte resultater foreligger i Juli 2016, så vel som i senere faser. Med dette følger et økende presisjonskrav til både resultater og de forutsetninger som legges til grunn, deriblant prosedyrer for nedstengning og krav til full og delvis oppetid, trafikksikkerhet og pålitelighet av tekniske systemer. Vurderingen av hva som er akseptabel oppetid bør til slutt ses i et ALARP-perspektiv, der tiltak for å øke oppetida bør avveies i lys av andre grunnleggende mål som sikkerhet, kostnad og effektivitet- og vice versa. Til slutt må det understrekes at oppetidsanalysene bygger på- og fordrer- valg og antagelser som er gjort for de respektive konseptene med hensyn til design, inspeksjon, vedlikehold og drift. Foruten å inngå som sammenligningsgrunnlag for valg av konsept for kryssing av Bjørnafjorden, har analysene derfor verdi i å gjøre oppetid til premiss for konseptutvikling i tidligfase, ved å synliggjøre konsekvenser og avveininger ved de valgene som tas.

28 Vedlegg Oppetidsanalyse multispenn hengebru Oppetidsanalyse rørbru Oppetidsanalyse flytebru Oppdaterte resultater oppetidsanalyse flytebru

29 MEMO TITEL Bjørnafjorden: Multi-Span Suspension Bridge on Floating Foundations Estimations on operation time DATO 4. April 2016 TIL Statens Vegvesen ADRESSE COWI A/S Parallelvej Kongens Lyngby TLF FAX WWW cowi.dk SIDE 1/11 KOPI FRA PROJEKTNR MGNN A Introduction This note provides a preliminary estimate of the expected yearly downtime for the TLP suspension bridge solution for the crossing of Bjørnafjorden. At this early stage in the process, quantitative estimates of downtime can only be given for a few of the contributing events. This includes the expected downtime from high wind speeds, which accounted for almost 50% of the total down time in the analysis of the floating bridge (Cowi, Aas-Jakobsen, Johs. Holt as, February 2016). Several of the events that might affect the availability cannot be estimated at this point in the project. However, where appropriate, analysis or statistics from the floating cable stay bridge or other existing bridges is used. In the final availability analysis to be finished June 2016, independent and separate analysis and calculations will be presented for all relevant aspects affecting the availability. The considered contributions is divided into three categories: Downtime due to weather conditions. Downtime due to foreseen O&M Downtime due to non-foreseen O&M and accidental events These might affect the availability of the bridge and the following sections will briefly consider their contribution. 2 Downtime due to weather condition This section covers the expected downtime from ice on cables or pylons, high wind speeds and accelerations in the deck arising from wind and wave impact. Addition- C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

30 SIDE 2/11 al situations related to weather conditions might arise later in the process and will be included in the final report. 2.1 Wind speed When the wind speed reaches a certain level, passing the bridge can be unsafe. Under such extreme conditions the bridge is closed. For the floating bridge, this was, by far the largest contribution to the overall downtime, contributing with almost 50% of the total downtime. On the Great Belt Bridge, a maximum wind speed of 25 m/s at the top of the bridge deck is accepted before the bridge is closed for all traffic. This has resulted in 129 hours of downtime in the period from 1999 to This criterion of 25 m/s has been adapted when estimating the downtime for the floating bridge solution. It is assumed that the TLP suspension bridge has to close for all traffic at a 10 min average crosswind of 25 m/s. A probabilistic analysis of wind data provided by the Norwegian Metrological Institute at a nearby location is performed to estimate the number of yearly hours that a certain wind speed will be exceeded. Wind in 60 sectors perpendicular to the bridge axis is considered to be most critical for traffic on the bridge. The bridge is assumed to run north-south. The calculations only include wind from the eastern sector ( ) and the western sector ( ). Assuming that the bridge has to close for all traffic at wind speeds exceeding 25 m/s, calculations show that the bridge can be expected to be closed for an average of 15.6 hours yearly due to high winds. 2.2 Accelerations from wind and wave load Accelerations arising from wind and waves has not been calculated at this early stage in the project. Furthermore, a comfort and safety criteria for acceptable accelerations has not been established. 2.3 Ice on cables and towers Ice on cables or towers can be dangerous for the users as it might fall down and cause an accident. The Great Belt Bridge has been closed in total 44 hours from 1999 to 2015 due to ice falling from cables or towers, see Appendix 7. On average this corresponds to 2.75 hours per year. The Great Belt suspension bridge is 2.7 km long, whereas the Bjørnafjorden TLP suspension bridge will be approx. 5 km. However, this does not necessarily mean that the occurrence of falling snow/ice will be more frequent, since the scenario is likely to affect the entire bridge irrespective of length. The height of the towers might influence the probability of atmospheric icing, which could lead to falling ice. The towers at the Great Belt Bridge are 254 m high whereas the towers in the cur- C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

31 SIDE 3/11 rent design of Bjørnafjorden TLP suspension bridge are 200 m high. Thus, Bjørnafjorden TLP should if all other conditions were the same be less prone to atmospheric icing. Another relevant factor is naturally the difference in climate between Great Belt and Bjørnafjorden, which could give increased closure time for Bjørnafjorden TLP. Comparing the two bridges as well as the environmental conditions there is, at this stage, no indication that the probability of closure due to falling ice or snow should be significantly different from the values obtained for the Great Belt Bridge. Further, investigations of snowfall and climate could reduce the uncertainty related to this estimate. 3 Foreseen O&M The following provides a preliminary assessment of the impact of Operation and Maintenance (O&M) on the availability. As the project progresses there might be changes to the assumptions stated below. 3.1 O&M under water All O&M under water will be done from sea level by boats and remote operated vehicles (ROVs), such that an easy direct access to the elements for inspection is made. This is the same over the bridge s entire length. Elements close to shore as well as the foundations on the sea bed and the floating structures mid-way on the bridge will be inspected and repaired from sea. By the use of an external platform for inspection there is no need for any dedicated area on the bridge/road that will constrain the traffic. Inspection of the tether system and anchors on the sea bed will be done by ROVs and inspection of the splash zone on the floater and the fixed foundation will be done by a small boat (dinghy). Any repairs that are located in this area will also be made from the seaside, from a boat or a barge. At this point it is not certain whether it will be possible to design tethers with a design life of 100 years. If the tethers have to be changed one by one during the bridge's lifetime this operation will be made from the sea from a construction vessel or barge with the help of ROV s. However, during the replacement, the bridge is more weather sensitive due to one of the tethers being replaced. Currently, comfort and safety criteria for acceptable levels of movements or accelerations due to wind or waves have not yet been established. However, during a tether replacement operation, the bridge will be less stable and likely more sensitive to wind and waves. Nevertheless, the changing of tether operation is a carefully planned marine operation that will be done in the calmest period of the year during summer, such that the bridge availability may not be affected. For O&M of the internal spaces of the floater where there is water ballast, a passive corrosion system must be maintained. The cathodes need to be replaced and C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

32 SIDE 4/11 transport is required of these elements to their installed location. For this, one lane on the bridge needs to be closed. 3.2 O&M above water It should be possible to design the bridge such that all foreseen O&M can be carried out without a complete closure of the bridge. In order to succeed with this, one must ensure that the O&M work is considered in design, construction and operation. One example is the expansion joints, which should be modular such that they can be replaced on one side at a time. Downtime due to inspections is expected to be on the same level as for the floating bridge. Inspection of cables will be carried out walking or with rope access. Downtime due to maintenance is also assumed to be similar to that of the floating bridge. Naturally, the major maintenance of the stay cable system for the floating bridge is replaced by minor and major maintenance of cables and hangers for Bjørnafjorden TLP. It is expected that there will be 3 inspections during the 100 years, where one lane is closed for 5 week and the shoulder for 77 weeks. 4 Non-foreseen O&M and accidental events 4.1 O&M resulting from inspections At this stage the downtime from unforeseen O&M resulting from inspection has not been estimated. This will require further analysis. 4.2 Fire In order to assess the down time due to fire a quantitative analysis should be carried out. This requires an estimate of the expected yearly traffic of goods and dangerous good. Furthermore, the probability of explosion/fire should be estimated e.g. based on statistics regarding fire on roads. Finally, the probability for a fire to start at a sensitive location at the bridge should be estimated. The probability of fire has been calculated for the Lillebælt Bridge in Denmark in connection with a risk analysis carried out after a fire on the bridge in These calculations result in a probability of fire between 1E-4 and 1E-3 varying for hangers, cables, and the type of transported goods (liquid, solid). The fire at Lillebælt Bridge resulted in a downtime of the entire bridge of approx. 5 hours. With this small level of downtime and the estimated frequency one obtain a yearly downtime that is extremely small. It will assumable not have any impact on the overall availability of the bridge and it is not analysed further in this preliminary analysis. 4.3 Ship collision From the analysis carried out by SSPA (SSPA, June 2015) the total collision frequency is reported as 3.1E-4 per year. This is significantly lower than the collision frequency found for the other alternatives. The low collision frequency is likely a C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

33 SIDE 5/11 result of a large navigational span both horizontally and vertically. Furthermore, the bridge remains at a relatively high elevation throughout the entire span reducing the risk of girder collisions from e.g. deck house. With an acceptance criteria of 1E-4 for ship collision, it can be assumed that the collision frequency of ships that exceed the bridge capacity never will exceed this frequency. It might even be lower, if ship collision is not governing in the design. From the statistics regarding the Great Belt Bridge, it is observed that the bridge has been closed 7 times with a total downtime of 6 hours 41 minutes from 1999 to On average this is 0.4 hour per year. Of these 7 incidents only one was a collision. In 2005 the Great Belt East Bridge was hit by the ship Karen Danielsen. The bridge was inspected for permanent damage and was closed for 5 hours and 35 minutes. The remaining 6 closures are due to ships on collision course. Procedures at the VTS centre at Great Belt prescribes the bridge to be closed in situations where a ship of critical size is on direct collision course with bridge elements and 4 minutes away. Closure for potential collisions will naturally lead to a higher downtime for the bridge, but simultaneously increase the safety for the users. This should be considered when deciding upon a VTS solution for Bjørnafjorden and the corresponding procedures. As a very rough estimate of downtime due to ship collision, the downtime from the Great Belt is used. This should be a conservative assumption as the ship traffic in Bjørnafjorden is more than 10 times smaller than the traffic through Great Belt ( yearly passages). In Great Belt vessels have to make a turn relatively close to the bridge, both in the north and south going directions. In Bjørnafjorden east going vessels will have to make an almost 90 degree turn. This will not be dangerous for the bridge in case they forget to turn as their course is not towards the bridge before the turn. For west going traffic the distance from the turn to the bridge is much larger than for the Great Belt Bridge. With a yearly downtime corresponding to 0.004% these preliminary results indicate that ship collisions are not likely to have significant impact on the overall availability. More detailed calculations including the collision frequency for the TLP suspension bridge will be carried out and included in the final report. 5 Preliminary estimate A preliminary estimate of the downtime has been made based on the available information for Bjørnafjorden as well as statistics from the Great Belt Bridge. The downtime is summarized in the table below, which also shows the final availability based on these estimates. As this is a very rough preliminary estimate that only include quantitative estimates some of the relevant contributions the resulting availability is connected with a large uncertainty. C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

34 SIDE 6/11 Reason for downtime Estimated yearly downtime [hours] Wind speed exceed 25 m/s 15.6 Falling ice 2.75 Ship collision 0.4 Total downtime Availability 99.79% C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

35 SIDE 7/11 6 References Cowi, Aas-Jakobsen, Johs. Holt as. (February 2016). Utredning av flytebru over Bjørnafjorden - Downtime due to non-planned maintenance and accidental events. SSPA. (June 2015). Fergefri E 39 - Ship collision risk analysis for the Bjørnafjorden crossing. Vegvesen, S. (2015). Håndbok N400 Bruprosjektering. Statens Vegevesen. 7 Appendix A Statistics from Great belt The table below shows the duration of closures of the Great Belt Bridge due to wind speed, ship collision alarm, traffic accident and falling snow or ice. C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

36 C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx SIDE 8/11

37 SIDE 9/11 8 Appendix B Calculations on wind speed C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx

38 C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx SIDE 10/11

39 C:\Users\mgnn\Documents\Bjornafjord\RAMS_technologyQualification\Oppetidsestimat_ docx SIDE 11/11

40 REPORT BJØRNAFJORD SUBMERGED FLOATING TUBE BRIDGE AVAILABILITY ANALYSIS

41 2 REPORT Project name: BJØRNAFJORD SUBMERGED FLOATING TUBE BRIDGE Document name: AVAILABILITY ANALYSIS Project number : Document number : OO-R-305 Date : Revision : 02 Number of pages : 22 Prepared by : Anette Fjeld Controlled by : Stein Atle Haugerud Approved by : Stein Atle Haugerud Revision Date Reason for Issue Prep. by Contr. by Appr. by Issued for client review AFJ - SAH Issued for client review AFJ SAH SAH AVAILABILITY ANALYSIS / OO-R-305, rev. 02

42 Table of Content 3 1 SUMMARY AND CONCLUSIONS INTRODUCTION SFTB SYSTEM DESCRIPTION System overview tether alternative System overview pontoon alternative ROAD AND TRAFFIC SYSTEM Road system Normal traffic situation Restricted traffic situations AVAILABILITY MODEL Definition of availability A Planned closure B Unforeseen closure Availability results TRANSIT REFERENCES APPENDIX A: Transcripts from Vegloggen. Eikåstunnelen, Knappetunnelen and Strindheimstunnelen AVAILABILITY ANALYSIS / OO-R-305, rev. 02

43 4 1 SUMMARY AND CONCLUSIONS The road system for the SFTB crossing from south to north consist of a 2,5 km rock tunnel followed by 5,5 km SFTB followed by 8 km rock tunnel. This availability analysis covers downtime related directly to the SFTB. Downtime in the SFTB caused by events in the rock tunnel system is assumed covered in a separate availability analysis. The normal traffic situation is one-directional traffic in two lanes in each tube. There are three degrees of restricted traffic situations and one with total closing of the crossing 1. Closing of one lane in one tube of the tunnel. Traffic, possibly with speed reduction, in the other lane. Typical for minor/moderate incidents, inspections 2. Closing of one tube of the tunnel. Two way traffic, possibly with speed reduction, in the other tube. Typical for planned maintenance. 3. Closing of one tube in entire or parts of the tunnel. Normal one way traffic in the other tube. Typical for major traffic incidents 4. Closing of both tubes in extreme accidental cases like major fire or ship impact. In this analysis the SFTB is define to be available when it is open for traffic in at least one lane in each direction. Planned maintenance is expected to be carried out with the bridge open for at least two-way traffic. The majority of the calculated downtime is related to traffic incidents and closing due to technical systems failure. The available publicly accessible statistics for traffic incidents in Norwegian tunnels is inadequate. We have therefore requested transcripts from Vegloggen, the five Norwegian road traffic centrals systems for recording road traffic-related events, from as similar tunnels as possible. What we see from these numbers is that for two lane, one directional tunnels with modern operating systems, the road traffic centrals are skilled at keeping the road open for traffic in case of incidents. Only incidents where both lanes are blocked will automatically lead to closing of the tunnel. In the 1,5 years Strindheimtunnelen has been open for traffic there has only been one incident of unforeseen closure, 27 minutes in 2015 due to a traffic incident. This equals an availability of 99,99% and shows the potential of modern road tunnels. We believe the SFTB will have excellent availability (>99,9%) as there is no downtime due to weather conditions. This can be further documented with a more extensive data gathering from Vegloggen. The present availability prediction is 99,8%. AVAILABILITY ANALYSIS / OO-R-305, rev. 02

44 2 INTRODUCTION As a part of the assessment study for a Submerged Floating Tube Bridge (SFTB) for crossing the Bjørnafjord an evaluation of the technological maturity of the SFTB alternative has been carried out. This evaluation includes a systematical mapping of uncertainties and risks, and an analysis of the serviceability of the SFTB. The work is documented in three reports: OO-R OO-R OO-R-305 SFTB - Technology assessment - Uncertainties SFTB - Hazid and FMECA SFTB - Availability AVAILABILITY ANALYSIS / OO-R-305, rev. 02

45 6 3 SFTB SYSTEM DESCRIPTION 3.1 System overview tether alternative The SFTB consists of a number of known elements applied in a new assembly. Rock anchorage Main tubes Horizontal bracing Cross tubes Vertical anchorage Temporary structures Structural concrete Tethers Mooring Electrical systems Anchors Splicing cofferdam Ventilation Bulkheads Ballast system Towers 3.2 System overview pontoon alternative The SFTB consists of a number of known elements applied in a new assembly. Rock anchorage Main tubes Landfall elements Horizontal bracing Cross tubes Vertical anchorage Temporary structures Structural concrete Truss towers Mooring Electrical systems Pontoons Splicing cofferdam Ventilation Bulkheads Ballast system Towers AVAILABILITY ANALYSIS / OO-R-305, rev. 02

46 4 ROAD AND TRAFFIC SYSTEM Road system The total tunnel system for the SFTB consist of the SFTB across Bjørnafjorden with rock tunnels in both ends. Figure 4-1 and Table 4-1 show the planned road geometry > Figure 4-1 Plan and profile of the SFTB and connecting rock tunnels (utvides med fjelltunneler) > Table 4-1 Profile overview Profile Length Inclination Rock tunnel south m Max 5 % SFTB m 0 % Rock tunnel north m Max 5 % This availability analysis covers downtime related directly to the SFTB. Downtime in the SFTB caused by events in the rock tunnel system is assumed covered in a separate availability analysis. 4.2 Normal traffic situation The normal traffic situation is one-directional traffic in two lanes in each tube. 4.3 Restricted traffic situations There are three degrees of restricted traffic situations and one with total closing of the crossing AVAILABILITY ANALYSIS / OO-R-305, rev. 02

47 8 1. Closing of one lane in one tube of the tunnel. Traffic, possibly with speed reduction, in the other lane. Typical for minor/moderate incidents, inspections 2. Closing of one tube of the tunnel. Two way traffic, possibly with speed reduction, in the other tube. Typical for planned maintenance. 3. Closing of one tube in entire or parts of the tunnel. Normal one way traffic in the other tube. Typical for major traffic incidents 4. Closing of both tubes in extreme accidental cases like major fire or ship impact. > Figure 4-2 System with traffic cross-connection and 250 m escape route crossconnections (Norconsult, Rogfast) AVAILABILITY ANALYSIS / OO-R-305, rev. 02

48 5 AVAILABILITY MODEL Definition of availability In this analysis the SFTB is define to be available when it is open for traffic in at least one lane in each direction. Downtime then happens when both tubes are closed, or when one tube is closed and there is normal one way traffic in the other tube. 5.2 A, Planned closure A1 Continuous maintenance Continuous planned maintenance is performed with minimum one tube open for two-way traffic. Thereby continuous maintenance does not cause downtime as defined in section 5.1. An overview of the normal tunnel maintenance operations is given in Table 5-1 and Table 5-2 for maintenance with one lane closed and one tube closed, respectively. > Table 5-1 Planned maintenance with one lane in one tube closed Activity Frequency [#/year] Duration [hours] Comment Simple inspection 1 Main inspection 1/5 Electrical inspection 2 Installations inspection 2 Technical cleaning 5 > Table 5-2 Planned maintenance with one tube closed, two-way traffic in the other tube Activity Frequency [#/year] Duration [hours] Comment Cleansing 1/5 Cleaning 2 Partial cleaning A2 Rehabilitation Structural steel will be protected by a combination of coating and cathodic protection system. Sacrificial anodes are designed to be able to be replaced with ROV if necessary. This is a relatively simple procedure and is performed with the SFTB in normal operation. Replacement of tethers is not expected due to the cathodic protection system. As the tethers have a low stress variation from cyclic loads and the utilization is low, fatigue is not an issue. Structural concrete is not expected to need rehabilitation during the 100 years design life. Performance studies on the offshore concrete platforms in the North sea show excellent AVAILABILITY ANALYSIS / OO-R-305, rev. 02

49 10 durability after almost 40 years in service. For comparison, the concrete elements for Femern immersed tunnel currently under construction have a design life of 120 years. Extensive testing of different concrete mixes is carried out to ensure that the requirements for the contractors will ensure the intended durability. Results so far confirms that the concrete behavior is as expected. > Figure 5-1 Concrete testing for Femern immersed tunnel ( The SFTB does not rely on any active systems in operation other than normal technical tunnel systems. Technical installations in the running bores can be rehabilitated/replaced successively for one tube at a time. At the present, there is not planned any rehabilitation within the 100 years design life that causes downtime. 5.3 B, Unforeseen closure B1 Traffic incidents The report Traffic accident in road tunnels 2 [1] analyses accidents in Norwegian tunnels. It is based on data from 797 tunnels with an accumulated length of 785,5 km. Accidents have been reported in 250 of the tunnels, and 299 if the 50 m outside the tunnel entrance is included. The study show that: - Entrance zones have the highest accident rate - The accident rate decreases with increasing tunnel length, tunnel width and AADT - The accident rate decreases with increasing horizontal radius AVAILABILITY ANALYSIS / OO-R-305, rev. 02

50 - The accident rate increases with increasing inclination - The accident rate is somewhat higher in the oldest tunnels 11 Thereby, we can assume that the SFTB will have a lower accident rate than the average tunnel in the study. To demonstrate a lower accident rate, a more detailed analysis can be performed, for instance with the risk analysis tool TRANSIT as described in section 5.4. When it comes to motion characteristics the SFTB show excellent behavior, so driving in the SFTB is comparable with any other tunnel, and probably better than any long span bridge. > Table 5-3 Computed global extremal acceleration (100 year return period storm condition) for the final concept variations, peak values Direction Requirement Tethers Pontoons Horizontal 0.3 m/s m/s m/s 2 Vertical 0.5 m/s m/s m/s 2 For a 1 year return period storm condition the accelerations is coarsely estimated to 50% of the 100 year values, and for normal operating conditions the accelerations are within 10%, i.e m/s 2. As comparison, vertical accelerations for Storebælt suspension bridge have been measured to around 0.1 m/s 2 at wind speed 8 m/s (peak values without lock-in) as described in the article Simultaneous pressures and accelerations measured full-scale on the Great Belt East suspension bridge [3]. Displacements is also a factor when discussing driving experience and traffic safety, and displacements should be limited by visible amplitudes. Table 5-4 show the computed displacements for the SFTB, which are very low compared to the span length. > Table 5-4 Computed global extremal dynamic and quasi-static displacement (100 year return period storm condition) for the final concept variations, peak values Direction Tether dynamic Tether static Pontoon dynamic Pontoon static Horizontal 0.8 m 0.3 m 0.8 m 1 m Vertical 0.03** m 0.56* m 0.9 m 2.1 m * Recorded in the mid-span, between the vertical supports ** The worst of every recorded at tether support Accidents with personnel injury: From the traffic accident report [1] we find the rate of accidents with personal injury. Here, statistics are given for countryside tunnels with one-directional traffic. As the SFTB goes into rock tunnels in both end, we use the accident rate for zone 4 (Figure 5-2) which is given to 0,03 accidents per million vehicle kilometer. > Figure 5-2 Zone definition [1] AVAILABILITY ANALYSIS / OO-R-305, rev. 02

51 12 > Figure 5-3 Accident rate for the different zones for countryside tunnels with onedirectional traffic [1] Minor traffic incidents and vehicle stop The available publicly accessible statistics for traffic incidents in Norwegian tunnels is inadequate. We have therefore requested transcripts from Vegloggen, the five Norwegian road traffic centrals systems for recording road traffic-related events, from as similar tunnels as possible, i.e: - Built after year Max. 5% inclination - One-directional traffic, tunnel profile T9.5 - AADT We have received reports from 5 comparable tunnels in Norway. > Table 5-5 Tunnel closing time from traffic incidents Name Year Length [km] AADT Mill veh.km pr year Incidents [#/year] Incidents [#/mill. veh.km] Average closing [hours] Eikåstunnelen , Knappetunnelen 2010* 2,6* * 1,0 0,077 0,4 Strindheimstunnelen , ,6 0,026 0,5 Skuitunnelen , Espatunnelen , Average 0,034 0,45 * Construction stage 2 opened Nov 2015 making the total length 5,4 km, but this is conservatively neglected in this analysis What we see from these numbers is that for two lane, one directional tunnels with modern operating systems, the road traffic centrals are skilled at keeping the road open for traffic in case of incidents. Only incidents where both lanes are blocked will automatically lead to closing of the tunnel. AVAILABILITY ANALYSIS / OO-R-305, rev. 02

52 Fire in vehicle: In 2012 the institute of transport economics issued a report Vehicle fires in Norwegian road tunnels [4]. The findings of the study of fires is summarized as follows: 13 Norway is one of the countries that constructs the most road tunnels, and there are well over 1,000 in the country. Road tunnels are usually at least as safe as, or safer than similar roads in the open air, but they have a disaster potential related to vehicle fires. The report maps and describes the characteristics of fires and smoke without fire in Norwegian road tunnels during the last 4 years. The average number of fires in Norwegian road tunnels is per year per 1,000 tunnels. The average number of smoke without fire is 12.5 per year per 1,000 tunnels. The fires and the instances of smoke without fire do usually not involve harm to people or the tunnels. Of the 135 fires and instances of smoke without fire, we know that 8 involved minor injury to people and that 8 involved serious personal injury or death. 40 of the 135 fires involved damage to vehicles and 20 involved damage to tunnels. Technical problems are the most frequent cause of fires and instances of smoke without fire in heavy vehicles, while single vehicle and collisions are the most frequent cause of fires in vehicles weighing less than 3.5 tonnes. Undersea tunnels are substantially overrepresented in the statistics of fires in Norwegian road tunnels. There are 31 undersea road tunnels in Norway. These have a high gradient, defined as over 5 %. In addition, there are 10 tunnels that are not underwater, but still have a high gradient. These 41 road tunnels, which together constitute 4% of road tunnels in Norway, had 44% of the fires and the instances of smoke without fire in the period Heavy vehicles were overrepresented in these fires, and technical problems were the most frequent cause. From the NPRA website ( we find: Average length of tunnel: 0,8 km Average AADT: , ,012 fires per year when excluding steep tunnels Approx. 0, ,46 mill veh.km per year for all tunnels For the availability analysis we thereby use 0,0085 fires per veh.km per year In the case for smoke without fire we conservatively assume that all incidents leads to tunnel closing and use 0,005 smoke without fire incidents per veh.km per year From the vehicle fire report [4] we also find the average closing time, which is 2 hours and 0,6 hours for fire and smoke without fire respectively B2 Repair/external cause We have identified following events that can cause downtime in the SFTB due to necessary inspection time/repair works: - Ship impact - Submarine impact - Tunnel fire Ship impact The ship impact accidental load case is only relevant for the pontoon supported SFTB. A major ship impact against one of the pontoons will most likely cause severe deformation to the pontoon shaft and some deformation to the pontoon itself. It is therefore a chance that AVAILABILITY ANALYSIS / OO-R-305, rev. 02

53 14 the pontoon will lose its ability to support the SFTB after such an event. For that reason, the SFTB is designed to withstand loss of one pontoon in ALS. The pontoon is designed with watertight compartments to prevent it from sinking after it is separated from the rest of the bridge. The deformation of the pontoon and its shaft will dissipate energy from the impact, but as a conservative assumption the bridge is designed to take the full blow of the design accidental impact. In other words, the pontoon and its shaft is assumed infinitely stiff. By following this design philosophy we are actually designing the SFTB for two extremes that cannot occur at the same time. With this approach, we achieve a very robust design that is able to accommodate future changes in the design conditions. > Table 5-6 Design impact energies Eimp for head-on collision without restrictions on ship traffic Return period Impact energy 100 years years 0.3 MJ years 339 MJ years 725 MJ A return period of 50 years corresponded to the characteristic value for variable loads. The SFTB must satisfy SLS-conditions at this impact energy. If we look at Table 5-6 we see that the impact energy for return periods lower than 1000 years is negligible. Figure 5-4 plot the impact energy against the return period. 400 Impact energy [MJ] Reoccurrence period [years] > Figure 5-4 Impact energy plotted against return period (oppdateres, SSPA) Based on the information above, we suggest the following inspection philosophy with the corresponding downtime. AVAILABILITY ANALYSIS / OO-R-305, rev. 02

54 > Table 5-7 Ship impact inspection philosophy Impact magnitude Action Probability per year Downtime [hrs] 15 < 50 MJ Inspection with normal traffic - - Betw. 50 and 250 MJ Betw. 250 and 350 MJ ROV inspection with tube bridge closed Thorough ROV inspection with tube bridge closed 4,5x x Above 350 MJ If loss of pontoon, perform reballasting to allow for operation with reduced traffic in the period while the pontoon is being replaced 1x (two weeks) Submarine impact Waiting for probability and energy from SSPA. Negligible downtime, SFTB can withstand a full head-on impact from a ULA-class submarine. Inspection/repair due to tunnel fire In case of a heavy tunnel fire, it is necessary to perform a special inspection to evaluate the condition of the fire protection. If exposed to high temperatures, it can be necessary to replace the fire protection in the area of the fire in order to reinstate the same level of safety for a subsequent fire. > Table 5-8 Ship impact inspection philosophy Share of fires with tunnel closing All Action Perform visual inspection in the area of the fire before reopening Downtime [hrs] Included in B1 1% Special inspection of the fire protection 48 0,1% Replacement of fire protection in the area (based on wet mix spray-applied) 336 (two weeks) B3 Structural failure Design of the SFTB is carried out according to relevant Eurocodes. With load factorization and combination, and material design resistance, we expect an annual failure probability equal or less than 1x10-6. This is the safety regime that forms the basis of structural design, that we accept a certain level of risk. The ultimate consequence if the SFTB is exposed to greater loads than what it can withstand is collapse of the structure. The corresponding downtime to that event is the time to rebuild the SFTB. AVAILABILITY ANALYSIS / OO-R-305, rev. 02

55 16 RESPONSE ANALYSIS 3Dfloat F k Characteristic actions INERTIA my OUTPUT: UN-FACTORED RESPONSE S k FACTORIZATION AND LOAD COMBINATION NS-EN 1990 N400 S OUTPUT: DESIGN FORCES d 0 f Sk CAPACITY CONTROL NS-EN DESIGN ACTION EFFECT S d < DESIGN RESISTANCE R k m TARGET: ANNUAL FAILURE PROBABILITY p 10 6 f > Figure 5-5 Eurocode structural integrity scheme B4 Technical systems failure Based on the transcripts from Vegloggen we also find temporary closure of tunnels due to technical systems failure. > Table 5-9 Tunnel closing time due to technical systems failure Name Year Length [km] ADT Mill veh.km pr year Incidents [#/year] Incidents [#/mill. veh.km] Average closing [hours] Eikåstunnelen , ,32 0,064 0,8 Knappetunnelen 2010* 2,6* * 0,19 0,015 47,9 Strindheimstunnelen , Skuitunnelen , Espatunnelen , Average 0,026 24,4 The permanent ballast system is designed to be inherently safe both because it is not normally connected and because it will draw water from a limited volume reservoir at either end of the SFTB. There is no need for ballasting during normal operation and the active parts (pumps etc.) are stored and preserved near bridge ends ready to be mobilized upon demand. The other systems are normal tunnel systems, and fai AVAILABILITY ANALYSIS / OO-R-305, rev. 02

56 5.4 Availability predictions 17 Input data AADT SFTB length [km] 5,45 Mill. veh.km/year 27,85 Rate #/mill. veh.km Rate #/year Duration h Downtime h/year Downtime % A PLANNED CLOSURE A1 Continuous maintenance A2 Rehabilitation B UNFORESEEN CLOSURE B1 Traffic incidents Accidents with personnel injury* 0,03 0,84 2 1,7 0,0191 % Traffic incidents and vehicle stop with closing 0,034 0,95 0,45 0,5 0,0057 % Fire in vehichle with closing 0,0085 0,24 2 0,5 0,0054 % Smoke without fire 0,005 0,14 0,6 0,1 0,0010 % B2 Repair/external cause 50 MJ < Ship impact < 250MJ 4,50E ,0 0,0000 % 250 MJ < Ship impact < 350MJ 1,00E ,0 0,0001 % Ship impact > 350 MJ 1,00E ,0 0,0004 % Submarine impact 1,00E ,0 0,0000 % Fire with subs. special inspection 0, , ,1 0,0013 % Fire with fire protection replacement 0, , ,1 0,0009 % B3 Structural failure 1,00E ,0 0,0005 % B4 Technical system failure** 0,026 0, ,4 0,1984 % Availability 99,77 % * Is included in the registered traffic incidents and vehicle stop with closing numbers from Vegloggen, but remains in this analysis as the data from representative tunnels is limited at the present stage ** Will probably be reduced with more data. Dominated by one incident in Knappetunnelen AVAILABILITY ANALYSIS / OO-R-305, rev. 02

57 TRANSIT Together with Swiss road authorities, the NPRA has developed a new quantitative risk analysis tool based on Bayesian networks. The model, named TRANSIT, calculates the risk of traffic accidents, people injured or killed and the rate of fire in the tunnel based on a number of geometric and traffic properties, which describes the tunnel. The principal is to divide the tunnel into homogenous segments as illustrated in Figure 5-6, perform calculations for each segment and summarize and add up the segment results to find the total tunnel accident risk. The method is described in the NPRA report no 156 Etatsprogrammet Moderne vegtunneler Utvikling av risikoanalysemodell TRANSIT for vegtunneler [5]. Figure 5-7 and Figure 5-13 is obtained from that report, and suggest that the risk of accident in the SFTB will be significantly lower than for the average tunnel. > Figure 5-6 Example of tunnel segment partition in TRANSIT > Figure 5-7 Relation between the AADT per direction and the AMF depend on the number of lanes AVAILABILITY ANALYSIS / OO-R-305, rev. 02

58 19 Relationship between AMF(light), accident modification factor for light and luminance in the tunnel interior > Figure 5-8 Relationship between AMFlightEnt, accident modification factor for light and luminance > Figure 5-9 Relationship between AMFlightExit, accident modification factor for light and luminance AVAILABILITY ANALYSIS / OO-R-305, rev. 02

59 20 > Figure 5-10 Accident modification factor depending on the curvature (radius) and the speed limit > Figure 5-11 Accident modification factor depending on the longitudinal gradient in the tunnel AVAILABILITY ANALYSIS / OO-R-305, rev. 02

60 21 > Figure 5-12 Modification factor for the fire frequency depending on the longitudinal gradient > Figure 5-13 Accident Modification Factor in dependency of the velocity and the lane width AVAILABILITY ANALYSIS / OO-R-305, rev. 02

61 22 6 REFERENCES [1] Trafikkulykker i Vegtunneler 2 En analyse av trafikkulykker på riksvegnettet for perioden , Statens vegvesen, [2] Etatsprogrammet moderne vegtunneler Vegtunnelers oppetid, Statens vegvesen Rapport nr 143, August 2012 [3] Simultaneous pressures and accelerations measured full-scale on the Great Belt East suspension bridge, J.B. Frandsen, Journal of wind engineering and industrial aerodynamics 89 (2001) [4] Kartlegging av norske kjøretøybranner i norske vegtunneler , Transportøkonomisk institutt, April 2012 [5] Etatsprogrammet moderne vegtunneler Utvikling av risikoanalysemodell TRANSIT for vegtunneler, Statens vegvesen Rapport nr 156, August 2012 AVAILABILITY ANALYSIS / OO-R-305, rev. 02

62 12149-OO-R-305 rev 02 Appendix A Meldingsrapport Periode: : Midlertidig stengt bilberging 2: Midlertidig stengt brann Meldingstyper, nivå 2: 3: Midlertidig stengt tekniske problemer Tidsformat: Faktisk tid: Antall og Tidsbruk - måneder Geografiske kriterier: 1: REGION: Vest * STED: Eikås tunnel * SØK KRITERIER: Ev 39,Ordinær veg 1: REGION: Vest * STED: Eikås tunnel * SØK KRITERIER: Ev 39,Ordinær veg Diagram: Ingen diagram Merk at det resultatet du får i statistikkrapporter vil være avhengig av hvordan du spesifiserer utvalgskriteriene. Les kapittelet i hjelpeteksten til vegloggen som omhandler statistikkmodulen grundig, og vær sikker på at du forstår hvordan de ulike valgene du har påvirker statistikken som genereres. I motsatt fall er det stor sannsynlighet for å mistolke hva statistikken faktisk sier.

63 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) t, 30 min (8.5 timer) t (4 timer) t, 59 min (4 timer) t, 59 min (11 timer) (0 timer) t (7 timer) t, 19 min (5.3 timer) t, 30 min (4.5 timer) t (4 timer)

64 12149-OO-R-305 rev 02 Appendix A Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden t, 14 min (1.2 timer) 18 2 d17 min (48.3 timer)

65 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt bilberging Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer)

66 12149-OO-R-305 rev 02 Appendix A Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden 0 0 (0 timer) 0 0 (0 timer)

67 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt brann Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer)

68 12149-OO-R-305 rev 02 Appendix A Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden 0 0 (0 timer) 0 0 (0 timer)

69 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt tekniske problemer Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) min (0.8 timer) (0 timer) (0 timer)

70 12149-OO-R-305 rev 02 Appendix A Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden min (0 timer) 1 49 min (0.8 timer)

71 12149-OO-R-305 rev 02 Appendix A Meldingsrapport Periode: : Midlertidig stengt bilberging 2: Midlertidig stengt brann Meldingstyper, nivå 2: 3: Midlertidig stengt tekniske problemer Tidsformat: Faktisk tid: Antall og Tidsbruk - måneder Geografiske kriterier: 1: REGION: Vest * STED: Knappetunnelen * SØK KRITERIER: Fv 557,Ordinær veg,hordaland,bergen Diagram: Ingen diagram Merk at det resultatet du får i statistikkrapporter vil være avhengig av hvordan du spesifiserer utvalgskriteriene. Les kapittelet i hjelpeteksten til vegloggen som omhandler statistikkmodulen grundig, og vær sikker på at du forstår hvordan de ulike valgene du har påvirker statistikken som genereres. I motsatt fall er det stor sannsynlighet for å mistolke hva statistikken faktisk sier.

72 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) min (0.8 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) d, 7 t, 26 min (55.4 timer) t (4 timer) t (15 timer) t, 30 min (12.5 timer) t, 30 min (22.5 timer) t, 49 min (1.8 timer) (0 timer) t (15 timer) t, 1 min (23 timer) (0 timer) (0 timer) d, 13 t, 30 min (205.5 timer) d (744 timer) d, 13 t, 47 min (301.8 timer) (0 timer) (0 timer) t, 30 min (22.5 timer) t, 36 min (17.6 timer) d, 22 t, 30 min (94.5 timer) d, 3 t (147 timer) d, 21 t (141 timer) d, 10 t, 45 min (106.8 timer)

73 12149-OO-R-305 rev 02 Appendix A d, 3 t, 11 min (195.2 timer) d, 2 t (242 timer) d, 4 t (172 timer) d, 12 t, 3 min (396.1 timer) d, 11 t, 39 min (203.7 timer) d, 6 t, 56 min (174.9 timer) d, 3 t (51 timer) t (15 timer) d, 4 t, 19 min (52.3 timer) d, 5 t, 9 min (77.2 timer) t, 30 min (4.5 timer) Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden d, 7 t, 47 min (55.8 timer) d, 10 t, 27 min ( timer)

74 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt bilberging Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) min (0.5 timer) (0 timer) (0 timer) (0 timer) (0 timer)

75 min (0.2 timer) (0 timer) (0 timer) (0 timer) min (0.7 timer) min (0.4 timer) (0 timer) (0 timer) (0 timer) min (0.2 timer) (0 timer) OO-R-305 rev 02 Appendix A Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden min (0 timer) 5 1 t, 52 min (1.9 timer)

76 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt brann Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer)

77 (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) OO-R-305 rev 02 Appendix A Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden 0 0 (0 timer) 0 0 (0 timer)

78 Meldingsrapport OO-R-305 rev 02 Appendix A Meldingstype Midlertidig stengt tekniske problemer Periode Nye i perioden Samlet varighet i perioden (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) d, 23 t, 56 min (47.9 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer)

79 (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) (0 timer) OO-R-305 rev 02 Appendix A Gjennomsnittlig nye registrerte i tidsperiodene Gjennomsnittlig tid i tidsperiodene Totalt antall for hele perioden Total varighet for hele perioden min (0.8 timer) 1 1 d, 23 t, 56 min (47.9 timer)

80 12149-OO-R-305 rev 02 Appendix A

81 12149-OO-R-305 rev 02 Appendix A Midlertidig stengt Rv 706 Strindheimtunnelen, i retning mot vest Sør-Trøndelag - Midlertidig stengt Stengt på grunn av tekniske problemer. Gjelder fra: kl. 08:41 Vegmeldingsrapport kl. 23:39 Statens vegvesen kl. 23:39 Side 1 av 1

82 BJØRNAFJORDEN ESTIMATIONS ON OPERATING TIME

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84 BJØRNAFJORDEN PROJECT REPORT 3/17 BJØRNAFJORDEN ESTIMATIONS ON OPERATING TIME ADRESSE COWI AS Grensev. 88 Postboks 6412 Etterstad 0605 Oslo TLF WWW cowi.no OPPDRAGSNR. A DOKUMENTNR. RAP-GEN-004 VERSJON 1.0 UTGIVELSESDATO UTARBEIDET HKJ KONTROLLERT KAA GODKJENT SWI J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

85 BJØRNAFJORDEN PROJECT REPORT 4/17 CONTENT 1 INTRODUCTION 5 2 ESTIMATED DOWNTIME Downtime due to weather conditions Downtime due to foreseen operation and maintenance Downtime due to non-planned maintenance and accidental events 7 3 RESULTS Straight bridge Curved bridge 11 4 CONCLUSION 13 5 REFERENCES 14 6 Appendix A 15 7 Appendix B 16 8 Appendix C 17 J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

86 BJØRNAFJORDEN PROJECT REPORT 5/17 1 INTRODUCTION This report summarizes the findings from the 3 documents NOT-GEN-013 Downtime due to weather conditions, Downtime due to operation & maintenance and NOT-GEN 018 Downtime due to non-planned maintenance and accidental events. The documents are found in Appendix A,B and C respectively. It is estimated a complete closure time of 29,8 hours annually, corresponding to a downtime of 0,34 %, or operating time of 99,66 %. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

87 BJØRNAFJORDEN PROJECT REPORT 6/17 2 ESTIMATED DOWNTIME The downtime due to weather conditions, planned operation & maintenance and non-planned maintenance and accidental events are presented in 3 different documents given respectively as appendix A,B and C in this report. A summary of each document is given in this chapter. 2.1 Downtime due to weather conditions An estimate of the number of annual hours the Bjørnafjorden Bridge may be closed due to unpredicted events, with emphasis on weather conditions is presented in this chapter. A probabilistic analysis of wind data provided by the Norwegian Metrological Institute at a nearby location is performed, to estimate the number of yearly hours that a certain wind speed will be exceeded. Wind in 60 sectors perpendicular to the bridge axis is considered to be the most critical for traffic on the bridge. The bridge is assumed to run north-south. The calculations only include wind from the eastern sector ( ) and the western sector ( ). Assuming that the bridge has to close for all traffic at wind speeds exceeding 25 m/s, calculations show that the bridge can be expected to be closed for an average of 13,6 hours yearly due to high winds. Acceleration of the bridge girder due to wind and wave loads is presented, and compared to maximum allowable vertical and horizontal acceleration defined in the Design basis /1/. This is done in appendix A. Closing of the bridge due to high accelerations in the bridge girder is not considered likely to occur on a yearly basis, and is neglected in the calculation of operating time of the bridge. Falling ice and snow from hangers and cables have caused suspension bridges and cable stayed bridges to close down temporarily. Statistics from the Storebælt Bridge shows that the bridge has been closed for a total of 44,5 hours due to falling ice and snow from This corresponds to 2,8 hours every year. Further investigations has to be performed to give estimations that are more accurate on annual hours the Bjørnafjorden bridge can be expected to close due to falling ice. If the same climatic conditions are assumed for the Bjørnafjorden Bridge as for the Storebælt bridge regarding falling ice and snow from cables, the bridge can be expected to close for an average of 16,4 hours a year due to wind and falling ice. Closing criteria for the Storebælt Bridge in addition to safety rules at times of high wind speeds is presented in the end of appendix A, together with a list of other causes for closing the bridge that is not evaluated extensively in this report. A statistical review of the operating time of the Storebælt bridge is also given. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

88 BJØRNAFJORDEN PROJECT REPORT 7/ Downtime due to foreseen operation and maintenance Appendix B deals with foreseen operation & maintenace (O&M) only. The document summarises possible downtime during a 100-year service life due to foreseen O&M activities. With due attention to O&M during future design stages, both alternatives, curved bridge and strait bridge, can be arranged in a way where no complete closure due to foreseen O&M is needed during a 100-year service life. Downtime due to foreseen O&M has been summarised based on the following reports which represent a snapshot of the design process as per July 2015: O&M Steel Structures /2/ O&M Concrete Elements /3/ O&M Moorings /4/ For the concrete elements of the bridge, the Pontoons, the most obvious way to ensure minimum traffic disturbance will be to perform all inspection, maintenance and replacement work with access from the sea. The mooring system may be approached entirely from the sea without traffic disturbance. However, as also highlighted by /4/, it may be economic feasible that some activities are performed without ship assistance, meaning performed via access from roadway. This will require closure of one lane during a limited period. Decision on seaside approach only require that the design mature. For this reason, no traffic disruption associated with O&M of moorings has been assumed throughout of the present document. 2.3 Downtime due to non-planned maintenance and accidental events The document found in appendix C deals with non-foreseen O&M activities for straight bridge with centered fair lane only. Most accidental events with the potential of resulting downtime for the Bjørnafjorden crossing are related to external forces i.e passing vessels, vehicle traffic and environmental forces. However, some incidents can be related to the planned maintenance activities, especially activities where large equipment and vessels are led onto, or to a close proximity of the bridge structure for a prolonged period of time. Alternatively major replacement work can affect the bridge system vulnerability to external forces. The non-foreseen accidental events are therefore dependent on the planned maintenance activities, and the final O&M plan for the bridge crossing should seek to minimize risk from maintenance activities, both related to structural damage as well as risk to road users and maintenance personnel. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

89 BJØRNAFJORDEN PROJECT REPORT 8/17 Identifying non-foreseen events are always characterized by a level of uncertainty highly dependent on the amount of comparable historical data. At this point of the project, focus has been on identifying hazardous scenarios. Finalizing frequencies related to component failures requires extensive knowledge of lifetime expectancies (MTTB). An effort has been made to quantify the effect on downtime from identified accidental events, the assumptions behind this quantification are presented in appendix C. The presented accidental events are identified in cooperation with the project consortium through HAZID FMECA, and design/engineering activities. The accidental events are sorted by which elements of the bridge that potentially are affected in the same manner as the performed FMECA. The following categories of elements (subsystems) are applied: 1. Pontoon system 2. Columns 3. Mooring 4. Superstructures 5. Towers 6. Stay cables 7. Fastenings and bearings 8. Roadway 9. Secondary steel 10. Auxiliary systems (including mechanical and electrical) J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

90 BJØRNAFJORDEN PROJECT REPORT 9/17 3 RESULTS Calculated downtime from Appendix A,B and C is summarized in the following chapter. Chapter 3.1 deals with the straight bridge alternative, while chapter 3.2 presents the results for the curved bridge alternative. Downtime due to weather conditions is considered to be the same for straight bridge and curved bridge according to Appendix A. With due attention to O&M during future design stages, both alternatives, curved bridge and straight bridge, can be arranged in a way where no complete closure due to foreseen O&M is needed during a 100-year service life. The results are presented for complete closure, operating time with only 1 roadway accessible, and operating time where 1 lane is closed. The total downtime is calculated by summing the terms. This is strictly speaking only valid for mutually exclusive events (meaning events that can not occur at the same time), which is not the case for the different causes that may lead to downtime. The result is still approximately correct when the probability of each event is small. 3.1 Straight bridge Estimated operating time for the straight bridge alternative is summarized in this part Complete Closure Full close down, assuming no traffic. Annual closing hours Annual closing percent Due to weather conditions 16,4 h 0,187 % Due to operation & maintenance (foreseen) 0 h 0 % Due to non-planned maintenance and accidental events 13,4 h 0,153 % Total 29,8 h 0,340 % J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

91 BJØRNAFJORDEN PROJECT REPORT 10/ Roadway closed One roadway closed, assuming traffic in the remaining roadway. Annual closing hours Annual closing percent Due to weather conditions 0 h 0 % Due to operation & maintenance (foreseen) 14,2 h 0,162 % Due to non-planned maintenance and accidental events 1,1 h 0,013 % Total 15,3 h 0,175 % Single lane closed One lane closed, assuming traffic in the 3 remaining lanes. Annual closing hours Annual closing percent Due to weather conditions 0 h 0 % Due to operation & maintenance (foreseen) 6,4 h 0,073 % Due to non-planned maintenance and accidental events 16,8 h 0,192 % Total 23,2 h 0,265 % J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

92 BJØRNAFJORDEN PROJECT REPORT 11/ Curved bridge Estimated operating time for the curved bridge alternative is summarized in this part. At present stage downtime due to non-planned maintenance and accidental events has not yet been investigated for the curved bridge alternative Complete Closure Full close down, assuming no traffic. Annual closing hours Annual closing percent Due to weather conditions 16,4 h 0,187 % Due to operation & maintenance (foreseen) 0 h 0 % Due to non-planned maintenance and accidental events NA* NA* Total NA* NA* NA* - At present stage downtime due to non-planned maintenance and accidental events has not yet been investigated for the curved bridge alternative Roadway closed One roadway closed. Assuming traffic in the remaining roadway. Annual closing hours Annual closing percent Due to weather conditions 0 h 0 % Due to operation & maintenance (foreseen) 7,1 h 0,08 % Due to non-planned maintenance and accidental events NA* NA* Total NA* NA* J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

93 BJØRNAFJORDEN PROJECT REPORT 12/17 NA* - At present stage downtime due to non-planned maintenance and accidental events has not yet been investigated for the curved bridge alternative Single lane closed One lane closed. Assuming traffic in the 3 remaining lanes. Annual closing hours Annual closing percent Due to weather conditions 0 h 0 % Due to operation & maintenance (foreseen) 30,0 h 0,34 % Due to non-planned maintenance and accidental events NA* NA* Total NA* NA* NA* - At present stage downtime due to non-planned maintenance and accidental events has not yet been investigated for the curved bridge alternative. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

94 BJØRNAFJORDEN PROJECT REPORT 13/17 4 CONCLUSION In this report estimated downtime due to weather conditions, foreseen operation & maintenance and non-planned maintenance and accidental events are presented for the straight bridge alternative. At present stage non-planned maintenance and accidental events are not investigated for the curved bridge alternative, but the remaining numbers are given in tables in chapter 3.2. The bridge is estimated to be completely closed for an annual 29,8 h corresponding to 0,34 %. For the downtime due to weather conditions, mainly wind and ice falling from cables, the downtime is considered independent of whether straight bridge or curved bridge is choosen, and does allways result in complete closure. Foreseen operation & maintenance is never related to complete closure, but only involves closing of single roadway or single lane. For the straight bridge one roadway is expected to close for 14,2 h annually, while the curved bridge alternative corresponds to 7,1 h downtime of a roadway. Closing of a single lane is expected to occure 30 h annually for the curved bridge and only 6,4 h annually for the straight. For detail it is reffered to Appendix A,B and C. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

95 BJØRNAFJORDEN PROJECT REPORT 14/17 5 REFERENCES /1/ RAP-GEN-001-Design basis Floating bridge /2/ NOT-GEN-006 Operation and maintenance Steel structures /3/ NOT-GEN-007 Operation and maintenance Concrete elements /4/ NOT-GEN-004 Operation and maintenance Moorings J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

96 BJØRNAFJORDEN PROJECT REPORT 15/17 6 Appendix A Downtime due to weather conditions J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

97 BJØRNAFJORDEN DOWNTIME DUE TO WEATHER CONDITIONS ADRESSE COWI AS Grensev. 88 Postboks 6412 Etterstad 0605 Oslo TLF WWW cowi.no OPPDRAGSNR. A DOKUMENTNR. NOT- GEN-013 BJØRNAFJORDEN DOWNTIME DUE TO WEATHER CONDITIONS VERSJON 1.0 UTGIVELSESDATO UTARBEIDET HKJ KONTROLLERT KAA GODKJENT KAA

98 ESTIMATIONS ON OPERATING TIME 2/18 CONTENT 1 SUMMARY 3 2 INTRODUCTION 4 3 WIND Statistical Data Weibull parameters Wind direction Converting between various wind averaging periods Probabilistic analysis 8 4 ACCELERATION OF BRIDGE GIRDER Review of criteria Accelerations from wind loads Accelerations from wave loads Evaluation of accelerations 13 5 FALLING ICE FROM CABLES 13 6 OPERATING TIME AT STOREBÆLT BRIDGE Safety rules at times of high winds at Storebælt Operating time at Storebælt bridge 15 7 OTHER POSSIBLE REASONS FOR CLOSE DOWN 16 8 CONCLUSION 16 9 REFERENCES 17 A APPENDIX: PROBABILITY OF EXCEEDING CERTAIN WIND SPEED CALCULATIONS 18 J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

99 ESTIMATIONS ON OPERATING TIME 3/18 1 SUMMARY This report intends to give an estimate of the number of annual hours the Bjørnafjorden Bridge may be closed due to unpredicted events, with emphasis on weather conditions. A probabilistic analysis of wind data provided by the Norwegian Metrological Institute at a nearby location is performed, to estimate the number of yearly hours that a certain wind speed will be exceeded. Wind in 60 sectors perpendicular to the bridge axis is considered to be the most critical for traffic on the bridge. The bridge is assumed to run north-south. The calculations only include wind from the eastern sector ( ) and the western sector ( ). Assuming that the bridge has to close for all traffic at wind speeds exceeding 25 m/s, calculations show that the bridge can be expected to be closed for an average of 13,6 hours yearly due to high winds. Acceleration of the bridge girder due to wind and wave loads is presented, and compared to maximum allowable vertical and horizontal acceleration defined in the Design basis /4/. Closing of the bridge due to high accelerations in the bridge girder is not considered likely to occur on a yearly basis, and is neglected in the calculation of operating time of the bridge. Falling Ice and snow from hangers and cables have caused suspension bridges and cable stayed bridges to close down temporarily. Statistics from the Storebælt Bridge shows that the bridge has been closed for a total of 44,5 hours due to falling ice and snow from This corresponds to 2,8 hours every year. Further investigations has to be performed to give estimations that are more accurate on annual hours the Bjørnafjorden bridge can be expected to close due to falling ice. If the same climatic conditions are assumed for the Bjørnafjorden Bridge as for the Storebælt bridge regarding falling ice and snow from cables, the bridge can be expected to close for an average of 16,4 hours a year due to wind and falling ice. This corresponds to an operating time of 99,81%, and is above the 99,5 % operating time SVV are aiming for, Closing criteria for the Storebælt Bridge in addition to safety rules at times of high wind speeds is presented in the end of the report, together with a list of other causes for closing the bridge that is not evaluated extensively in this report. A statistical review of the operating time of the Storebælt bridge is also given. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

100 ESTIMATIONS ON OPERATING TIME 4/18 2 INTRODUCTION In this report an attempt is made to estimate the number of hours annually the Bjørnafjorden Bridge may be closed due to unpredicted events, with emphasis on weather conditions. The Norwegian Public Roads administration (Statens Vegvesen) wants an operating time of the bridge at 99,5 %. In this report some brief calculations are done to show that such demand is realistic with the current configuration of the bridge. 3 WIND It is assumed that the bridge has to close for all traffic at a 10 min average crosswind of 25 m/s. According to chapter in Håndbok N400 /5/, the wind load should be calculated for a gust wind speed of 35 m/s at the highest point of the bridge deck. The turbulence intensity at the highest point of the road on the bridge (55 m above sea level) is: ln 1 ln 55 0, Assuming a gust factor at 3,5, the gust wind speed corresponding to a 10 min mean wind speed is 3,5 3,5 25 3,5 0, ,15 This shows that a 10 min wind speed of 25 m/s at the bridge location 55 m above sea level corresponds very well with a maximum gust wind speed of 35 m/s. 3.1 Statistical Data Statistical wind data used in this report is based on the findings in the SINTEF report Bridge across Bjørnafjorden Metocean conditions /1/. Recorded wind data is provided by The Norwegian Metrological Institute from 1995 to 2004 at a nearby location called Slåtterøy fyr. This is considered to be representative wind data for Bjørnafjorden, though the report concludes that the Slåtterøy data probably underestimates the effect of easterly winds relative to other wind directions. As long as there are no local wind data from Bjørnafjorden that could be compared to simultaneous data from Slåtterøy, it is beyond the scope of this analysis to correct for this. The prevailing wind direction is southerly, approximately 1/3 coming from sector However the strongest winds are from between west and north, a westerly storm of 27.3 m/s being the greatest. The wind speed is considered to be Weibull distributed. A 3-parameter Weibull distribution is applied. The wind data is provided by SINTEF in the report Bridge across Bjørnafjorden Metocean conditions /1/. The probability density function is given below. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

101 ESTIMATIONS ON OPERATING TIME 5/18 The corresponding cumulative probability distribution is given by: 1 The shape parameter is denoted k, the scale parameter λ and the location parameter θ. 3.2 Weibull parameters The parameters in the Weibull distribution are taken from /1/ chapter 2.4. The parameters are based on wind data from Slåtterøy fyr provided by the Norwegian metrological institute. It is only given for wind from west ( ) and east ( ). Figur 1 Weibull parameters for wind from west. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

102 ESTIMATIONS ON OPERATING TIME 6/18 Figur 2 Weibull parameters for wind from east. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

103 ESTIMATIONS ON OPERATING TIME 7/ Wind direction A distribution of wind direction and speed at Slåtterøy is shown below. The dominating direction is wind from south, but the strongest winds are coming from between west and north. The northward heading of the two alternative bridges are 4 to the east (for the western route) and 3 to the west (for the eastern route). Since the deflection from north is less than the accuracy of the measurements (±5 ), the bridge is considered to run north-south. The cross wind is considered the most critical for traffic on the bridge, and in the calculations performed in 3.5, only wind from the eastern sector ( ) and the western sector ( ) is included. The Weibull parameters provided by SINTEF are only valid for wind in these sectors. 3.4 Converting between various wind averaging periods The wind data provided by Metrological Institute is a 3 hour mean wind speed. To obtain a 10 min mean wind speed, an equation from Offshore Standard DNV-OS-J101 /3/ is applied. The equation is said to be representative for North Sea conditions, and is valid for extreme mean wind speeds corresponding to specified return periods in excess of approximately 50 years. The expression can be used for conversion of the one-hour mean wind speed U0 at height h above sea level to the mean wind speed U with averaging period T at height z above sea level. Where h = 10 m, T0 = 1 hour T < T0. C and IU are defined as: J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

104 ESTIMATIONS ON OPERATING TIME 8/ Probabilistic analysis A probabilistic analysis is performed in appendix A in order to quantify the expected number of hours where a certain wind speed will be exceeded. Calculations are performed for two different heights, 55 m and 17 m. The bridge deck of the cable stayed part is assumed to be at 55 m above sea level, and the low part of the bridge is assumed to be at 17 m above sea level. The calculations only include wind from east ( ) and west ( ). Cross wind is considered to be the most critical for traffic on the bridge. A summary of the results are given below: Annual number of hours with wind above certain wind speed 10 m/s 15 m/s 20 m/s 25 m/s Low part of bridge (17 m above sea level) High part of bridge (55 m above sea level) 458,9 127,8 24,8 3,2 620,9 224,0 63,7 13,6 Percentage of wind below certain wind speed 10 m/s 15 m/s 20 m/s 25 m/s Low part of bridge (17 m above sea level) High part of bridge (55 m above sea level) 94,76 % 98,54 % 99,72 % 99,96 % 92,91 % 97,44 % 99,27 % 99,85 % J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

105 ESTIMATIONS ON OPERATING TIME 9/18 Diagram for high part of bridge (55 m above sea level) Diagram for low part of bridge (17 m above sea level) J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

106 ESTIMATIONS ON OPERATING TIME 10/18 4 ACCELERATION OF BRIDGE GIRDER Accelerations in the bridge girder due to wind and wave loads are presented and compared to acceleration criteria. 4.1 Review of criteria Chapter Motions under Design criteria in the Design basis /4/, gives maximum allowable vertical and horizontal acceleration of the bridge girder. Bridge shape Vertical acceleration Horizontal acceleration Straight bridge 0,5 m/s 2 0,3 m/s 2 Curved bridge 0,5 m/s 2 0,5 m/s 2 The values for horizontal acceleration apply for speed 110 km/h. 4.2 Accelerations from wind loads Horizontal and vertical accelerations of the bridge girder due to wind loads with a return period of 1 year are shown below. The cable stayed bridge is here at mid span. Figur 3 Plots of horizontal acceleration of bridge girder for wind direction 270 with 1 year return period. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

107 ESTIMATIONS ON OPERATING TIME 11/18 Figur 4 Plots of vertical acceleration of bridge girder for wind direction 270 with 1 year return period. Figur 5 Plots of rotational acceleration about bridge axis of bridge girder for wind direction 270 with 1 year return period Total vertical acceleration can be computed as vertical acceleration added to rotational acceleration multiplied with B/2 * sin(angle). The distance from the bridge axis to the outer part of the runway of one of the girders is assumed to be 11 m + 16 m = 27 m. An upper estimate for the contribution from rotational acceleration to the vertical acceleration with a return period of 1 year is calculated: J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

108 ESTIMATIONS ON OPERATING TIME 12/18 av,r = 27 m * sin(0.002) * 27 m * rad/s 2 = 0,005 m/s Accelerations from wave loads Horizontal and vertical accelerations of the bridge girder due to wave loads with a return period of 100 years are shown below. Results with return period of 1 year are obtained by multiplying the values below with 0,5. Figur 6 Horizontal acceleration in bridge girder for 100 year return period for waves incident at 225 and year values can be obtained by multiplying plotted values with 0,5. Figur 7 Vertical acceleration in bridge girder for 100 year return period for waves incident at 225 and year values can be obtained by multiplying plotted values with 0,5. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

109 ESTIMATIONS ON OPERATING TIME 13/ Evaluation of accelerations Approximated values with return period of 1 year, based on the diagrams above, are listed in the table below. Contribution from rotational acceleration to the vertical acceleration is included in the table for wind load, but not for the wave load. Horizontal acceleration Vertical acceleration Wind 0,07 m/s 2 Cable stayed bridge: 0,37 m/s 2 Low part of bridge: 0,17 m/s 2 Waves 0,30 m/s 2 0,25 m/s 2 The values show that horizontal accelerations from wind load can be neglected. The vertical accelerations are also at a modest level for the low part of the bridge, but considerably larger for the cable stayed bridge when it is assumed to be at mid span. It is still fairly low compared to defined acceleration criteria in vertical direction. The wave loads tend to give higher accelerations than wind in general. The value in the horizontal direction with return period of 1 year is approximately at the same level as the acceleration criterion in the Design basis for the straight bridge alternative, but considerably lower than the criterion defined for the curved bridge. Closing of the bridge due to high accelerations in the bridge girder is not considered likely to occur on a yearly basis, and is neglected in the calculation of operating time of the bridge. 5 FALLING ICE FROM CABLES Falling Ice and snow from hangers and cables have caused suspension bridges and cable stayed bridges to close down temporarily. Statistics from Storebælt bridge that will be presented in chapter 6, shows that the bridge has been closed for a total of 44,5 hours due to falling ice and snow from This corresponds to 2,8 hours every year. It is difficult to predict whether this could be a problem at Bjørnafjorden bridge. The climatic differences from Storebælt may cause the problems to be worse, or it could turn out not to be a problem at all. Further investigations has to be performed to give estimations that are more accurate on annual hours the Bjørnafjorden bridge can be expected to close due to falling ice. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

110 ESTIMATIONS ON OPERATING TIME 14/18 6 OPERATING TIME AT STOREBÆLT BRIDGE Closing criteria for the Storebælt bridge in addition to safety rules at times of high wind speeds is presented in this chapter. Statistics on operating time is also given. 6.1 Safety rules at times of high winds at Storebælt When the wind is coming from north or south (crosswise) and exceeds 25 m/s the Storebælt bridge is closed to all traffic. Warnings and restrictions on speed is given for lower wind speeds. Wind Wind speed Safety action High winds 10 m/s Yellow flashing lights, signs and wind cones on the bridge warn wind-sensitive vehicles of side winds. Strong breeze 15 m/s Wind-sensitive vehicles (caravans and light commercial vehicles) are warned of temporary closures ahead of the last exit before the bridge. Recommended speed for other vehicles, max 80 km/h. Fresh gale 20 m/s Wind-sensitive vehicles (caravans and light commercial vehicles) are warned on temporary closures ahead of the last exit before the bridge. Recommended speed for other vehicles, max 50 km/h. Gale 25 m/s The bridge is closed to all traffic with barriers. Signs warn of the closure and expected time of reopening ahead of the last exit before the bridge. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

111 ESTIMATIONS ON OPERATING TIME 15/ Operating time at Storebælt bridge Storebælt is closed to all traffic for wind speeds above 25 m/s from northern or southern direction. The table below shows when the bridge has been closed due to wind, traffic accidents or falling ice from hangers and main cable. Since 1999 the bridge has been closed 25 times due to wind at a total time of approximately 130 hours, about 8 hours a year on average. In total the bridge has closed down 47 times for a total time of 190 hours. At 15 m/s the bridge closes for tall and light vehicles. This is not included in the statistics above. The total time this has happened is approximately 2500 hours since 1999, corresponding to more than 150 hours every year on average. For the cable stayed part of the Bjørnafjorden bridge it is interesting to note that the Storebælt bridge has closed down for 44 hours due to falling ice since J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

112 ESTIMATIONS ON OPERATING TIME 16/18 7 OTHER POSSIBLE REASONS FOR CLOSE DOWN A list of other possible reasons for closing the bridge temporarily is listed in the table below. Non-planned closings: Traffic accidents Fire Slippery roads Planned closings: Maintenance work. Changing wearing course. These are not included in the calculations for operating time of the Bjørnafjorden bridge in this report, but should be considered at a later stage. 8 CONCLUSION Assuming that the bridge has to close for all traffic at wind speeds exceeding 25 m/s, calculations show that the bridge can be expected to close for an average of 13,6 hours yearly due to high winds. Closing of the bridge due to high accelerations in the bridge girder is not considered likely to occur during a year, and is neglected in the calculation of operating time of the bridge. If the same climatic conditions are assumed for the Bjørnafjorden bridge as for the Storebælt bridge regarding falling ice and snow from cables, the bridge can be expected to close for an average of 16,4 hours a year due to wind and falling ice. This corresponds to an operating time of 99,81%. Further investigations should be performed to give more accurate results for closing due to falling ice from cables. J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

113 ESTIMATIONS ON OPERATING TIME 17/18 9 REFERENCES /1/ Bridge across Bjørnafjorden. Metocean conditions. SINTEF /2/ /3/ Standard DNV-OS-J101 /4/ RAP-GEN-001-Design basis Floating bridge /5/ Håndbok N400 Bruprosjektering. Statens Vegevesen J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

114 ESTIMATIONS ON OPERATING TIME 18/18 A APPENDIX: PROBABILITY OF EXCEEDING CERTAIN WIND SPEED CALCULATIONS J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\NOT-GEN-013.docx

115 Traffic climate - probability of exceeding certain wind speeds If the transverse wind speed is too high, traffic limitations should be imposed, e.g by limiting high vehicles to enter the bridge. It is of interest to know how different wind speeds will affect the opening hours of the bridge- This can be evaluated by a probabilitic approach. The probability is calculated based on the wind climate at a nearby site as reported by SINTEF in the report "Bridge across Bjørnafjorden Metocean conditions". Wind perpendicular to the vehicles is caused by wind from West (15.3%) and East (16.7%). A 3-paramter Weibull distribution of the wind speed are used in these calculations. Probability density function f( xλ k θ) k x θ λ λ 0 otherwise k1 Cumulative density function k xθ λ e if x θ xθ λ CDF( xλ k θ) 1 e if x θ 0 otherwise Probability of ecceding certain wind speed, u k Parameters P( ϕu λ k θ) ϕ( 1 CDF( uλ k θ) ) The following paramters are given in the reference above (valid for elevation z=10m): W: ϕ W λ W k W θ W E: ϕ E λ E k E θ E 0.851

116 Converting between various wind averaging periods To adjust between different wind averaging periods, an equation from Standard DNV-OS-J101 is used. This is based on a mean wind reference period of 1 hour. Mean Wind speed reference factor: Reference period: Reference Hight: Defined constant: U 0 1 T 0 h 3600s 10m C T U 0 Equation from Standard DNV-OS-J101: U 0 1 C T ln z h U c T 1 z U 0 z h 0.22 Factor for converting from 3 hour mean wind to 10 min mean wind: ln T 1 T 0 U c ( 33600s10m) U conv U c ( 600s10m) Calculations for high part of bridge 55 m above sea level. A factor is calculated to adjust between wind speed at z=10m and deck level, z=55m. This also includes converting from 3 hour mean wind to 10 min mean wind. U fact z deck 10 ln 0.01 U z 10H U conv U fact ( 55) deck ln 0.01 This gives the following hours pr year where the wind blows above the threshold U perpendicular to the bridge: Pϕ E u P hh ( u) P ϕ W u λ W k W θ W λ E k E θ E

117 Examples: Closing wind speed, deck level = 10m/s: P hh 10U 10H Closing wind speed, deck level = 15m/s: P hh 15U 10H Closing wind speed, deck level = 20m/s P hh 20U 10H Closing wind speed, deck level = 25m/s P hh 25U 10H hours above U hours above U hours above U hours above U 800 Yearly hours with wind speeds above U 600 Hours [h] P hh UU 10H U Wind speed at deck level [m/s] Percentage of wind below 10 m/s: 1 Percentage of wind below 15 m/s: 1 Percentage of wind below 20 m/s: 1 P hh 10U 10H 8760 P hh 15U 10H 8760 P hh 20U 10H Percentage of wind below 25 m/s: 1 P hh 25U 10H

118 Calculations for low part of bridge 17 m above sea level. A factor is calculated to adjust between wind speed at z=10m and deck level, z=17m. This also includes converting from 3 hour mean wind to 10 min mean wind. U 10L U conv U fact ( 17) This gives the following hours pr year where the wind blows above the threshold U perpendicular to the bridge: Pϕ E u P hl ( u) P ϕ W u λ W k W θ W λ E k E θ E Examples: Closing wind speed, deck level = 10m/s: P hl 10U 10L Closing wind speed, deck level = 15m/s: P hl 15U 10L Closing wind speed, deck level = 20m/s P hl 20U 10L Closing wind speed, deck level = 25m/s P hl 25U 10L hours above U hours above U hours above U hours above U

119 500 Yearly hours with wind speeds above U 400 Hours [h] P hl UU 10L U Wind speed at deck level [m/s] Percentage of wind below 10 m/s: 1 Percentage of wind below 15 m/s: 1 Percentage of wind below 20 m/s: 1 P hl 10U 10L 8760 P hl 15U 10L 8760 P hl 20U 10L Percentage of wind below 25 m/s: 1 P hl 25U 10L

120 BJØRNAFJORDEN PROJECT REPORT 16/17 7 Appendix B Downtime due to operation and maintenance J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

121 OPERATION AND MAINTENANCE DOWNTIME DUE TO OPERATION AND MAINTENANCE

122

123 ADRESSE COWI AS Grensev. 88 Postboks 6412 Etterstad 0605 Oslo TLF WWW cowi.no OPERATION AND MAINTENANCE DOWNTIME DUE TO OPERATION AND MAINTENANCE OPPDRAGSNR. A DOKUMENTNR. A xxx VERSJON 2.0 UTGIVELSESDATO UTARBEIDET HPE/PLI KONTROLLERT PLI/HPE GODKJENT SWI

124

125 1 Introduction This document is part of a series of documents dealing with operation and maintenance (O&M) of the crossing of Bjørnafjorden south of Bergen. O&M comprise foreseen and non-foreseen inspection and maintenance activities as listed below. Foreseen inspections: Foreseen maintenance: Scheduled inspections: - Routine Inspections - Yearly Inspections (Enkel inspeksjon) - Principal Inspections (Hovedinspeksjon) Non-scheduled inspections: - Special Inspections Scheduled maintenance: - Routine maintenance (day by day activity, no project) - Standard repair (ad hoc, no project) - Major maintenance (expected acc. to design, maintenance project) Replacement (expected acc. to design life, replacement project) Non-foreseen inspections: Non-foreseen maintenance: Due to extreme events (extreme wind, ship collsion, etc.) Due to extreme events (extreme wind, ship collsion, etc.) This document deals with foreseen O&M only and will feed into a complete summary of downtime of the crossing of Bjørnafjorden. This document summarises possible downtime during a 100-year service life due to foreseen O&M activities. With due attention to O&M during future design stages, both alternatives, curved bridge and strait bridge, can be arranged in a way where no complete closure due to foreseen O&M is needed during a 100-year service life.

126 Downtime due to foreseen O&M has been summarised based on the following reports: O&M Steel Structures /1/ O&M Concrete Elements /2/ O&M Moorings /3/ For the concrete elements of the bridge, the Pontoons, the most obvious way to ensure minimum traffic disturbance will be to perform all inspection, maintenance and replacement work with access from the sea, ref /2/. This has been assumed throughout of the present document. According to /3/, the mooring system may be approached entirely from the sea without traffic disturbance. However, as also highlighted by /3/, it may be economic feasible that some activities are performed without ship assistance, meaning performed via access from roadway. This will require closure of one lane during a limited period. Decision on seaside approach only require that the design mature. For this reason, no traffic disruption associated with O&M of moorings has been assumed throughout of the present document.

127 2 Foreseen inspections 2.1 Inspection frequency With due attention to O&M during future design stages, both alternatives, curved bridge and strait bridge, can be arranged in a way where Routine Inspections will not cause traffic disruption. Hand over Inspections are performed before hand over and are therefore not included in this report. Warranty Inspections are one-off inspections that will typically take place during (or replace) the first Principal Inspection. Yearly Inspection (Enkel inspeksjon) is performed with a frequency of 1 year according to SVV Handbook R411. According to SVV Handbook R411 this visual inspection can be performed from a distance using binoculars, i.e. without using access equipment. As for Routine Inspections, and with due attention to O&M during future design stages, both alternatives, curved bridge and strait bridge, can be arranged in a way where Yearly Inspections will not cause traffic disruption. It is assumed that Principal Inspection (Hovedinspeksjon) is performed with a frequency of 5 year and in accordance with SVV Handbook R411. Special Inspections are typically foreseen but not scheduled inspections. The actual time for the inspection is normally settled from evaluation of a recent principal inspection report. The primary purpose of a Special Inspection is to ensure that the cause of a defect is known and understood, to assess the extent of the defect, to assess the effect that a defect may have on other elements, and to assist with the development of an appropriate monitoring or repair strategy to deal with the defect. Depending on the outcome of a Special Inspection (repair/no repair), a Principal Inspection will be performed 5 years after a repair or 5 years after the Special Inspection has been performed. It is assumed that the bridge is designed properly according to the governing codes and standards, with due attention to O&M. In this case, non-foreseen

128 inspections are only triggered by extreme events such as extreme wind, ship collision etc. and will not be included in the present document. 2.2 Curved bridge In Table 2.1 inspection type, frequency and duration are summarised for elements where inspections require traffic disruption. Frequencies and durations are approximated from information in /1/, /2/ and /3/. Traffic disruption types are also listed as affecting Roadway, Lane, Shoulder, Bike/pedestrian track or Emergency walkway. It is expected that all inspections will meet the requirement of minimum traffic disturbance. The inspection plan can be refined as the design mature. It is foreseen that Principal and Special Inspections of outer surfaces of towers and stay cables will be performed using rope access with access from the tower. Special Inspection of cable anchorages shall be performed from bridge interior. As reported in /1/ mobile self-propelled inspection gantries are expensive. However, at present they are considered technical and economic feasible compared to a Under Bridge Inspection Unit (UBIU) during a 100 year service life. Also, exploitation of Unmanned Aerial Vehicle (UAV) needs further consideration. In addition, it is assumed that: the design will enable inspection of bearings and buffers (if any) from permanent access facilities. access to bottom surface of expansion joints will be made available from permanent access platforms beneath the bridge girder or from a mobile selfpropelled inspection gantry. access equipment as well as I&M equipment are designed such that they can be inspected without traffic disruption.

129 Inspection type (SI year) Element Table 2.1 Inspections that cause traffic disruption on the curved bridge alternative. PI: Principal Inspection, SI: Special Inspection. Top: Duration in weeks per activity Bottom: f = number of activities during a 100 year service life Roadway Lane Shoulder Bike/pedest (one rian track direction) PI Roadway and bike/pedestrian track incl drainage f = 17 f = 17 SI (40, 80) Roadway and bike/pedestrian track incl drainage f = 2 f = 2 PI Barriers/railings 2 x 0.1 f = 17 2 x 0.1 f = 17 2 x 0.1 f = 17 SI (50, 100) Barriers/railings 2 x 0.2 f = 2 2 x 0.2 f = 2 2 x 0.2 f = 2 PI Overhead sign structures and signs 2 x 0.2 f = f = 16 SI (25, 55, 85) Overhead sign structures and signs 2 x 0.4 f = f = 3 PI Electrical and mechanical installations 2 x 0.2 f = 16 2 x 0.2 f = f = 16 SI (30 60, Electrical and mechanical installations 2 x x ) f = 3 f = 3 f = 3 PI Structural Health Monitoring System 2 x x (partial) f = 14 f = 14 f = 14 SI (15, 35, Structural Health Monitoring System 2 x x 0, , 75, 95) (partial) f = 5 f = 5 f = 5 Total number of downtime weeks N/A Percentage downtime, % N/A Total life time: 100 x 52 = 5200 weeks

130 2.3 Strait bridge In Table 2.2 inspection type, frequency and duration are summarised for elements where inspections require traffic disruption. Frequencies and durations are approximated from information in /1/, /2/ and /3/. Traffic disruption types are also listed as affecting Roadway, Lane, Shoulder, Bike/pedestrian track or Emergency walkway. It is expected that all inspections will meet the requirement of minimum traffic disturbance. The inspection plan can be refined as the design mature. It is foreseen that Principal and Special Inspections of outer surfaces of towers and stay cables will be performed using rope access with access from the tower. Special Inspection of cable anchorages shall be performed from bridge interior. As reported in /1/ mobile self-propelled inspection gantries are expensive. However, at present they are considered technical and economic feasible compared to a Under Bridge Inspection Unit (UBIU) during a 100 year service life. Also, exploitation of Unmanned Aerial Vehicle (UAV) needs further consideration. In addition, it is assumed that: the design will enable inspection of bearings and buffers (if any) from permanent access facilities. access to bottom surface of expansion joints will be made available from permanent access platforms beneath the bridge girder or from a mobile selfpropelled inspection gantry. access equipment as well as I&M equipment are designed such that they can be inspected without traffic disruption.

131 Inspection type (SI year) Element Table 2.2 Inspections that cause traffic disruption on the strait bridge alternative. PI: Principal Inspection, SI: Special Inspection. Top: Duration in weeks per activity Bottom: f = number of activities during a 100 year service life Roadway Lane Shoulder Bike/pedest Emergency (one rian track walkway direction) PI Roadway and footway/bicycle track incl. 2 x x 0.1 drainage f = 17 f = 17 f = 17 SI (40, 80) Roadway and footway/bicycle track incl. 2 x x 0.2 drainage f = 2 f = 2 f = 2 PI Barriers/railings 2 x x x x 0.1 f = 17 f = 17 f = 17 f = 17 SI (50, 100) Barriers/railings 2 x x x x 0.1 f = 2 f = 2 f = 2 f = 2 PI Overhead sign structures and signs 2 x 0.1 f = f = 16 2 X 0.1 f = 16 SI (25, 55, Overhead sign structures and signs 2 x x ) f = 3 f = 3 f = 3 PI Electrical and mechanical installations 2 x 0.2 f = f = 16 2 x 0.2 f = 16 SI (30 60, Electrical and mechanical installations 2 x x ) f = 3 f = 3 f = 3 PI Structural Health Monitoring System 2 x x 0.1 (partial) f = 14 f = 14 f = 14 SI (15, 35, Structural Health Monitoring System 2 x x , 75, 95) (partial) f = 5 f = 5 f = 5 Total number of downtime weeks Percentage downtime, % Total life time: 100 x 52 = 5200 weeks

132 3 Maintenance and Replacement 3.1 Maintenance types The following types of maintenance are foreseen: Routine maintenance Repair according to standard specifications, no project Major maintenance, according to project Replacement It is assumed that the bridge is designed properly according to the governing codes and standards, with a sufficient robustness so that no non foreseen maintenance will be needed. 3.2 Frequency Routine Maintenance Routine maintenance is carried out according to standard procedures, hereunder standard Temporary Traffic Plans as based on routines. Routine maintenance is normally carried out by the in house I&M team, along with routine inspections. Routine I&M activities typically includes, but are not limited to: cleaning debris removal litter removal vehicle damage repair

133 lighting check and maintenance (bulp exchange etc) graffiti removal pothole repair check and maintain functionality of doors, hatches, locks, sensors, cameras, signs, lifts, weather stations, drainage inlets, fire fighting system, emergency telephone system etc Repair, Major Maintenance and Replacement Many of the elements in the bridge will need maintenance in order to achieve the design life. Such maintenance will be performed as repair works based on standard specifications or as major maintenance according to actual maintenance projects. It is assumed that standard repair works do not affect the traffic on the bridge. The type of maintenance and the time for execution are options related to the initial design. An example is an overhaul of the coating on steel structures. Some of the elements in the bridge are designed for a service life less than the service life of the bridge. Replacement of such elements is foreseen and handled in the initial design and in the construction method. In Table 3.1 is given the frequencies for major maintenance and replacement for components expected to need maintenance and/or replacement. The values are taken from /1/.

134 Table 3.1 Initial Maintenance Plan, service life < 100 years Component Service life Repair (standard maintenance) Major Maintenance Replacement Coating of primary steel structures 30 As needed After 15 and 25 years 30 years Waterproofing of bridge deck (isolation) Wearing course Safety barriers and railings 40 None None 40 years 40 As needed As needed 40 years 50 As needed As needed 50 years Drainage 50 As needed As needed 50 years Cable stay system 75 As needed As needed > 100 years for total system Bearings 50 None After 25 and 40 years 50 years Buffers (if any) 50 (non movable components) None After 20 and 35 years 50 years Systems: - Electrical - Mechanical 30 As needed As needed 30 years SHMS (sensors: 10 infrastructure part: 20) As needed As needed years Secondary steel elements (access facilities etc) 60 As needed After 30 and 45 years 60 years Lifts in towers 30 As needed After 20 years 30 years

135 3.3 Duration It is expected that some of the major maintenance and/or replacement works will affect the traffic on the bridge, whereas standard repair works do not affect the traffic on the bridge. It is expected that all maintenance- and replacement projects will meet the requirement of minimum traffic disturbance. However, in the following sections it has been conservatively assumed that traffic disturbance is 24 hours a day. This may be further optimised. It is estimated that the routine maintenance activities, for the individual traffic passages, will cause the following downtimes per week and the following accumulated downtimes in the 100 year service life: lane: 1 hour. 1 x 4 x 52 x 100 / (7 x 24) = 123 weeks shoulder: 2 hours. 2 x 2 x 52 x 100 / (7 x 24) = 123 weeks bike/pedestrian track: 1 hour. 1 x 1 x 52 x 100 / (7 x 24) = 31 weeks emergency walk: 1 hour. Strait bridge: 1 x 2 x 52 x 100 / (7 x 24) = 62 weeks Curved bridge: N/A Traffic disturbace related to standard repair works is for: coating of primary steel wearing cource and isolation safety barriers and railings drainage cable stay systems E&M installations access structures (secondary steel) included in the down time estimates for routine maintenance. The duration of the major maintenance / replacement works are based on the following execution methods: Replacement of isolation and wearing course: Machine milling. The down time related to replacement of wearing course

136 includes 10 % as related to major maintenance in the period between total renewal. *) Major maintenance of stay cable system: One bucket truck and possibly working platforms for tower anchorage works Major maintenance / replacement of drainage outlets: Dismantling, adjustment of steel flanges and reinstallation of water outlets Major maintenance / replacement of safety barriers and railings: Dismantling and re-installation in safety barrier area Replacement of electrical and mechanical system (incl. SHMS): On Bucket Truck, use of drilling machine and ordinary tools *) It is highlighted that maintenance strategy is dependnt on the chosen isolation / wearing course system. Further technical ans oeconomical (life cycle cost) analysis is required as the design mature Curved bridge In Table 3.2 below is listed estimated disturbance periods in weeks per major maintenance/replacement work related to components above road level. The estimated downtime for a certain passage is a summation of downtimes for all passages of the same type. Moreover is given the factor which expresses the number of times the work is foreseen to be performed in the 100 years service life.

137 Table 3.2 Disturbance periods in weeks per major maintenance/replacement work, curved bridge Work Roadway (one direction) Lane Shoulder Bike/ pedestrian track Replacement of isolation and wearing course on deck 2 x 20 f = 2 1 x 10 f = 2 Major maintenance of stay cable system 2 x 10 f = 2 Major repair / replacement of drainage outlets 2 x 30 f = 1 1 x 30 f = 1 Major repair / replacement of safety barriers and railings 2 x 10 f = 1 2 x 10 f = 1 2 x 10 f = 1 Replacement of electrical and mechanical systems, parts over roadway level 2 x 5 f = 3 1 x 3 f = 3 Routine maintenance Total number of downtime weeks Percentage downtime, % Total life time: 100 x 52 = 5200 weeks Strait bridge In Table 3.3 below is listed estimated disturbance periods in weeks per major maintenance/replacement work related to components above road level. The estimated downtime for a certain passage is a summation of downtimes for all passages of the same type. Moreover is given the factor which expresses the number of times the work is foreseen to be performed in the 100 years service life.

138 Table 3.3 Disturbance periods in weeks per major maintenance/replacement work, strait bridge Work Roadway (one direction) Lane Shoulder Bike/ pedestrian track Emergency walkway Replacement of isolation and wearing course on deck 4 x 7 f = 2 2 x 6 f = 2 1 x 15 f = 2 2 x 10 f = 2 Major maintenance of stay cable system 2 x 10 f = 2 2 x 10 f = 2 Major repair / replacement of drainage outlets 1 x 30 f = 1 1 x 30 f = 1 Major repair / replacement of safety barriers and railings 2 x 10 f = 1 2 x 10 f = 1 2 x 10 f = 1 4 x 10 f = 1 Replacement of electrical and mechanical systems, parts over roadway level 1 x 5 f = 3 1 x 3 f = 3 2 x 3 f = 3 Routine maintenance (ref. section Total number of downtime weeks Percentage downtime, % Total life time: 100 x 52 = 5200 weeks

139 4 Total downtime due to O&M In Table 4.1 the total downtime due to O&M has been summarised from chapter 2 and 3. Table 4.1 Total downtime due to O&M Roadway (one direction) Lane Shoulder Bike/ pedestrian track Emergency walkway Curved bridge Total number of downtime weeks N/A Curved bridge Percentage downtime, % N/A Strait bridge Total number of downtime weeks Strait bridge Percentage downtime, % Total life time: 100 x 52 = 5200 weeks

140 5 Optimization Downtime due to foreseen O&M has been summarised in the present report based on /1/, /2/ and /3/. Also in future stages of the design as well as during the construction stage there shall be a continuous interaction between O&M and the design/construction of the bridge. Design impose requirements to O&M and vice versa. References /1/, /2/ and /3/ present various improvements that need further analysis during future stages of the project. This interaction or optimization process is driven by technical and economic considerations that may include: Reliability (functional and structural) Availability Maintainability Safety (Safety for users) Life Cycle Costs Security (avoiding vandalism and securing of objects) Health Environment It is recognised that the first 4 bullets above constitute what often is referred to as RAMS. RAMS is often dealt with using a risk-based approach. Ensuring a smooth and safe flow of traffic at low Life Cycle Costs is what drives O&M planning in all stages of a project.

141 6 References (PLI) /1/ NOT-GEN-006, Operation and maintenance, Steel Structures, /2/ NOT-GEN-007, Operation and maintenance, Concete Elements, /3/ NOT-GEN-004, Operation and maintenance, Moorings,

142 BJØRNAFJORDEN PROJECT REPORT 17/17 8 Appendix C Downtime due to non-planned maintenance and accidental events J:\AKTIV\Bru\11543 Flytebru Bjørnafjorden\RAMS_Oppetid\RAP-GEN-004.docx

143 UTREDNING AV FLYTEBRU OVER BJØRNAFJORDEN OPERATION AND MAINTENANCE DOWNTIME DUE TO NON-PLANNED MAINTENANCE AND ACCIDENTAL EVENTS ADRESSE COWI AS Grensev. 88 Postboks 6412 Etterstad 0605 Oslo TLF WWW cowi.no OPPDRAGSNR. A DOKUMENTNR. NOT-HYDA-009-A VERSJON 1.0 UTGIVELSESDATO UTARBEIDET RML KONTROLLERT GODKJENT I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

144 CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES 2/20 INNHOLD 1 INTRODUCTION 3 2 ACCIDENTAL EVENTS STRAIGHT BRIDGE PONTOONS COLUMNS MOORING SUPERSTRUCTURE (girder boxes) TOWERS STAY CABLES FASTENINGS AND BEARINGS ROADWAY SECONDARY STEEL STRUCTURES AUX SYSTEMS EXTERNAL FORCES (EXCLUDING SHIP COLLISIONS) 15 3 RESULTS NON PLANNED MAINTEANCE AND ACCIDENTAL EVENTS Downtime by system Full downtime by system Road downtime by system Lane downtime by system 18 4 References 20 I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

145 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 3/20 OPERATION AND MAINTENANCE DOWNTIME DUE TO NON-FORESEEN MAINTENANCE 1 INTRODUCTION This document is part of a series of documents dealing with operation and maintenance (O&M) of the crossing of Bjørnafjorden south of Bergen. O&M comprise foreseen and non-foreseen inspection and maintenance activities as listed in figure 1 below. Foreseen inspections: Foreseen maintenance: Scheduled inspections: - Routine Inspections - Yearly Inspections (Enkel inspeksjon) - Principal Inspections (Hovedinspeksjon) Non-scheduled inspections: - Special Inspections Scheduled maintenance: - Routine maintenance (day by day activity, no project) - Standard repair (ad hoc, no project) - Major maintenance (expected acc. to design, maintenance project) Replacement (expected acc. to design life, replacement project) Non-foreseen inspections: Non-foreseen maintenance: Due to extreme events (extreme wind, ship collsion, etc.) Due to extreme events (extreme wind, ship collsion, etc.) Due to unforeseen accidental events related to planned maintenance activities Due to unforeseen accidental events related to planned maintenance activities Figure 1 O&M scope of work This document deals with non-foreseen O&M activities for straight bridge with centered high-bridge and will feed into a complete summary of downtime for this particular bridge concept. Most accidental events with the potential of resulting downtime for the Bjørnafjorden crossing are related to external forces i.e passing vessels, vehicle traffic and environmental forces. However, unwanted incidents can also be related to planned maintenance activities, especially activities where large equipment and vessels are led onto, or to a close proximity of the bridge structure for a prolonged period of time. Alternatively major replacement work can affect the bridge system vulnerability to external forces. Finally, corrective maintenance activities may be required if deviations are detected through inspection and monitoring. The non-foreseen downtime is therefore dependent on the planned maintenance activities. The final O&M plan for the bridge crossing should seek to minimize risk from I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

146 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 4/20 maintenance activities, both related to structural damage as well as risk to road users and maintenance personnel. For detailed information regarding quantified frequencies and resulting downtime, it is referred to full excel-@risk model. 2 ACCIDENTAL EVENTS STRAIGHT BRIDGE Identifying non-foreseen events are always characterized by a level of uncertainty highly dependent on the amount of comparable historical data. The presented accidental events are identified in cooperation with the project consortium through HAZID, FMECA and design/engineering activities. As more information regarding the maintenance philosophy and detail design solutions of the floating bridge structure is developed, the knowledge of potential downtime related to non-planned events will increase. The accidental events with potential for downtime are sorted by which elements of the bridge that potentially are affected, the categories are presented below: 1. Pontoons 2. Columns 3. Mooring 4. Superstructure (girder boxes) 5. Towers 6. Stay cables 7. Fastenings and bearings 8. Roadway 9. Secondary steel 10. Auxiliary systems (including mechanical and electrical) 11. External forces (excluding ship collision) An effort has been made to quantify the effect on operational downtime from identified accidental events and the resulting corrective maintenance. Only the assumptions used in the quantification of the resulting downtime is presented in this report. 2.1 Quantification of downtime A complete quantification of non-planned downtime has been carried out in cooperation with project consortium. This has resulted in an excel based Monte Carlo model in which the results presented in this report are extracted from. As an example of the applied quantification method, the calculation of downtime from vessel impacts on pontoons is shown below: Frequency of impact: The frequency of vessel impact on pontoons is represented as a normal function, with mean value according to the calculated ship collision frequency as used in design of floating bridge concept. I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

147 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 5/20 Downtime (full): Full downtime of the bridge due to vessel impact is represented by a discrete probability function. In 99% of the vessel impacts no full downtime of the bridge is expected. 0,9% of the impacts (large impacts) are assumed to result in 2 days of full downtime (investigate, declare safe for traffic). The remaining 0.1% of the impacts are assumed to result in 50 days of full downtime. This scenario is meant to cover impacts from vessels with size or speed above design limitations, resulting in loss of pontoon, heavy structural damage etc, leaving the bridge in a prolonged unsafe state. Downtime (road): No impact scenario resulting in road-specific downtime is identified, as corrective maintenance is assumed to at most require shutdown of a single lane. Downtime (lane): Corrective maintenance is conservatively assumed to require a single lane in certain scenarios, despite the possibility of accessing pontoons from the sea. Corrective maintenance on pontoons is assumed to require 14 days of downtime on a single lane. The need for corrective maintenance is determined during the investigation activities after a large impact. It is assumed that 50% of large impacts requires corrective maintenance. An illustration of the quantification method is shown in Figure 2 below: 99% No downtime 50% Investigation shows safe bridge, no corrective mainteance required. Vessel imapct on pontoon. 0.9% 0.1 % 2 days full downtime (investigate, declare safe for traffic 50 days full downtime (major damage, loss pontoon etc) 50% Investigation reveals need for corrective mainteance. 14 days of single lane downtime expected. Figure 2 Example of quantification method: Vessel impact on pontoon 2.2 PONTOONS The pontoons are those elements that are most likely to be affected by vessel impacts, with a return period of vessel impacts equal to 420 years. The pontoons are designed to withstand the foreseen impact energy, and additionally two of the pontoon chambers may be filled with water without affecting the safety of the bridge. Conservatively it is still assumed that the bridge will be fully closed while each exposed pontoon is inspected and cleared for signs of structural damage affecting the integrity of the bridge system. In the event of chamber penetration, or other significant damage that still leaves the bridge in a safe state, it is assumed a prolonged downtime for a single lane for easy access of required maintenance equipment. Serious findings from periodical inspections may result in a temporary shutdown until the causes of findings are discovered and bridge declared safe. Any potential I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

148 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 6/20 corrective maintenance resulting from the findings is assumed to require no more than shutdown on a single lane. Table 1 Assumptions on non-planned bridge downtime related to pontoons Planned and stochastic events affecting pontoons Yearly inspection (crack, damage concrete above/below sea, corrosion, erosion, chloride content) SI (crack width, damage to concrete, cracks, algae growth, corrosion, leaks inside pontoon) Damage from ship collision above sea level Replace coating Damage from ship collision below sea level Replacement of anodes Damage from ship collision during inspection/maintenance activities Assumptions on corrective actions contribution to downtime Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. Vessel impact to pontoon will lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. No foreseen downtime due to corrective actions Vessel impact to pontoon will lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. No foreseen downtime due to corrective actions Vessel impact to pontoon will lead to a temporary shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. Table 2 Calculated non-planned bridge downtime related to pontoons MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to pontoons. Mean downtime (in % of service life) % % % Mean annual days of downtime I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

149 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 7/ COLUMNS Serious findings from periodical inspections may result in a temporary shutdown until the causes of findings are discovered and bridge declared safe. Any potential corrective maintenance resulting from the findings is assumed to require no more than shutdown of a single lane. Table 3 Assumptions on non-planned bridge downtime related to columns Planned and stochastic events affecting columns Yearly inspection Principal inspection Assumptions on corrective actions contribution to downtime Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. Major maintenance coating 15 and 25 years Planned replacement coating No foreseen downtime due to corrective actions No foreseen downtime due to corrective actions Table 4 Calculated non-planned bridge downtime related to pontoons MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to columns Mean downtime (in % of service life) % % % Mean annual days of downtime I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

150 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 8/ MOORING The bridge is designed to withstand weather conditions with a return period of 100 years, even after a single line failure (including anchor). A damaged or broken line implies by definition that the bridge is in a damage state. The bridge will be temporarily closed down and inspected until the causes are known and the bridge can be declared safe. Equipment used in corrective maintenance activities will require access from a single lane. Table 5 Assumptions on non-planned bridge downtime related to mooring Planned and stochastic events affecting Mooring Assumptions on corrective actions contribution to downtime Annual inspections/continuous monitoring: (visual inspection accessible parts/chain stopper/fairlead, verify operation limits, verify calibration certificates) Complete periodical (ROV inspection, diameter measurement every 100th link 1/8 chains, 2-neck measurement values to be noted every 100th link, chain attachment visual survey as far as possible) Full Replacement: All line elements are dismantled and replaced. The fairleads are removed and inspected dry. Replacement of protective anodes. Accidental event or incident indicating abnormal or accidental state of the mooring system (including line break) Serious findings from inspection activities will lead to a temporarily full shutdown. Adjustment of lines as required by tensioning tool, requires single lane shutdown. Serious findings from inspection activities will lead to a temporarily full shutdown. Corrective maintenance requires single lanes shutdown. Corrective activities includes: Replacement of anchor chains if diameter with breaking strength reduced by 2%). Extended/detailed inspection upon findings, possible MPI No foreseen downtime due to corrective actions. Assumed detailed method for replacement. Accidental inspection, potential for immediate closedown of bridge traffic until bridge declared safe. Corrective maintenance requires shutdown of single lane. Table 6 Calculated non-planned bridge downtime related to mooring MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to Mooring Mean downtime (in % of service life) % % % Mean annual days of downtime I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

151 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 9/ SUPERSTRUCTURE (girder boxes) In addition to the pontoons, the superstructures of the low-bridge are exposed for vessel impacts. The return period is 1957 years, (420 for pontoons). The bridge is conservatively assumed to shut down in full for a period of time, until declared safe. Then one roadway will be closed while potential final inspections and repairs are made to the area of impact. Serious findings from periodical inspections may result in a temporary shutdown until the causes of findings are discovered and bridge declared safe. Any potential corrective maintenance on superstructure is assumed not to require shutdown on any lane (access). Table 7 Assumptions on non-planned bridge downtime related to superstructure Planned and stochastic events affecting Superstructure Assumptions on corrective actions contribution to downtime Yearly inspection Principle inspection Major maintenance coating 15 and 25 years Coating planned replacement Ship impact bridge girder boxes, low bridge Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. No foreseen downtime due to corrective actions. (Access from below roadway). No foreseen downtime due to corrective actions. (Access from below roadway). Vessel impact to superstructure will lead to a temporary shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance is assumed to require shutdown of one roadway. Table 8 Calculated non-planned bridge downtime related to superstructure MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to superstructure Mean downtime (in % of service life) % % % Mean annual days of downtime I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

152 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 10/ TOWERS Serious findings from structural inspections may result in a temporary shutdown until the causes of findings are discovered and the bridge declared safe. Any potential corrective maintenance on towers requires shutdown of single lane for access. Table 9 Assumptions on non-planned bridge downtime related to towers Planned and stochastic events affecting towers Assumptions on corrective actions contribution to downtime Yearly inspection Principle inspection Major maintenance coating 15 and 25 years Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. Serious findings may lead to a temporary full shutdown, until bridge is declared safe for traffic. Prolonged corrective maintenance requires shutdown of single lane. No foreseen downtime due to corrective actions Table 10 Calculated non-planned bridge downtime related to towers MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to towers Mean downtime (in % of service life) % % % Mean annual days of downtime STAY CABLES The stay cables are mainly exposed to environmental forces. The bridge system is designed to withstand a 100 year return period of weather, even after loss of a single stay cable. Icing of cables are described in detail in NOT-GEN-013. A serious traffic collision involving heat/explosion in close proximity of stay cables will lead to a full shutdown of the bridge until the affected cables are inspected. It is only foreseen that such a scenario could affect one cable due to the distance between each cable. The full closedown is a conservative safety measure. Serious findings from inspections of the mooring system may result in a temporary shutdown until the causes of findings are discovered and bridge is declared safe. Findings that require major maintenance closes one roadway for access. I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

153 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 11/20 Table 11 Assumptions on non-planned bridge downtime related to stay cables Planned and stochastic events affecting Stay cables Assumptions on corrective actions contribution to downtime Yearly inspection stay cables Principle inspection stay cables Major maintenance of stay cable system Icing on cables Heat/explosion related to major traffic accident in proximity of stay cable. Accidental event or incident indicating abnormal or accidental state of the stay cable system (excluding traffic accident) Serious findings may lead to a temporary full shutdown. Major corrective maintenance requires one roadway for access. Serious findings may lead to a temporary full shutdown. Major corrective maintenance requires one roadway for access. No foreseen downtime due to corrective actions Falling ice has historically led to temporarily shutdown of bridge (Storebælt) 2.8 hours per year. High uncertainty. Full shutdown during accidental investigation until bridge declared safe. Replace stay cable if strength reduced by heat. Replacement/corrective maintenance requires shutdown of roadway for access. Accidental inspection, potential for full shutdown of bridge until declared safe, and/or corrective maintenance that closes one roadway. Table 12 Calculated non-planned bridge downtime related to stay cables MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to stay cables Mean downtime (in % of service life) % % % Mean annual days of downtime FASTENINGS AND BEARINGS Only the south fastening will have an expansion joint. The single expansion joint must allow for heat induced expansion from nearly 4km of steel. Naturally wear and tear must be expected. The expansion joints are divided by lanes to allow for replacement with minimal traffic disturbance. The bearings are replaced by jacking, this is assumed not to require closure of the affected roadway. As the bearings and expansion joints are divided between lanes, there are not identified any hazardous events related to these elements that may result in full closure of the bridge. I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

154 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 12/20 Table 13 Assumptions on non-planned bridge downtime related to stay fastenings and bearings Planned and stochastic events affecting fastenings and bearings Yearly inspection bearings and expansion joints Principal inspection bearings and expansion joints Planned replacement bearings Assumptions on corrective actions contribution to downtime Findings resulting in replacement of expansion joint requires shutdown of single lane. Findings resulting in replacement of expansion joint requires shutdown of single lane. Replacement assumed to be performed while traffic no roadway. (Jacking from below). Jacking failure could lead to some downtime and/or structural damage. Not quantified. Table 14 Calculated non-planned bridge downtime related to fastenings and bearings MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to fastenings and bearings Mean downtime (in % of service life) % % % Mean annual days of downtime % ROADWAY The wearing course constitutes a high percentage of the carried weight of the bridge system. Naturally replacing such a large part of the bridge weight requires planning and careful execution. The surface is planned to be replaced one lane at the time. Replacing the wearing course and isolation may lead to unwanted damage to the underlying steel, if not performed carefully. Significant steel damage may lead to prolonged closing of the affected roadway. Table 15 Assumptions on non-planned bridge downtime related to roadway Planned and stochastic events affecting roadway Assumptions on corrective actions contribution to downtime Yearly inspection Principal inspection Replacement No foreseen downtime due to corrective actions No foreseen downtime due to corrective actions Damage to underlying steel during replacement of wearing course and isolation may lead to prolonged downtime beyond planned duration. I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

155 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 13/20 Table 16 Calculated non-planned bridge downtime related to roadway MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to roadway Mean downtime (in % of service life) % % % Mean annual days of downtime I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

156 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 14/ SECONDARY STEEL STRUCTURES Secondary steel on the bridge consists of safety barriers and railings, access stairs, sign and portals. The main accidental scenario affecting bridge availability is identified as traffic collisions resulting in unsafe barriers and/or railings. In such a scenario a special inspection and/or repair should be performed on the affected area which may result in closing of a single lane during a period of time. Table 17 Assumptions on non-planned bridge downtime related to secondary steel structures Planned and stochastic events affecting secondary steel Major maintenance Safety barriers and railings Principal inspection Safety barriers and railings Assumptions on corrective actions contribution to downtime No foreseen downtime due to corrective actions No foreseen downtime due to corrective actions Safety barriers and railings replacement No foreseen downtime due to corrective actions Principal inspection Signs, portals etc. No foreseen downtime due to corrective actions Major maintenance Signs, portals etc. Accidental loads No foreseen downtime due to corrective actions Car accident affecting safety barriers may require accidental inspection, potential repair safety barriers. Closedown of affected lane until barriers are considered safe. Table 18 Calculated non-planned bridge downtime related to secondary steel structures MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to secondary steel Mean downtime (in % of service life) % % % Mean annual days of downtime I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

157 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 15/ AUX SYSTEMS AUX systems consists of electrical and mechanical systems designed to support the functions of the bridge, not directly related to structural integrity. Monitoring, traffic control systems, drainage, access elevators, fire dampers etc. The vessel monitoring system, (VTS), is in place to alert the bridge of potential vessels on collision course. This means that besides the downtime related to vessel impacts, also vessels on collision course may lead to the decision of closing the bridge preventively. A signal failure in the traffic control systems may give a false signal for road users not to access the bridge (false red light), or may in itself be considered an unsafe state due to the reduced traffic control. Table 19 Assumptions on non-planned bridge downtime related to AUX systems Planned and stochastic events affecting AUX systems VTS Lighting and warning systems Assumptions on corrective actions contribution to downtime Large vessel on collision course, shut down bridge until safe. Signal failure, (loss of signal, or false red light ). Principal inspections. Electrical and mechanical installations Major maintenance/replacement. Electrical and mechanical installations No foreseen downtime due to corrective actions No foreseen downtime due to corrective actions Table 20 Calculated non-planned bridge downtime related to AUX systems MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to AUX systems Mean downtime (in % of service life) % % % Mean annual days of downtime EXTERNAL FORCES (EXCLUDING SHIP COLLISIONS) The bridge system has established operational criteria for wind and sea-states. The wind limit is set to 25 m/s, (ref NOT-GEN-013), which is assumed to result in corrective closing of the bridge 14.6 hours a year. I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

158 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 16/20 Major collision scenarios will lead to temporary closing of one or more lanes due to investigation/blockage. This scenario excludes the worst case event where the stay cables are affected. Loss of bridge power is seen as an external force. Assumed to have redundant power source(s). Frequency of sabotage/terror has not been quantified. Table 21 Assumptions on non-planned bridge downtime related to external forces Planned and stochastic events affecting external forces Wind limit 25 m/s Assumptions on corrective actions contribution to downtime Shut down bridge wind above 25 m/s. Major collision scenario (excluding fire/heat stay cables) Loss of bridge power (external) Clear roadway/lane; investigate causes (evidence etc.) Shut down bridge upon failed or depleted redundant power source Table 22 Calculated non-planned bridge downtime related to external forces MONTE CARLO SIMULATION Downtime from corrective action FULL ROADWAY LANE related to external forces Mean downtime (in % of service life) % % % Mean annual days of downtime I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

159 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 17/20 3 RESULTS NON PLANNED MAINTEANCE AND ACCIDENTAL EVENTS 3.1 Non-planned downtime sorted by system Table 23 below summarized the non planned downtime sorted by systems. Table 23 Non-planned Downtime sorted by systems Full Road Lane Pontoon system % % % Columns % % % Mooring % % % Superstructure % % % Towers % % % Stay cables % % % Fastenings and bearings % % % Roadway % % % Secondary steel % % % Aux systems % % % External forces % % % SUM % % % Annual hours downtime Full non-planned downtime by system Various structural inceptions may lead to temporary closure of bridge upon serious findings. Wind and ice equals to roughly ¾ of the non-planned downtime. Annual hour of downtime due to icing has a high uncertainty, the current quantification is believed to be conservative. I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

160 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 18/ Road non-planned downtime by system Damage to steel during replacement of wearing course main contributor. Very low sum in total, meaning that the distribution by system will change drastically by only minor changes in assumptions. 3.4 Lane non-planned downtime by system Mooring highest contributor due to high inspection and failure frequency, where corrective maintenance requires access by lane. Secondary steel is affected by traffic incidents, where damaged safety barriers is assumed to require closedown of affected lane. Maintenance on the pontoon system is conservatively assumed to require single lane for access, even though most of the corrective maintenance should be done from sea- I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx

161 BILAG E RESULTS FROM LOAD EFFECT ANALYSIS - WIND CURVED BRIDGE STAGE4 ENVIRONMENTAL LOADING ANALYSES. 19/20 I:\03 PROJECTS\ COWI Design Bjornafjorden\02 Project Folder\Risk\RAMS og teknologi\oppetid\not-gen-018 Downtime corrective maintenance docx