{ "id": "ep6xnb1tyh", "slug": "eiksund-tunnel", "title": "Eiksund Tunnel", "updated": "2026-10-15", "topic_path": [ { "id": "technology", "label": "Technology and the built world", "api_url": "https://www.edgepedia.org/api/v1/topics/technology" }, { "id": "technology.built", "label": "Architecture, buildings, and civil works", "api_url": "https://www.edgepedia.org/api/v1/topics/technology.built" }, { "id": "technology.built.civil", "label": "Civil and water works", "api_url": "https://www.edgepedia.org/api/v1/topics/technology.built.civil" }, { "id": "technology.built.civil.tunnels", "label": "Tunnels", "api_url": "https://www.edgepedia.org/api/v1/topics/technology.built.civil.tunnels" }, { "id": "technology.built.civil.tunnels.tunnels-by-mode", "label": "Tunnels by mode and use", "api_url": "https://www.edgepedia.org/api/v1/topics/technology.built.civil.tunnels.tunnels-by-mode" }, { "id": "technology.built.civil.tunnels.subsea-underwater-tunnels", "label": "Subsea and underwater tunnels", "api_url": "https://www.edgepedia.org/api/v1/topics/technology.built.civil.tunnels.subsea-underwater-tunnels" }, { "id": "technology.built.civil.tunnels.subsea-underwater-tunnels.norwegian-nordic-subsea", "label": "Norwegian and Nordic subsea rock tunnels", "api_url": "https://www.edgepedia.org/api/v1/topics/technology.built.civil.tunnels.subsea-underwater-tunnels.norwegian-nordic-subsea" } ], "geo": [ { "id": "geo.weu.t2001.technology.built.civil", "label": "Western Europe · 2001 to 2020: Civil and water works", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.weu.t2001.technology.built.civil", "path": [ { "id": "geo.weu", "label": "Western Europe", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.weu" }, { "id": "geo.weu.t2001", "label": "Western Europe · 2001 to 2020", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.weu.t2001" }, { "id": "geo.weu.t2001.technology", "label": "Technology and the built world", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.weu.t2001.technology" }, { "id": "geo.weu.t2001.technology.built", "label": "Architecture, buildings, and civil works", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.weu.t2001.technology.built" }, { "id": "geo.weu.t2001.technology.built.civil", "label": "Civil and water works", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.weu.t2001.technology.built.civil" } ] } ], "excerpt": "The Eiksund Tunnel is a subsea road tunnel in Møre og Romsdal, Norway, opened in 2008 and the world's deepest undersea road tunnel at 287 m.", "snippet": "The Eiksund Tunnel is a subsea road tunnel in Møre og Romsdal, Norway, opened in 2008 and the world's deepest undersea road tunnel at 287 m.", "node": "technology.built.civil.tunnels.subsea-underwater-tunnels.norwegian-nordic-subsea", "markdown": "# Eiksund Tunnel\n\nThe **Eiksund Tunnel** is a subsea road tunnel on county road 653 in the municipalities of Ørsta and Ulstein in Møre og Romsdal, Norway, running under the Eiksundet strait between the islands of Eika and Yksnøya and under Vartdalsfjorden as part of the Eiksundsambandet fixed link. Opened on 23 February 2008, it reaches 287 m below sea level, which made it the world's deepest undersea road tunnel at the time of construction.[1](https://snl.no/Eiksundtunnelen) • [2](https://www.ntnu.no/concept/eiksundsambandet)\n\n| Key fact | Detail |\n|---|---|\n| Length and depth | 7,765 m long, 10 m wide at its widest, lowest point 287.32 m below sea level[1](https://snl.no/Eiksundtunnelen) • [3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) |\n| Opened | 23 February 2008, replacing the Eiksund–Rjåneset ferry[1](https://snl.no/Eiksundtunnelen) |\n| Gradients | 9.6 percent over three lanes on the Eika side, 7.6 percent over two lanes to Steinnes[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) |\n| Cost and financing | About 970 million NOK in 2008 value (NTNU's evaluation lists 1,062 million NOK); roughly 75–80 percent state-financed, the rest tolls and local contributions[4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet) • [2](https://www.ntnu.no/concept/eiksundsambandet) |\n| Water control | 1.6 million kg of cement used for pre-grouting; residual inflow about 1,500 liters per minute, half the regulatory upper limit[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) |\n| Traffic | Projected at about 1,000 vehicles per day; nearly double that at opening, and about 2,800 daily after tolls were removed six years later[5](https://www.worldatlas.com/articles/which-is-the-deepest-undersea-road-tunnel-in-the-world.html) |\n| Record status | Deepest road tunnel in the world in 2008; the Solbakk tunnel reaches about 290 m below sea level[15](https://svbergteknik.se/wp-content/uploads/2024/11/BK2014.009.pdf), while Rogfast, under construction toward a 2033 opening at 392 m below sea level, is set to exceed that depth[6](https://www.ngi.no/en/news/rogfast-project/) |\n\n## Background and purpose\n\nBefore the fixed link, the island municipalities of Hareid, Ulstein, Herøy, and Sande, home to about 22,000 people, were connected to the mainland municipalities of Ørsta and Volda by three ferry services and a fast-boat connection.[2](https://www.ntnu.no/concept/eiksundsambandet) The project was established as early as 1978 under the company AS Eiksundbrua, and the Storting approved it on 1 February 2000 on condition of 25 percent local financing; ground was broken on 24 February 2003, twenty-five years after the company was founded.[2](https://www.ntnu.no/concept/eiksundsambandet) • [4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet)\n\nBusiness pressure shaped the decision. Industry in the region, including the Ulstein Group, threatened to relocate operations if no fixed link was built, and promised investment equal to the project's cost if it was.[2](https://www.ntnu.no/concept/eiksundsambandet) On opening day the link gave the four island municipalities a ferry-free road connection, and the Eiksund–Rjåneset ferry was discontinued.[4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet)\n\n## Design and construction\n\nThe alignment follows a mountain ridge that plunges to a seabed at 230 m; the road surface lies a further 57 m lower, and in places only 50 m of rock flanks the tunnel at its sides.[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) The Norwegian Public Roads Administration required the steeper gradients, 9.6 percent on the Eika side against 7 percent in the [Oslofjord Tunnel](https://www.edgepedia.org/oslofjord-tunnel), to shorten the tunnel and reduce its cost.[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) Norwegian practice allows subsea tunnel slopes typically between 6 and 8 percent depending on traffic, with up to 10 percent for low-traffic tunnels.[7](https://nff.no/wp-content/uploads/sites/2/2020/04/Publication-18.pdf)\n\nThe tunnel was excavated by drill and blast, the method used for all Norwegian subsea rock tunnels, through gneiss with a typical 63 m² cross-section on the two-lane side and 87 m² on the three-lane side.[8](https://www.tunnelsandtunnelling.com/news/mesta-holes-through-at-eiksund/) • [9](https://kipdf.com/sub-sea-tunnelling-as-an-option-for-strait-crossings_5aaddbf11723dd37770c463b.html) Contractor Mesta began in June 2004 under a contract priced at US$54 million and drove the 7.78 km tunnel for more than two and a half years, with about 1,800 blasts and 1,250 tonnes of explosive; in the best week almost 73 m was excavated.[8](https://www.tunnelsandtunnelling.com/news/mesta-holes-through-at-eiksund/) The final blast was fired on 1 February 2007 at 12:00, with breakthrough about 245 m below sea level; the drivers had reached the maximum depth of 287 m on the 31st of the previous month.[10](https://www.tu.no/artikler/gjennomslag-i-eiksundtunnelen/325320)\n\n**Geology and water.** The Geological Survey of Norway (NGU) identified two major refraction-seismic low-velocity zones along the alignment that could pose construction problems, and indicated that NW–SE oriented fracture zones had the greatest potential to be open to water flow.[11](https://www.ngu.no/publikasjon/regionalgeologisk-vurdering-av-omradet-rundt-eiksundsambandet) Two zones of poor rock quality were known in advance and were hit as predicted during excavation.[12](https://www.tu.no/artikler/apner-verdens-dypeste-tunnel/323205) Water control relied on pre-grouting: cement slurry is injected into fan-drilled holes ahead of the face to build an impervious zone around the tunnel, so that water pressure acting on the tunnel contour and lining can be close to nil, and the tunnel is not allowed to advance until the grouting criteria are met.[13](https://nff.no/wp-content/uploads/sites/2/2020/04/Publication-12.pdf) In total 1.6 million kg of cement sealed the leaks, leaving an inflow of about 1,500 liters per minute.[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) Permanent support consists of about 16,000 m³ of steel-fiber-reinforced shotcrete, 70 to 300 mm thick, and about 40,000 rockbolts typically 3 to 4 m long.[8](https://www.tunnelsandtunnelling.com/news/mesta-holes-through-at-eiksund/)\n\n## By the numbers\n\nThe tunnel is 7,765 m long and 10 m wide at its widest, with three lanes.[1](https://snl.no/Eiksundtunnelen) • [5](https://www.worldatlas.com/articles/which-is-the-deepest-undersea-road-tunnel-in-the-world.html) Its lowest point lies 287.32 m below sea level, where the water pressure above the tunnel is about 30 kg per square centimeter.[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) The full new road of national road 653 between Eiksund and Furene, including bridges and land tunnels, totals 14,880 m.[4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet)\n\n**Cost figures differ between sources.** The official project brochure and trade press put final costs at about 970 million NOK in 2008 value, 25 million under the 995 million estimate, with the state covering 75 percent (727.5 million NOK), tolls at most 20 percent (194 million), and 5 percent (48.5 million) from municipalities, business, and private donations.[4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet) • [12](https://www.tu.no/artikler/apner-verdens-dypeste-tunnel/323205) NTNU's later project evaluation lists a final cost of 1,062 million NOK and a state share of about 80 percent.[2](https://www.ntnu.no/concept/eiksundsambandet) The brochure figure is the indexed 2008 value, while the NTNU figure is described only as the final cost. Prepaid tolls collected from 1997 as a surcharge on ferry tickets raised about 3 million NOK per year for planning, and the car toll at opening was set at NOK 76 per crossing.[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) The toll was expected to be removed around 2014/15, roughly six years after opening, once the local share was covered.[2](https://www.ntnu.no/concept/eiksundsambandet)\n\n## How it compares with other subsea tunnels\n\nNorway has built more than 40 subsea tunnels since the early 1980s, including 25 road tunnels, 8 pipeline tunnels, and 8 water and sewerage tunnels; within that family, Bømlafjord is 7.9 km long and Eiksund reaches 287 m below sea level.[7](https://nff.no/wp-content/uploads/sites/2/2020/04/Publication-18.pdf) Hitra at 264 m, Bømlafjord at 260 m, and Eiksund at 287 m have not experienced any special problems.[7](https://nff.no/wp-content/uploads/sites/2/2020/04/Publication-18.pdf)\n\nThe [Ryfast](https://www.edgepedia.org/ryfast) project's Solbakk tunnel near [Stavanger](https://www.edgepedia.org/stavanger) consists of two parallel tubes 14.3 km long, reaching about 290 m below sea level.[14](https://nva.sikt.no/registration/0198cc90aaca-3100f4f5-3154-4c1f-ad71-c36ddacbdc19) • [15](https://svbergteknik.se/wp-content/uploads/2024/11/BK2014.009.pdf)\n\n## Operation and safety\n\nThe tunnel carries 26 ventilation fans of 25 kW each in the tunnel roof.[4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet) Emergency laybys are provided every 500 m, widened to turning niches every 2,000 m, and three turnaround points can accommodate reversing trailers.[4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet) • [3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) The whole facility is remotely monitored from the road traffic control center in [Trondheim](https://www.edgepedia.org/trondheim), and the tunnel is equipped with a leaky-feeder radio antenna cable, rescue communication, mobile phone coverage, and SOS cabinets with fire extinguishers and emergency telephones.[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) • [1](https://snl.no/Eiksundtunnelen)\n\n**Water management** continues in operation: five pump stations lift the inflow, and an emergency basin at the lowest point can hold water for two days if the pumps fail during a power outage, until repairs are made.[3](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663) This matches the Norwegian standard that a subsea tunnel's sump must store at least 24 hours of allowed inflow.[7](https://nff.no/wp-content/uploads/sites/2/2020/04/Publication-18.pdf)\n\n## Regional impact\n\nTravel time between Volda and the island municipalities fell by up to 20 minutes, and annual average daily traffic between the mainland and the island communities nearly quadrupled.[2](https://www.ntnu.no/concept/eiksundsambandet) Traffic ran at nearly double the projected 1,000 vehicles per day from the start, and grew to about 2,800 daily after the toll was removed.[5](https://www.worldatlas.com/articles/which-is-the-deepest-undersea-road-tunnel-in-the-world.html) The link also increased air traffic at Hovden airport, where [Widerøe](https://www.edgepedia.org/wider-e) introduced a new morning flight and doubled capacity, and Ulstein Group chairman Idar Ulstein credited the link with expanding the labor market and making the area's municipalities more robust.[16](https://ulsteinhistorielag.no/kultur/liv-og-lagnad/ulstein-veks-fram/2000-talet/eiksundsambandet-kommunikasjonar-og-boss/) Together with the Kvivsvegen road, travel time to Oslo was reduced by over an hour.[4](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet)\n\n## Recent developments\n\nEiksund's depth record is being overtaken by [Rogfast](https://www.edgepedia.org/rogfast), the Rogaland fixed link that will cut travel time between Stavanger and Bergen. The Norwegian Geotechnical Institute lists it at 27 km long and 392 m below sea level, figures that would make it the world's longest and deepest road tunnel, with two bores connected by escape passages and a planned opening in 2033.[6](https://www.ngi.no/en/news/rogfast-project/) As of April 2025 the project was roughly half complete, with about 65 percent of tunnelling done on the north side and about 45 percent at the south end, at a cost of 25 billion NOK (about €2 billion).[17](https://www.euronews.com/2025/04/09/norway-is-building-the-worlds-longest-and-deepest-subsea-road-beneath-its-fjords) Construction began in January 2018, was halted in late 2019 over predicted cost overruns, and resumed in late 2021.[18](https://edition.cnn.com/travel/norway-longest-deepest-underwater-tunnel-spc) The main construction challenge at 300 m depth has been extensive saltwater leaks, controlled by the same family of grouting techniques used at Eiksund: when leakage at the rock face exceeds roughly four liters per hole per minute, cement-like slurry is pumped into fan-drilled holes to seal the rock.[18](https://edition.cnn.com/travel/norway-longest-deepest-underwater-tunnel-spc) • [19](https://www.technologyreview.com/2026/06/22/1138821/inside-worlds-deepest-longest-subsea-road-tunnel/)\n\n## References\n\n1. [Eiksundtunnelen – Store norske leksikon](https://snl.no/Eiksundtunnelen)\n2. [Eiksundsambandet – NTNU Concept project evaluation](https://www.ntnu.no/concept/eiksundsambandet)\n3. [Eiksundsambandet – byggeprosjekter.bygg.no project documentation](https://byggeprosjekter.bygg.no/2008-bildekarusell-more-og-romsdal/eiksundsambandet/1882663)\n4. [brosjyra – Eiksundsambandet (official project brochure)](https://www.yumpu.com/no/document/view/18388247/brosjyra-eiksundsambandet)\n5. [The Eiksund Tunnel – the World's Deepest Undersea Road Tunnel, WorldAtlas](https://www.worldatlas.com/articles/which-is-the-deepest-undersea-road-tunnel-in-the-world.html)\n6. [Rogfast project – Norwegian Geotechnical Institute](https://www.ngi.no/en/news/rogfast-project/)\n7. [Publication No. 18: Subsea tunnels – Norwegian Tunnelling Society](https://nff.no/wp-content/uploads/sites/2/2020/04/Publication-18.pdf)\n8. [Mesta holes through at Eiksund – Tunnels and Tunnelling](https://www.tunnelsandtunnelling.com/news/mesta-holes-through-at-eiksund/)\n9. [Sub-sea tunnelling as an option for strait crossings (Eivind Grøv, SINTEF)](https://kipdf.com/sub-sea-tunnelling-as-an-option-for-strait-crossings_5aaddbf11723dd37770c463b.html)\n10. [Gjennomslag i Eiksundtunnelen – Teknisk Ukeblad](https://www.tu.no/artikler/gjennomslag-i-eiksundtunnelen/325320)\n11. [Regionalgeologisk vurdering av området rundt Eiksundsambandet – NGU](https://www.ngu.no/publikasjon/regionalgeologisk-vurdering-av-omradet-rundt-eiksundsambandet)\n12. [Åpner verdens dypeste tunnel – Teknisk Ukeblad](https://www.tu.no/artikler/apner-verdens-dypeste-tunnel/323205)\n13. [NFF Report No. 12: Water control – Norwegian Tunnelling Society](https://nff.no/wp-content/uploads/sites/2/2020/04/Publication-12.pdf)\n14. [Main challenges related to deep subsea tunnels – research repository record](https://nva.sikt.no/registration/0198cc90aaca-3100f4f5-3154-4c1f-ad71-c36ddacbdc19)\n15. [RV 13 Ryfast, world's longest subsea road tunnel – SV Bergteknik project documentation](https://svbergteknik.se/wp-content/uploads/2024/11/BK2014.009.pdf)\n16. [Eiksundsambandet, kommunikasjonar og boss – Ulstein Historielag](https://ulsteinhistorielag.no/kultur/liv-og-lagnad/ulstein-veks-fram/2000-talet/eiksundsambandet-kommunikasjonar-og-boss/)\n17. [Inside Norway's project to build the world's longest and deepest subsea road – Euronews](https://www.euronews.com/2025/04/09/norway-is-building-the-worlds-longest-and-deepest-subsea-road-beneath-its-fjords)\n18. [Milestone for the world's longest underwater road tunnel – CNN](https://edition.cnn.com/travel/norway-longest-deepest-underwater-tunnel-spc)\n19. [Inside the world's deepest and longest subsea road tunnel – MIT Technology Review](https://www.technologyreview.com/2026/06/22/1138821/inside-worlds-deepest-longest-subsea-road-tunnel/)\n\n---\n*Topic: Encyclopedia › Technology and the built world › Architecture, buildings, and civil works › Civil and water works › Tunnels › Tunnels by mode and use › Subsea and underwater tunnels › Norwegian and Nordic subsea rock tunnels*\n\n*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Sep 30, 2026; Oct 15, 2026 · Last review: Oct 15, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/eiksund-tunnel", "markdown_url": "https://www.edgepedia.org/eiksund-tunnel.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"Eiksund Tunnel\", Edgepedia (EdgeChat), https://www.edgepedia.org/eiksund-tunnel. Edgepedia Community License 1.0.", "credit_md": "\"[Eiksund Tunnel](https://www.edgepedia.org/eiksund-tunnel)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/eiksund-tunnel](https://www.edgepedia.org/eiksund-tunnel). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"Eiksund Tunnel\", Edgepedia (EdgeChat), https://www.edgepedia.org/eiksund-tunnel. Edgepedia Community License 1.0.", "speakable": "The Eiksund Tunnel is a subsea road tunnel in Møre og Romsdal, Norway, opened in 2008 and the world's deepest undersea road tunnel at 287 m." }