The Bjorøy Tunnel () is a subsea road tunnel in Vestland county, Norway. The tunnel is part of the Norwegian County Road 5236 which connects the island of Bjorøyna in Øygarden Municipality to the mainland near Håkonshella and Hilleren in Bergen Municipality. It crosses underneath the Vatlestraumen strait, reaching below mean sea level. It serves as a fixed link for the 900 residents of the islands of Bjorøyna and Tyssøyna as well as a large number of cottage owners who vacation on the islands. The first proposal was launched in 1980, and construction started on 29 September 1993. There were severe problems because the tunneling encountered an area of sandstone, causing a year's delay. The total construction cost was . It opened on 7 May 1996 and remained a toll road until 29 January 2005.
Specifications The Bjorøy Tunnel is a subsea tunnel which runs below the Vatlestraumen strait between the island of Bjorøy and the mainland of Bergen. It carries two lanes of Norwegian County Road 5236. It is the only fixed link for the islands of Bjorøy and Tyssøy (Tyssøy is connected to Bjorøy by a bridge). The tunnel is long and reaches below mean sea level. The maximum gradient is 10 degrees (about 18% grade). It is one of few tunnels in Norway without mobile telephone coverage, although there are emergency telephones that connect to the operation center of the Norwegian Public Roads Administration, and the tunnel will receive coverage with the future Norwegian Public Safety Radio.
Before the construction of the Bjorøy Tunnel, the geology of the area was thought to consist entirely of metamorphic basement rocks similar to those exposed on the surrounding islands. The Jurassic sediments encountered in the tunnel included breccia and conglomerate in contact with the underlying gneisses and a sandstone with coal fragments, some of which was quite unconsolidated. Spore and pollen samples gave an Oxfordian age (Late Jurassic) for the sequence. The sedimentary rocks appear to have been deposited into an eroded depression caused by a fault zone, which later reactivated, disrupting the bedding and causing steep dips.
History
Planning Since 1966, Bjorøyna had been served by the Alvøen–Bjorøyhamn Ferry. The plans for a tunnel to Bjorøyna were first launched by the engineer Jack Jahnsen in 1980. These were based on the then under construction Vardø Tunnel, which became the first subsea tunnel in Norway when it opened in 1982. He had a meeting at his place on 18 December 1980, to which the three municipal councilors from Bjorøyna also were invited, where he tried to get support for the tunnel, which would be the topic of a municipal council meeting on 20 December. The council unanimously voted in favour of establishing a committee to look into the tunnel. The committee was established on 6 January 1981 and concluded that there were three alternative possibilities to build a fixed link to Bjorøyna: a bridge from the island over Søre Steinsundet via Vestre Steinsundholmen, Kjerringholmen and Kaggen to Søre Snekkevik on Litlesotra; a tunnel under Vatlestraumen to Håkonshella; or a bridge over Vatlestraumen to Håkonshella or Kongshaug.
At the time, a bridge to Litlesotra was estimated to cost , a tunnel was estimated to cost , while a bridge over Vatlestraumen was estimated to cost . All three included a road connection to Tyssøyna, with the bridge proposals costing for the Tyssøyna connection, and the tunnel having a cost of , in part because the earthworks volume from the tunnel could be used to build a mole with a short bridge. Seismology tests conducted in August 1983 concluded that the ground had good conditions: the uncompacted material laid mostly only deep, albeit at times as deep as . The proposed tunnel crossing followed a mountain ridge, and the maximum depth was between , although the topography went steep down to those depths.
The plans were presented to Johan J. Jakobsen, Minister of Transport and Communications, and cooperation was started with the Norwegian Public Roads Administration to find a suitable connection to Tyssøy, so that they could also take advantage of the tunnel. To connect the two islands, it was chosen to build across Nautasundet, which was shallow and wide. In 1987, Kaare Hartman joined the committee and proposed that the tunnel be built with borrowed money, guaranteed by land-owners on the islands, and repaid using tolls. At the time the project was not on any prioritized investment list, and this way the project was not dependent on public grants. On 7 September 1987, Hartmann reached agreement with Norges Skibshypotek to borrow the estimated . The bank had a guarantee in the income from the tunnel.
However, Norges Skibshypotek had to withdraw, as it was not permitted to invest in non-shipping investments. Instead, a loan was taken in Bergens Skillingsbank. Four land-owners made a guarantee for NOK 9 million, with a judicial registration covering an area of . They hoped that the value of their land would increase after the tunnel had been built. The same amount was also guaranteed by Fjell Municipality. Public grants were also secured, so the debt would be NOK 27 to 30 million. The planning was done by Chr. F. Grøner, for which the municipality paid the costs. Statistics from the ferry showed that 26,400 cars and 93,902 people had taken it in 1986, which had grown to 40,400 and 121,000 in 1989. The estimates were for a 90% increase until 2000, given an opening in 2002. A bid for the project was gathered from Selmer–Furuholmen, which gave a maximum price of NOK 55 million, given that construction started in 1989.
On 12 December 1989, the committee sent an official offer to Hordaland Public Roads Administration whereby they, as a company under establishment, offered to fully finance the tunnel. The plans called for tolls of for a car and an investment cost of NOK 47 million. The plans were at first nearly discarded by the administration, as they felt it was impossible for a community of 400 people to finance such a large project without other grants. However, it became evident that the administration was spending NOK 2 million per year on the ferry service, and as the ferry soon would have to be replaced, this would increase to NOK 3 to 5 million per year. On 1 October 1990, the issue was considered by Hordaland Transport Board, which approved the plans. This was followed up by Hordaland County Council on 19 June 1991, which involved NOK 27 million being financed by debt and NOK 28 to 33 million being financed through reduced subsidies to the ferry.
The plans were met with criticism from locals on the Bergen side where the tunnel would emerge. They stated that the plans had "cheap solutions" and had unnecessary negative impact on their local environment. This included the demolishing of a football field and lack of noise barriers. Bergen Municipality demanded that the costs of a new field be paid for by the project, and that the tunnel be slightly extended. A new estimate was made, which increased the price by NOK 10.3 million; however, Hordaland Public Roads Administration protested, stating that it would give an inferior road technically, that the existing development plans permitted the construction, and that the noise would not exceed the permitted limits. They concluded that should these demands remain, the increased costs would terminate the project. On 16 November 1992, Bergen City Council voted to allow the tunnel, under the condition that the tunnel project financed a new football field. The decision was appealed by lawyers representing the local community, but this was rejected by Hordaland County Governor on 30 August 1993.
Originally the unlimited company Bjorøy og Tyssøy ANS had been established with capital from locals, but instead the company Fastlandssambandet Bjorøy – Tyssøy AS was established on 29 September 1993. Capital for NOK 40,000 was paid by Fjell Municipality, NOK 20,000 by Sund Municipality and NOK 10,000 by Jack Jahnsen. The plans were sent to the Ministry of Transport and Communications in October 1992, who started working on a proposal for parliament in January 1993. Issues raised by the ministry were that the loans had been issued in 1987, and whether the land estimated value of the guaranteed real estate was real. The project was presented to the Parliament of Norway, who must approve all toll roads. By then the costs were estimated at NOK 61.5 million, including NOK 4.5 million in ordinary county grants and NOK 30 million in extraordinary county grants. The proposal estimated annual toll collection costs to NOK 825,000, with the collection taking place at Bjorøy. It was originally planned that the toll plaza would be staffed between 06:00 and 22:00, meaning passing would be free at night.
An agreement was made between the ministry, the tunnel company and the county municipality on 6 January 1994 to build the tunnel. The company had the right to collect tolls for up to 15 years on fees dictated by the county municipality, and would have to pay NOK 27 million for the tunnel, with the county paying the rest of the costs. The construction would be the responsibility of Hordaland Public Roads Administration, with the tunnel company only responsible for their part of the financing and the collection of tolls. An agreement was made with Selmer, whereby they would charge NOK 59,422,500 and take the risk of the project, including any expenditures for unknown geological conditions or similar costs increases. They were also responsible for an insurance to reclaim the investments should it prove impossible to build the tunnel.
Construction The construction of the tunnel started on 29 September 1993, with the original plans calling for the tunnel to open on 15 June 1995. The original construction consisted of blasting from Bjorøy, but by January 1994 there were problems with water leaks through cracks. The contractor described these as "common problems" when building tunnels, but that construction would be delayed by up to two weeks. To keep up with the schedule, the company started also blasting from the mainland. However, the problems increased, and by September the tunnel was leaking per minute, which was 50% more than estimated. This caused extra work to be done on the exterior to the tunnel, and costs had increased by several tens of millions of kroner. In particular, a different type of rock had been struck, and of concrete had been injected without this giving the desired effects.
On 30 September, Selmer stopped construction from the Bjorøy side, although it continued from the mainland. About from the Bjorøy side, the construction found a section of sandstone, the upper Jurassic Bjorøy formation, a condition that had never been encountered during subsea tunnel construction before. Geological engineers stated that there was no known solution to overcoming the problem, and that if the contractor had blasted into the area, the tunnel would have been filled with sand and water within minutes.