The Oslofjord Tunnel () is a subsea road tunnel which traverses the Oslofjord, connecting Hurum and Frogn in Norway. Carrying three lanes, the long tunnel reaches a depth of below mean sea level. The tunnel has a maximum gradient of seven percent. It acts as a link connecting eastern and western Akershus county, supplementing the Moss–Horten Ferry which runs further south. The tunnel is since 2018 a part of European route E134, until 2018 it was part of National Road 23.
The crossing was originally served by the Drøbak–Storsand Ferry, which commenced in 1939. Plans for a fixed link were launched in 1963, originally based on two bridges which would connect to Håøya. Plans resurfaced in the early 1980s with the advent of subsea tunneling technology and the Oslo Airport location controversy, which proposed airports in Hurum, Ås and Hobøl. Even though Gardermoen was ultimately built as the airport, the tunnel had raised sufficient support to be built irrespectively. Parliament gave approval on 13 December 1996 and construction started on 14 April 1997. The tunnel was official opened on 29 June 2000 and was financed in part by a toll, collected by Bompengeselskapet Oslofjordtunnelen at a toll plaza in Frogn. In 2014, the manual toll station was replaced by an automatic station. Since 30 August 2016, it is free to pass through the tunnel.
The tunnel was flooded in 2003 and 2008 and experienced a landslide in 2003. All of these incidents resulted in the tunnel being closed for weeks. There have been two major truck fires, one in 2006 and one in 2011. After the latter incident, the tunnel has been closed for heavy traffic exceeding 7.5 tonnes. In an effort to eliminate the problem, the Public Roads Administration has proposed building a second tube.
Specifications The Oslofjord Tunnel is a long subsea tunnel which constitutes part of European route E134 and is hence part of the Trans-European road network. The tunnel traverses below Drøbaksundet of the Oslofjord, reaching a maximum depth of below mean sea level. The tunnel has three lanes, with one used as a climbing lane in the uphill direction to overcome the seven percent gradient. It has a speed limit of , which is enforced by traffic enforcement cameras. The tunnel has a width of and was at the time of construction build after criteria for a traffic of up to 7,500 vehicles per day.Alteren (2004): 7
The tunnel is equipped with 25 evacuation rooms. These can be sealed off from the main tunnel and can each provide pressurized space for thirty to fifty people while a fire is being fought. There is a natural flow of of sea- and ground water into the tunnel every minute. To handle this a pump system is installed capable of draining per minute. There is a natural reservoir under the tunnel able to retain of water, which can act as a buffer. It can also be used as a water source for the fire department. The tunnel is built with continual concrete elements to ensure better protection against water leaks. The structure has received artistic decorations in the form of gobo lighting.
The tunnel is indefinitely closed for vehicles exceeding in length. From the onset it was designed to be expanded to two tubes, hence a second tube was designed to be built on the south side.Norwegian Public Roads Administration (2013): 5 European Road 134 is long and runs from Haugesund through Drammen to the E6 at Vassum in Frogn. The section from Bjørnstad in Røyken to Vassum was built at the same time as the tunnel and is referred to as the Oslofjord Link (Norwegian: ). The crossing primarily serves as a quicker link connecting Buskerud to Follo and Østfold. Alternative crossing involve driving north via Oslo or south via the Moss–Horten Ferry. The route saves and 30 minutes compared to driving via Oslo.
The tunnel is owned and operated by the Norwegian Public Roads Administration. As part of a national road, its operation and maintenance is financed by the national government. Toll collection is carried out by Bompengeselskapet Oslofjordtunnelen AS, a limited company owned in equal shares by Akershus County Municipality and Buskerud County Municipality. They have subcontracted the operations of their administration and the toll plaza to Vegfinans. Undiscounted toll prices are NOK 60 for cars and NOK 130 for trucks (vehicles exceeding 3.5 tonnes). Payment is automated through Autopass. The tunnel experienced a traffic an average 4,432 vehicles per day in 2003. The average annual peak was reached at 7,138 in 2010, before falling to 6,827 in 2012. The road is owned and maintained by the Norwegian Public Roads Administration as a nationally financed project.
History
Planning
The connection between Follo and Hurumlandet was originally served by the Drøbak–Storsand Ferry, a service operated by Bilferjen Drøbak–Hurum. Planning of the ferry service commenced in 1939 and its first ferry, Leif 1, serve the crossing until 1954. It was then replaced with Drøbaksund, which was itself replaced with the larger Drøbaksund II in 1968. The company took over the Svelvik–Verket Ferry, which connects Hurumlandet to Vestfold, in 1971. Drøbaksund I was put into service in 1978 and Drøbaksund III in 1985. From 1993 it was supplemented with Hurumferja, hence the service having two ferries. The ferry had a daily traffic of 320 vehicles in 1980.Asplan (1980): 25
A fixed crossing of Hurumlandet and the Oslofjord was first proposed by Anton Grønsand in 1958.Messel (2004): 429 It was followed up in a regional transport plan published in 1963, with a horizon of forty years. Road planning was in the following decade reorganized so that most planning fell within the jurisdiction of a single county. As a crossing of the Oslofjord invariable would have to cross a county border, plans fell outside the natural planning framework.Asplan (1982): 21 As the idea fell out of the main workload of planners, a limited company, A/S Fjordbroene, was established in 1967. Initiated by Hurum Municipality, it was also partially owned by larger companies in the municipality. It attempted to revitalize the proposal and launched a detailed plan in 1974 which called for two bridges which would connect each side of the fjord to the island of Håøya. The cost of the project was steep, the Håøya bridges alone estimated at 510 million 1981 Norwegian krone (NOK). The plans were rejected by the road administration because of the steep cost and low traffic prognosis, while others criticized the environmental impact it would create on Håøya and at the towns of Svelvik and Drøbak.Asplan (1982): 21
Interest in the project was rekindled in the late 1970, when the subsea Vardø Tunnel was planned and later built. The choice of a subsea tunnel alternative would allow for major costs savings, easily shaving away half the cost. Another contributing factor was the Oslo Airport location controversy, which proposed various locations for a new airport. A fixed crossing would be allow for a fixed service from Vestfold and Buskerud if an airport was located in Hobøl or Ås, and it would allow for a fixed service from Follo and Østfold if the airport was located in Hurum. Also the construction of a new plant at Tofte Cellulosefabrikk was expected to give a large rise in lumber transport to the region and could contribute to cross-fjord traffic.Asplan (1982): 22 Previous analysis had been based on traffic data collected for other uses, so in 1980 a dedicated traffic survey was carried out.Asplan (1982): 23
A report from 1982 recommended that construction be carried out in two phases. First a road departing from the E18 at Jessvoll near Drammen through Røyken and then under the fjord before terminating at an intersection with the E6. The second phase would see the construction of a road from the tunnel through Hurum to Verket, in a new subsea tunnel under the Drammensfjord near Svelvik and then through a tunnel to Sande, where it would intersect with the E18.Asplan (1982): 37 Cost estimates for the tunnel ranged between NOK 200 and 360 million.Asplan (1982): 41 The plans were based on partially using part of National Road 154 in Buskerud for part of the feeder road. Cost estimates for the auxiliary road system was estimated at between NOK 340 and 400 million, depending on the amount of reused road and the standard chosen.Asplan (1982): 45
The bridge alternative had some proponents during the 1980s. It was proposed consisting of the Drøbak Bridge, a three-pylon cable-stayed bridge with main spans of , respectively, with the central pylon placed on Askholmen. On Håøya the route would largely run through a tunnel. Across Vestfjorden the road would cross on another three-pylon cable-stayed bridge with main spans of , with the central pylon placed on Stedgrunnen.Styri (1988): 44 The bridge could also serve as possible route for the Hurum Line, a railway which was proposed to link the new airport to the capital.Styri (1988): 58 Fjordbruene worked for a bridge alternative, but also made detailed plans for a tunnel. The tunnel plans were passed unanimously by the municipal councils in Røyken and Frogn in February 1986 and by a large majority in Akershus County Council in April. By 1988 three of the four bridge alternatives had been vetoed by the Norwegian Armed Forces. On 21 June Action Against a Bridge was established in Drøbak and had more than 2,000 members within days.
Parliament voted on 8 June 1988 to build the new national airport at Hurum. The decision included a four-lane motorway-crossing of the Oslofjord. The Public Roads Administration published six alternatives for a crossing, including four bridge alternatives, a conventional tunnel and an immersed tube. Planning halted in 1990 after the airport construction decision was shelved. By then only the Socialist Left Party in Hurum Municipal Council being opposed. Without the airport traffic, the profitability in the project fell through and the Public Roads Administration called to instead prioritize other investments. However, Minister of Transport and Communications Kjell Opseth was a staunch supporter of the Oslofjord Link, in part as a compensation for the loss of the airport after it in 1992 was decided to be built at Gardermoen.
The Public Roads Administration landed in 1992 at a bridge alternative as their preferred solution,Messel (2004): 430 backed among others by the Norwegian Haulier’s Association and Hurum Municipality. The former stated that a bridge would result in trucks consuming only half as much fuel on the segment, while the latter was also enacted by the prospect of the bridge becoming a tourist attraction. On the other hand, the bridge was met with protests from environmental organizations and residents of Drøbak and the ministry thus decided to go for a tunnel. A full-scale construction was debated, with two tubes and a new highway all the way to Lier.