The Askøy Bridge () is a suspension bridge that crosses Byfjorden between Bergen Municipality and Askøy Municipality in Vestland county, Norway. It is long and has a main span of . Its span was the longest for any suspension bridge in Norway, until the Hardanger Bridge, also in Vestland, opened in August 2013. Now the bridge is the third longest in Norway. It carries two lanes of County Road 562 and a combined pedestrian and bicycle path. The bridge's two concrete pylons are tall and are located at Brøstadneset in Bergen municipality (on the Bergen Peninsula of the mainland) and Storeklubben in Askøy Municipality (on the island of Askøy). The bridge has seven spans in total, although all but the main span are concrete viaducts. The bridge has a clearance below of .
The first plans to replace the Kleppestø–Nøstet Ferry with a bridge, which would allow the island of Askøy to have a fixed link, was launched in the 1960s. Various proposals were made, including placing the bridge further east and closer to Bergen, and building a submerged floating tunnel. In the early 1970s, a toll company was established to finance the bridge, but the planned costs were too high to cover with just tolls and there was the lack of a motorway to Bergen from the west. Because of this, the construction of the bridge was postponed. In the early 1980s, there was controversy about whether advanced tolls should be charged on the ferry; these were ultimately charged from 1984 until the bridge opened. Construction started in 1989 and the bridge opened ahead of schedule on 12 December 1992, along with a new section of the road which included the Stongafjell Tunnel and Olsvik Tunnel. The bridge remained a toll road until 2006.
Specifications The bridge is a long suspension bridge with a main span of . It has two concrete pylons, each , albeit tall when including the mounts for the suspension cable. The pylons are wide and vary in width between at the top to at the bottom. They pylons have three horizontal connectors, one under the deck at , one at and one at the top.Fossen (1995): 154 The bridge has seven spans, with all but the main spans being concrete viaducts, and thus not connected to the suspension cable. The aerodynamic closed bridge girder has a vertical radius of , a height of and a width of . The bridge deck is wide; each of the two main lanes are wide, while the pedestrian and bicycle path is wide. The bridge can be reconfigured to instead carry three lanes, with a new bicycle and pedestrian path being mounted on the side.
There are two main cables, one on each side, which consist of twenty locked coil cables in a seven wide and three tall matrix. Each strand has a diameter of . The cable has a quality of 1,570 megapascals. Each coil, which consists of 289 wires, can tolerate at least and weighs . The cables are anchored in rock below the road level. The main span's sag-to-span ratio is 1:10. The bridge has a wide clearance below of . The bridge carries two lanes of County Road 562 across Byfjorden, between Storeklubben in Askøy and Brøstaneset in Bergen.Fossen (1995): 155 In 2010, the bridge had the daily average traffic of 17,251 vehicles.
History
Proposals and planning The first official discussion of a bridge from the mainland to Askøy was on 15 December 1960, when municipal councilor Alf Fagerli took up the issue in the municipal council based on the plans for the Sotra Bridge, which would create a fixed link for Sotra to the mainland.Fossen (1995): 17 The council asked Engineer Caspar Trumpy to make proposals for a bridge. It was followed by a public meeting on 8 March 1961 in Laksevåg, where the transport for the areas west of Bergen, Laksevåg, Sotra and Askøy, was discussed.Fossen (1995): 18 On 8 September the municipal council considered Trumpy's five proposals, which varied in cost from . Four of the proposals ran to Kvarven, while one proposal went from Storeklubben to Bøstadneset. All would require additional roads on both sides.Fossen (1995): 19 To follow up the proposals, the municipality established a bridge committee on 30 November 1961, which was chaired by Mayor Olav Bjørkaas and with Johan Sørensen as deputy chair.Fossen (1995): 20
The committee presented its conclusions to the municipal council on 8 December 1966: they felt it would be economically feasible to have the bridge completed by 1975, that it should be built between Storeklubben and Brøstadneset, and that it was necessary to establish a toll company to finance part of the bridge.Fossen (1995): 21 The chief-of-administration commented that the estimates had only vague guesses at the frequency at which people would use the bridge and that if these fell short the toll company would have large losses which would have to be covered by the municipality. There was also a discussion as to whether ferry should be kept, but as a passenger-only service.Fossen (1995): 22 Estimates also showed that travel time from Askøy to Bergen would remain the same as with the ferry, and that few people would use cars to work with the prospected tolls.Fossen (1995): 24 The council voted with 35 against 8 votes to support the proposal from the committee.Fossen (1995): 27 Additional plans from Trumpy for the bridge were presented in 1969, this time also including proposals for both a two-lane and four-lane bridge. The latter would increase the costs with . At the time the bridge was estimated to cost .Fossen (1995): 31
Because of the depth of Byfjorden, which reaches below mean sea level, Trumpy had not looked into a conventional subsea tunnel. However, he had instead considered a submerged floating tunnel, but concluded that it was unrealistic, in part because of the anchoring depth, in part because of the strong current and in part because no such tunnel had ever been built.Fossen (1995): 29 On 21 March 1969, Engineer Per Tveit held a lecture in Bergen, where he projected that a tunnel to Askøy at Kvarnen would cost NOK 28 million.Fossen (1995): 30 Trumpy estimated the cost of the tunnel, which would be in water and to NOK 150 million.Fossen (1995): 34 In 1970, modified plans were launched for a submerged tunnel which instead of being anchored in the seabed instead was horizontally suspended at each end in bedrock.Fossen (1995): 35
On 12 November 1970, the municipal council voted to establish a limited company to finance the bridge.Fossen (1995): 37 Askøybrua AS was founded with a share capital of NOK 775,000 and owned by the municipalities of Askøy, Laksevåg, Åsane, Fjell, Sund and Øygarden, Hordaland County Municipality and Rutelaget Askøy–Bergen—the latter who operated all the islands bus routes and the ferry.Fossen (1995): 38 During the council meeting, representatives for the municipal administration commented that 85 percent of the people from Askøy who worked outside the municipality worked in the city center of Bergen; they were transported quickly with ferries which were not hampered by congestion. Should a bridge be built, it would only be able to be financed if people traveled using the bridge, and therefore terminating the ferry, even though it provided a superior service, was proposed.Fossen (1995): 39
The plans and financing estimates for the bridge were sent to the Norwegian Public Roads Administration on 7 July 1972, who from then took the leading role in planning the bridge. The administration stated the same month that they intended to work on the plans for the bridge between Storeklubben and Brøstadneset.Fossen (1995): 41 In 1974, the administration stated that they would pay for maintenance of the bridge and auxiliary roads, which would save the toll company NOK 700,000 per year.Fossen (1995): 43
Bergen Municipality, which merged with the surrounding municipalities of Arna, Åsane, Fana, and Laksevåg on 1 January 1972, was skeptical to the plans for a new bridge. They were concerned that additional cars and buses would clog up the city center additionally. The issue about joining the toll company was placed on hold within Bergen Municipality, and without Bergen signing for the required shares, the company could not be established.Fossen (1995): 40 Not until 5 November 1973 did Bergen Municipal Council vote to purchase the shares in the company. This was in part motivated by a report that showed that 46% of the traffic on the ferry was going to places south and west of the city center—traffic which would not contribute to congestion with a bridge. The company was officially founded on 14 March 1974 with Bjørkaas being appointed chair and Sørensen deputy chair.Fossen (1995): 42 They would both remain in these positions until 1993.Fossen (1995): 148Fossen (1995): 149
After the proposals for a tunnel died out in 1970, there remained two critical groups against the project: those who were in favor of the bridge, but critical to the details in the plan, and those who were opposed to a bridge and wanted to keep the ferry service. The former group was largely concerned about the choice of the outer route, rather than the inner crossing to Kvarven. The latter would give a significantly shorter route to the city center, and the same driving distance to places south of Bergen, including Bergen Airport, Flesland.Fossen (1995): 44 Another issue was that there was not a sufficient road network in Bergen to handle the traffic from the bridge.Fossen (1995): 46 Starting in late 1970, a petition was created demanding a referendum about which crossing should be chosen.Fossen (1995): 47 The issue was discussed in the municipal council on 23 April,Fossen (1995): 48 and was dismissed with five votes in favor of a referendum.Fossen (1995): 49
Inflation during the early 1970s increased the cost estimates for a four-lane bridge to NOK 120 million in 1974, and to NOK 166 million including auxiliary roads. In 1976, the Public Roads Administration proposed that the bridge be built with two lanes and a pedestrian and bicycle path which later could be converted to a third lane.Fossen (1995): 53 On 6 June 1977, the toll company sent an application to the county asking for how much county and state grants they could get for the bridge, and if it would be possible for the county to guarantee for the loan. The company stated that they felt they should receive the same conditions as the by then completed Sotra Bridge, where they state had paid for the auxiliary roads and a third of the bridge. The company offered to advance most of the state's grants, and receive them back in a period of twelve years. The plans at the time involved connecting the bridge to the existing county road at Kjøkkelvik and use it onwards to Loddefjord.Fossen (1995): 54