The Sotra Bridge () is a suspension bridge which crosses Knarreviksundet between Knarrevik in Øygarden Municipality and Drotningsvik on the mainland of Bergen Municipality in Vestland county, Norway. It carries two road lanes and two narrow pedestrian paths of National Road 555, providing a fixed link for the archipelago of Sotra. The bridge is long, has a main span of and a clearance of . In 2007, it had an average 25,494 vehicles per day.
The bridge was brought into use on 11 December 1971, although not officially opened until 1972. It cost 40 million Norwegian krone (NOK) to build, of which NOK 23.5 million was paid for with tolls, which were collected until 1983. When it opened, it was the longest suspension bridge in Norway, but is now the seventh longest. There exist plans to build a second bridge to either expand the road to four lanes, or carry a proposed extension of the Bergen Light Rail. Alternatively, a subsea tunnel could be built to carry a motorway.
Specifications
The concrete bridge crosses Knarreviksundet, which separates the island of Litlesotra, part of the Sotra archipelago, from the mainland and Bergen. The western part of the bridge, on Sotra, lies in Knarrevik in Fjell, while the eastern part lies in Drotningsvik in Bergen. The bridge is long with a main span of . It carries two lanes of National Road 555, with a combined width of . In addition, it has a wide sidewalk on each side. In 2009, it had an annual average daily traffic of 25,494 vehicles. Because it is located across the sound, the bridge is vulnerable to winds from the north and south. It is closed whenever the wind speed exceeds .
History
Planning
The first discussion of a bridge in a public forum was in 1954, when Anton P. Torsvik proposed a bridge to the major and municipal engineer of Fjell. Torsvik lived in Oslo and had worked with public relations for various other bridge projects. The issue was discussed in the municipal councils of Fjell and Sund, but they both concluded that there were more pressing needs on the islands' road network, so they did not want to prioritize a bridge. National Road 555 was completed in 1957, and the following years various road projects were completed.
Another person who took up the initiative in the late 1950s was Rangvald Iversen, who was plant manager at Norwegian Talc at Knarrevik. The plant had large costs freighting their products across the sound on the Alvøy–Brattholmen Ferry. In 1958, he took the initiative to conduct a traffic count, which along with estimates of increased traffic from other places that had replaced a ferry with a bridge, would give estimates for the revenue from tolls. Norwegian Talc also paid for a draft plan for a bridge. In 1959, Iversen presented an estimate that a bridge would cost NOK 15.5 million, and on 19 December 1959, the council voted unanimously to recommend that a committee be established to continue work on the bridge plans. In 1960, the bridge was included in the road plan for Hordaland.
There were also some plans for the future which would remove the last ferries within the Sotra and Øygarden archipelagos, meaning that the entire twin archipelago would have ferry-free access to the mainland, should the Sotra Bridge be built. The plans had been spurred by a large decrease in fishing during the late 1950s, and the need for increased tax revenue from new industries. The framework for the plan started in 1961 with the creation of an inter-municipal cooperation, which in 1964 resulted in the merger of the municipalities of Hjelme and Herdla to create Øygarden. On 8 May 1962, an inter-municipal road committee was established, which recommended that a limited company be established to finance the bridge. In Bergen, Bro og Tunnelselskapet had similarly built the Puddefjord Bridge and Eidsvåg Tunnel, and the inter-municipal council recommended a similar model. However, they wanted a separate company for Sotra and Øygarden, so extra tolls could be used to help finance road projects on the archipelago.
On 29 June 1962, Fjell Municipality sent an official application to the County Governor to start planning, and this was sent onwards to the Directorate for Public Roads. They concluded that it would be possible to finance the bridge with tolls collected over 13 to 14 years, with the state paying for one-third of the bridge. The plans called for the bridge to run south of Norwegian Talc, but it was later routed slightly north, so that the span could be reduced from . The optimal location would be within the Norwegian Talc plant, and by placing the western pylon on a skerry, it was possible to reduce the span to .