Ship services in Nordhordland started in 1866, and in 1923 the first car was purchased. A car ferry service between Isdalstø in Lindås and Steinestø in Åsane on the mainland was established on 7 July 1936. A plan was launched whereby all traffic from Nordhordland would be collected in one place and transported across Salhusfjorden to Åsane. By moving the ferry quay from Isdalstø to Knarvik, the length of the ferry service could be reduced. However, the fares would be kept the same and the extra revenue used to finance a bridge from Flatøy to Lindås. This allowed the Alversund Bridge to open in 1958, and the ferry service from Flatøy and Meland to move to Knarvik. The proposal to cross Salhusfjorden was launched during the planning of the Alversund Bridge. Cost estimates were made based on the Golden Gate Bridge in the United States, but it proved too expensive for a suspension bridge crossing between Frekhaug and Salhus.