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. 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. Trumpy estimated the cost of the tunnel, which would be in water and to NOK 150 million. 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.