A road trip through Norway’s fjords is drool-inducingly gorgeous but also painfully expensive (gas averages slightly less than $7 per gallon) and excruciatingly slow (most roads involve numerous mountain switchbacks and ferry crossings).
To solve the latter problem, Norway’s public roads administration is considering a $25 billion network of bridges and tunnels, including one that would float underwater to alleviate a ferry bottleneck between two of the country’s largest cities. The idea of floating tubes is born out of necessity: conventional bridges would impede ship traffic, while a conventional tunnel would be even more expensive.
The idea is also not new. Tunnels that float 500 feet beneath the surface of the water were first proposed in the 1980s for the Høgsfjorden, near the southern city of Stavanger, according to a presentation from the public roads administration. Although several construction firms submitted design proposals, including buoyant tubes anchored to the fjord’s floor or regular tubes suspended from floating pontoons, the project fizzled.
Last fall, the administration revisited the proposal for the Bjørnafjorden, a crossing of on the busy route between Stavanger and Bergen, Norway’s second largest city. The main span would be almost 3 miles long, according to the administration, and its twin tunnels would have a separate dedicated area for bikes and pedestrians.
The problem, according to engineers, is that the pontoon-stabilized and floating tether concepts need further evaluation and testing. One key step is understanding how the swells driven by the wind and the nearby Atlantic Ocean would affect the tunnels’ stability.
The project cost would include adding conventional bridges along the E39 road between Kristiansand in the south and Trondheim in the north, according to Wired. The project is expected to be completed by 2035.
As for whether Norwegians will trust the technology enough to drive through it, the project’s manager Kjersti Kvalheim told Wired she doesn’t think that will be a problem. “Norwegians are quite used to going underwater in tunnels,” she said.