The Halsafjord crossing, an asymmetric two-span suspension bridge with deep-water gravity-based foundation.

One of the considered concepts for crossing the 500 m deep Halsafjord is a two-span suspension bridge, with a main span of 1 641 m and a suspended side span of 560 m. The crossing proposal is part of the current campaign for a ferry-free E39 coastal highway route, which is the largest infrastructure project in modern Norwegian history. The concept uses a local reef with water depth about 90 m named the “Aakvikgrunnen” to land the deep-water gravity-based foundation (GBS).An extensive marine survey has been available for the detailed planning of the deep-water foundation. The foundation concept is largely derived from construction and installation techniques from the offshore industry. The paper demonstrates how bridge and offshore engineering can be combined to create novel concepts for crossing the deeper fjords and straits in the world.The concept development utilizes in-house developed computer code for optimizing the suspension bridge properties regarding cost, sustainability, risk and robustness. We have developed this system from our engineering work with some of the largest suspension bridges in Norway. We also couple our analysis with our BIM-software, so there is a 1:1 connection between important bridge parameters.The paper will also discuss the design of the concept, as well as methods applied in the work regarding the suspension bridge computer code, PAM and BIM xD.