As part of the project to establish a ferry-free E39, the Norwegian Public Roads Administration (NPRA) is working on solutions for ferry-free connections across the fjords along the 1,100km coastal route between Kristiansand and Trondheim. The combination of water depths up to 550m and bridge lengths of up to 5 km make it impossible to build conventional bridges. Floating bridges and submerged tubular bridges are the only feasible ways of making a road link across such wide and deep fjords.

To achieve this, the NPRA needs to better understand the floating bridge’s response to acceleration, displacement and excitation sources such as wind, vehicle traffic, wave excitation, wave impact on wind turbulences and vibrations. Hence, the  Nordhordland bridge will be the perfect real-life testing environment.

It was necessary to design a test system able to provide highly valuable recordings, describing both the environment and the bridge response. First, statistical data representing the relationship between environmental factors and the response will be established. Furthermore, the measurements will serve as a starting point for establishing the modal parameters, which characterise the bridge behaviour in an easily interpretable manner and quantifying them according to the changes in environmental conditions. The continuous recordings can also be used for structural health monitoring. 

Numerous land-based civil structures have previously been instrumented for measuring response and environmental excitation, but structural monitoring surveys of floating bridges are not widespread.