Grejsdal Bridge: safe installation
Significant assets and, in the worst case, human life and safety can be at stake when a complex sectional structure must be transported, lifted into position, and secured. At ISC, this type of assignment is a core competence, which we brought into play when a 128-metre-long, curved footbridge was installed in Grejsdalen, north of Vejle.
The bridge carries cyclists and pedestrians across both the Grejs River and the busy railway line between Vejle and Struer and is supported by steel columns up to 5.5 metres high.
Seven sections become one bridge
The bridge was fabricated as seven prefabricated steel sections. During installation, the sections were lifted into position individually, temporarily connected using erection brackets and finally welded together to form the completed bridge.
This method means that each stage of the installation constitutes a temporary structural configuration in its own right, with specific requirements for stability, load-bearing capacity and deformation. ISC therefore analysed the bridge's condition throughout the installation stages and documented the temporary load conditions.
The installation design included, among other things, selecting lifting principles and designing lifting lugs, erection brackets, and temporary installation welds. ISC also calculated stability, load paths, internal forces, and deformations, and planned the installation sequence and welding procedure to ensure the structure maintained the required load-bearing capacity and stability throughout the process.
Installation across a river and an operational railway
The surrounding environment further complicated the assignment. By Danish standards, Grejsdalen has high, steep slopes and is densely built-up. At the same time, the bridge sections had to be installed above both the Grejs River and an operational railway line. This placed particular demands on planning, safety and coordination during execution. ISC was responsible for technically coordinating the installation works with the contractor and worked closely with the client’s consultant and the design team throughout the design and construction phases.
