La Marga bypass. Santander, Spain

The project consists of 300 m of cut and cover tunnel plus three floors for car park and two secondary bridges. 

Depth of bottom slab of the tunnel was up to 30 meters below ground level. Soil, consisting of different layers of sand plus soft silt deposits, and the water table almost at ground level, combined with the very deep excavation, led to very challenging conditions for the design. 

SILGA was responsible for detail design and assistance during construction.