Precision measurements have helped to replace stays

Tjörnbron is a cable-stayed bridge over Askeröfjord with a main span of 366 metres, around 50 kilometres north of Gothenburg in Sweden.

Because of corrosion, the Swedish Transport Administration decided to start replacing the damaged stays, so COWI Geoservice took measurements of the cable lengths for the worst damaged stays in 2014. The measurements are used to order new stays from the supplier, and the replacements have been a great success. In 2015 the remaining 14 stays on the east side of the bridge were surveyed for replacement in 2019, and a further 16 stays were surveyed in March 2018.

COWI is responsible for project management and coordination, while local contractors are handling safety and accessibility. Data from Geoservices is quality-checked and delivered to COWI’s Bridge, Tunnel and Marine Structures (BTM) department in Denmark, for them to calculate the final ordered lengths and dimensions.