The Norwegian Public Roads Administration – Statens vegvesen– will order an external review of how it manages the country’s hundreds of bridges.
Statens vegvesen, a government agency, is responsible for national and county public roads including planning, construction and operation. It also handles driver training and licensing, vehicle inspection and subsidies to car ferries.
Earlier this month the Norwegian Road Safety Authority published a report focussing on how 5,422 bridges across the country have been examined. According to the report, single inspections have been carried out on the vast majority of bridges – 98.3%.
The report was overall very favourable, said Ingrid Dahl Hovland, director of Statens vegvesen. “Now I want to know if we are using this knowledge correctly and how it forms part of comprehensive bridge management,” she said.
The agency has been doing extensive bridge examinations, especially of wooden bridges, after the failure of the wooden Tretten Bridge over the Lågen River in August 2021. The 150m-long, 10m-wide Tretten Bridge – only a decade old – broke in two, collapsing into the river stranding two vehicles and their occupants. There were no casualties or injuries in the early morning accident, but one driver was airlifted to safety.
A preliminary investigation by the Norwegian Safety Investigation Authority in 2022 suggested that the cause of the Tretten collapse was “a break in one of the diagonals in the main span towards the western river foundation”. This could have caused overloading and unloading of other elements in the truss, leading to a failure.
Norway has been constructing building timber bridges for many decades. The success of the wooden bridges meant the country started to build larger structures in the 1990s such as the 196m Flisa Bridge that opened in 2003. It was the world’s longest timber bridge designed for normal traffic loads.
But in 2016, the wooden Perkolo Bridge in Gudbrandsdalen near Lillehammer collapsed under the weight of a timber truck.
“We must be confident that we have a system that captures the type of deviations that were not caught in the review after the Perkolo collapse in 2016, and where the recommendation was, among other things, to reinforce Tretten bru [bridge],” said Hovland. “Therefore, the review will also look at how the internal expert report from 2016 on wooden truss bridges was followed up internally within the Road Administration.”
