The timber truss bridge that collapsed on 15 August at Tretten was built in 2012 as part of the E6 Øyer–Tretten project. Innlandet county council owns and maintains the bridge.

Tretten Bridge after its collapse

“A day after the Tretten Bridge on county road 254 collapsed, the cause is still unclear,” said road director Ingrid Dahl Hovland. “After assessing the situation today, we have come to the conclusion that we must close 14 corresponding truss bridges until we know more about the cause.”

The Norwegian Public Roads Administration and Innlandet county have launched an investigation into the collapse. An independent expert panel is being put together.

Tretten Bridge after its collapse

Innlandet county head of transport Aud Riseng said: “The aim of the investigation is to find out how this could happen and not least how we can prevent this from happening again.”

The total of 14 wooden truss bridges are located in Viken county (eight), Innlandet county (five) and Nordland county (one). Temporary bridges will be installed at locations where the closure has the greatest consequences for road users.

Thirteen bridges had an individual inspection on 3 June 2022, and a main inspection in 2021. The inspections are carried out by the county council, but the reports are entered into the Roads Directorate's bridge management system Brutus. A comprehensive review of wooden truss bridges had been carried out in 2016 following the collapse of the Perkolo Bridge.

Below: Tretten Bridge before its collapse

Tretten Bridge before its collapse