[1] Permission was given for a temporary replacement bridge in October 2022, on the condition that work above the waterline is finished before the spring flood in April 2023.

[6] While the bridge was being constructed in 2012, a temporary crossing was made using 45,000 cubic metres (1,600,000 cu ft) of stone filling in the river.

The existing stone pillars were reinforced with concrete and two steel core piles were driven 40 metres (130 ft) into the river bottom.

[7] Prior to the collapse, road users reported a kind of rocking when they were on the bridge at the same time as larger vehicles.

The Norwegian Road Administration then recommended strengthening the Tretten Bridge: "There are no design errors here, but according to the current regulations, the safety against certain brittle fracture mechanisms, which were previously controlled more indirectly, is too low."

Anders Rønnquist, professor of structural engineering, maintained that errors in planning, dimensioning or in the construction phase would normally have become apparent shortly after the bridge was opened, and he assumed instead that wear damage has occurred in the foundation.

Tormod Dyken, retired chief engineer in the Norwegian Public Roads Administration, stated that the bridge was too new for rust or rot to be the cause.

The National Road Administration's press release did not clarify if it has the authority to close county municipal bridges.