Hammersmith Flyover: A4 remains closed in west London
Commuters returning to work on Tuesday have been advised to avoid the A4 in west London, where engineers are still inspecting extensive rust to a bridge.
The Hammersmith Flyover has been closed since 23 December after serious defects were found in its structure.
Motorists experienced delays throughout the festive period as traffic using diversions has clogged up the area.
Transport for London (TfL) said it would not reopen this week, but teams were "working as fast as we can".
About 90,000 vehicles per day travel along the 900m (0.56-mile) route, which was built in the 1960s.
Seeping water has caused the cables, which help to support the road, to rust and has left them weak, TfL said.
"We're working around the clock to get to a position where we understand what loading it can take, and then we'll move from there as to when, and if, we're able to reopen it," said Garrett Emmerson, TfL's director of strategy and policy.
An extra lane had been added to the A4 Talgarth Road to try to ease congestion, special signals were being used and extensive diversions were in place, he added.
Engineers were undertaking "a complete analysis and investigation of the whole structure", which was taking some time, Mr Emmerson said.
This amends an earlier story which stated the route was likely to remain closed until the end of January.