A busy west London flyover that closed before Christmas due to major structural problems will partially reopen before this morning's rush hour, transport chiefs have said.
One lane of light traffic will be permitted in each direction along the Hammersmith flyover as vital repair works continue, Transport for London (TfL) said.
However, drivers are still being advised to avoid the area with more traffic chaos, which has blighted the area since the route was shut, expected.
The thoroughfare, on the A4 at Hammersmith, was closed on December 23 due to water damage that corroded and weakened cables that give the bridge its strength.
TfL said engineers have been working around the clock to fix the problem and expect the flyover to be repaired and fully operational in four months time, ready for this summer's London Olympics.
More work will be carried out on the bridge after the 2012 Games.
Structural engineers say it is safe for cars, vans and other light vehicles to use the route, but width restrictions will prevent large vehicles such as HGVs and coaches from crossing.
The closure has caused long delays over the past three weeks, with the 1961-built flyover not only used by those going to and from Heathrow airport, but also one of the main routes into London as it is an extension of the M4.
Boris Johnson, Mayor of London, said: "I made it very clear the Hammersmith Flyover should not be closed for one minute longer than it has to be and this partial reopening will provide some relief for the thousands of motorists and local people whose lives have been disrupted."
Garrett Emmerson, chief operating officer for surface transport at TfL added: "Our engineers, contractors and suppliers have worked day and night during the Christmas period and beyond to enable us to partially reopen the flyover as quickly as possible.
"This should significantly reduce the traffic disruption many thousands of drivers have been experiencing since the flyover closed, and means that work to fully reopen the flyover will be completed well before the London 2012 Games."