Contractors are racing against time to carry out essential repairs to crash barriers before the Olympic Torch arrives in Southampton on July 14.
But Councillor Asa Thorpe admitted that motorists should have been given better warning of the lane closures both ways along a stretch of the A33.
Long queues had already begun to form on Millbrook Road West early this morning as motorists filtered into the single lane over Millbrook flyover.
It comes after the roadworks yesterday morning caused tailbacks on the M271 south from the M27, and eastbound on the A35 from Ashurst.
And last night traffic heading out of the city was backed up as far as the Central police station.
The lane closures, which are scheduled to remain in place until July 17, stretch both ways along the A33 between the junction with Waterhouse Lane and the flyover.
The council initially said that it expected the impact of the works on traffic flows to be “moderate” but last night advised motorists to avoid the route during peak hours and to allow extra time for their journeys where they can.
It said that contractor Balfour Beatty was now working extended hours seven days a week to complete the works as soon as possible to minimise future disruption.
Cllr Thorpe said: “The crash barriers are in urgent need of replacement and we have no option than to complete these as soon as we possibly can. I apologise that commuters for the inconvenience – better advance warning should have been provided.”