Delays on the A4 into Newbury could continue until the end of the week.
Thames Water has been working to repair a leaking sewer on the A4 near Craven Dene since Monday morning.
The emergency works and temporary traffic lights led to gridlock into the town, turning a three-mile commute from Thatcham into a 50 minute slog.
Thames Water said that it had expected the works to be completed by today (Wednesday) but has now extended the timeline.
A spokesperson for Thames Water said: "We’re sorry for the ongoing disruption our work on the A4 is causing.
"It’s really important we fix the sewer pipe properly to reduce the risk of us having to return and do more work in the same place at a later date.
"We’ve finished work on the eastbound side of the road and have now moved to the westbound side to investigate how much further work is needed.
"We’re aiming to be finished by the end of the week."