A £43m scheme to ease congestion on Gloucester's A38 Bristol Road is now due to open on 25 May, according to the county council.
The project should ease traffic congestion on the A430 Bristol Road
The final section to join the Hempsted bypass to the A38 at Cole Avenue junction has included the first re-routing of a canal in 200 years.
The scheme should reduce traffic on Bristol Road and "provide better bus, cycling and pedestrian facilities".
A spokesman said the bypass would provide welcome relief to motorists.
Councillor Stan Waddington added: "It has been a huge project and we've completed each section on time, including rerouting the two-mile bend."