More delays are likely for drivers in Kettering from today.
The section of Northampton Road between Lake Avenue and the double roundabout is now shut for six weeks until September the 4th.
The reason for the closure is for work on the railway bridge as part of the electrification of the line between Kettering and Corby.
The work will strengthen the bridge to allow more trains to use it.
Network Rail says it`s doing the work during the school holidays to minimise disruption.
The official diversion will take motorists on to the A14 at Junction 8 and down the A43 Northern Bypass.
Road users should then travel down Rockingham Road on to Northfield Avenue.