The Highways Agency is set to carry out improvement work on the M40 motorway near Bicester.
The five-month project involves increasing the capacity of the motorway by adding a lane to the busiest parts of the junction 9 interchange - from the southbound M40 to the southbound A34.
The work is aimed at reducing congestion and improving traffic flow on the busy junction.
Surinder Bhangu, project manager at the Highways Agency, said: "Peak time congestion is a real problem for drivers on this busy section of road.
"The work we are doing will increase the capacity of the junction, improve traffic flow and reduce the safety risk of traffic queuing for the exit on the M40 main carriageway."
He added: "We have planned every section of this project carefully to keep delays to road users to an absolute minimum.
"Throughout the work, there will be no reduction in the number of lanes available to road users during peak periods, and when we do need to temporarily close lanes or slip roads we will do it overnight when traffic flows are lowest."
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