Work to convert part of the M27 into a smart motorway will get underway tonight, Highways England has said.
Narrow lanes and speed cameras will be in place between Junction 4 and Junction 8 while the work is carried out.
The £244m smart motorway project, which is due to be completed by the middle of 2021, is converting a 15-mile stretch of the route between Portsmouth and Southampton to four lanes.
Highways England has said speed cameras will be turned on from tonight with a 50mph speed limit.
It is estimated that the roadworks will add an average of 13 minutes onto current journey times.
Smart motorways are designed to ease motorway congestion by allowing cars to drive on the hard shoulder at least some of the time.
Traffic is typically monitored by cameras and ‘active’ speed signs which can vary the limit.
The initial work will include strengthening the hard shoulder, installing noise barriers, widening the carriageway into the central reserve.
Existing gantries will be removed and smart motorway technology and a new concrete barrier will be installed.
Lane closures will be in operation at night, but should be reopened in time for the morning commute.