Motorists using the A49 in Shropshire face three weeks of delays.
Contractors for the Highways Agency have begun work to resurface almost four miles of the A49 between Bushmoor and Craven Arms in south Shropshire.
The work, which was due to start in Craven Arms last night, will include upgrading traffic signs and installing pedestrian crossing points.
Highways Agency project manager Laura Mobley said: “We have planned this work carefully to keep disruption to motorists and local residents to a minimum. More information is available from the Highways Agency information line on 0300 123 5000.”
Work will be undertaken overnight from 8pm till 6am, and during the works, northbound traffic heading towards Shrewsbury will be diverted east along the B4368 towards Much Wenlock. To continue north traffic can then use the A458, past Cressage towards the A5 at Bayston Hill.
Southbound traffic heading towards Ludlow will be diverted eastbound along the B4371 at Church Stretton towards A458 Much Wenlock. Traffic can then continue south and join the B4368 towards Craven Arms roundabout.