M5 roadworks at Huntworth will last six months
A £4.9m scheme to resurface and waterproof a stretch of the M5 in Somerset begins later and will continue until March 2015.
The works, between junctions 23 and 24 at Huntworth, also include replacing more than half a mile of worn-out steel barriers with a concrete system.
There will be speed limit changes and closures on the slip roads during the day and the motorway will occasionally be completely closed overnight.
Traffic will be diverted onto the A38.
Highways Agency manager Andrew Clark said: "This work is needed to maintain safety and prolong the life of the bridge. Improved drainage will also be installed.
"We would remind all drivers to pay extra attention while driving through roadworks and observe all speed limits which are there for everyone's safety."
Real-time traffic information on the closures is available on the Highways Agency's website.