Resurfacing work starts on two sections of the A10 in Hertfordshire on Tuesday night and drivers are warned of delays.
Work will be carried out overnight at Chipping, north of Buntingford, where a 40mph speed limit will be imposed on the approaches to the section.
Interchanges at the A414 Rush Green junction and on the Hailey/Amwell section, south of Ware, will also be resurfaced over several nights.
Diversions will be put in place or traffic led in convoy through the work.
Crews will close the road at 2100 BST and reopen it at about 0500 BST the next morning.