Roadworks to resurface the westbound carriageway on the A421 Bedford Southern Bypass began on Monday.
The worn out carriageway, road markings and studs are being replaced and drainage cleared out.
Works are taking place between 8pm and 6am on weeknights and, to keep motorists a safe distance from workers, the westbound bypass between the A4280 Goldington Road and the A6 at Elstow is closed off at night between these times.
During the daytime traffic will run on the A421 on a milled surface with a temporary 40mph speed limit for safety.
Works to the eastbound carriageway are due to be completed on Friday.
A Highways Agency spokesman said: “Our intention is to better deliver a road surface that has fewer joints reducing maintenance works in the future. The operations should also reduce the duration of the works compared with using the traditional method.”
Drainage repairs are being carried out on the A421 Castle Mill viaduct alongside the bypass work.
Night-time roadworks are also being carried out to strengthen bridge joints on the A421 Cardington Cross and should be completed by February 6.
Diversions will be in place to direct motorists around the works.