An artist's impression of the Cambridgeshire guided busway
Drivers in Cambridge are warned that diversions are in place as the latest roadworks are put in place to allow construction of the Guided Busway.
Originally the road between Swavesey and Over was due to be closed for seven weeks but this has been reduced to five weeks, starting on Monday.
The 25km guideway mainly along a former St Ives to Cambridge railway line will link Huntingdon and Cambridge.
It will also cater for cyclists and pedestrians when complete.
Head of the busway project Bob Menzies said: "We understand how frustrating these road works are and closing a road is always a last resort.
"We are constantly looking at ways to reduce road works or work much more efficiently and learn from earlier schemes."