The A1 southbound between the A428 and Blunham will be closed overnight for two nights from 9pm until 6am on Friday 17 October and Saturday 18 October.
The road will be closed to install ducts and drainage pipes under the existing road.
There will be a clearly signed diversion route via the A428 and Barford Road, re-joining at Tempsford Road, Blunham.
Drivers intending to travel on the A1 are advised to plan their journeys and allow some extra time to reach their destinations.
The scheme to ease congestion at this important roundabout is progressing well and is on track to complete early next year.
It is part of the Government’s £317 million pinch point programme, which aims to boost local economies by reducing congestion and delays at key locations.
The pinch point programme was developed with Local Enterprise Partnerships, and each of its 123 road improvement schemes is designed to boost local economies, reduce congestion and improve safety on the strategic road network in England. It is part of the Government’s long term economic plan, and was announced in the Chancellor’s Autumn Statement in November 2011.
Live traffic information is available on the Highways Agency website and mobile app, and drivers can also listen to traffic bulletins on local radio for updates.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000.
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.