As the £1.5 billion project progresses, highways officials say work needs to move closer to the existing A1 carriageway so safety barriers and a temporary 40mph speed limit, as well as average speed cameras, are set to be installed.Senior stakeholder manager for the A14 project, Mike Evans, said: The A14 Cambridge to Huntingdon improvements scheme is progressing well and to schedule. Weve been building pillars for the new Brampton Interchange bridges between the A14 and A1 and preparing the ground for the new carriageways over the past few months and now need to work closer to the existing A1 to continue with this work, including begin construction of the new, three-lane southbound A1. Well need to close the southbound A1 to install safety barriers, average speed cameras and signs for the temporary 40mph speed limit to make sure our workers are safe while they build these vital improvements so close to this busy stretch of the A1. Once installed, the narrow lanes and temporary speed limit will stay in place until construction along this stretch has been completed but full capacity will be maintained during the day. The southbound A1 will be closed between 9pm and 6am each night, weather permitting, as follows:Monday to Tuesday, September 18-19: Alconbury to Buckden Wednesday to Friday, September 20-22: Alconbury to Brampton Hut While the road is closed between Alconbury and Buckden, drivers will be diverted via the A14 spur to Spittals Interchange, A14 eastbound to exit at junction 24 for Godmanchester. Traffic will then follow the A1198 southbound to the A428 and take the westbound A428 to rejoin the A1 at St Neots. While the road is closed between Alconbury and Brampton Hut, drivers will be diverted via the A14 spur and the Spittals Interchange to rejoin the A14 at Brampton Hut. Drivers can check travel conditions before setting out on journeys. Highways England provides live traffic information via its website at www.trafficengland.com, local and national radio travel bulletins, electronic road signs and mobile apps. Information is also available from Twitter via https://twitter.com/highwayseast as well as services in other regions and at www.highways.gov.uk/traffic-information.