The A428 is set to close for an entire weekend while National Highways continue to work to upgrade the road.
From 6am on Saturday, November 30 to 5am on Monday, December 2, the A428 will be closed between the B1040 St Ives Road to the Caxton Gibbet roundabout.
The closure is in place to allow for the National Highways workforce to carry out "essential water main diversion works" which will require the road to be closed.
National Highways has confirmed that water supply in the area will not be affected during the closure, and local access to residential properties and businesses will be maintained throughout.
A diversion route will be in place which is estimated to add an additional five minutes onto journey times.
A spokesperson for National Highways said: "Traffic will be diverted along the A428 towards St Neots.
"Traffic to continue northbound on B1040, St Ives Road and rejoin the A1198 south to Caxton Gibbet roundabout."
Motorists are being advised to plan their journeys accordingly and allow extra time to travel.
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