A stretch of the A428 between St Neots and Wyboston has re-opened after emergency repair works were completed.
The road was closed between its junctions with the B1043 and the B1428, with delays of "at least 15 minutes" covering several miles.
The closure was put in place to allow Highways England to carry out repairs following an "infrastructure damage incident".
A spokesman for Highways England said: "[We have] resources deployed working hard to restore normal conditions as soon as possible.
"For traffic approaching the closure locally, you are advised to expect disruption with extra journey times and you may potentially have to re-route your journey."