A serious crash involving an overturned car shut the A1 between Stamford and Peterborough this morning, Saturday April 14.
The A1 was closed northbound between the A43 near Stamford and the A47 junction west of Peterborough and there were long delays in the area.
The air ambulance landed at the scene of the crash, which took place at around 7.30am.
The road was shut in both directions but has now re-opened as of 3pm.
Traffic was already busy in the area due to the Belton Horse Trials taking place today.
A spokesman for Highways England said: "The A1 northbound in Cambridgeshire is closed between the A47 (Wansford) and the A43 (Wothorpe) due to a serious collision. This incident is being led by Cambridgeshire Police.
"Diversion Route: Follow signs with the hollow diamond symbol. Exit the A1 and join the A47 westbound and continue to the junction with the A43. Join the A43 northbound towards Easton on Hill and continue to re-join the A1 northbound.
"Road users are advised to allow plenty of extra time for their journeys and may wish to consider using an alternative route if possible."