There were long delays earlier as the M1 was closed on the northbound carriageway between J12 for Flitwick and J13 for Milton Keynes South.
Bedfordshire Police re-opened the southbound carriageway between 7pm and 7.30pm this evening.
The northbound carriageway then re-opened just before midnight.
The closure began at around 1.30pm in the afternoon.
Traffic was queueing on all approaches to the closure and motorists were being advised to avoid the area.
Emergency services from Bedfordshire Police were.at the scene.
Support was also being given by Highways England Traffic Officers.
Diverted traffic was told to follow the hollow black diamond diversion symbol if travelling northbound.
