A stretch of the road at Ranby, near Worksop, in north Nottinghamshire, was closed in both directions following the accident at 11.20pm last night.
Nottinghamshire Police said two lanes of the northbound carriageway had now reopened but diversions remain in place for southbound traffic.
The A1 was closed between Five Lane Ends and Blyth, near the border with South Yorkshire, in the aftermath of the collision.
A police spokesman said: “Two lanes of the northbound carriageway reopened at about 7am this morning.
“The southbound carriageway is closed from Blyth and is expected to be shut for the duration of the morning.”
Anyone who witnessed the crash is urged to contact Nottinghamshire Police on 101.