The M1 northbound has now reopened between junction 10 and 11 at Luton following a serious accident this morning.
Cars were at a standstill as the collision caused long delays as far back as junction 7, affecting drivers travelling up to Milton Keynes.
A man was airlifted to a specialist trauma centre at the Royal London Hospital following the incident, which involved two Heavy Goods Vehicle and a car shortly after 7am.
The Highways Agency say there are currently delays of one and a half hours and that normal traffic conditions are expected from 12pm.
Two ambulances, a response car, a duty officer and the Herts Air Ambulance attended the scene.
An EEAST spokesman said: “The man suffered a serious leg injury and following treatment by land and air ambulance crews, he was flown direct to the Royal London Hospital in Whitechapel for further care.”