The M11 was closed near Stansted airport following a multi-vehicle crash this afternoon.
Drivers faced delays of around 45 minutes as emergency services attended the scene.
The motorway was closed southbound between junction 10 Royston and junction 8 Stansted Airport.
A diversion was set up, and heavy traffic has been reported in the area.
National Highways have now confirmed one side of the road has reopened.
Congestion is said to have largely eased, but slow traffic is still reported.
Drivers have been warned to avoid the area if possible.
