There was “significant damage” to the central reservation barrier and emergency repairs would be needed, National Highways said.
All traffic caught within the closure on the southbound carriageway has been released, and vehicles were being diverted via local routes, National Highways said.
It advised people to plan ahead and stated if the closure “impacts on your planned route, please allow extra journey time”.
The roads body added that all emergency services attended the scene.
On Tuesday night, police said they were working as quickly as possible with partners to recover vehicles and to help those stuck in traffic, adding: “Thank you for everyone’s patience.”