The M23 near Gatwick Airport is blocked after a car rolled over.
According to traffic reports, the accident happened in the second lane of the southbound carriageway at Junction 9, where there are roadworks, at around 5.30am.
As a result, both lanes were closed. One lane was briefly reopened to clear some of the trapped traffic and allow emergency services to get to the scene.
The accident has lead to four-mile queues backing up on the M23, with delays of 90 minutes.
At around 7.30am, Highways England tweeted that recovery vehicles had arrived at the scene and would clear the car, at which point the road would be reopened.