The A27 has been closed in both directions after a crash between Falmer and Lewes this morning (Tuesday 9 January).
Sussex Police said: “We are currently responding to a serious single-vehicle collision which occurred on the A27 eastbound, between Falmer and Lewes, shortly before 3am.
“The road will remain closed in both directions for some time to allow for forensics and recovery.
“We only get one opportunity to do this and we thank you for your patience and understanding.”
Rush-hours traffic has jammed the A27 as well as diversion routes along the A259 coast road and the A273 and through Ditchling, with three-way traffic lights at Clayton compounding the delays.
The BBC warned drivers: “The queues are absolutely horrendous. The whole area is jammed.”
The broadcaster also said that freezing winds would bring a “feels like” temperature of minus 7C (19F) as some faced delays expected to last more than hour.
The crash happened between Falmer and the Ashcombe roundabout at Kingston
No timescale has yet been given for the reopening of the road.