Motorists encountered delays in Brighton, with queues reported on the A270 Lewes Road, according to AA.
A closure affecting both a carriageway and a lane remains in force on the A27 between Patcham and Falmer while survey work takes place.
AA also reported increasing traffic on the A27 in the direction of Lewes.
Congestion remains heavy on the eastbound section of the A27 towards Lewes, while traffic queues have formed on Falmer Road in the direction of Woodingdean.
Sussex Police has been contacted in an effort to obtain further information about the incident.
An update from AA indicated that congestion on Lewes Road had subsequently eased substantially.
Heavy traffic, however, continues on the eastbound A27 approaching Lewes.