According to the AA, one lane is blocked with slow traffic due to the incident, in which a car collided into the central barrier on the A23 Southbound near B2110 (Handcross).
Congestion is being reported halfway to Pease Pottage.
Elsewhere there are reports of slow traffic on the A27 Westbound around the Ripe turn-off between Polegate and Lewes, towards Brighton.
A road is also closed due to emergency repairs on the A285 Duncton High Street both ways between Dye House Lane and The Cricketers pub following recent rainfall.
An accident has also occurred on the A27.
According to the AA, it involved two vehicles on the A27 Eastbound near Busticle Lane (Hilllbarn Traffic Lights) near Worthing.
Elsewhere on the A27 there are reports of slow traffic both ways between A22 (Cophall Roundabout) and the Eastbourne turn-off in the construction area.
The road is partially blocked with queueing traffic due to an accident on A283 Steyning Bypass Northbound at A2037 Shoreham Road.
Elsewhere, according to the AA, the road is partially blocked due to an accident involving two cars on Western Road between Western Road North and Osborne Drive in Shoreham.
There are reports of slow traffic due to an accident involving a cyclist on the A259 Brighton Road near B2223 Ham Road in Worthing.