Police are appealing for witnesses to a two-vehicle collision that led to the A272 being closed between Bolney and Cowfold on Monday morning (September 8).
It involved a van and a car, and happened at about 7.40am.
The driver of the car, a silver Ford Focus, was trapped and suffered serious injuries.
Wineham Lane was also closed at its junction with the A272 and motorists were advised to avoid the area while emergency services dealt with the incident.
PC Chris Welsh, of the Haywards Heath road policing unit, said: “We would like to hear from anyone who saw what happened or noticed either vehicle being driven just prior to the collision.”
Anyone able to help is asked to email firstname.lastname@example.org or phone Sussex Police on 101, quoting serial 211 of 8/9.