The Princes Highway, South of Nowra, is closed in both directions at Bewong due to a fatal truck and van crash near the Bewong Roadhouse.
The crash happened about 3.30am on Thursday, June 18 after a B-double truck and a Hyundai van collided about a kilometre south of the Roadhouse.
The driver of the van died at the scene.
It is understood the truck, that was carrying an asphalt removal machine, rolled and came to rest on its side.
The car and truck are about 100 metres apart.
The driver of the truck was not injured and was taken to Shoalhaven District Hospital to undergo mandatory tests.
NSW Police crash investigators are on the scene and emergency services remain at the crash site, awaiting the arrival of a crane to right the overturned truck.
Fire and Rescue NSW and Rural Fire Service crews are at the location cleaning up a diesel spill.
It has been estimated around 100 litres of fuel has spilt following the accident, with fire crews attempting to stop it getting into nearby waterways.
The highway is blocked in both directions and appears it will be for some time.
Northbound and southbound traffic is diverting via Turpentine Road, Braidwood Road (Nerriga Road), and Kings Highway.
The diversion is not suitable for heavy vehicles, which should delay their travel or consider the Hume, Federal and Kings highways instead.
Motorists are advised to exercise caution, allow plenty of extra travel time, and follow directions of traffic crews and emergency services.
For the latest traffic information, visit www.livetraffic.com, download the Live Traffic NSW app or call 132 70