Emergency services were called to the scene at the intersection of the highway and Jenolan Caves Road around 6.45pm.

A semi-trailer and small car had collided, with the driver and only occupant of the car trapped inside the vehicle after being killed instantly in the collision.

Police said the 53-year-old Sydney man had crossed to the wrong side of the road before the incident.

The Volunteer Rescue Squad, Lithgow Police, Ambulance, Fire and Rescue and the Rural Fire Brigade attended the scene with the VRA cutting the driver from the vehicle using the Halmatro jaws of life.

The highway was closed in both directions for four hours after the truck’s fuel tank ruptured, spilling fuel on the highway.

The 48-year-old truck driver was taken to Lithgow Hospital where he was treated for shoulder injuries and shock.

He also submitted to the mandatory drug and alcohol testing.

The highway was reopened at 11pm.

Police are still investigating the incident.

This is the second accident in weeks involving a truck along the Great Western Highway after a motorcyclist veered in front of a truck at Yetholme last fortnight.

The motorcycle rider was killed instantly, and the road closed for several hours.