The accident occurred at Glanmire at 6pm.

Inspector Mick Aldridge said police believe the male motorcyclist was aged somewhere in his 40s or 50s and is from Sydney.

While the cause of the fatal collision is still being investigated, it has been determined the motorcyclist was travelling in a westerly direction when he crossed over to the wrong side of the road while negotiating a sweeping right hand bend.

It is believed this brought him straight into the path of the oncoming truck, which ended up in a culvert.

The 38-year-old male truck driver from Orange, who was not injured, assisted police with inquiries.

He was taken to Bathurst Base Hospital for mandatory blood and urine testing.

Police have determined that alcohol was not a factor and wait for the other results to be returned.

The driver of the heavy vehicle suffered from smoke inhalation after the fuel tank on the motorcycle ignited, setting fire to the cabin of the truck.

The truck was well-alight when emergency services personnel arrived. It was completely destroyed by fire and the trailer extensively damaged.

Inspector Aldridge said the driver of the prime mover had been able to escape.

He added that initially there were grave concerns regarding fire spreading to any load the truck may have been carrying, however, it turned out to be empty.

Five fire engines from Bathurst Fire Brigade and the Glanmire Rural Fire Service attended, along with HAZMAT, police, ambulance and SES volunteers.

The highway was closed for five hours because of the danger caused by fire and fuel. The closure was also necessary for the truck’s removal.

One lane of the highway was opened sporadically to allow heavy vehicles through, however most traffic was diverted via Oberon and other back roads.

The Great Western Highway reopened at 11pm.

Chifley Local Area Command are investigating the circumstances surrounding the crash.

Anyone who witnessed the incident, and who hasn’t already spoken to police, should contact Bathurst Police or Crime Stoppers on 1800 333 000.

A report will be prepared for the Coroner.