The RCMP in Falcon Lake were contacted about the blaze around 8:00 this morning.
Police say the driver of the rig noticed a mechanical problem and pulled over in a parking lot and discovered the fire.
He tried to put it out, without any success.
The Mounties say the rig is a total loss, but both the driver and a passenger from Ontario managed to escape unharmed.
The Trans-Canada remained open while emergency crews dealt with the fire.