MAJOR Crash officers are investigating a fatal crash on the Kwinana Freeway north-bound lanes at the Nambeelup Bridge in Stake Hill at 3.10am on Sunday.
A white prime mover towing two yellow cylindrical tankers failed to negotiate a lefthand bend and entered the centre median reserve immediately prior to the Nambeelup Brook Bridge.
It continued between the north and southbound lane carriageway, entering a deep culvert and coming to rest directly below the south bound carriageway.
The 42-year-old male driver died shortly after at the scene.
Major Crash investigators are seeking witnesses who may have seen the vehicle driving in the Martin area before the crash.