2pm: The truck has been removed from the arrester bed and the M1 Princes Motorway off-ramp to Mount Ousley Road has reopened.
12.30pm: A vehicle-salvage operation is under way after a truck left the M1 Princes Motorway on Mount Ousley and came to a halt in a safety ramp.
The southbound B-Double ended up in the sand arrester bed at the base of the mountain, next to the Mount Ousley Road exit, about 12am on Thursday.
An operation to remove the stuck truck began about 10.30am and was still under way at 12.30pm.
Motorists have been advised of changed traffic conditions in the area.
The M1 off-ramp to Mount Ousley Road has been closed while heavy vehicle tow truck operators work to pull the truck out of the sand.
Southbound motorists on the M1 have been told to use the University Avenue exit. The Masters Road exit is another alternative route.
Drivers should allow extra travel time.
NSW Roads and Maritime Services (RMS) crews, including heavy vehicle inspectors, are on the scene.
The recovery is expected to take some time.
Once the truck has been salvaged, it will be towed to a RMS heavy vehicle inspection station.
The Mercury has contacted the RMS for comment, including why the truck was forced to leave the motorway.
Drivers heading west on Mount Ousley Road are still able to access the M1.