All southbound lanes on the M1 Princes Motorway (Mount Ousley Road) in Cataract are now open following two earlier accidents and an oil spill.
All incidents have been cleared, heavy southbound traffic has eased and conditions are returning to normal.
Southbound motorists were temporarily diverted via Bulli Pass and there was long traffic queues.
Atrocious weather conditions and poor visibility led to the pile-up on Monday afternoon.
One car was flipped onto its roof and traffic was banked up for kilometres after the accident.
Emergency crews were called to the scene around 4pm.
A NSW Ambulance spokesman said paramedics treated some of those involved in the crash for minor injuries.
For the latest traffic information, visit www.livetraffic.com or call 132 701.