A 35-year-old woman was trapped for more than 45 minutes after the ute in which she was travelling and a semi-trailer collided on Mount Ousley Road yesterday morning.
Paramedics and firefighters were involved in a complicated operation to free the woman, from Airds near Campbelltown, before she was taken by road to St George Hospital suffering serious leg and head injuries.
The driver of the ute, 41, and the truck driver were both taken to Wollongong Hospital for mandatory blood and alcohol testing.
Sergeant Darren Moulds said investigations were under way to determine the cause of the crash between the two northbound vehicles.
Three NSW Fire and Rescue and two Rural Fire Service units attended.
The accident, which happened about 8.10am, caused traffic chaos on the busy highway, with all northbound lanes closed while the police crash investigation unit was on scene.
Northbound traffic was initially forced to perform a U-turn just metres behind the crash, resulting in delays for southbound motorists until a diversion was put in place via Picton Road.
For Bulktrans truck driver Tony Ray, the crash meant he was forced to park on the side of the highway for several hours.
He said the delay would have an impact on his pay packet.
"While they're not turning, we're not making any money," Mr Ray said, pointing to his wheels.
The traffic chaos experienced yesterday morning was a problem all too familiar for University of Wollongong associate professor Phillip Laird, who is a fellow of the Chartered Institute of Logistics and Transport.
Prof Laird said Mount Ousley Road, also known as the M1, had been identified as being at full capacity during morning peak hour rush as far back as 2006 in a draft AusLINK Sydney Wollongong Corridor Strategy.
"The demands on the existing road and rail network have been compounded by the further development of Port Kembla and an expected growth in the number of people commuting between Wollongong and Sydney," he said.
Prof Laird said the problem could be handled through a combined upgrade of road and rail infrastructure to move freight, and advocated a "long overdue grade separation" (overpass or underpass) of the intersection at the foot of Mount Ousley.
"This intersection was the scene of a fatal accident just before Christmas 2012 and is one of the busiest intersections on the Princes Highway," he said.
"The draft strategy also notes that completion of the Maldon-Dombarton line could play a future role ... as part of a Maldon-Port Kembla railway."
In October, the state government earmarked $4 million in funding for "safety improvements" for vehicles turning left from Picton Road on to the M1 by replacing the T-intersection with a new 700-metre northbound acceleration lane.
It was a far cry from the $84 million previously earmarked for climbing lanes on Mount Ousley.
The $84 million climbing lanes project was to be jointly funded by the state and federal governments but Minister for Infrastructure and Regional Development Warren Truss put the kybosh on the plan in September when he confirmed the federal government would not provide funding.
Mount Ousley and Maldon-Dombarton also missed out in the allocation of $100 million from the long-term lease of Port Kembla.
All lanes of Mount Ousley Road were reopened about 1.15pm yesterday.