The other driver, a woman believed to be aged in her 40s, was freed from her car by police rescue crews more than two hours after the incident. She suffered serious leg injuries and was taken to hospital for treatment.
Another man was treated and taken with head and facial injuries to Royal North Shore Hospital in a critical condition.
Drivers were advised to take the Harbour Tunnel as an alternate route. The Transport Management Centre advised people to work from home.
Before 10am, traffic queues stretched to Edgecliff in the east, past Mosman and Artarmon in the north, and to Haberfield and across the Gladesville Bridge to Hunters Hill.
At 9am, buses from the city’s north that would usually cross the Harbour Bridge were ending their journeys at North Sydney, Chatswood and Macquarie Park.
Buses travelling through the city were terminating at Wynyard and those that would have crossed the Anzac Bridge citybound were instead terminating and restarting their routes at Town Hall.
Sydney Trains asked passengers to maintain social distancing “as much as possible” due to an increase in patronage from the cancelled bus services.
Ambulance and police crews attended the scene, with staff from The Rocks Fire Station reportedly walking to the site to avoid the traffic queues.
NSW Emergency Services Minister David Elliott said the incident was “tragic”.
“It’s tragic, and just a reminder for everybody that they’ve got to take care on the road,” he told Ben Fordham on 2GB.
Shortly after the crash, Secretary of the Police Association of NSW Pat Gooley called into 2GB to ask drivers stuck in the traffic to stop making U-turns to leave the queue.
Mr Gooley, who was in the traffic himself, said the manoeuvres were making it difficult for emergency services to access the crash.
“What we do have is people doing U-turns, and we have emergency services trying to make their way on the other side of the road,” he said.
“People have to stop doing these U-turns, it’s too dangerous.”
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Mary Ward is a reporter at The Sydney Morning Herald.