A driver in Sydney's south careened on to train tracks at Penshurst station at 9am but managed to escape.

The grey sedan was on its side on the tracks, causing delays on the T4 Eastern Suburbs and Illawarra Line, a Transport Management Centre spokeswoman said. Trains could pass the vehicle but they were slowing down and taking turns, with commuters advised to allow extra travel time.

The Hume Motorway was closed in both directions at 8.30am after a truck crashed and caught alight at the Wingecarribee Bridge at Berrima, south-west of Sydney, causing major delays.

The driver and sole occupant of the double-B, aged in his 60s, was pulled from the vehicle with minor injuries

He was treated by paramedics and taken to Bowral District Hospital. His injuries are not considered life-threatening.

The fire was extinguished by Fire & Rescue NSW, but the truck, carrying frozen goods, was destroyed.

Part of the trailer fell from the bridge and started a small grass fire that was being extinguished by Rural Fire Service crews.

Motorists were advised to avoid the area while the accident was cleared.

By 10.30am, all southbound lanes of the Hume Motorway had reopened, the Transport Management Centre said.

Northbound lanes remained closed as the clean-up and vehicle salvage operation continued.

The safety barrier has been damaged so repairs will need to be carried out, the centre said.

A woman driving a four-wheel-drive also escaped serious injury after the vehicle rolled at a busy intersection in North Sydney during peak hour.

She was taken to the Royal North Shore Hospital with minor injuries, a NSW Ambulance spokesman said.

The accident, at the corner of Berry and Walker streets, created delays for peak hour commuters.

Light rain will continue throughout the morning before clearing in the afternoon, the Bureau of Meteorology forecasts.