REPAIRS to the Tarro Rail Bridge have started and are expected to take weeks, as train services are boosted to ease the traffic gridlock.
Specialist engineers assessed the site on the New England Highway on Thursday, allowing Transport for NSW crews to start urgent work on top of the bridge.
The outside lanes of the Tarro Rail Bridge were suddenly closed earlier this month and a slower speed limit remains in place after a structural defect was discovered in the supporting columns.
Transport for NSW acting chief customer officer Roger Weeks said the essential work required to get four lanes on the bridge back open had started on Thursday night.
"We urge motorists to consider the safety of road crews and drive to the conditions," he said.
Instructions are signposted for oncoming traffic on electronic message boards facing both directions.
The rail bridge, between Hexham and Maitland, is expected to stay open to vehicles before repairs are finished "in the coming weeks".
Transport for NSW is working with its maintenance contractor and the Australian Rail Track Corporation to make the fixes as soon as possible.
Heavy vehicles have been asked to use an alternate route if they can to avoid congestion in the area.
Regular uses of the route have also been encouraged to car pool, travel outside peak hours, use public transport, use a different road, or work from home, if possible.
Traffic has been consistently heavy on the New England Highway at Tarro since the snap lane closures earlier this month.
Extra trains will operate on the Hunter line from Monday to give commuters more transport options while bridge restrictions are in place.
Transport for NSW has put on an extra train on the Hunter line - able to seat about 180 passengers - to cope with a significant increase in demand.
It will run each weekday during morning and afternoon peak periods from October 23 until further notice.
It will leave Maitland at 7.01am on Monday, then 6.55am all following days, stopping at the usual express stops and arriving at Newcastle Interchange just after 7.30am.
The extra service will leave the interchange at 4.22pm daily, stopping at the usual express stops, and arrive in Maitland just after 4.50pm.
Mr Weeks said the transport authority was listening to the Hunter community and would add the 10 additional services weekly for as long as needed.
NSW TrainLink has also amended its timetable temporarily so Maitland to Newcastle services stop at all stations during peak times.
Mr Weeks thanked the community for their patience, and said Transport for NSW appreciated the impact the rail bridge restrictions were having.
"I urge all commuters, road and rail, to plan ahead and travel at times that will help reduce the pressure on the network while these crucial safety repairs are carried over the coming weeks," he said.
A Transport for NSW spokesperson previously said it was hard to estimate how long the urgent repairs would take or how much they would cost.
