Both directions of traffic on New England Highway at Tarro affected by lane closures as school holidays end

One lane in each direction of the New England Highway across the Tarro rail bridge will be closed until further notice while urgent repairs take place, transport authorities have confirmed.

A reduced speed limit of 60 kilometres per hour will also be in place while crews work.

A Live Traffic NSW spokesperson said heavy traffic was expected as the school holidays end on the weekend.

The spokesperson said on Saturday afternoon traffic conditions were already heavy on the Tarro rail bridge and people in the area should expect "significant delays".

The affected area is about 17km north of Newcastle, heading to and from Maitland on the New England Highway, or A1.

All road users have been advised to plan ahead, allow plenty of extra travel time and be patient while driving.

The latest warnings and conditions can be found on the Live Traffic NSW website.