The changed traffic conditions will apply from February, but some maintenance work will begin next week.
Maintenance work will be carried out between 7am and 5pm on weekdays from Tuesday, January 9 through to mid-April, causing minimal impacts to traffic.
Work will be carried out under the bridge from a barge and will involve installing steel plates underneath the bridge supports.
As this work progresses, a reduced speed limit of 40 km/h will be in place across the bridge, 24 hours a day, and is expected to come into effect in February.
Motorists are advised to allow an additional five minutes of travel time, drive to the conditions and follow the directions of signs and traffic control.
The carpark on the NSW side of the bridge (adjacent to Miss Ross Hill) will be closed during this period while the area is used as a site compound.
Transport for NSW thanked the community for its patience during this time.
For the latest traffic updates, download the Live Traffic NSW app, visit livetraffic.com or call 132 701.