If you are heading north on the highway this week, be prepared for changed traffic conditions on the Pacific Motorway at the Tugun Bypass Tunnel.

While essential maintenance work is carried out, the northbound and southbound fast lanes of the tunnel will be closed for one night, on Thursday 5 December between 7pm and 6am.

A reduced speed limit of 40km/h will be in place for the safety of workers and motorists during the work, which will include sensor repairs and calibration, and power supply maintenance.

Motorists are advised to drive to the conditions, and follow the direction of signs and traffic control.

Transport for NSW thanks motorists for their patience during this time.

For the latest traffic updates download the Live Traffic NSW App, visit http://livetraffic.com or call 132 701.