Motorists are advised of changed traffic conditions on The Northern Road from this Friday night for essential maintenance work.
A new interchange will be built across the M4 at The Northern Road in South Penrith.
A Roads and Maritime Services spokesperson said detours would be in place for traffic from Friday, July 13 to Friday, August 10, weather permitting.
Motorists should plan their trip, allow extra travel time and follow the direction of traffic control and all signs.
These signs will include a reduced to 40 km/h speed limit through the work zone.
Electronic message signs and traffic controllers will be in place to direct road users through the work site.
The Australian and NSW governments are jointly funding this work as part of the $1.6 billion upgrade of The Northern Road between Narellan and South Penrith.
Details: 132 701, www.livetraffic.com or download the Live Traffic NSW app.