All southbound lanes of Pennant Hills Road are closed in Normanhurst due to a truck breakdown.
The truck has broken down just past Stuart Avenue.
Motorists are advised to avoid the area as southbound traffic is very heavy.
Light vehicles are advised to use the Pacific Highway, Fox Valley Road and The Comenarra Parkway instead.
Heavy vehicles are advised to use the Pacific Highway and Ryde Road instead.
Route 589 buses are also diverting away from Pennant Hills Road, missing 12 stops.
Traffic crews are on site, along with a heavy tow truck.
For the latest traffic information, visit www.livetraffic.com.