UPDATE: All citybound lanes on the West Gate Freeway have been reopened following an earlier collision near Williamstown Road.
Delays remain but are expected to ease quickly.
All inbound lanes are closed on the West Gate Freeway at Williamstown Road following a serious collision.
Traffic is being diverted onto Williamstown Road, using the exit ramp and then returning to the freeway via the Williamstown inbound entry ramp.
Motorists are however advised to avoid citybound lanes of the West Gate Freeway and use Geelong Road instead.
The closure is under the control of emergency services and all lanes will open as soon as it safe to do so.
Signals team are adjusting traffic lights to minimise congestion in the area and the Incident Response Service is assisting with traffic management.
Real-time traffic conditions are available at traffic.vicroads.vic.gov.au or via the VicTraffic mobile app. The latest public transport information and network status is available at ptv.vic.gov.au or in the PTV mobile app.