**UPDATE: As of 4pm, three lanes on the M4 have been re-opened, however there are queues of nine kilometres almost back to the Prospect Highway.**
Anyone travelling on the M4 is in for a slow trip, with significant delays following a multi-vehicle crash in Merrylands.
Two of four citybound lanes are currently closed just past the Pitt Street overpass, with traffic heavy in the area.
There are currently queues back approximately four kilometres, with motorists advised to allow extra time and exercise caution.
Emergency services are currently attending the scene.
Westbound lanes are open, however there is also a backlog building as motorists are slowing down while passing the site of the crash.