The M4 motorway near St Marys in Sydney was emporarily closed, causing significant disruptions for commuters.
The highway was shut shortly before 7 am due to a police operation at the Kent Road pedestrian overpass.
All lanes have reopened but traffic conditions are heavy.
Citybound traffic was backed up to Mulgoa Rd, while westbound traffic is locked back to Mamre Rd.
Commuters are strongly advised to seek alternative routes to avoid delays.
The M4 highway was temporarily closed early Thursday morning due to a police operation (pictured, map of the closure)
Meanwhile, commuters travelling on the T1 North Shore and Western train lines suffered delays after a train needed mechanical repairs at Wynyard Station at 6am.
Please allow extra travel time on North Shore Line and Western Line, services due to urgent train repairs at Wynyard,' Sydney Trains wrote on X.
'Journey time will be longer, and stops may change for some trains.'
CEO of Sydney Trains Matt Longland said the train had a 'mechanical failure'.
'We do have a failure of a mechanical issue on a train at Wynyard platform three at the moment,' he told 2GB's Ben Fordham.
'We're in the process of clearing the platform within the next 10 minutes or so. We'll have that platform cleared and trains back moving.
'If you're travelling at the moment, apologies for those delays, we're moving the train as quickly and efficiently as we can.'
Citybound traffic on the M4 (above) was backed up to Mulgoa Rd while westbound traffic was locked back to Mamre Rd
