Photo - NSW RFS
UPDATE - 2:15PM
Two north and southbound lanes are now open on the M1 Motorway.
Traffic is slowly easing for southbound motorists - but there's still plenty of northbound delays.
Lanes are closed in both directions on the M1 Motorway following a serious truck accident at Berowra.
A tanker carrying liquid bitumen has lost control before crossing the median strip close just after midday - blocking north and southbound lanes.
Paramedics and HAZMAT teams at the scene with the driver freed in the past half hour.
Fire and Rescue are offering fire protection at the scene.
If you are heading that way take the Pacific Highway exit at Cowan to avoid delays - with only one southbound lane open at the moment.
There's already more than 6km of northbound delays.