M1 reopens after fiery truck crash

All lanes of the M1 Pacific Motorway north of Sydney have reopened nearly 24 hours after a fiery crash between a B-Double and a mobile crane lead to traffic woes, with cars banked up 20km.

Road crews worked through the night to repair the motorway's surface after the two vehicles burst into flames after colliding at 4am on Tuesday while travelling north on the motorway about 2km south of the Hawkesbury River.

The blaze was so intense that the two vehicles fused together, complicating the task of removing the wreckage.

The massive salvage operation lead to traffic woes for thousands of drivers on Tuesday with cars banked up 11km on the M1 and more than 19km on the Pacific Highway.

The Traffic Management Centre said repairs to the road service were made overnight and all diversions were lifted on Wednesday morning.