All southbound lanes of the M1 motorway are closed north of the Hawkesbury river after a serious motorcycle crash.
Traffic is being diverted at Mount White onto the Old Pacific Highway to rejoin the motorway at the Hawkesbury River Bridge.
Police advised motorists to exercise caution and allow plenty of additional travel time.
All emergency services, a rescue helicopter and traffic crews are at the scene of the crash at Jolls Bridge.
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