The Cowan rail accident occurred at 7:20pm on 6 May 1990 when the 3801 Limited special steam passenger train returning from the Morpeth Jazz Festival was struck in the rear by the following CityRail inter-urban passenger service. The steam train had stalled while attempting to climb the steep gradient from the Hawkesbury River to Cowan, New South Wales, and it was found that sand applied to the rails to regain traction had interfered with the signals and given the following train a false clear indication.