The Zig Zag Railway is an Australian heritage railway, situated near Lithgow, New South Wales. It was opened by the not-for-profit Zig Zag Railway Co-op as an unpaid volunteer-staffed heritage railway in October 1975, using the alignment of the Lithgow Zig Zag line that formed part of the Main Western line between 1869 and 1910. The line climbs the western flank of the Blue Mountains, using railway zig zags to gain height.