 It was added to the New South Wales State Heritage Register on 2 April 1999.The Main Western line was built in stages, radiating west from Central station to Parramatta, opened on 26 September 1855; Blacktown on 4 July 1860; Rooty Hill in 1861 and by May 1862, St Marys; Kingswood on 7 July 1862; and Penrith on 18 January 1863; at which point the Nepean River and Blue Mountains were significant barriers.Various plans were considered to cross the Blue Mountains, with the NSW Government selecting the submission of John Whitton, Chief Engineer of Railways, that involved the construction of the Victoria Bridge over the Nepean, completed in 1867; the Lapstone Zig Zag, completed in 1867; and The Great Zig Zag at Clarence, completed in 1869.