Creek section, which was dictated by the opening of the Hawkesbury River bridge, passengers disembarked from either Hawkesbury River, from the south, and Mullet Creek (closed 11 September 1897), from the north. Mullet Creek was located north of the current Wondabyne station and from the western entrance to the Tunnel. Passengers were required to catch a ferry between Hawkesbury River and Mullet Creek that met with trains at both terminus. Gauge and loading gauge The line was built with tracks and a loading gauge that accommodated carriages on double track with centres. In 1910, a new nation standard loading gauge was adopted for all mainland states, which was applied to all new works. In the 1920s, in the Sydney electrified area, the wider standard allowed for 3+2 seating in lieu of 2+2 seating. Problems started to arise when in 1960 when the line though Woy Woy was electrified using so-called narrow stock. More problems arose in the 1972 with the introduction of double deck carriages, which required the removal of brickwork in the top corners of the circular tunnel profile with the roadbed lowered. In the 1990s so-called medium width stock of , such as the Tangara trains, were allowed through Woy Woy Tunnel. Original planned tunnel location The following extract is from the New South Wales Legislative Assembly, 1 December 1881, Answers to Questions, as reported by The Sydney Morning Herald, in relation to connecting the Great Southern and Northern Lines via the construction of the Homebush-Waratah Line:...From this point the line takes a north-easterly direction towards Flat Rock Point, crosses the channel between the southern mainland and Long Island; thence across the Hawkesbury River to Dangar Island ( from Redfern); and thence across the main channel of the river to a tunnel through the cliffs on the northern bank to Patonga Creek; thence by a tunnel through the high land between that creek and Woy Woy Creek, thence across that creek and skirting the western shore of Brisbane Water, across Narrara Creek through to the village of Gosford ()...'' This original route and Tunnel location was not adopted. Heritage listing The Woy Woy Railway Tunnel has historic significance, as at the time of its construction it was the longest tunnel in Australia and was recognised as one of two major engineering feats on the Short North line, the other being the Hawkesbury River Rail Bridge. The tunnel has