 Between 1869 and 1910 the railway was a major force in the development of western New South Wales.Eventually traffic became so dense, due to the growth of the railway system through the spread of settlement, together with the loss of time in working over the Great Zig Zag, that alternatives were considered.From the 1880s many inquiries and investigations were held including consideration of John Whitton's original proposal for a two-mile tunnel.