1884, in 1885, in 1886 and Clifton through to and North Kiama () in 1887. The missing Waterfall to Clifton section comprised four large brick-arch culverts (and many small ones) and eight tunnels with a total length of over , delaying its opening until 1888. The section between and (servicing Nowra) opened in 1893. According to the official papers on the line's construction, when the line first opened for trains between Sydney and Sutherland construction was not quite complete, so excursion services initially ran on weekends only until the entire line was handed over. The first official train ran within the modern-day suburban area on 9 December 1885, although the line was closed once again between December 1885 and January 1886 to permit testing on the new bridge over the Georges River. Track amplification The line was originally constructed as double track between Illawarra Junction (near Macdonaldtown) and Hurstville with single track thereafter; however, its rising use meant that the line required duplication soon afterwards. The line was duplicated between Hurstville and Loftus Station (with the exception of the Como bridge over the Georges River) in April 1890, then southward to Waterfall by 12 December 1890. The section of track between Illawarra Junction and Hurstville was quadruplicated between 1913 and 1925. After duplication in 1890, the original lattice-girder Como Bridge across the Georges River was laid as gauntlet track. This arrangement remained in place for many decades, causing a notorious bottleneck on the line, until the New South Wales Government commissioned John Holland & Co to build a new bridge in 1969. Construction of the new bridge, made of prestressed concrete box girders, commenced in 1969 and was first used by the 18:17 service from Como on 19 November 1972. The old bridge, as well as a former alignment of the line between Mortdale and Oatley replaced in 1905, is now used as a rail trail for pedestrians and cyclists. Duplicated track now continues to Unanderra, except for the section through the Clifton Tunnel. Deviation Many goods trains were routinely divided at Stanwell Park and taken through to Waterfall in stages, effectively increasing the number of train movements on the line. The increasing congestion and steepness led to construction of a double track deviation, which opened between Waterfall and Helensburgh in 1914, Helensburgh and Otford in 1915, and Otford and Coalcliff (bypassing the by now infamous Otford Tunnel) in 1920.