Sand from the bed of the Barron River was used as the base material for concrete work on the second section; all the tunnels were concrete lined, and culverts and drains were also built in concrete. The Cairns Railway's range ascent tunnels represent the largest group of tunnels in Queensland and were the 24th to 38th of the 64 tunnels opened in Queensland from 1866 to 1996. By 30 January 1889 tunnels 1 and 2 were finished; Tunnel 3 was in a forward state, while 4-9 and 12-13 were ready for lining. Tunnels 10 and 11 had headings through only, while tunnels 16 and 19 were not yet opened. Work was authorised on the redesigned and lengthened Tunnel 19 in December 1889. Due to the cancellation of four tunnels, tunnels 16 and 19 were renumbered as today's tunnels 14 and 15. As well as tunnels, bridgework was a major element of the construction work on the second section. The total length of steel required to complete the bridgework was around . The steel work was all cut, fitted and partly riveted by Walkers Ltd of Maryborough. In 2011 the steel bridges between Redlynch and Kuranda included: six with lattice girders; plus Bridge 42 (1890), where fishbelly plate cross- girders have been reused as main span members; Bridge 50 over Mervyn Creek (which replaced an earlier timber bridge in the 1920s); and Jumrum Creek Bridge (Bridge 51), which although mainly timber has a steel central span (the bridge was reconstructed in 1962). There were also five very short steel bridges by 2011. About past Kuranda is Crooked Creek Bridge, which in about 1900 reused (shortened) plate girders from the 1867 Bridge 51 on the Main Range. The bridge has been strengthened with new steel piers either side of the concrete pier, and its replacement steel cross girders also originally came from Bridge 51 on the Main Range. There were 24 timber trestle bridges extant in 2011, but none of these retain their original timber. The local scrub hickory originally used in the bridges was of poor quality, requiring replacement work in the 1890s to 1900s. Components of the timber bridges are also gradually being replaced with steel, due to the scarcity of suitable hardwood, and over the years some bridges have been replaced with concrete culverts. The steel bridges have retained their integrity to a greater degree. The bridges with highest heritage significance are the steel lattice-girder bridges; all built during the construction of the second section.