Remediation of flood damage on the Toowoomba Range Railway, Queensland, Australia

摘要

The Toowoomba Range Railway is located on the eastern side of the Great Dividing Rangernapproximately 110 km west of Brisbane, Australia and was originally constructed in 1867. This localityrnin the Upper Lockyer Valley is characterised by steep terrain with surface elevations reachingrnapproximately 600 m above sea level. Following the flash flood events of January 2011, the railwayrnsustained significant damage including washouts of embankments and culverts, failure of upsloperncuttings, destruction of a bridge and damage to a gas pipeline. A geotechnical assessment wasrnundertaken along a 25 km length of railway and over 100 failure features were identified as having anrnimpact on operation of the railway. Twenty failure features were considered significant in nature andrnrequired engineering input during the remedial design and/or reconstruction phase. Initial estimates byrnQueensland Rail predicted a 3 to 6 month repair program. Detailed topographic information forrnselected sites was obtained by an aerial photogrammetric survey from a manned helicopter using thern3DM Analyst digital photogrammetry system. Reconstruction of the flood-damaged earthworks andrnculverts utilised robust solutions that could be implemented quickly and this typically comprisedrnexcavation of failed material and replacement with rockfill, installation of large steel culverts, and atrnone location the use of pre-cast concrete L-section panels to retain a steep rockfill embankment. A sixrnweek program of investigation, pile design and construction was implemented for replacement of therndamaged bridge. The first train resumed service on 28th March 2011, about two and a half monthsrnafter the flood, which was well ahead of schedule.