Slope hazard management on the Toowoomba Range Rail Corridor, Queensland

The Toowoomba Range Rail Corridor (TRRC) forms part of the West Moreton Line and runs from Harlaxton to Murphy’s Creek. This section of track is approximately 26 km in length and was built circa. 1860’s, through the steep terrain and complex geology of the Toowoomba Range. This section of the rail corridor has been subject to historic and ongoing slope instability which has impacted on the operational use of the railway. Over the past five years a programme of routine and emergency site assessments have been conducted to ensure safe operation of the railway. The assessments have been supplemented by UAV-obtained LiDAR and photogrammetry data to create Digital Terrain Models (DTMs). These DTMs have significantly aided in the assessing, planning and managing of slope maintenance activities.

Additionally, automated instrumentation has been installed in high-risk instability zones using GNSS satellite-based movement monitors, track tiltmeters and inclinometers.

The above methodologies have facilitated the development of a comprehensive register of instability events, zones of concern, associated risks and required maintenance works. This register also includes recommendations for further work at all assessed slope sites. This has proven extremely beneficial in assisting the Asset Owner with prioritising and targeting critical locations during the limited Scheduled Corridor Access System closures (SCAS closures) available.

An outline of the remediation works undertaken for one of the larger landslides at Chainage (CH.) 141 km, which reactivated and mobilised following the intense rainfall events in February/March 2022, is also presented.