THE PROJECT
To improve commuter and freight rail efficiency, the NSW Government commissioned an upgrade to the Sydney Main Northern Line by introducing a third track between Epping and Thornleigh train stations. A 12 m high sandstone cutting required widening to allow northbound freight trains to operate independently from commuter trains while maintaining uninterrupted commuter rail operations.
PSM were engaged to analyse and design rockfall protection measures to ensure rail safety during excavation of the slope, which was approx. 1 metre from the rail kinematic envelope.
ENGINEERING AND TECHNICAL OPPORTUNITIES
Eliminate rockfall risk impacting the live corridor due to the adjacent active rail line.
Rockfall protection installation within the tight rail shutdown period.
Engineering solutions were required due to the tight spatial constraints (active line <1 m from slope toe).
APPROACH AND INNOVATION
Completed detailed site investigation including photogrammetry and cliff geometry modelling to assess defect spacing, maximum boulder size and release mechanisms.
Rock mass characterisation and assessment of material properties critical for estimating block runout distances and bounce heights.
Performed numerical modelling of rockfall paths, interactions with the slope geometry and mitigation measures. Analyses guided the design of protection fences and slope modifications required to ensure no credible boulder could impact the live corridor.
Verification during construction showed accurate prediction of rockfall sources, runout paths and protection requirements.
OUTCOMES
PSM delivered innovative and pragmatic engineering solutions in a timely and effective manner that eliminated rockfall impact and allowed the commuter rail to remain operational during the works. Targeted site investigations, modelling and rigorous design methodology instilled stakeholder confidence in the successful delivery of a high-profile, high consequence public infrastructure project.
Services: #CivilGeotechnical #EngineeringSolutions #Geotechnical #Railway #Infrastructure
