Arncliffe Pedestrian Tunnel
Tunnelling Solutions completed the excavation and permanent lining of the Arncliffe Pedestrian Tunnel on time and without incident.
The tunnel was constructed through a rail embankment with only 2.5m of cover to live rail tracks and extremely poor ground conditions.
The original design was for a complete array of clutched canopy tubes to be installed by the previous contractor but unfortunately during the installation process they ran into significant problems.
The Canopy Tubes became unclutched resulting in significant gaps between them of up to 1m which caused major challenges through the excavation and support phase.
A Permit to Tunnel process was strictly applied during the excavation period with attendance from the client and the designers signing off on the sequence of excavation that was required for that day.
Steel sets were installed every metre along with infill shotcrete which made up the temporary support along with 50mm-100mm of shotcrete applied daily for face support.
Surface and convergence monitoring was frequently carried out but with good tunnelling practices being implemented no settlement was reported.
The excavation was completed well ahead of schedule then a purpose built form was erected and used to line the tunnel. Both portals were constructed using traditional formwork systems that were challenging to build due to the potential of significant uplift pressures but with a robust design in place the final product was excellent.
Collaboration was fundamental to the success of the this project with the main contractor John Holland Bouygues Joint Venture and TFNSW all involved.
Tunnelling Solutions have excavated and lined a complex 30m long pedestrian tunnel under four live railway tracks with very low cover for us. They have shown great professionalism and have always worked with us cooperatively to get the best outcome for the project. Harry is a great leader to the workforce, is very safety conscious and is solution driven. His drive to perform and continuously improve was successfully instilled to his team and enabled a breakthrough ahead of schedule and without any incident.
Craig was very helpful in preparing the contract scope and optimising the delivery model. He also admirably administered the contract in the delivery phase.
In summary, Tunnelling Solutions promised they could excavate a complex tunnel safely and efficiently, and they did. Beyond our expectations. I would consider them for my next tunnelling project.
Nicolas Law de LauristonAlliance Manager NSRU Alliance