Sydney Metro West has achieved a world-first in tunnel construction with a Lining Erector Machine (LEM) successfully being used to line the mined service tunnels that connect to the future stabling and maintenance facility at Clyde.
The LEM has been custom-designed to line the two 700-metre service tunnels with precast segments, which were manufactured at the project’s Eastern Creek precast yard.
Traditionally, tunnels excavated by roadheaders require cast-in-situ lining. This is unlike tunnels built using tunnel boring machines (TBMs), which have the capability to both excavate and install tunnel segments to line the tunnel walls as they move.
Lining the service tunnels in the usual way would have involved assembling large formwork sections, pumping concrete from the surface, and staging multiple pours – a slow and labour-intensive process.
Inspired by TBM technology, project engineers adapted and refined the LEM while on the job, enabling it to complete an entire tunnel ring, built by piecing together four segments, in about one hour.
It took two months to line the final service tunnel, which measures 762 metres in length and 6 metres in diameter.
The LEM approach is set to be a game-changer for the tunnelling industry, speeding up lining while delivering a higher-quality, watertight finish that matches the strength and finish of TBM-built tunnels, and making the job safer for tunnel workers.
LEM figures
- The LEM is approximately 55 metres long and six metres wide.
- It weighs 310 tonnes (equivalent to 62 African elephants).
- The LEM has installed 3438 segments.
- The tunnels it is lining will take trains to the future Sydney Metro West Stabling and Maintenance Facility and are over 700 metres long.
- It takes around 60 minutes to build a complete ring (four segments).
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