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Historic last journey as metro factory finishes tunnelling work


Tunnel segments on a truck Tunnel segments on a truck

A state-of-the-art Marrickville factory has finished building almost 100,000 pieces of concrete for Sydney’s new twin metro railway tunnels.

At its peak, the pre-cast factory pumped out one four-tonne concrete segment every six minutes by a workforce of more than 140.

Its final segment will be installed in the second metro tunnel deep under Sydney Harbour.

Since April 2018, the facility has delivered 99,746 segments, which were installed by five tunnel boring machines to line 15.5-kilometre twin tunnels between Chatswood and Sydenham.

More than 39,600 segments travelled across the Sydney Harbour Bridge so they could be installed underground north of the harbour. Pictured are the final segments to be delivered over the Bridge.

Six concrete segments make up one tunnel ring, which forms the permanent waterproof lining of the tunnels. The rings for the under-harbour section have a seventh concrete segment, called a keystone.

A total of 358,920 tonnes of concrete was used in the specialised facility - enough to fill 55 swimming pools.

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