18 MAY 2021 WorldWide Drilling Resource® Workhorses of the Cross River Rail Project Adapted from Information by the Government of Australia The Cross River Rail Project in Brisbane, Australia, is a huge undertaking, designed to unlock a public transport bottleneck caused by a single-rail river crossing. The 3.7-mile twin tunnels running under the Brisbane River and Brisbane CBD (Central Business District) will enable a smoother flow for the whole of southeast Queensland. Tunnelling on this massive scale presents complex engineering challenges, and the workhorses of the project are two machines, each suited to different types of work: roadheaders for excavation and tunnel boring machines (TBMs) for the actual tunnelling. Using a roadheader to break rock, excavation began in May 2020, with a 919-footlong cavern about 89 feet underground. Six roadheaders are being used to tunnel simultaneously. These are electrically powered tunnelling machines, which perform the finely-controlled digging needed for shallow tunnel, escape passage, and station cavern excavation. Each 126-ton roadheader is 72 feet long. A “pineapple,” the rotating excavating head with metal picks, cuts the rock. The roadheader is controlled by a cabin operator, while a cable spotter assists in safely maneuvering the machine. Excavating 66 tons of rock per hour, the roadheader’s cone will wear away more than 30 picks during an eight-hour shift and travel 3 to 16 feet in 24 hours. Two giant TBMs will dig the project’s twin tunnels after the roadheaders finish initial access. These machines are like huge underground factories, each supporting a 15-person crew and fully equipped with crew facilities, offices, and toilets. Each 541-foot-long TBM weighs 1488 tons. The cutterhead alone weighs 116.5 tons and measures 24 feet in diameter. There are 39 cutting disks, each exerting up to 35 tons of pressure. The two TBMs will each progress at a rate of 66 to 99 feet per day. As they bore, the machines will install massive 4.5-ton precast, interlocking, concrete segments to line the tunnels. Six concrete segments are needed to create just one ring. No gallop to the finish line, the project will, instead, be a slow, but steady, trot to completion. Expected total project completion is in 2024, with extensive safety testing to follow. Actual services are expected to commence in 2025. Roadheader TWO at Woolloongabba. Tunnel Boring Machine. DIR
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