For those outside the UK, the Crossrail project is a mega-project upgrade to the London metro area’s subway system. The tunneling portion of the project will consist of 21-km of twin-bore tunnels excavated by eight closed-faced tunnel boring machines, six of which will be earth pressure balance machines (EPBMs). The UK’s Geological Society has published an interesting article on the geology of the crossrail project. Some of the geological and geotechnical challenges of the project include the famous London Clay, sensitive structures, faults, and rapid transitions between permeable and relatively impermeable formations creating potential water pressure issues. [Source: Geological Society. Image: Geological Society]
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Pittsburgh PA Light Rail Tunnel Construction and Cost Overruns
The Port Authority of Allegheny County (Pittsburgh, Pennsylvania) has a major transit improvement project dubbed the North Shore Connector. Its main components are twin bored tunnels 1.2 miles long that will connect the Port Authority’s Light Rail Transit system, the T, 1.2 miles from the Gateway Subway Station underneath Stanwix Street and the Allegheny River to the North Shore. It will travel under the river and provide three new stations and allow for future improvements beneficial to future development and continued downtown revitalization. The $435 million project is making news recently for cost increases, drawing comparisons to Boston’s Big Dig much to the dismay of the Port Authority. Read on for project maps, links and more info.