February 16, 2009
Pittsburgh Sees the Light at the End of the North Shore Tunnel
Port Authority of Allegheny County workers in Pittsburgh can see “the light at the end of the tunnel” following the Jan. 15 completion of the mining phase of the agency’s North Shore Connector project. The Port Authority used a 500-ton tunnel boring machine (TBM) to mine twin tunnels, each 2,200 feet in length, underneath the Allegheny River as part of constructing the 1.2-mile light rail extension from downtown Pittsburgh to its neighboring North Shore.
The project took less than a year to complete since its beginning Jan. 22, 2008, at the “launch pit” adjacent to PNC Park, home field of the Pittsburgh Pirates. From there, the TBM mined approximately 50 feet below ground level under the Equitable Resources building on the North Shore, then under the river at a rate of 30 to 40 feet per day, eventually reaching the heart of downtown Pittsburgh.
On July 10, 2008, the TBM completed the first tunnel when the TBM broke through the “receiving pit” wall in downtown Pittsburgh. Mining of the second tunnel resumed Oct. 14, 2008. The Port Authority estimates that the North Shore Connector will enter service in 2011, providing a link between Pittsburgh’s South Hills communities and its North Shore neighborhoods, entertainment venues, and business centers.
Now that the mining phase is complete, the Port Authority will disassemble the TBM and ship it back to the manufacturer, Herrenknecht A.G. in Germany.