REPORT | NORTH AMERICA


TUNNELS FACILITATE WATER FLOW


Water system upgrades are keeping the North American tunnelling industry busy. Keren Fallwell reports


Above:


Big Tex, a Robbins TBM, is boring the Mill Creek Drainage Tunnel in Dallas, and is the largest


hard-rock TBM ever used in the US


President Biden’s US$1.2 trillion infrastructure spending plan, passed by the US Senate in August, will give a welcome leg-up to improving the US’s transport and utilities networks, and no doubt provide work for the tunnelling industry. Among the projects that may benefit from the


Infrastructure Investment and Jobs Act is the long- delayed Hudson rail tunnel connecting New York and New Jersey. But while industry waits to see where the money will


be spent, there are plenty of projects underway, and many of them are upgrading water and wastewater systems in Canada and the US. Among them is the five-mile Mill Creek drainage relief tunnel in Dallas which is setting records for the US


22 | November 2021


tunnel industry. The Robbins main beam TBM, named Big Tex, is the largest hard-rock TBM ever to bore in the US, and the first dual-diameter machine. Earlier this year, Southland/Mole Joint Venture


successfully made the conversion from 11.6m to 9.9m at 1.8 miles into the bore. The two sizes were required because of the different flow rates for the upstream and downstream sections of the tunnel. To achieve the conversion, the TBM features a


specialised cutterhead with removable spacers and adjustable bucket lips. Deep below Lake Ontario, contractor Southland


Holdings has also set a Toronto city record with progress on the 2.2-mile Ashbridges Bay Outfall tunnel using a Robbins single shield TBM. The crew completed 30 rings


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53