TYSSE TBM makes final breakthrough

Breaking through the headwall of Downsview extraction shaft in Toronto, this is the second TBM, called Moley, to finish tunnelling on the project. The first TBM, called Holey, completed excavation late last year, and the final breathrough took place December 7, 2012. The contractor for both drives is the joint venture of McNally, Kiewit and Aecon, constructing the southern tunnels package including 5.8km of tunnels in four drives.

The JV launched Moley in fall 2011 and the TBM finished its first northbound drive on June 4, 2012, at the Keele Street extraction shaft. After being moved back to Sheppard West launch shaft, it started its 1.32km-southbound drive and reached the final breakthrough on March 5. The Cat TBM bored 2.89km of tunnels and installed 1,813 segment rings through glacial till, sand, silt and clay grounds under Toronto.

There are two other TBMs working on the subway extension, all supplied by Cat, formerly Lovat, to the project owner, Toronto Transit Commission, in 2010. The Contract Works include 10 TBM drives totaling 13.4km of tunnels and were awarded to two contractor joint ventures, the second is comprised of Spanish companies OHL-FCC.