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Tunneling for Toronto-York Spadina Subway Extension Marks 90 Percent Completion

TTC Tunneling As of Sept. 19, 90 percent of tunneling has been completed as part of the Toronto-York Spadina Subway Extension (TYSSE) subway project. There are two sets of tunnel boring machines (TBMs) that will build the tunnels for the project:  Holey and Moley are one pair, Yorkie and Torkie are the second pair. Holey and Moley have built the tunnels south of Finch West Station, the southern tunnels, and Yorkie and Torkie are building all of the tunnels north of Finch West Station, or the northern tunnels.

Yorkie and Torkie are expected to arrive at the extraction shaft located at Highway 7, just east of Jane Street before the end of the year, according to the Toronto Transit Commission (TTC), the project owner.

In summer 2011, tunnel boring machine Holey began tunneling operations from the launch shaft at the Downsview Park Station site. Holey completed the first drive on May 1, 2012, and on Dec. 7, 2012, broke through the headwall at the extraction shaft located on the east side of W.R. Allen Road, just north of Sheppard West Station (currently Downsview). In total, Holey has drilled 2.8 km of tunnel and placed 1,826 rings.

In fall 2011, tunnel boring machine Moley began boring in the tunnel adjacent to Holey and arrived at the Keele Street extraction shaft on June 4, 2012. On March 5, 2013, Moley broke through the headwall at the extraction shaft located just north of Downsview Station. Moley placed 799 rings and completed 1.2 km of tunnel.

In December 2011, Yorkie began the first northern tunnel drive from the Pioneer Village Station launch shaft and broke through at the Keele Street extraction shaft on Nov. 29, 2012. Torkie began tunneling in February 2012 and also broke through at the extraction shaft on Nov. 29. This made project history as the first double TBM breakthrough, a rare occurrence in North America. Yorkie and Torkie have completed 1.7 km of twin tunnel.

On March 19, 2013, Torkie began tunneling south from the Highway 407 Station site and arrived on June 13, 2013, at Pioneer Village Station extraction shaft, located north of Steeles Avenue West, east of Jane Street. On April 2, 2013, Yorkie launched tunneling operations boring southbound in the adjacent tunnel to Yorkie, and broke through at the Pioneer Village Station extraction site on June 14, 2013. During this drive, Yorkie and Torkie bored 1,020 m of twin tunnels and placed a total of 1,354 rings. Both TBMs were then dismantled and moved to the Highway 407 Station northern launch shaft. Tunnel boring machines are expected to tunnel an average of 15 m a day.

On Aug. 5, 2013, Yorkie began the second last tunnel drive from the Highway 407 Station northern launch shaft and is headed north to the extraction shaft at Vaughan Metropolitan Centre Station, located south of Highway 7 and west of Jane Street. Yorkie has just passed under Highway 407, marking the completion of the first milestone for this drive. TTC anticipates that Yorkie will arrive at its final destination before the end of this year. Torkie began boring the final drive for the project on Sept. 13, 2013 and will tunnel just over 1 km and place approximately 686 tunnel liners in the tunnel.

Tunnel boring machines typically tunnel or ‘bore’ on average about 15 metres a day.

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