Second breakthrough for Spadina Subway

On Friday, June 1st, ‘Moley’ the second of two owner-procured 6.134m (20ft) diameter mixed face EPBMs built by Caterpillar Tunneling Canada for the Toronto Transit Commission (TTC) broke through on the first northern headings for the Southern Tunnels Contract of the 8.6km (5.3-mile) long Toronto-York Spadina Subway Extension (TYSSE).

At a press conference on Monday, June  11th, the Honourable Julian Fantino, Associate Minister of National Defence and Member of Parliament for Vaughan; along with His Worship Rob Ford, Mayor of Toronto; York Region Chairman and CEO Bill Fisch; and TTC Chair Karen Stintz, marked the completion of the first 1.6km (5,249ft) of twin tunnels.

“Today, we are one step closer to completing the Toronto-York Spadina Subway Extension, cutting commute times and easing traffic congestion in the Greater Toronto Area,” said Minister Fantino. “The Harper government is pleased to invest in this project that is creating jobs for Canadians and boosting the regional economy.”

The CA$279 million Southern Tunnels Contract, which is being carried out by the MKA (McNally Kiewit Aecon) Partnership, has been split into four tunnel drives; two 1549m (5,082ft) long north headings and two 1185m (3,888ft) long south headings (see NATJ, Feb/March digital edition).

Good effort was rewarded with “Moley“ outperforming her counterpart on the later stages of the drive achieving advance rates over the three shifts of around 25m (82ft) per day. The TBM arrived at the shaft wall on May 8th. Some time was required before breaking through to install the eye seal and reception frames. ‘Holey’, the first TBM broke through earlier this month.

Work is now underway on the breakdown of the two machines, which are to be relocated to the second launch shaft at the southern end of the new Sheppard West Station. The machines will be re-launched south, towards the Spadina line’s existing Downsview Station with approximately 1000m (3,280ft) of tunnel per machine.

Within the completed tunnels cross-passage construction, involving a series of hand-mined tunnels between the two bores, has now commenced. These 3.66m (12ft) diameter tunnels will provide permanent access between the two tunnels. The construction involves the installation of a sophisticated propping system to support the segmental liners before excavating the passages.

The Toronto-York Spadina Subway Extension (TYSSE), which features 6.7km (4.1-miles) of EPBM bored tunnels and six state-of-the-art stations, will be the first subway in Toronto to extend over the City’s boundary into the new corporate developments within York Region – one of the fastest growing areas of North America. The CA$2.63 billion extension, which is being funded by the Government of Canada, the Province of Ontario, the City of Toronto and the Regional Municipality of York – involving over 100 different stakeholders – runs in a north westerly direction from Downsview Station.

The TYSSE project is split into six construction packages. These include four separate construction contracts for the Finch West, York University, Steeles West and Vaughan Corporate Centre cut and cover stations; as well as two 5.4m (17.7ft) i.d. twin-bored EPBM tunnel construction contracts that each also include a cut and cover station to facilitate TBM mobilization (the Southern tunnels combined with Sheppard West and the Northern tunnels packaged with Highway 407 Station).

HMM/Delcan/MMM Group JV holds the project management contract for the project. In October 2008, three design groups – Spadina Group Associates (Stevens Group with Alsop); Arup Canada; and EarthTech Canada (Aecom) – were each awarded the design of two stations and Hatch Mott MacDonald (HMM) was chosen for the twin-bore tunnel design.

In mid-2009, following a competitive tender process, TTC placed an order with Lovat (now Caterpillar Tunneling Canada) for four 6.13m (20.1ft) diameter mixed face EPBMs and later that year Armtec Holdings won the contract to manufacture the traditionally reinforced pre-cast concrete liner rings for the project (see NATJ, Oct/Nov 2010, digital edition).

The CA$405 million Northern Tunnels contract is held by the OHL/FCC JV and incorporates six tunnel drives between the new Finch West and Vaughan Corporate Centre stations, which are being driven using the remaining two owner procured Caterpillar TBMs. This contract also includes a 230m (755ft) long section of Sequential Excavation Method (SEM) tunnelling for a mid-alignment turn back facility within a double-ended pocket track (DEPT) near Finch West Station; as well as the first known use of compensation grouting in the Toronto area to mitigate tunnel induced settlements at York University.

Running at an average depth of 20-22m (65-70ft), the vast majority of the TYSSE tunnel alignment lies in favorable geology consisting of stiff upper, and even stiffer lower, glacial till with isolated lenses of sands and silts. To the north of the project alignment however, lies the challenging geology of York Region – encountered on a number of recent sewer drives – with sands and silts giving way to layered gravels. Some of these conditions could be encountered as the Northern Contract’s drives progress towards Vaughan Corporate Centre Station.

The TYSSE project is targeted for completion by the end of 2015.

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