One year ago, Toronto elected Rob Ford as mayor. He ran on a campaign promising, among other things, better transit, better roads and more subways.

By the end of March, a revised transit plan had been announced for Toronto that favored more underground options than previously planned. The entire Eglinton-Scarborough Crosstown LRT would become a single line running mostly underground for 25km; rather than tunnelling for 11km, the project will now see 19km excavated by TBM.

Ontario’s minister of transportation Kathleen Wynne called the project their ‘top regional priority’ and by the end of summer construction had started on the launch box for the project’s first TBM.

Design work is still underway on the no-longer surface level portion of the line, particularly in the Don Valley, where it will cross the Don River.

Metrolinx, an agency of the province of Ontario and owner of the Eglinton-Scarborough Crosstown LRT, is responsible for planning and funding commuter rail and rapid bus transportation in the Greater Toronto-Hamilton Area, which has a population of more than three million. The Toronto Transit Commission (TTC) is Metrolinx’s agent for the project and will operate the line following completion.

Ontario is funding 100 per cent of the CAD 8.4M (USD 8.48M) project, and it is the largest investment in transit the province has made in history.

Hatch Mott MacDonald is in charge of tunnelling design, and numerous design teams from the Greater Toronto-Hamilton Area are doing station design. There will likely be 26 stations in total. A joint venture of URS and Parsons Transportation Group is in charge of systems design.

Project and construction management is being carried out by the Transit Expansion Department of the TTC, with the assistance of a number of consulting firms.

Adjusting Eglinton Avenue
As it transverses the entire length of Toronto, Eglinton Avenue is a key east-to-west roadway. At the same time it’s somewhat diverse as it changes from a downtown corridor with storefronts and parking spots to a suburban arterial road.

Two primary bus routes currently serve Eglinton Avenue and they are heavily used, says Jack Collins, vice president of rapid transit implementation for Metrolinx. “They carry approximately 66,000 daily weekday riders. The existing Scarborough Rapid Transit line, which is going to be totally retrofitted to larger vehicles, is carrying 45,000 daily weekday riders. That’s what’s being carried along this corridor.”

Collins continues, “When we looked at our travel demand forecast with the TTC, by 2031 we’re coming up with ridership in this corridor that reaches 100 million annual riders.”

The Eglinton-Scarborough Crosstown line will connect with three subway stations and future commuter rail transit hubs. There are also several local transit lines that intersect with the project. Moving the line underground for most of its length will significantly reduce the number of buses that currently run on Eglinton Avenue.

The original plan called for the project to have 11km of tunnelling in the congested downtown area where Eglinton is a narrow four-lane road. Another 6km, the Scarborough Rapid Transit portion Collins previously mentions, is already grade separated and just being upgraded to larger vehicles. With the revised plan, all 25km will be grade separated, nearly doubling the amount of tunnelling to be done.

“The primary reason for grade separating the entire line was to minimize the impact on traffic, but it also speeds up the travel times,” says Collins. He adds that the City of Toronto is updating its official city plan, and is looking at making changes to public land uses along Eglinton Avenue that will complement the investment being made with the Crosstown project.

The 19km will be divided into several tunnelling sections, and contract packages are still being finalized for all of the line. Portions of the originally planned 11km underground line will likely be in the bidding process before the end of the year.

With the new plan for the line, Metrolinx and its design team is facing a new challenge on the east side of the project in the Don Valley, which includes a river crossing. “When we were at surface it was fairly easy and cost effective to do, and now we’re looking at tunnelling beneath that, which needs to be really deep. So that’s a huge challenge for us,” explains Collins.

“But, in our environmental documents that we’re updating, we’re looking at another alternative that would put us on an elevated guideway running down the center of the street or off to the side of the street to get across the Don Valley.

“So that’s an option that we’re seriously looking at as a result of this change.”

Getting underground
The Eglinton-Scarborough Crosstown LRT line will comprise twin tunnels of 5.75m diameter, excavated by TBM directly under Eglinton Avenue in the road’s right of way (see Figure 1 above). With the Don Valley area of the project, off-road sections are being examined for an underground alternative, in addition to the aerial alternatives being considered for this portion of the line.

TBMs are being furnished by the owner, and a contract for four EPB machines had been awarded to Lovat, now Caterpillar Tunneling Canada Corporation, in summer 2010. Precast concrete segments will be used to line the tunnels, and local manufacturer Munro Ltd., will be supplying the project.

Chris Smith, Munro’s tunnelling specialist for the Eglinton-Scarborough Crosstown project, says each ring will be 1.5m long and consist of five segments plus a keystone. The segments will have a tapered, universal configuration with two trapezoidal segments and four parallelogram segments. They will be reinforced with standard high-yield steel reinforcement cages, structurally welded. All segments, a total of 14,775, will be produced at Munro’s facilities and delivered as required to the Toronto job site. Production will start this November on the segments and should last about two and a half years.

The depth varies throughout the entire 25km project, but typically the alignment will be 15m to 30m deep (see figure 2 overleaf). The geology of the area is soft ground, generally consisting of glacial till and interglacial granular, with a mix of sand and clay with some small boulders to be expected. “There is bedrock in some areas, but we’re above the bedrock along the entire alignment, or at least trying to stay out of it,” explains Collins.

The water table is reasonably high in this area, he says. “There may be some areas of loose, running sands that we’ll do some pre-grouting, probably from the street level down in advance and along the path.” Otherwise tail grouting will be used on the TBMs; however the design team doesn’t expect much settlement.

The revised plan didn’t really affect the 11km of tunnels originally planned, located on the west end of the line, where the first phase of tunnelling will start. At the time of publication Metrolinx hadn’t finalized the exact number of tunnelling contracts for the first section, and is still investigating how and where to extract the TBM. Collins says 3km drives are being considered.

“At approximately 3km we’d like to be pulling the machines out and then relaunching them, after we check them out, for another drive. The plan right now is to take that 11km and have four TBMs, two running from west to east and the other ones on the eastside running west and eventually they would meet each other somewhere in the middle.”

The plan depends on which alternative is chosen for the Don Valley, which will also determine how many TBMs will need to be added to the project. However, whether the alignment is underground or elevated in the east, after crossing the valley, there is still tunnelling to be done over to Kennedy Station.

“So we are looking to use at least four machines, possibly two extra for overall schedule considerations, and if we tunnel under Don Valley we’ll need another two for a total of eight TBMs,” says Collins.

Metrolinx plans to have design for the first contract package completed, with the bid advertised, by the end of this year. Early 2012 would hopefully see the first tunneling package awarded with the first two TBMs arriving on site next summer and excavation in early fall.

Right now, local contractor Kenadian is building the west launch shaft, from which the first tunnelling contract will start. The Eglinton-Scarborough Crosstown line is scheduled to be completed by 2020.

Station location
The alignment passes under two subway lines and ties into existing Kennedy Station, on a third line. “Our thoughts right now are that we’ll extract the machines just shy of the subway tunnel and then put a launch shaft at the opposite side. And then have a very careful excavation underneath the actual subway line,” explains Collins.

For the other stations on the Eglinton-Scarborough Crosstown line, exact location is still being finalized; however their development should not affect the tunnelling schedule. Each station will be approximately 140m long and design plans call for a headwall strategy to prep the alignment for station excavation.

“We’ll put a headwall at each end and run the machine through that. It will be lean soil/cement so the machine will just excavate right through and you have a tight seal through the liner and the end of the station,” he explains. “Then when the station is actually excavated from the top down by the station contractor they will pull the liner out when they come down to the bottom of the station and then pour concrete.

“That way we get the tunnels done and out of the way rather than [deal] with the risk associated with one of the stations falling behind in terms of construction and you can’t get through. So the philosophy here is we’re just going to ‘blow and go’ and get the tunnelling done.”

Stations will be built using cut and cover. The design team is looking at techniques used in Los Angeles for the Hollywood extension on the Red Line and the Pasadena Gold Line extension where top-down excavations using precast deck beams have been used to allow traffic flow during construction.

Beyond Eglinton
Metrolinx recently finished its overall transportation planning document ‘The Big Move 2020’, which covers more than 50 transportation improvements that will be implemented over the next 20 years.

Collins points out one of the impacts of bringing 9km from surface level to underground is the increased cost of tunnelling. To cover this, Metrolinx and the TTC are looking at deferring other projects being planned for surface light rail in the Finch West area. Instead, an enhanced bus service will be introduced until future funding becomes available at a later phase in the city’s transportation development program.

The main reason for choosing to use owner-furnished TBMs is to stay on schedule and complete the project by 2020. Collins says, looking at the larger plan for the Greater Toronto-Hamilton area when the contractors turn the machines back end at the end of the project, Metrolinx will likely have additional projects for which they can be redeployed.


Figure 1, map of the Eglinton-Scarborough Crosstown alignment Figure 2, typical geology of the Crosstown alignment One of the TBMs being manufactured for the Crosstown line