GO Transit/McCormick Rankin Corp.

One of the things railroads have in common with skiing is that diamonds represent difficulty, whether you’re talking about a diamond-rated slope or a diamond crossing of two tracks. That’s why Ontario’s interregional public transit system, GO Transit and engineering firms McCormick Rankin Corp. (MRC) – a member of the MMM Group – and Delcan Corporation have come together to untangle a diamond crossing at the busiest railroad crossing in Canada.

The West Toronto Diamond Grade Separation project is part of a larger initiative to upgrade Toronto’s transportation infrastructure in anticipation of the Pan Am Games in 2015, but the need for this particular portion of the work has been evident for a long time.

“It is a very complex project, and it’s been in the planning stages for almost 20 years,” explains Michael Wolczyk, GO Transit’s director of Union Station infrastructure. The project involves separating two railway lines that currently cross each other at grade and relocating one over the other. Once completed, one set of tracks will be moved to a depressed corridor and the other set will be elevated above them on a bridge.

The crossing has been a less-than-ideal arrangement for the railroads, commuters and nearby residents for a long time, Wolczyk says, making this project a welcome relief. For starters, the diamond crossing often meant trains would have to slow down or stop before crossing the other tracks. “The analogy I use it that it’s like two highways that cross each other at a traffic light, and that doesn’t work very well,” Wolczyk says. “When you have a train full of 2,000 people coming and there’s a freight train coming by, we have to stop and wait. That adds up to a lot of delays.”

Because trains often have to stop at the diamond crossing, they spend a lot of time idling, creating unnecessary pollution and added noise when they start up again. Additionally, the sounds of trains rolling over the diamond crossing irritated nearby residents.

“With diamond crossings, there’s a lot of pounding noise when a train goes over,” Wolczyk notes.

To help bring this project to completion successfully, GO Transit turned to Delcan as its structural designer and transportation engineering firm MRC as construction managers and contract administrators, each bringing more than 50 years of experience to bear. MRC Project Manager Leon Stambolich says that although the project doesn’t seem like a lot of work on paper, there’s more to a diamond grade separation than meets the eye, and with this particular project in downtown Toronto especially.

“It’s a pretty common project, it’s just in a complicated urban environment,” he says. “It has introduced a number of complexities to completing the construction work.”

Driving Force

Building the depressed corridor means the installation of more than 2,300 900-millimeter pipe piles that form the corridor’s structural walls. Wolczyk explains that the pipe piles were chosen because of the unique site conditions. A lake was on the site millions of years ago, meaning sand from the lake’s ancient shoreline still exists deep underneath the water table. The piles need to be watertight and structurally sound, Wolczyk says.

Ordinarily, driving such piles would be done with impact hammers, but nearby residents were very concerned about the amount of noise generated by the work. Crews limited the number of hours the impact hammers were in use to try and lessen the impact, but Wolczyk says GO Transit challenged its contractors and consultants to come up with better ways to mitigate the noise.

One of the main techniques utilized on the project was a hydraulically operated sound-dampening shroud system that encloses the impact hammer as it forces the pile into the ground. Wolczyk says the system has resulted in a 50 percent reduction in the amount of noise created. However, this system was still not enough to completely alleviate the concerns of residents, and so MRC and the other project partners looked for more alternatives.

Quieter Alternative

One option was a system developed by Japanese manufacturer Giken International. Rocco Cacchiotti, project manager for CN Rail – which was responsible for the pile installation work – says the system utilizes a push system with an auger to press the piles into place. This system was much quieter than the impact hammers, but that quiet came at a cost.

“It’s a slow machine,” Wolczyk says. “You couldn’t do the entire job with it, it would take about six years if you tried.” Cacchiotti says half of the project was completed with impact hammers in about six months, while the second half was completed in about 15 months using a variety of methods, including the Giken system.

However, the Giken system helped mitigate residents’ complaints about noise, and it proved useful when working around some of the older buildings in the area. Stambolich says some of those buildings would not have been able to withstand the vibrations created by the impact hammers or vibratory hammers, a key advantage of the Giken method.

Next Phase

Pile installation began in January 2009 and was completed in October 2010. The next phase, which was just initiated, involves drilling out the piles and filling them with concrete, Wolczyk explains.

“In the process, what they do is they have to make sure the walls are watertight and part of the work in this contract is testing to make sure that it doesn’t leak,” he says.

After that is completed, the next phases call for the excavation of the depressed corridor, finishing the walls, and building the bridges, the stormwater management system and the roadway over the corridor. Once all of that is completed, Wolczyk says, the tracks will be laid in the corridor. GO Transit expects all of this to be completed by 2014, well ahead of the 2015 Pan Am Games.

Wolczyk credits the contributions of MRC and the entire project team for the project’s success to date.

“It’s been good, MRC has done a good job,” he says. “They’re one of the key team members, but it’s a large team.”

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