Joint venture begins work on West Diamond grade separation
Published: February 26th 2009
Source: Daily Commercial News
A multiple-phased and complex rail grade separation in Toronto is
employing the expertise of two foundation contractors to get the job
West Diamond Joint Venture, a partnership of Bermingham Foundation Solutions and Anchor Shoring & Caissons Ltd., recently started installing steel pipe pile and caisson walls for the $277-million Toronto West Diamond grade separation.
Designed by Delcan, the separation will allow east-west double CN rail lines to pass underneath double north-south CP lines instead of crossing them, as has been the case since the 1880s when the junction area of west Toronto was settled. The term diamond stems from the shape where the four lines converge.
The new underpass will eliminate scheduling conflicts between CP freight trains, which have the right of way over passenger trains, including GO Transit’s heavily used Georgetown-to-Toronto commuter service.
“The West Toronto Diamond rail-to-rail grade separation is one of the largest and most comprehensive projects in the GO Transit Rail Improvement Program,” says Gary McNeil, managing director of GO Transit.
Not only will the separation allow GO Trains and freight trains to pass through the area with fewer interruptions, but it will also lay the groundwork for future development of GO Train service for customers for that part of the Greater Toronto Area, says McNeil.
But the much anticipated interrupted train service from Georgetown to downtown Toronto won’t occur until sometime in 2011 when the project is finished.
It will take at least 18 months just to install foundation walls along the approximately one-kilometre route, says Bermingham Foundation’s chief executive officer Patrick Bermingham. The actual excavation will be handled by a different contractor later in the project schedule.
The magnitude of the undertaking is the reason his firm formed the joint venture with Anchor. “If we took on this project alone, we wouldn’t have the resources to take on any other ones.”
The walls will be comprised of 36-inch diameter steel piles which will be driven into the ground along the route by two 165-ton cranes and a 160-ton crane with hammers that have 200,000-pound energy rating and they will be set to a depth ranging from 30 to 70 feet, he says.
“We’re building both a foundation wall and cofferdam as the train tracks will be passing, not just below grade, but also below the water table.”
To ensure very tight tolerances, five piles are installed in a sequenced operation. “We install the first, third and fifth piles and then come back and hammer in the second and fourth ones. This is done to ensure each pile goes in vertically and doesn’t lean.”
The piles are linked with “PT” connections which enable the joints to be grouted, forming a tight water barrier. “It’s a system commonly used in Japan, but not so much here,” says Bermingham.
“This is a very technical and challenging project,” adds Anchor project manager Toben Jerry.
Not only are the crews working adjacent to active rail lines with numerous trains passing daily, the site is located in very densely populated area close to homes and businesses.
Construction practices used by the joint venture partners are designed to impose minimum risks to the environment, the buildings, services and utilities, while ensuring worker safety, says Jerry.
“When a train passes through, all work has to stop until we get the all clear signal from CN officials.”
This first phase of the project requires installation of three permanent walls and temporary shoring walls which will ensure safe train diversions and protect sensitive foundation structures. The first phase will be completed in 2010.
Later phases will include drilling out the 36-inch diameter interlocking pipe piles and placing concrete within them to form a composite steel and concrete section.
The interlocking pipe pile walls will provide lateral support by retaining earth as the grade of the train rails are relocated under the CP rails and Weston Road to the west. At those locations, the walls will also provide vertical structural support for future bridge installations, says Jerry.