Toronto’s PATH system continues to grow almost organically, allowing pedestrians to walk in comfort through underground malls and across busy roads through any type of weather.
Last summer, three new sections of PATH were added to the system: a 22-metre section from the Air Canada Centre (ACC) to the Gardiner Expressway; a 40-metre section over Lake Shore Boulevard and under the Gardiner Expressway to 90 Harbour St; and a 34-metre segment from 90 Harbour St. to Oxford Properties’ RBC Waterpark Place III.
The bridge segments were designed by WZMH Architects and built and assembled by Lorvin Steel of Brampton, with Western Mechanical Electrical Millwright Services Ltd. of Barrie orchestrating the final placement of the segments.
Astro Man, a transportation planner with the City of Toronto, notes that the city owns part of the underground PATH system on city rights-of-way, but not the elevated portions. While the city reviews and approves design elements of extensions to the PATH system, each addition provides unique challenges.
"The construction of the elevated PATH between ACC and Waterpark Place is one of the key requirements for the property owner to secure potential tenants," he says. "For the Waterpark Place development, because it is an elevated bridge walkway, the property owners own the pedestrian bridge and pay a licensing fee to the city for the use of the bridge over the public right-of-way."
Lorvin Steel fabricated the glass-and-steel segments at its Brampton facility, where previous PATH segments had been built, including the curved PATH segment connecting the Delta Toronto hotel to the Metro Toronto Convention Centre. The three most recent segments were assembled at an open lot on nearby Cherry Street.
"We assembled them raised on temporary supports about four feet off the ground so we could slip the delivery trailers right under them," says Lawrence Verduci, owner of Lorvin Steel. "That way we could eliminate the need for a crane at the Cherry Street site."
Each segment was moved into place starting midnight on a Saturday to avoid inconveniencing traffic. The 22-metre segment, weighing 100,000 pounds, was delivered in June on a 10-axle trailer and lifted into place by a 550-tonne crane supplied by All Canada Crane.
"There were a lot of underground tunnels in the area, so we had to find a sweet spot to park the crane," says Mark Carney, a structural engineer with Western Mechanical. "We wound up placing support shoring in the middle of a driveway in one of the underground garages. We had to orchestrate the lift very carefully, because the glass was already inserted in the bridge and we could not deflect the bridge in any way that would compromise the glass."
The most challenging operation involved the placement of the second segment over Lake Shore and under the Gardiner. Delivered by a 16-axle trailer and weighing 250,000 pounds, the segment was lifted into place using gantry jacks.
"The tolerances were so tight that the segment had to be lifted to within five inches of the underside of the Gardiner," says Carney. "They installed a barrier to keep pigeons from roosting in that gap. What’s really interesting is that WZMH designed this segment to unbolt and slide along a nylon surface, so that it can be moved aside to allow inspectors to examine the underside of the Gardiner at that location."
The 550-tonne crane made a return engagement in September when the final Harbour Street segment, weighing 180,000 pounds, was lifted into place. Carney notes that the 14-axle trailer had to be driven part way up the Harbour Street ramp to the Gardiner, allowing the crane to access the segment and swing it 90 degrees into place.
"I’d also credit EllisDon for their planning on the buildings," says Lorvin. "The PATH segment had to fit perfectly through niches in the buildings to fit perfectly on arrival."
For Carney, the successful placement of each segment proved satisfactorily anti-climactic.
"The segments moved like turtles and nothing exciting happened," he says. "Just the way I like it."
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