Rapidly replaced highway bridge ready for eventual Queensway widening
Inside the fourth-floor Ottawa offices of the Ministry of Transportation – which conveniently overlook Highway 417 at Preston Street – Ken Polson breaks down a 15.5-hour engineering marvel into a little more than two minutes.
Playing on his desk monitor is a time-compressed video, shot from a parking lot next to the Ford dealership across the street from the Queensway's Carling Avenue overpass.
It shows traffic slowly thinning on Saturday evening, as lanes are closed and on-ramps blocked.
Backhoes soon advance to either side of the bridge and start excavating the asphalt-covered granular "approaches" that were laid temporarily a month earlier when the overpass was disengaged from its concrete supports.
Dutch-made transporters raise the two 21-metre-long pieces above the highway and wheel them north, clearing the way for the wider replacements built over the past few months in a staging area on the north side of the overpass. The approaches are refilled and paving crews crisscross the entire bridge as the Sunday morning sun rises.
But Mr. Polson, an area contracts engineer and 27-year MTO veteran, sees other stories in the images.
Like how each of the 52-year-old bridge decks weighs 700 tonnes - almost twice as much as a Boeing 747.
Or how contractors were carefully working around a four-foot watermain that runs along the south side of the highway, limiting their ability to excavate certain areas.
Or, perhaps most significantly, how the overnight operation avoided the traffic nightmare that would have occurred had the overpass been replaced using traditional methods. Those would have required daily lane reductions on one of the busiest sections of the highway for two years.
This is the third Queensway bridge removed in the last five years using so-called rapid replacement technology, but it marked the first time an Ottawa company has led the project.
R.W. Tomlinson, which lost out to Toronto-area firm Dufferin Construction in bidding for the previous replacements of the Island Park Drive and Clyde Avenue bridges, began work in June 2010.
The first step in the $11.6-million job was rehabilitating and widening the abutments to accommodate the larger new decks. The span will handle four lanes of traffic in each direction when the Queensway is expanded, which is expected to occur sometime during the bridge's 75-year lifespan.
Construction on the new pieces started this spring. The sections were wheeled into place during the overnight replacement project by a Dutch subcontractor, Mammoet, which specializes in heavy lifting.
"Everything went off without a hitch," said Garry Carriveau, the manager of R.W. Tomlinson's heavy civil division.
"It's a high-profile job, and there are going to be more in the future. We feel we're in a good position to be able to compete on the future ones."
Indeed, the province has already hired consulting firm McCormick Rankin Corp. to design the replacement of the two overpasses above Kirkwood and Carling avenues to the east.
Mr. Polson said the plan is to award a construction contract next year, with work slated for 2013.
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