Canadian contractor travels far and wide in bridge demolition spree.
Despite the logistics and huge distance from its Aurora-area headquarters in southern Ontario, Priestly Demolition has been busy demolishing three aging steel box-frame bridges in the far reaches of the province’s north.
In September, a small team of supervisors and equipment operators demolished the approximately 50-year-old Steel River Bridge on Highway 17 about 28 kilometres east of Terrace Bay.
From there the crew travelled northeast to Cochrane to demolish the 260-foot-span Wicklow River Bridge on Highway 11 just south of the town. In early November, it started taking down the 450-foot-long, five-span 63-year-old Frederick House Bridge which crosses the Frederick House River west of Cochrane.
There is an extra layer of complexity involved in demolishing bridges over rivers, says company president Ryan Priestly. “It’s a very complicated process. You have to protect the water 100 per cent. There can be no debris, no slurry, no anything in the water.”
Demolition is carefully sequenced. A steel beam platform is installed across the river and then covered with a geotech filter cloth to catch any material particularly the slurry created by the concrete saw cuts that might drop from the demolition activity on the bridge above, Priestly says.
The protective measures are spelled out in a plan that has to be approved by a design engineer and then a quality verification engineer and finally by the Ministry of Transportation, says Priestly. “If you don’t follow the plan to a T, there are significant penalties.”
And safeguarding environmental sensitive rivers isn’t the only challenge. Usually bridges being demolished, as is the case in the Terrace Bay and Cochrane ones, are immediately adjacent to the new bridges which have to be protected. As well, the crews often have to work in tight spaces hemmed in by deep embankments, he says.
Read the full story here.
