April 18, 2007
Bridges to undergo more inspections
Quebec government not demolishing 15 bridges
The media were scrambling last Friday when La Presse reported that Transport Quebec was planning to demolish and rebuild 15 highway overpasses over the next five years.
The overpasses have a similar design to the one that partially collapsed in Laval and claimed five lives.
However, Mario St. Pierre, a Transport Quebec spokesperson, said the bridges, which were inspected last October following the Laval incident, will be thoroughly inspected on a yearly basis and the results of those inspections will determine whether they will be repaired or rebuilt.
“We were talking about four bridges — the de la Concorde bridge that collapsed and the de Blois bridge which was demolished as a safety precaution,” he said. “There was a bridge near Joliette, over Highway 31, that was reinforced last fall and is very safe. The other is a little bridge in the Eastern Townships, an overpass over Highway 10 and will be demolished and replaced by the end of the year.”
The 15 bridges at the centre of the La Presse report, St. Pierre said, are “not exactly the same design. It is a modified type of cantilever bridge.
“We are going to monitor them more closely.”
The Angrignon overpass in Montreal, which spans Highway 20, is one of the structures that will be inspected. Close to 140,000 vehicles pass under it every day.
Bala Ashtakala, a professor emeritus with Concordia University, who specializes in transportation engineering, unofficially examined the Angrignon overpass last Friday.
“As it stands now, there is no danger, but you never know what is happening inside,” he said. “Damage is there, but it is not very extensive. I saw reinforcing rods on the pillars and on the beams. That means the concrete is gone. It had chipped off. There is also a wire mesh underneath the overpass. It shows there is probably more chipping concrete.”
Ashtakala explained that concrete becomes brittle over time and the bonding becomes weak.
“It has nothing to do with the design. It is the materials, concrete and steel, where the real problem is. Concrete is chipping off and the steel is exposed to the natural elements like the rain, snow and sleet and with elements such as salt, it deteriorates fast.
“Cement is meant to be an integral part of reinforced concrete,” he added. “Once you just have a bunch of steel rods, they don’t maintain the strength. The rebar needs protection.”
The overpass was built in 1966.
“Its life is almost over,” said Ashtakala. “Over the next few years, until they replace it, they have to be very careful.
“In this case, it is better to replace and put up a new bridge. Regardless of how it was maintained, the age element is there.”
Ashtakala endorses the annual inspections and urges modern equipment be used to determine the state of the internal workings of the structures to detect faults and cavities.
This should be bolstered by taking core samples to examine the density and strength of the materials.
“A bridge can collapse any time,” he said. “There are things we should be guarding against. At the de la Concorde bridge, the (inspector) saw all this white stuff coming from the crack. That was cement that had disintegrated — it had combined with water. We call that ‘frying’ and that happens inside.
“When you mix cement with water and all that, after a period of time, it changes chemically. You see this on many sidewalks.”
|MOST POPULAR STORIES|
|TODAY’S TOP CONSTRUCTION PROJECTS|
These projects have been selected from 541 projects with a total value of $2,992,674,310 that Reed Construction Data Building Reports reported on Thursday.
$290,000,000 North York ON Prebid
$105,000,000 Metro Toronto Reg ON Prebid
$75,000,000 Ottawa ON Prebid
- VIDEO: Economic Update May 21, 2013
- Prompt payment bill headed to committee
- Final Phase
- A return to core values a must for banks: Carney
- OHMPA on the road with informative seminars
- Local 675 strike ends after new agreement ratified
- NDP says it will support Liberal budget, averting spring election
- Measure of U.S. economy’s future health rises 0.6 per cent in April after March dip
- Terratec awarded Brighton, Ont. Lagoon Clean-Out Project contract
- Fundraising campaign to reach target for new Shriners Hospital for Children
- George Brown College building named after Tridel CEO
- Construction Site Arson
- VIDEO: Journal of Commerce Update for the week of May 27th, 2013
- Historic church renovation reaches new heights
- Hiring of foreign workers for hospital project outrages union
- Acetylene torch explosion causes significant damage
- Festival of Architecture hits Halifax
- Winnipeg Southwest Transitway wins award
- Vendor performance is key measurement
- NDP leader spoke to police about corruption
- Big contract down under for ATCO Structures
- RFQ issued for Kamloops hospital project
|ALEX’S ECONOMICS BLOG|
Reed Construction Data Canada’s Chief Economist Alex Carrick discusses current developments in the North American economic environment with emphasis on the construction industry.
- An Overview of Prices and Sales in the Diverging U.S. and Canadian Housing Markets (April 25, 2013)
- Canada’s Precarious Dependence on the Commodity Price Super-Cycle (April 22, 2013)
- Twenty major upcoming residential and transportation terminal construction projects - April 2013 (April 15, 2013)