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Traffic Guru appears Friday in The National Post
"Salt":
(from page 1) ...design and construction. However the commission inquiry also highlighted a third reason -- the inferior quality concrete used in the bridge did not provide adequate protection from deicing salts. Some transport agencies are already looking for ways around the problem, but the path is not easy. On August 1, 2007 a bridge carrying Interstate 35 over the Mississippi River in Minneapolis collapsed during the evening rush hour. Investigations are ongoing, and it turns out the bridge was being treated with an alternative to road salt -- a substance considered less toxic and corrosive. There have been other recent infrastructure failures, including in the Montreal area -- but there is unlikely to be one clearly smoking gun to explain them. Yet we must nonetheless examine the link between known causes of corrosion and this wave of collapses. Aside from designing brand new rust-proof bridges, underpasses and roadways, we’ve got the massive challenge of dealing with existing ones that have been salted for years. Carleton University professor Burkan Isgor, an expert in the corrosion of reinforced concrete, says, "We have (a) clear understanding of what the problems are. There are procedures to mitigate most of these problems -- we can rehabilitate structures to extend their service life. The only thing is that the money has to be coming from all levels of the government." He says research has proven the damaging effect of salt, and current studies are now focusing on how much is too much. Most road departments are reducing the amounts spread over driving surfaces, but the allure is still cost. Isgor points out, "Unless someone comes up with an alternative which is economically more feasible, eliminating the general use of deicing salts will not be easy." Complicated options include installing heating devices or sealing structures in the way gas and oil pipelines are protected from corrosion. The technology is there, but the price is high. Politicians may not be easily coaxed into a major cost-benefit analysis, but perceived crises have a way of opening minds -- even as they precipitate some dumb short-term decisions. More research and bean counting ought to consider the following question: Is the money we save on road salt being eaten up by premature repair and replacement costs? And should this numbers game be swayed by the possibility of suddenly losing more transport links? Ed Drass
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