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| Cold weather = broken or cracked rails (1337206) | |||
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Cold weather = broken or cracked rails |
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Posted by GOlD_12tH on Sun Feb 1 00:29:29 2015 Washington DC - The cold weather has not been kind to Metro this month, with dropping temperatures are being blamed for several cracked or broken rails that have disrupted commutes.On Wednesday morning, a rail broke between Naylor Road and Southern Avenue stations on the Green Line, wrecking the commute for thousands of riders. But cracked or broken rails are not unique to Metro. "Anytime you have severe drops in temperature you increase the potential for fractures in rails in the same way a lot of roadways will fracture if you have sharp drops in temperature," explains Charles Schwartz, chair of the civil engineering department at University of Maryland. He says the age of a section of rail is not as important as other factors, when it comes to cracking or breaking. "Steel, like most materials, contracts as the temperature goes down, and if the temperature drops very quickly, then the rails contract a lot in a short period of time. That thermal contraction causes stress concentrations to increase at the tips of these little flaws from fatigue in the rail. And then compounding that, the fracture resistance of steel decreases with temperature," he says. Wednesday morning was the fourth time this month a rail cracked or broke messing up a morning rush hour. It usually requires time-consuming repairs, forcing trains to single track and leaving platforms packed with cold, frustrated commuters. The rail that broke Wednesday was installed in 1998. http://wamu.org/news/15/01/30/with_cold_weather_comes_additional_commuting_challenge_cracked_metro_rails |
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