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January 21, 2010 / Dave Gorham

Warping Heat Down Under

 

It’s been a week of heat, wind and fire for areas of Australia. Cooler weather for the east coast over the past few days has followed a week of extreme heat in the Southeast, while a return to warmer-than-normal temperatures for many areas begins today. Fire Weather Warnings continue to be posted for areas of Victoria where temperatures are nearing 110F, relative humidity is at 4% and winds are blowing at 30mph. A portion of the warning includes, “Some fires will be unpredictable, uncontrollable and fast-moving.” Heat caused the cancellation of more than 100 trains last week. Yesterday alone, due to the continuing heat and fire, another 35 trains were cancelled.



Video from last week’s news coverage of the heat and fires.

Last week YourWeatherBlog blogged about how the snow and cold was (is) hampering rail operations in Europe and North America. Would it surprise you to know rail operators are challenged by extreme heat and temperature change, as well?

Steel contracts with cold and expands with heat – the sort of heat Australia has been experiencing. Rail travel can be shut down entirely or, under less extreme conditions, can be limited, restricted or the speed of trains reduced. In the United States these speeds can be dropped to as little as 20mph for passenger trains and no more than 10mph for freight trains.


Australia News: news.com.au

Weather forecasting services around the world provide detailed temperature forecasts to rail companies in order to expedite freight and minimize delays during periods of extreme weather.



Australian rail worker attempts to keep tracks from kinking under extreme heat.

By the way, expanding and contracting track was less of an issue in the “old days” of rail. Before modern rail technology, 39ft rail segments were hammered into place and the space between these rails allowed for expansion or contraction. Those 39ft segments didn’t alter their length that much from one temperature extreme to the other. Not so with “continuous rail.” Rails are now 1800ft in length from the factory with each length then welded together. The new rails are much more prone to temperature variations; a single 1800ft segment can expand nearly 12 inches which can buckle or kink a track enough to allow derailment.

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