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Frozen Train Tracks? Set 'Em on Fire (theatlantic.com)
It might look dangerous, but flames have kept switches moving and rails intact for a century. From a report: As if the horrors of the polar vortex were not already enough -- temperatures that look like typos, Canada Goose robbers, and something called frost quakes -- the nation's railroad system took a turn for the apocalyptic this week, too. Rails broke in three different places between Baltimore and Washington on Thursday, causing severe delays. Amtrak canceled dozens of trains passing through Chicago, and viral videos appeared to show commuter tracks in the city on fire. Of course, the tracks themselves were not burning -- they are made out of steel, prized for its tendency to rarely go up in flames. But the sight is still dramatic. The videos of the fires in Chicago last week show flames smoldering in patches of melted snow around the tracks.
Fires have been employed on railroads -- and remained the preferred fix for many a winter hazard -- for most of their roughly two-century history. While railroads have developed impressive tools for dealing with snow on the tracks, extreme temperatures remain a challenge. Though steel is flame-resistant, it's subject to cold, which can jam up railroads' many moving parts. When cold weather does wreak havoc on railroads, lighting fires on train tracks can serve a couple of uses. One is to thaw the switches that determine which track a train goes down, which is what Metra, the Chicagoland commuter-rail authority, said was going on this week. Switches are moving parts, and if ice gets into them, they can freeze in place. There are various types of switch heaters, which might use electric current or gas to melt ice -- or even an open gas flame, which is what's appearing in the Metra videos. Where there aren't switch heaters, crews might use temporary torchlike devices with a flame, the railroad equivalent of the smudge pots farmers use to keep citrus groves and apple orchards from freezing on cold nights.
Fires have been employed on railroads -- and remained the preferred fix for many a winter hazard -- for most of their roughly two-century history. While railroads have developed impressive tools for dealing with snow on the tracks, extreme temperatures remain a challenge. Though steel is flame-resistant, it's subject to cold, which can jam up railroads' many moving parts. When cold weather does wreak havoc on railroads, lighting fires on train tracks can serve a couple of uses. One is to thaw the switches that determine which track a train goes down, which is what Metra, the Chicagoland commuter-rail authority, said was going on this week. Switches are moving parts, and if ice gets into them, they can freeze in place. There are various types of switch heaters, which might use electric current or gas to melt ice -- or even an open gas flame, which is what's appearing in the Metra videos. Where there aren't switch heaters, crews might use temporary torchlike devices with a flame, the railroad equivalent of the smudge pots farmers use to keep citrus groves and apple orchards from freezing on cold nights.
You know that one of the most common ways of shaping steel is heating so it is more malleable. It also causes steel to expand. In this case the expansion of the steel rails is what is being done to keep the joints from pulling apart. Since this is done in a controlled fashion they know not to heat the rails to the point they would deform much, just enough to get them back to their usual length. So while jet fuel(aka kerosene) isn't hot enough to melt steel, it is hot enough to cause steel to expand and possibly buckle under the pressure. Railroads often have this issue in extreme heat where the rails expand to the point that they buckle and twist up...
Did you ever think that maybe some of those physical processes that would occur when heating steel with burning jet fuel would maybe, just maybe cause some sort of structural failure?
Did you know that bridges are often damaged by fires below them from major accidents. Those fires also are not enough to melt the steel, but...they structurally damage the bridge
http://www.dot7.state.pa.us/BPR_PDF_FILES/Documents/Research/Complete%20Projects/Maintenance/Effects%20of%20Fire%20Damage.pdf Note in the introduction:
Now you go ahead and explain to me how a fuel tanker on the highway is any different than a jet fuel laden airplane? Explain to me that somehow the steel in buildings is substantially different than the steel in bridges? Tell me again why would a bridge collapse under intense heat from burning diesel and gasoline but a skyscraper would not collapse from burning jet fuel and building materials.
This is well known materials engineering stuff...