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CEM in new train cars – Metrolink’s investment likely saved lives p2

In the 1952 movie, “The Greatest Show on Earth,” the locomotive of one train hits an automobile and another train, both of which are stopped on the tracks. The force of the impact jolts the locomotive backwards and slows it down considerably. Each car behind it is slammed, in turn, by the car in front of it, but the train continues to move forward. When everything finally stops, both trains are one twisted mess. Cars overturned, crushed like soda cans, pushed far off the tracks.

Collision energy management technology sends the force of impact away from the passenger compartments. As we said in our last post, the rail cars are like automobiles: They have crumple zones at each end to absorb most of the impact and redirect remaining force away from the rail car — a little like the way water splashes in every direction when you point a garden hose at the pavement.

The CEM elements in Metrolink’s cars don’t stop with the crush zones. There are couplers, too, that separate and send the cars in different directions. If you look at the aerial photographs of the crash, the cars are strewn across the accident site. Had they stayed connected, they may have piled up. The couplers are aided by bumpers and shock absorbers that, again, protect the passengers from being tossed around.

The particular safety measure that passengers noticed immediately was the windows with emergency releases. The passengers did not have to break windows to escape the overturned cars. All they had to do was release the escape window and climb out.

The way the train cars reacted in this crash has attracted the attention of railroad authorities across the country. Metrolink is one of very few rail lines to use CEM technology in their cars. The barrier to more widespread use may be cost: CEM is not a thing that a mechanic can bolt onto a rail car. It is technology and design that must be engineered into the car.

Metrolink officials made the conscious decision to move ahead with the new cars after an accident in 2005. An accident in 2008 reinforced the wisdom of their choice. At the moment, individual rail systems must decide for themselves whether to make the investment — government regulators seem to be stumped on the best way to move forward.


The Alpena News, “Life-saving train design is rarely used,” Feb. 26, 2015

CNN, “Train technology prevented tragedy in Southern California, officials say,” Kyung Lah, Steve Almasy and Ashley Fantz, Feb. 25, 2015

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