Brake-by-Wire Comes To Freight Trains

Electronically controlled pneumatic brakes could help stop accidents and speed cargo

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Inside a large boxy ­building in Germantown, Md., a 150-car freight train is braking to a halt. At engineer Chuck Wolf’s signal, air from each car’s reservoir instantly begins pounding into the cylinder in a cacophony of clangs and chuffs. The brakes are fully set in just 12 seconds: unusually fast, but this is an unusual train. It’s made up only of brake components: the air pipes that normally run underneath the cars instead arc overhead in a skeletal canopy. Wolf, who is principal systems engineer at Germantown’s Wabtec Railway Electronics, is ­testing a revolutionary electronic system that activates all of a train’s brakes simultaneously.

Developed separately by Wabtec and New York Air Brake Corp., the U.S. ­subsidiary of Munich-based Knorr-Bremse, electronically controlled pneumatic brakes (ECP) are intended to displace the venerable air brake ­system first patented by George Westinghouse in 1869 and now used around the world. New rules by the Federal Railroad Administration (FRA) may finally start to make ECP mainstream in the United States, which is home to the largest rail freight network in the world.

ECP was developed in the early 1990s as longer and heavier trains strained the Westinghouse system, which signals the brakes ­sequentially from the engine by draining compressed air from a pipe that runs the length of the train. It’s a ­relatively slow process: the brake signal travels at just 152 meters per second along a train that can be three kilometers long. ”We think that technology’s been pushed about as far as it’s going to go,” says Dana Maryott, director of locomotives and air brakes at the Burlington Northern Santa Fe (BNSF) Railway.

ECP’s advantages are many: improved control, greater safety, and higher ­efficiency—as trains stop faster and more reliably, they can also go faster, with less wear and tear. What’s more, if anything goes wrong with a car’s brakes, the car’s onboard computer automatically takes them off-line and signals the locomotive. ”The operator in the cab gets much more information than he ever had before,” says Wabtec’s Wolf. The ECP cable could also be a ­platform for sensors that one day might allow the ­engineer to monitor other systems, like wheels and bearings.

But the technology is also expensive, and outfitting the United States’ 1.6 million rail cars and locomotives could cost US $7.6 billion, ­according to an FRA report. The fact that U.S. railroad ­companies swap equipment further ­complicates matters: the seven major carriers will all have to buy in for ECP to fully take hold. ”ECP has great genes, but it’s hard to get the railroad ­industry to change,” says FRA deputy administrator Cliff Eby.

So in 2006, for trains operating with ECP, the FRA provisionally relaxed rules that require brake inspections en route. If universally implemented, the rule change could save the industry $125 million a year.

The rule change already appears to be having an effect. Last October in Pennsylvania, Norfolk Southern Railway ­inaugurated the first U.S. train to operate ­exclusively with ECP. The railway, the country’s fourth ­largest freight operator, plans to equip 400 coal cars and 30 locomotives with ECP by this spring, with an eye toward replacing most of its 20 000 hoppers if the new system proves itself, ­according to railroad vice president Gerhard Thelen. Meanwhile, BNSF Railway, the ­biggest U.S. carrier by tonnage, plans to start ­running a container train with ECP between Chicago and the Port of Los Angeles, and an electric utility with its own fleet of coal cars will ­follow suit.

About the Author

ROBB MANDELBAUM, a freelance ­journalist based in Brooklyn, N.Y., reports in Update on the first big upgrade since the 1870s of the technology used worldwide to stop freight trains. Look for his feature article on the struggle to deploy this revolutionary technology in a forthcoming issue of IEEE Spectrum.

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