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the engineer to care. Information that an engine is using IS percent more fuel than normal, for instance, is oflittle concern to the engineer but of great interest to the maintenance technicians monitoring the locomotive. Installing computers on locomotives is not exactly like putting them in the controlled environment of an office. Dirt, vibration and extremes of hot and cold are part of everyday railroad operation. Union Pacific experimented for months with various types of shock mountings and vibration-controlling material. According to chief teclmology officer Lyden Tennison, lessons were drawn from another enterprise that knows a thing or two about adapting high-tech equipment for inhospitable conditions. "We learned a lot from the military," he says. Locomotive technicians were at first amused, for instance, to learn that the military kept processors plugged into their sockets under constant vibration by tying them down with dental floss. Amused, but impressed: Union Pacific adopted this solution. AC/DC

Throughout the diesel age, locomotives worked according to a simple principle: a diesel engine turned a generator that produced alternating electrical current, which was then convetied to direct current to run the traction motors that drove the axles. The leap forward that made possible that pull up the Toponas grade depended on a fundamental shift in technology during the ] 990s from DC motors to AC motors. This change has been enabled by the availability of fast, inexpensive microprocessors. Power for both a DC locomotive and an AC locomotive starts its path to the wheels in the same way. In both types, a diesel engine turns a generator that produces AC power, which is then converted to DC. (The starting AC power, at a constant 60 cycles per second, could run the locomotive at only one speed.) Here, though, the technologies diverge. In a DC locomotive, the DC power goes directly to motors that turn the wheels. In an AC motor, the direct current passes through a series of computer-controlled components called inverters, which "chop" the DC power into AC power. This AC is in turn fed to the motors. Computer chips make AC motors practical by regulating the flow of power with a precision impossible by any other means. The chips monitor and control the DC entering the inverters and make sure that they deliver the proper amount of AC to the traction motors. This is no small feat: each inverter may require as many as 500 on-off commands per second to regulate the AC flow. And while 500 commands per second may seem unimpressive in a day of gigaheltz chips, the proper comparison is Hard at work at Harriman: Providing uninterrupted service requires a fill! complement of IT professionals to manage railcar scheduling, shipment tracking, customer service and train dispatching.

not with other computers but with human beings. Imagine a train engineer trying to make 500 changes in throttle position every second. AC motors are more robust than their DC cousins. They've been put through brutal tests that demanded maximum possible power production, sometimes for days on end. Those tests went far beyond anything the worst railroad environment could produce, and the motors never came close to overheating, according to Michael E. Iden, Union Pacific's general director of car and locomotive engineering. As long as the equipment is operating properly, AC motors "really should never burn out," Iden says. Many railroads are even usingAC locomotive power-instead of air brakes-to hold trains stationary on heavy grades, Iden says. This technique, which avoids the time-consuming process of pumping off air brakes, would fry a DC motor in minutes. Beyond their ability to pull heavier loads, AC motors improve overall efficiency. Each locomotive wheel makes contact with an area of rail no larger than a nickel. The percentage of weight on that wheel that is converted into pulling power is called "adhesion." While the best DC motors can muster an adhesion of about 30 percent, AC locomotives take advantage of precise computer control of the traction motors to achieve adhesion averaging 34 to 38 percent; each percentage point gain in adhesion provides the pulling power for five additional fuJly loaded coal cars. MAKING

TRACKS

Trains must run on tracks, of course. And once laid, the rail and ties must be maintained and inspected. Information technology is playing a transforming role in this traditionally labor-intensive affair. The last two or three years, for instance, have seen the advent of rail alignment systems that use lasers to gauge distance and direction. Computers then figure a track's correct curvature and angle of elevation and feed the information to machines that put the rail and ties into place. "The important thing is the ability to measure track geometry rapidly, without depending on human sight," says Louis Cerny, an independent railroad consultant in Gaithersburg, Maryland. One particularly time-consuming rail maintenance job--spreading rock ballast between tracks-is also getting a shot of adrenal ine. In June 200], Herzog Contracting-a railroad construction company based in St. Joseph, Montana-delivered a new ballast train to

Profile for SPAN magazine

SPAN: July/August 2003  

An American Gharana?; Digital Railroad to Fly; Think Tanks & U.S. Foreign Policy; Can Economic Diplomacy in South Asia Work?; Muscle & Magic...

SPAN: July/August 2003  

An American Gharana?; Digital Railroad to Fly; Think Tanks & U.S. Foreign Policy; Can Economic Diplomacy in South Asia Work?; Muscle & Magic...

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