If I lose my iPhone, Apple’s Find My iPhone feature will pinpoint its location anywhere in the world within a few feet. Railroads, though, have only a very rough idea, at any given moment, of where their 18,000-ton freight trains are and what they’re doing. Although each railroad operates vast control rooms that look like they belong on the set of Dr. Strangelove—with enormous electronic schematics of their tracks displayed across the walls—the information that controllers receive is amazingly crude.
First, about half the nation’s trackage is “dark territory,” devoid of signals and invisible to controllers. Out there, it’s 1850. Conductors operate by written instructions and their watches, stopping their trains and climbing down to open and close switches by throwing big iron bars. While it’s true that the vast majority of freight traffic and all passenger traffic travels on tracks with signals, even there, controllers can’t see their trains the way I can “see” my lost iPhone. They know only when a train has passed a given point—a switch or a signal that is wired into the grid. Those points are anywhere from one and a half to three miles apart, creating “blocks” of track. Controllers know when a train’s locomotive has entered or left a block, but not how fast it’s moving. They can talk to engineers by radio, but if they notice that a train has passed a red signal, all they can do is shout into the radio, and often they’re too late even for that.
Positive train control, as conceived today, is intended not to replace control rooms and signals but to supplement them. The railroad farthest along in post-Chatsworth implementation is, not surprisingly, Metrolink, which lost 24 passengers and an engineer on September 12, 2008.
At six o’clock one recent morning, Darrell Maxey, who’s in charge of building Metrolink’s PTC system, picked me up at my hotel at the far eastern end of the L.A. basin and drove immediately to a doughnut shop. In his mid-fifties, with a bristle-gray moustache and glasses, Maxey exudes a Midwestern-style bemusement at the breathtaking convolutions of his job. He’s an old railroader, a systems engineer by training, but installing positive train control at Metrolink is making him an IT guy as well. “This is the most complicated project I’ve ever worked on,” he said. “Two, three hundred pages of documents at a time! For a guy who’s made his career piecing railroad systems together, this is heaven.”
We drove to Metrolink’s maintenance yard, a sprawling, sun-blasted expanse of concrete where Maxey issued me a hard hat and reflective vest, hoisted himself aboard one of Metrolink’s test trains’ passenger cars, and ushered me up after him. Slumped on every seat and scattered across the floor were hefty sandbags, simulating the weight of a full load of passengers. We walked forward, and Maxey opened a door to the back of the locomotive. We threaded our way through the length of its interior, which felt like the engine room of a U-boat: hot, noisy, and diesel-pungent. We emerged into the sunlit engineer’s cab, and Maxey motioned me into the engineer’s seat.
Transforming railroads from a 19th- to a 21st-century mode of transportation means making the train itself responsible for its actions. Were I this train’s engineer, I’d start my day by downloading into the train’s onboard computer a program about that day’s run: the weight and length of the train, as well as everything the system needs to know about the upcoming length of track, such as speed restrictions, grade, curves, signals, switches, and stops. If I were using track owned by other railroads, I’d download a separate program for each, because every railroad has its own way of signaling and communicating. Another download would alert me to temporary issues, such as workmen on the tracks. I could watch these downloads on an LCD screen mounted on the engine’s dash; after that, I wouldn’t have to look at the screen again, and, in fact, Metrolink is hoping I won’t. It wants my eyes straight ahead.
As I start down the track, the onboard computer is constantly comparing the train’s progress to the downloaded programs. Doing this means communicating wirelessly with every switch and signal along the way. If I fail to slow when I should or if the computer thinks I’m about to run a red signal, the system warns me. If I don’t respond, it applies the air brakes and shuts down the train. It is designed never to let my locomotive pass a red signal, so it is constantly looking six miles—three signals—ahead. It measures the speed and weight of the train along with the steepness of the grade. A heavy train going downhill will get an earlier warning than a light train going uphill, but as a rule of thumb, it takes about a mile, or 90 seconds, to stop a three-car Metrolink train.
The onboard electronics that make positive train control work on Metrolink’s test train are stuffed into a tiny compartment down in the nose of the locomotive, where, were this a freight train, the engineer’s toilet might be. I peered in at an incomprehensible tangle of wires surrounding a rank of plastic and aluminum boxes: a cellular modem, data radios that communicate with signals and the control room, a train management computer containing the downloads, and a big orange “black box” that the NTSB looks for after a crash. It goes by the polite euphemism “event recorder.”
For an industry that operates in much of the country as though it’s in a western, this looked like a jump to Prometheus. We made our way back through the locomotive and stepped off, and Maxey pointed to the new adornments on the locomotive’s roof. Up where a light and maybe a radio antenna used to sit, a forest of aerials sprouted: two 220MHz antennas for the data radios, two cellular antennas for redundancy, a GPS antenna, and the Wi-Fi antenna through which the train downloads its instructions prior to departure. “What all this is for, basically, is to make it impossible for you to speed or run a red light,” Maxey said. It sounded simple.single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.