When we think legacy technology, we think of an outmoded system that is slow and gnarled. In our desktop computers, it's annoying but not exactly debilitating. In New York City's subways, however, the legacy technology is not just out-of-date but ancient, 75 to 100 years old and nearly unrecognizable to many engineers. What's more, millions of people rely on it.

On January 25th, scores of New Yorkers found out just how antiquated the system is, when a small subway fire paralyzed a major subway line serving Manhattan, Brooklyn and Queens. The blaze took out a signal room housing some 600 electromechanical relays and a maze of signal wires--critical parts of a fixed-block signaling system that has maintained appropriate headway between trains for decades. In fact, many of the relays and wires that burned in the fire were discovered to be the original components, installed for the line's very first run on September 10, 1932. And that particular line can be considered one of the younger ones as others date back even further, to 1904.

The components have escaped modernization because of several reasons. For one, they're still functional, though barely. Additionally, commuters would hardly notice the difference if they were upgraded, but they would notice the renovation process, which would be disruptive and highly inconvenient. In fact, tight underground spaces that make revamping a tricky proposition--and one that would surely interrupt service--are behind the preservation of several extremely outmoded subways around the world, including those in Paris (circa 1900), Boston (1897), Budapest, Hungary (1896) and London (1863).

Also, the monopoly behind the subway has grown used to doing things the old way, relying on the same ol' suppliers. For instance, two companies--Alstom Signaling Inc. in West Henrietta, NY, and Union Switch and Signal in Pittsburgh--still provide the subway with the relays (both would not talk about their businesses with IEEE Spectrum, the source of this story). Also tightlipped is the MTA New York City Transit, which divulged few details about the relay system's components.

When federal and state funds became available in the 1980s, the transit authority's efforts to improve the subway system started with clean-up. It spruced up stations and retired dilapidated, graffiti-covered trains in favor of new air-conditioned models. Meanwhile, tunnels and signal rooms remained untouched.

The transit authority is slowly working to remedy that. This summer--thanks to a six-year $288 million investment--commuters can expect the debut of an automated L line, which covers 20 of the system's 1,200 kilometers and serves 24 of its 468 stations. Computerized train systems will monitor speed, open and close doors and manage routes--without the need for a conductor or train operator. Moreover, the modernization of the signals and relays on the No. 7 line, which traverses midtown Manhattan and ends in Flushing, Queens, is in the preliminary design phase.

"The two biggest obstacles to changing out the signals are funding and finding a way to install the new technology in a subway system that runs 24 hours a day, seven days a week," says Charlie Seaton, a spokesman for the transit authority. Even throwing a few billion dollars more at the problem would not make it go away because the subway's around-the-clock work shift puts a damper on the rate of work. Also, parallel systems can't be set up to avoid disruption. Subway control systems are directly on the tracks, meaning they can't be replaced without stopping service.

"And you wouldn't believe the pressure we were under from local politicians and advocacy groups when we shut down the L line on weekends" for the upgrade, Seaton tells IEEE Spectrum. Indeed, upgrading any part of the subway entails stoppages, which would be scheduled for nights and weekends. And to modernize the entire system, it would take around 35 years, says the transit authority. By that time, the subway would be obsolete yet again.

Source:

New York Unearths Paleotech Relic
Willie D. Jones
IEEE Spectrum, April 2005
www.spectrum.ieee.org/WEBONLY/resource/apr05/0405nsub.html