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<\/figure>\n<\/div>\n\n\nAbout 85 percent of New York City\u2019s subway system still operates with this analog signal system. The outdated equipment is no longer manufactured and has to be manually operated, around the clock.<\/p>\n\n\n\n
It\u2019s no surprise then that the system is a leading cause of delays. Over the past 15 months, it has led to an average of nearly 4,000 train delays a month, according to data from the Metropolitan Transportation Authority, the state agency that runs the city\u2019s transit system.<\/p>\n\n\n\n
The subway has long depended on \u201cfixed block\u201d signaling, a method of maintaining safe distances between trains that uses track circuits to detect the location of trains, wayside signals similar to traffic lights and mechanical trips to stop trains that pass a red light.<\/p>\n\n\n\n
The authority is replacing the system with a modern upgrade known as communications-based train control, or C.B.T.C.<\/a>, which is becoming the standard for transit systems worldwide, including those in London and Paris. It relies on computers and wireless technology \u2014 instead of people \u2014 to automatically control train movements.<\/p>\n\n\n\n But the system upgrade is at risk. The Trump administration is attempting to kill congestion pricing<\/a>, a tolling program in Manhattan that would raise billions of dollars for the work. The M.T.A.\u2019s next capital budget<\/a> could also be in jeopardy, if Washington follows through on its threats to defund transit projects in New York State.<\/p>\n\n\n\n New York\u2019s subway is vastly more complicated to run than other major subway systems because it never closes and its trains crisscross tracks. The city\u2019s subway has more than 200 crossing points known as \u201cinterlockings.\u201d<\/p>\n\n\n\n Much of the old signal system is run from a network of underground control towers that sit beside the tracks. Inside each tower are operators like Ms. Pryor who change signals and switches.<\/p>\n\n\n\n Ms. Pryor operates a device the size of a grand piano called an interlocking machine. By manipulating a row of 24 levers, she merges traffic at a busy intersection, where local trains cross tracks with express ones.<\/p>\n\n\n\n In the center of the board, each green dot on the lines represents a stretch of occupied track. Here, an approaching A train, on the third line, and a C train, on the fourth, must merge onto one track to travel to Manhattan.<\/p>\n\n\n\n Each command requires a careful sequence of pushed and pulled levers, a safeguard meant to prevent human error. Levers marked with red turn signal lights green, yellow or red. Levers with black switch tracks.<\/p>\n\n\n\n About 300 operators like Ms. Pryor are stationed at interlocking machines, but their ranks are thinning as the subway has gradually moved to centralized controls. The work pays around $40 an hour on average, according to a Transport Workers Union wage sheet.<\/p>\n\n\n\n While the signaling system still works most of the time, it has become more fragile and unreliable with every passing year. Equipment and parts break or wear out. In January, a relay failure at the Hoyt-Schermerhorn station took about an hour to fix and delayed 25 trains.<\/p>\n\n\n\n \u201cIf you had a car from the 1930s and drove it every day you\u2019d be lucky if it was still working like this, right?\u201d said Salvatore Ambrosino, the M.T.A.\u2019s chief officer for signals.<\/p>\n\n\n\n Directly behind the interlocking machine, a closed door leads to a back room filled with hundreds of wires, most of which are so old they are wrapped in braided cloth, not rubber, and are prone to failure.<\/p>\n\n\n\n When riders are delayed by \u201csignal problems,\u201d the issues often start with wires like these. Finding an outage is a tedious, manual process and replacing damaged parts must be done delicately.<\/p>\n\n\n\n The electrically operated devices at the heart of the operation cannot simply be replaced. New parts for the glass cylinders \u2014 long discontinued relays \u2014 need to be custom made in an M.T.A. workshop.<\/p>\n\n\n\n Fixed block signaling divides the tracks into blocks, or sections of roughly 1,000 feet on average, that carry an electrical current. When a train occupies a block, it cuts off the current, letting the system know its general position.<\/p>\n\n\n\n The system cannot pinpoint exactly where a train is, so a buffer of two or more blocks is maintained between every train to keep them at safe distances. But that limits how many trains can run at the same time. As subway ridership has grown, it has resulted in overcrowded cars and longer waits.<\/p>\n\n\n\n The old signals are gradually being replaced with C.B.T.C., which keeps trains in constant contact with a centralized computer system that controls their every movement. This technology allows trains to run closer together, which means more trains on the tracks and faster service.<\/p>\n\n\n\n \u201cThink of it like moving from a Walkman with all the moving parts to an iPhone that\u2019s solid state,\u201d said Jamie Torres-Springer, president of M.T.A. Construction & Development, which is overseeing the signal projects. \u201cThere\u2019s no moving mechanical equipment \u2014 it\u2019s all digital.\u201d<\/p>\n\n\n\n In 2006, the L line became the first route to convert to the more modern system. The 7 line followed in 2018. Those routes now consistently have the best on-time performance.<\/p>\n\n\n\n C.B.T.C. has also been installed on sections of the E, F, M and R lines in Queens and the F line in Brooklyn.<\/p>\n\n\n\n The advantage of the new system is that computerized equipment is installed on every train to monitor its exact location and speed. The computers digitally manage signals and switches while routing the trains.<\/p>\n\n\n\n The home of C.B.T.C. is the M.T.A.\u2019s Operations Control Center in Midtown Manhattan. Security is extremely tight and photos are rarely permitted.<\/p>\n\n\n\n Entering the control center is like walking onto the bridge of a spaceship. The nearly 21,000-square-foot room is almost half an acre in size with soaring 30-foot high ceilings. An entire wall is covered by a digital map showing trains moving in real time in Brooklyn, Manhattan and Queens.<\/p>\n\n\n Between 75 and 90 M.T.A. workers are on the floor, day or night, surrounded by 432 computer screens. They keep an eye on train movements, stepping in only to troubleshoot. Each time another route is converted to C.B.T.C., more workers join them.<\/p>\n\n\n\n The next round of projects will bring modern signals to 66 miles of track in Brooklyn and Manhattan. These tracks are shared by six different routes \u2014 the A, C, B, D, F and M lines \u2014 and carry about 1.6 million daily riders.<\/p>\n\n\n\n C.B.T.C. will eventually be expanded to subway routes across Manhattan, Brooklyn, Queens and the Bronx.<\/p>\n\n\n\n But modernizing the signals, which have been called the subway\u2019s central nervous system, is enormously expensive. While the transit authority has brought down costs significantly as the scale of work has increased, installing C.B.T.C. costs about $25 million per mile. The work<\/a> also includes overhauling tracks and infrastructure and retrofitting trains.<\/p>\n\n\n\n M.T.A. officials are counting on $3 billion from New York\u2019s congestion pricing program to pay for the new signaling system. But that funding is in question now that President Trump has vowed to kill the program.<\/p>\n\n\n\nAncient Signals<\/h2>\n\n\n\n
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<\/figure>\n\n\n\nMission Control<\/h2>\n\n\n\n
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