Maintaining Subway Cars for a Smooth Ride
A rolling amalgam of 40 tons of motors, components, systems and a stainless-steel shell, New York City subway cars are some of the most complicated pieces of machinery ever built and each and every day, they go out and perform a tough job, operating in an extremely harsh environment.
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Subway cars travel an average of 60,000 miles each year and 2.4 million miles throughout their service lives with steel wheels pounding on steel rails through rain, sleet, snow, blazing sunshine and through subway tunnels saturated by summer heat -- all while carrying upwards of 1,500 customers per train. While a high level of durability is designed and built into each car class, much of what makes a New York City Transit subway car so dependable in daily service can be attributed to a maintenance program developed more than 20 years ago.
The mechanical reliability of MTA New York City Transit’s fleet of 6,200 subway cars has been a major source of pride for employees. That achievement stems from a simple idea; fix things before they break. That is the philosophy behind the Scheduled Maintenance System (SMS) program developed by the Division of Car Equipment as a way of maintaining the reliability of new subway cars and older subway cars that had gone through the General Overhaul (GOH) program.
SMS essentially pre-determines the failure point for a subway car component or system and then refurbishes the systems by replacing or reworking key components prior to the point of failure. It’s like knowing that your automobile’s timing belt will be good for 100,000 miles prior to failure and then changing it out at 90,000 miles. By performing that task, you keep yourself from getting stuck on the side of the road. By renewing components through the SMS program, the likelihood of component failure which could leave customers stuck on the platform is substantially decreased and the need for a costly mid-life General Overhaul is eliminated.
SMS is the evolution of a two-decade maintenance philosophy that has seen subway fleet reliability rise from an average of 9,000 miles between mechanical failures in 1984 to the current level of 160,000 plus miles. A major element of the SMS program is the linking of cars into permanent sets of either four or five units. Permanent linking of cars in this manner allows for the elimination of redundant components, such as air compressors.
“It wasn’t that long ago when train failures were a common occurrence trying the patience of our customers and drove us to develop a means of improving our performance,” said Michael Wetherell, Vice President and Chief Mechanical Officer, Car Equipment Division. “Fleet reliability, or more accurately the lack of, in the late 1970s and early 80s spurred the development of the SMS program, which is a tremendous source of pride for us and of great value to the 5.4 million customers who ride the subway daily.”
The GOH program helped pave the way for SMS. Funding for that program was provided through the MTA’s Capital plan to perform a complete overhaul on more than 60% of the subway car fleet – essentially stripping the cars to their steel shells and installing new components and systems, including the introduction of air conditioning in cars manufactured in the 1960s. The GOH program, which addressed cars at about the halfway point in their 40-year service lives, produced remanufactured cars that were like new in appearance, performance and reliability.
But in order to keep them that way, the SMS program was developed for the 4,100 GOH cars as well as the nearly 1,800 new cars being delivered in the 1980s and every new car class since then. Instead of waiting until the cars reach 20 years of age before doing a major remanufacturing job, engineers determined the service lives of the major systems — air conditioning, car body, doors, brakes, trucks, etc. — and established a maintenance/replacement schedule for each of them.
Most of the cars that went through the GOH program were shipped to a contractor who would perform the work, however, the SMS program is done almost entirely in house by NYC Transit employees. The replacement work for heavier car systems such as trucks, door system, HVAC, and propulsion is carried out at both the Coney Island and 207th Street maintenance facilities, while the exchange of system components such as battery banks, air compressors and air brake valves is accomplished in the maintenance shops.
All of these components are renewed at one of the component repair shops located at either of the two overhaul shops or electronic systems at the NYCT electronic component maintenance shop. The process is then brought together by the Engineering Work Scope and Production Planning groups, with support from the Procurement and Logistics Divisions.
Car Equipment Maintainers are highly-skilled craftsmen with years of experience in fabrication and a high level of familiarity with what it takes to keep a subway car rolling. They are capable of repairing anything associated with a subway car and, in a pinch, even re-building one. Workers involved in the SMS program do a lot more than swap out parts. Worn components are removed from the car and often rebuilt by hand. This saves the expense of purchasing that part new, or in some cases adds new life to a part that is no longer available.
Most recently, the outstanding performance of NYC Transit’s subway fleet was recognized at the international level with the receipt of the Best Maintenance Programs award at the 2008 Metro Awards in Copenhagen, Denmark. The award was one of 11 announced by a panel of judges who had to consider 1,000 nominations from 76 competing transit operators from around the world.