Upgrading Subway Signals: Inviting innovation while mitigating risk

RPA was one of the first groups to identify signals as the Achilles heel of the subway system, issuing a report and video back in 2014 on the need to expedite the modernization of the signaling system or else face increasing delays and safety risks. At the time few New Yorkers were even aware that the “central nervous system” of the subway functioned much as it did when the first subway line opened back in 1904.

Our report focused on Communications Based Train Control*, which was being implemented or had been installed in many cities with subway or metro systems at comparable scales to New York.

In our recently released Fourth Regional Plan we continued to argue that it was essential to upgrade to modern signal technology and to do it much faster that was planned. According to MTA forecasts last year, it would take the agency upwards of 50 years to complete the upgrades. We argued that with more funding and more creativity about how to schedule the work, the upgrades could be done in as few as 10-15 years, with significant benefits to riders.

We support more resources being devoted in the MTA capital plan being dedicated to this work. We have even endorsed the idea of the MTA using more overnight closures on lines (with additional express bus service as an alternative for late night riders) to do these upgrades more quickly.

Now there are new technologies that may allow us to implement modern train control faster and more cost-effectively. The MTA to their credit is exploring these new technologies, in particular one that relies on ultra-wide band radio. UWB would provide a way to locate trains (and other objects on the tracks) and supports limited communications between trains and the wayside. It might replace some of the functions of CBTC.

But this technology is still so new that it has not yet been adopted at scale by any other city. So the MTA is doing the appropriate thing and vetting it first.

While we would all love to find a way to upgrade the signal system, which is a massively expensive proposition, more cost effectively and more quickly, we cannot bank on an unproven technology when dealing with the system the size and scale of the New York City subway.

What we are advocating for, and what the MTA is smartly doing, is to continue to move full speed ahead with the installation of CBTC at the same time as these tests are going on.

We applaud the MTA’s recent efforts to find more innovative solutions. The openness of the new MTA leadership to new ideas, along with initiatives like the Transit Innovation Partnership are an excellent sign that the agency is committed to finding smart ways to modernize our transit system.

We need the openness to innovation and the rigor to test new technologies, as well as the openness to rethink how we budget and plan for these types of system-wide upgrades to bring the nation’s largest transit system into the 21st Century.

Read more:

Moving Forward: Accelerating the Transition to Communications-Based Train Control for New York City’s Subways

Modernizing Subway Technology: How CBTC Works (video) 

*What is CBTC?

Communications-Based Train Control (CBTC) is a moving block signaling system that consists of computerized signal equipment installed along the trackside and on subway trains – all controlled by millions of lines of complex software. “Communications-Based…” refers to the constant two-way communication between the trains and the trackside equipment, which enables the system to precisely track the trains and maintain a safe separation distance based on the performance of the vehicle and its operating speed. CBTC equipment consists of several major components: on the trackside there are transponders, radios and zone controllers and onboard the trains there are radios, vehicle controllers and speed sensors. All these subsystems have redundant components. The most dramatic change between moving block and fixed block systems is the inclusion of the vehicle as part of the signaling system. Under CBTC train cars are equally as critical as trackside equipment.


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  1. 1
    Asa Robertson

    I am an engineer who submitted a Signal system proposal to the MTA as a part of the Genius Challenge. One of the reasons why I did not consider UWB is because it
    uses frequencies in the 3 to 6 Ghz range. Antennas used in the tunnels at these frequencies are susceptible to attenuation caused by steel dust generated by wheel track and brake friction. This degradation has rendered large sections of radiating cables used for [VHF and UHF] train communications useless in the past requiring replacement. Any system using these frequencies must have a way to prevent or remove the buildup of steel dust on antennas. Asa Robertson e mail: asa.robertson@ngc.com Mobile: 347 419 3359

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