I read with great interest the Railway Age article on March 9 announcing the winners of the New York Metropolitan Transportation Authority (MTA) Genius Transit Challenge.
In the article, MTA New York City Transit President Andy Byford is quoted as stating: “A modern signal system is the key to running more trains, to driving up reliability and to increasing network capacity.” As this is a statement I would very much agree with, I was particularly interested in the winners of the Signalling challenge.
Having spent my entire career of some 40 years championing the deployment of new technology systems to enhance safety and improve the operational performance of rail transit systems, I applaud this MTA initiative and their willingness to invest in the research and development of new signalling technologies.
From my perspective and experience, however, whatever the “next generation” of signalling/train control system may look like, and whatever acronym we may give it (CBTC, PTC, ERTMS, UBW, etc.), I am sure it will still have to include:
- Equipment (hardware) on the train, interfacing to train subsystems such as brakes, propulsion, passenger doors, train operator displays, etc.
- Equipment (hardware) on the wayside, interfacing, as a minimum to track switches and possibly wayside signals and other wayside devices, and potentially interfacing to secondary means of train detection for unequipped trains or trains with failed train-borne equipment.
- Equipment (hardware) at central control locations, interfacing to various central office subsystems, including displays, supervisory control facilities, and passenger information systems, for example; and
- A data communications network that links this hardware together.
In addition, any new signal system will still have to deliver the same automatic train protection (ATP), automatic train operation (ATO) and automatic train supervision (ATS) functions necessary to provide for safe train movements while at the same time reliably delivering the required passenger service levels during normal, abnormal and degraded-mode operating scenarios.
Since in a modern signal system, these functions are implemented in safety-critical software, defining the next generation of signalling/train control system architecture essentially comes down to deciding what software functions you install in the train-borne, wayside and central control hardware respectively, and what sensors you use to determine train location and speed, and to confirm a safe route. There has been a long-standing debate in the signalling profession regarding the pros of cons of wayside versus train-centric system architectures. Today, however, I would say there is a clear trend toward train-centric (“smart train”) concepts, and the results of the MTA Genius Transit Challenge are therefore consistent with this trend.
Where I would, however, be critical of the MTA is its apparent failure to take a more holistic view of the problems facing New York’s subways. Their overarching strategic objective surely is to accelerate the modernization of the subway signal systems in order to achieve a state-of-good-repair (with improved system reliability/availability) and to provide increased line capacity (ability to move more people). To meet this strategic objective, the MTA appears to have focused solely on the technology (looking for that “magic bullet” perhaps?), and specifically have focused primarily on one ATP function (train location determination).
As such, the MTA has potentially fallen into exactly the same trap that BART in San Francisco fell into in the late 1990s where “radio ranging” communications technology, to locate trains, worked well under ideal conditions on a test track, but the concept fell apart once BART tried to integrated and deploy this technology, system-wide, as an element of a complete signalling/train control solution on a “real” rail network, and with consideration of “real” operating conditions and “real” failure modes. Rather than accelerating the modernization of BART’s signalling infrastructure, this focus on one specific technology instead delayed essential signalling upgrades for decades. (I understand BART is now in the procurement process to award a contract to re-signal the entire BART rail network with CBTC).
Given MTA’s overarching strategic objective, embarking on an ambitious R&D program to develop one component of a new signal system seems a narrow, high-risk approach, and I would suggest largely fails to address the root cause of MTA’s subway problems.
The fact that re-signalling projects in New York take longer to implement, and cost at least twice as much as anywhere else in the world, has little to do with the technology and more to do with project complexity and delivery method.
An International Technical Committee of the Institution of Railway Signal Engineers (IRSE) has recently completed an article on “Why Do Signalling Projects Fail” (to be published in the May edition of IRSE News) reflecting experience and lessons learned from around the world. This article suggests that the primary factors that drive the implementation schedule and cost for signalling/re-signalling projects is not the technology per se, but rather:
- The complexity of the rail network (including the level of interoperability required between lines, and the legacy equipment the new signal system has to interface with).
- The signalling functionality to be provided (including the extent to which “mixed-mode” operations have to be supported, with both “equipped” and “unequipped” trains operating on a given line).
- The operating and regulatory environment in which the signalling work is to be undertaken (specifically constraints on track access and access to rail vehicles, not only for equipment installation but also to fully test and commission the new equipment; as well as the regulatory process that has to be followed to certify the new signal system as safe for passenger-carrying service).
- The procurement/delivery model adopted (including how project delivery risk, and financial liabilities, are allocated to the various entities responsible for delivering the project).
In addition to the Genius Transit Challenge, with its narrow focus on a number of specific “new technologies”, it is to be hoped that the MTA is also addressing these other factors, noted above, in delivering its mission and strategic objectives going forward.