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One of the most significant technological challenges facing rail systems is the implementation of Positive Train Control (PTC), which has been described as a “system of systems” that requires long-range strategic planning, highly advanced engineering, and extensive integration with existing systems of all types.
Passenger Transport recently posed two questions to Robert G. Ayers, president, Ayers Electronic Systems, a member of the APTA Research and Technology Committee, and Lou Sanders, APTA’s director-operations and technical services, to get their perspectives on the state of PTC technology and the challenges it represents. Their comments follow.
PT: Please share your assessment of the current technological obstacles and opportunities related to PTC, particularly in terms of its critical segments such as back office, locomotive, and wayside.
Robert Ayers: In the communications area, there continue to be issues with obtaining timely FCC approval for the required 220 Base station sites. Additionally, the allocation of spectrum in the 220 band continues to be an area of contention.
In the back office, it has been a challenge to develop servers that can provide interoperable messaging on one side and custom integration with each railroad’s dispatch and back office environment. Additionally, most railroads require modifications to their dispatching system to accommodate PTC.
On the locomotive, integration with existing onboard systems such as various types of electronic braking systems, energy management systems, and locomotive computer feeds (e.g. LIG, LSI) provides challenges. There are a wide variety of locomotive environments, even within a single large railroad, that need to be accommodated.
On the wayside, PTC necessitates additional testing after any change is made to a wayside location. PTC brings new requirements to rapidly report minor changes to the wayside and to incorporate those changes into the track files. Additionally, the volume of wayside locations that require new installations or upgrades is very high. Finally, changes made to the wayside at subdivision boundaries and at diamonds have more implications as data must be updated for all affected subdivisions.
Lou Sanders: Commuter railroads have been confronted with special challenges in spectrum acquisition due to lack of funding and inexperience on the part of smaller operations. Commuter railroads present a range of applications, including:
* Setting up independent networks to accommodate PTC operations;
* Integrating with host networks;
* Internal integration with existing communications systems; and
* Cab cars in addition to locomotives operating in push pull service.
Data
Ayers: Each railroad that has its own track will need to develop, validate, maintain, and configuration manage Track Files (sometimes called “subdiv files”), which specify the track, grade, curvature, signal switches, permanent speed restrictions, and so on that are necessary for PTC operations. Developing and maintaining these data with the requisite accuracy is a much more significant challenge than many people in the industry envisioned.
Configuration management of the very large datasets required to support PTC is a long-term challenge. Historically different departments in the railroads maintained their own datasets that met the business needs of the departments; however, PTC requires datasets to be integrated across engineering, technology, and operating organizations. PTC also requires that data be updated and distributed within a much shorter timeframe than has ever been the case in the past.
Sanders: Some commuter railroads have IT management infrastructure, but smaller operations do not. This poses difficulties in maintaining software configuration for communications and back-office systems.
Organizational Issues
Ayers: In organizations that are first starting to deal with PTC, there is a tendency for each person to see the problem from a perspective that is based on their background. This is true both for railroad employees and consultants.
Effective PTC implementation requires a horizontal “system” view of the railroad, and relatively few people are currently able to bring this perspective.
The need for management to have a crosscutting view of the railroad business may lead to structural changes in many railroads.
Sanders: Commuter railroads may have bits and pieces, but not necessarily coherent organizations to address PTC requirements. New patterns of communications with tenants and hosts may challenge some existing organizations.
PT: What are the strategic issues? What trends should agency and business member leaders be aware of as discussions of PTC’s role in public transportation evolve?
Next Generation Dispatch Systems
Ayers: Current PTC implementations are connecting conventional dispatch computers to PTC to allow operations to continue on the railroads with minimal changes to operating practices. Once the intensive effort to deploy PTC is completed, it is likely that railroads will take a new look at how dispatching is performed with an eye to more efficient and safer operations.
Currently dark territory authorities are read to crews by dispatchers, and read back by the crew prior to making the authorities “active.” This process is labor-intensive and error-prone. Future dispatch systems could eliminate this process and allow crews to operate solely on authorities delivered digitally by PTC.
Future dispatch systems could take advantage of real-time location information from PTC and could implement moving block operations where the dispatch system automatically “rolls up” authority behind a train and allows another train to follow it more closely than is possible currently.
Sanders: Commuter rail schedules are more elaborate than freights and operate in more confined areas. This adds complexity to scheduling, and it increases communications and data requirements to support operations.
Integration with New Sensors
Ayers: New sensor systems are on the drawing board that will provide predictive broken rail detection, replace track circuits, and provide more precision train location. Eventually, the integration of these sensors with PTC will provide opportunities to improve safety and lower operating costs. |
