Positive Train Control — Ready to Go?

Initial Steps Toward Deployment
Amtrak made the first use of PTC technologies. Based on advice regarding requirements from FRA’s Office of Safety, and ultimately supported by a 1998 order requiring its deployment, Amtrak rolled out the Advanced Civil Speed Enforcement System (ACSES) which, coupled with the existing cab signal and automatic train control systems, provides PTC capabilities supporting train speeds of up to 150 mph. Although ACSES uses transponders to determine train location, Amtrak decided to pursue the GPS-based approach for its Incremental Train Control System (ITCS), which is deployed on its Michigan line. This system has been employed in service under an FRA waiver granted in March 2000 and has supported 90-mph service since January 2002.

On the freight side, PTC remains a technology undergoing testing and demonstration, but the overall pace of its implementation is increasing rapidly. When the 1999 RSAC report was delivered, FRA was already working with CSX Transportation (CSXT) on its Communication-Based Train Management System (CBTM) and a number of other related freight railroad projects were underway (several of which were later terminated or significantly redirected). At that time it became clear to FRA that the Class I railroads were serious, but still striving to identify reliable and properly scaled technology.

FRA’s Next Generation High-Speed Rail Program had also spearheaded a partnership with Illinois DOT and other stakeholders, including the AAR, to establish the North American Joint PTC program (NAJPTC). NAJPTC had as its central objective to effectively demonstrate and deploy a new form of PTC that could support high-speed passenger rail operations (to at least 110 mph), with the potential for moving blocks and intermingled freight traffic. While that program did not result in the deployment of a fully capable train control system on the designated corridor, it did ultimately help accelerate the development of some of the technologies used in other projects.

Regulatory Support
The appearance of advanced train control systems and the envisioned size of their implementation on U.S. passenger and freight railroads underscored the critical need for regulatory support of the PTC initiative. The prescriptive nature of existing Title 49 Code of Federal Regulations (CFR), Part 236 requirements for signal and train control systems did not support microprocessor-based PTC-type system designs and the unique newly emergent train control architectures. Responding to the need for regulations, FRA worked through the RSAC to develop Performance Standards for Processor-Based Signal and Train Control Systems, published in March 2005 and effective in June 2005. These regulations, often referred to as the “PTC rule,” grandfathered PTC systems in revenue operation prior to the effective date of the regulations, and a limited allowance was made for systems under development at the time. All other PTC systems that were not otherwise exempted were required to comply with the PTC rule.

The new regulations are unique among the current federal rail safety regulations because of the extent to which they are technology-neutral and performance-based. Prior to the new rule, the existing regulations for signal and train control systems prescribed requirements for specialized, precise and inflexible electromechanical and fixed electrical and electronic circuitry. The prescriptive regulations hindered or restricted the use of newer, more advanced train control systems using versatile, general purpose and software-controlled microprocessors. In contrast, the new rule gives the railroads and vendors significant freedom to innovate and make better use of advances in technology. The realistic assessment of operational, economic and safety benefits and costs observed during the last decade of PTC systems implementation did not allow FRA to mandate PTC implementation. Instead, FRA has encouraged the voluntary implementation of PTC technology.

Despite the relative complexity of the PTC rule, the performance-based standards are quite simple and straightforward in principle. The fundamental regulatory precept of the rule is that the new system must be at least as safe as the system it is replacing or augmenting. The railroads seeking to adopt such systems must provide a comparative risk assessment for the old and new systems as evidence that the proposed system is sufficiently safe for a particular operational environment. This requirement is applicable to both passenger and freight rail systems.

The performance-based regulations establish the conditions for revolutionary changes, as opposed to evolutionary and incremental advancements, providing an environment favorable to develop innovative and technologically advanced PTC systems.