Positive Train Control — Ready to Go?

Of the several PTC projects undertaken by freight railroads, the most advanced, in terms of deployment, is the ETMS implemented by BNSF. ETMS is an overlay on existing methods of railroad operations. Its use is currently limited to freight operations. In December 2006, ETMS had the distinction of being the first PTC system in the United States that successfully completed the regulatory review required by 49 CFR Part 236 Subpart H. As part of the approval, FRA authorized ETMS deployment on 35 BNSF subdivisions. BNSF continues to enhance ETMS capabilities, including potential integration of Amtrak-equipped locomotives. If successful, this would allow Amtrak to provide PTC-protected passenger service when transiting BNSF territories.

The freight railroads are pursuing other additional innovative and interoperable PTC systems with potential applicability to passenger rail. CSXT continues work on its CBTM overlay and UP is developing the VTMS. When complete, VTMS will be capable of replacing existing methods of operations, providing PTC functionality in a fail-safe manner. NS has commenced work on its version of a vital PTC system called optimized train control (OTC). The Ohio Central Railroad System (OCRS) has started working on its version of PTC called Train Sentinel. The CSXT, UP and NS PTC systems are all variants or derivatives of the BNSF ETMS system, while the OCRS represents a completely different design.

In addition to the preceding, deployment of other PTC systems is being actively undertaken to support revenue passenger operations. Metra has started adaptation of the BNSF ETMS to provide overspeed enforcements. Like the BNSF system, the Metra PTC system is a safety-critical overlay on existing methods of operations.

While significant progress has been made in the technical area, there are a number of ongoing issues that, if not resolved, could adversely impact PTC deployment. Systems that have been implemented are not interoperable between railroads. Trackage rights, haulage rights, shared power agreements and joint terminal operations are extensive and service requirements demand seamless transitions from one property to another. For both passenger and freight locomotives, avoiding the additional expense of equipping each locomotive with every PTC system that could be encountered underscores the critical need for proven interoperability. Closely related to standardization of the hardware is the need to establish compatible human/machine interfaces. These interfaces are crucial to allow engineers to operate the shared PTC hardware without requiring significant additional training.

Another area requiring resolution is ensuring the effective use of the radio frequency (RF) links between PTC components. Experiences on the NAJPTC project and on ITCS in particular have highlighted the need for this. The NAJPTC project sustained difficulties in resolving communication capacity issues, which necessitated its removal from revenue rail corridor originally planned and relocation to the controlled environment of the Transportation Technology Center Inc. (TTCI) in Pueblo, Colo., for further development and testing. ITCS reliability has been slightly less than optimal, necessitating installation of a new communications infrastructure to obtain a satisfactory level of reliability.

Related to the effective use of the RF links is the Federal Communications Commission’s (FCC) re-hosting of the railroad command and control frequencies to the 160MHz range channel bandwidths from 25 kHz to 12.5 kHz, with an eventual target of 6.25 kHz. The mandatory re-hosting that is required to be completed by 2013, adds pressure and complicates the resolution of RF issues for PTC. There is, however, a positive aspect to the re-hosting issue. The conversion to narrow-band communications requires that all radio systems currently in the railroad inventory be replaced. Since all radios must be replaced anyway, it provides an opportunity for railroad locomotive owners to re-equip their fleet, and make them PTC-ready.

Finally, there is the need to demonstrate the extension of PTC technologies to combined heavy freight density and passenger service corridors. The newer PTC systems designed for application to major freight lines have neither been implemented nor tested under conditions of mixed traffic. Given the relative vulnerability of passenger trains with respect to freight trains in a collision scenario, such testing is necessary to ensure that the PTC functions will correctly operate, with associated protections provided.

FRA has a number of current ongoing research projects that provide the industry with technical and funding support in resolving immediate and long-term issues discovered during deployment. Priorities are given to those projects that enhance the accuracy, capability and reliability of the PTC technology.