By harnessing the latest in communications technology; positive train control (PTC) potentially offers a far safer and efficient means of operating a rail network.
The system, which combines a number of technologies to effectively monitor the positioning of trains across a rail network, has been coined as a breakthrough solution to the prevention of train collisions and derailment through drastically reducing operator reliance on manual procedures.
Although it has made encouraging progress in recent years, widespread deployment of PTC systems remains a future goal. Technical and financial restraints have often hindered its implementation, but the Federal Rail Administration (FRA) has shown considerable initiative in developing PTC across the US.
This fiscal year, the US governing rail body earmarked $735,000 to the research and development budget of Alaska Railroad for the purpose of developing PTC. The move symbolises the FRA's growing commitment to the new technology, having sponsored a number of projects for improving and enhancing PTC technology capabilities.
According to the director of FRA's Office of Research and Development Magdy El-Sibaie, the grant is part of a larger policy aimed at promoting the use of PTC across the country. "The FRA has long sought to promote and facilitate deployment of advanced signal and train control technologies in order to improve the safety, security, and efficiency of freight, intercity passenger and commuter rail services in the US," he says. "The agency has done so through regulatory reform, project safety
oversight, technology development and the provision of financial assistance.
"After extensive participation by and contributions from railroads, rail labour, suppliers and other agencies, FRA promulgated performance-based regulations to support the introduction of innovative technologies, including systems utilising computers and data radio links, to accomplish PTC functions. In addition to advancing adoption and implementation of PTC systems, these regulations also permit more widespread use of microprocessor-based equipment and functionality in conventional signal
and train control systems."
The FRA has identified three key operating elements to ensure for a successful PTC system. Train tracking, computer networking technologies and a solid communication network must all be effectively integrated in order to form precise navigation and location data. Modern GPS technology should be accompanied by office, wayside, onboard and intercommunication technologies that are able to transmit and interpret safety critical data.
Furthermore, such technologies used to control the train can also be extended to non-train control-related functionality. "In some cases railroads can leverage PTC technology to provide additional business functionality to help optimise the use of railroad assets, and in doing so, provide enhanced services to customers," says El-Sibaie.
"Among the most significant potential business benefits are possible increased operational efficiencies through enhanced line or route capacity. Another important attribute is the significant reduction or near elimination of many track-side installations, typically required by contemporary signalling systems, with the potential for reduced construction and maintenance costs and improved performance."
Restraints of the business
The FRA believes the current climate for the technology has altered since the Railroad Safety Advisory Committee (RSAC) first established the PTC working group in September 1997. At that time, the level of technical knowledge possessed by rail operators exceeded that of the vendors, while today the operators often lack the expertise required to implement and deploy PTC systems independently due to the advanced levels of technology entailed.
"Modern microprocessor and software (digital system) design has become such a specialised field, that railroads are often at a disadvantage in trying to make sound procurement and acquisition decisions when trying to evaluate detailed technical specifications and system performance," says El-Sibaie. "Furthermore, much of the detailed information associated with digital systems is valuable intellectual property owned by the vendor which it may not routinely or ever release to customers."
Understanding the technology is only part of the problem.
Developing standards and procedures to support microprocessor-based PTC-type designs and architecture adds substantial complications for both government and industry. During 2005 this was first fully addressed with the introduction of performance standards for processor-based signal and train control systems, following a period of collaboration between RSAC and FRA.
Often referred to as the 'PTC rule', the standards are made distinct by their technology-neutral and performance-based nature. However, the FRA has since encountered issues of enforcement and compliance from regulators accustomed to working with prescriptive standards.
"Performance-based standards, by definition, create uncertainty for both regulators and regulated entities with respect to enforcement and compliance issues," says El-Sibaie. "Regulators accustomed to enforcing prescriptive standards are frequently uncomfortable with the discretion inherent in loosely specified performance standards. Similarly, regulated entities are uncomfortable with loosely specified performance standards because they believe they give regulators too much discretion when
considering enforcement issues or making compliance decisions.
"However, by minimising unnecessary competitive obstacles, and emphasising a more flexible, results-oriented policy than specific design standards, the choice offered by performance standards can ultimately produce significant cost savings, and provide incentives for innovation. In turn, freeing industry from the design limitations imposed by prescriptive regulation, and allowing the use of virtually any functional process and technology available, establishes the conditions for revolutionary changes, as opposed to incremental evolutionary advancements."
Stretching from Seward on the Southern Gulf of Alaska up to the northern tip of Fairbanks, the Alaska Railroad (ARR) is one of the state's major tourist attractions.
Carrying nearly 500,000 passengers each year, the rail network is also a powerful economic force in Alaska – responsible for hauling millions of tonnes of freight per year, which supports the state's construction, coal, petroleum and gas industries.
Unlike many other state-owned rail entities in the US, the ARR is incorporated and run like a business, having been governed by the Alaska Railroad Corporation (ARRC) since 1984. In 1997, the ARRC first began planning for the introduction of PTC and the company's vice president of projects and technology Eileen Riley says she believes the system will offer a significant contribution to operations.
"The Alaska Railroad Corporation was looking at moving from an entirely manual system for issuing authorities to trains in order to ensure overlaps did not occur," Riley explains. "The risk of a freight train and a passenger train having an incident was high so we received approval to begin the search for a positive train control system.
"The most significant issue to overcome was the need and then implementation of a robust communication system."
Phase by phase
The ARRC eventually selected the Collision Avoidance System (CAS), the first phase of which was installed in May 2005 and the second in May 2006. Focusing on the communications segment, a computer-aided dispatch (CAD) system was introduced which consisted of mobile and base station packet data radios and GPS receivers on the locomotives. The system is currently operational and provides complete situational awareness of trains across the railroad.
A further three phases of the project remain before the CAS is fully operational. Phase III is estimated to cost approximately $20m while phases IV and V are estimated to cost a combined $20m.
"Equipping locomotives with a fail-safe on-board computer system to allow digital delivery and enforcement of authorities is scheduled for September 2009, while demonstration service and full revenue service will fall in 2010," says Riley.
"Once complete, the system will reduce risk of over-speed and outside of authority violations that contribute to incidents and accidents. The stage that is currently being tested is for onboard computes that will enforce speeds and authority limits alongside delivering digital authorities."
The fundamental difference highlighted by the ARRC between its current system and the CAS system is that the room for human error will drastically decrease. By 2010 the system will present human operators with improved information for decision-making and will also detect infrastructure failure and potential violations quickly, intervening when necessary.
"The dispatcher to train engineer and conductor conversation to issue authorities to operate will be primarily digital," says Riley. This
will eliminate miscommunication of authorities and reduce the time to issue authorities."
The long track ahead
The timescale and cost of the Alaska Railroad's CAS illustrates the level of transition required of rail operators wishing to convert to PTC.
Because of this, the FRA anticipates that the widespread deployment of PTC technology will be gradual, since its development depends upon the ability of railroads to obtain the necessary capital investment funds needed to acquire and institute the systems.
"As PTC systems are developed and implemented the cost of the technology is expected to decrease, and its use is anticipated to become more widespread," says El-Sibaie.
"While FRA encourages the introduction of digital-based PTC technologies we also recognise that these technologies are not necessarily the most cost-effective solution for every situation and location. Many railroads may not have the complexity of operations that warrant the implementation of PTC."