Positive Train Control Systems
A Quick Introduction to PTC
1. The Truth About PTC
2. Lessons From PTC Failures
3. Strategic Railroading as an Answer
4. The History of PTC
5. Positive Train Control (PTC) Regulation
What is PTC? How do you define Positive Train Control ?
There is an alphabet soup of acronyms tracking around the railroad industry all claiming to be PTC – ATCS, ETMS, CBTM, etc…and the list goes on. There also seems to be an array of beliefs assigned to PTC, both business and safety. While PTC is clearly a safety system, it is also being presented by many as a rail operations optimizer with ravenous claims of efficiency gains in traffic management, fuel consumption, equipment utilization, and other desirable business benefits.
But, what is the truth behind PTC?
A decade ago, a joint effort by the FRA, railroads, labor unions, and suppliers referred to as Railroad Safety Advisory Committee (RSAC), was initiated to define the core objectives for PTC. All agreed to the following:
1. keep trains from hitting trains;
2. keep trains from over-speeding, and
3. keep trains from endangering workers in work zones.
Since that time, a fourth objective has been added:
4. keep trains from moving through improperly aligned switches.
The current PTC systems being pursued by the Class I railroads meet those objectives by monitoring the performance of the train’s operator relative to the movement authority that has been provided to advance the train. If the locomotive-borne PTC system determines that the train may violate the authority, then the operator is provided warnings to bring the train back within safe limits. Failure to do so will result in an enforcement by the PTC system that brings the train to a full stop.
Simply stated then, Positive Train Control is a system that prevents train accidents due to operator errors. PTC consists of locomotive-borne platforms linked to central office dispatching systems via wireless data networks. If the operator exceeds his movement authority, the train is sent a wireless signal and is automatically stopped. The availability of the wireless data infrastructure that provides PTC is the basis for the argument that PTC provides business benefits. The problem is that these business benefits could be provided independent of, and even prior to, the deployment of Positive Train Control. If a wireless data network was utilized across the railroads, the promised business benefits could be delivered without PTC.
The wireless network is also the source for most of the confusion around what is or isn’t PTC. In actuality, some of the alphabet soup of systems that claim to be PTC (as discussed in detail below) were in fact wireless traffic management systems that also incorporated some (but not all) of the safety aspects of PTC. The confusion starts with the trend in US rail to refer to any wireless communication system as PTC.
The last important point is that most of these systems were never deployed due to their complexity and excessive capital expenditure. In the quest to combine PTC functionality with business efficiency most rail companies created overly complex and expensive systems – instead of using existing commercial technology.
Hence, the PTC functionality of those well-touted systems was never delivered.
Lessons Learned from PTC Failures
The lesson from the failures to deploy advanced traffic management systems is clear – bringing Positive Train Control and business benefits from wireless integration requires technical and business perspectives that have eluded an industry steeped in traditional operating practices based upon technologies that have changed little in a century, i.e., track circuits and wireless voice.
Unfortunately, the fatuous association between PTC safety benefits and business benefits in concert with the intense focus on PTC is having a substantial negative impact on the railroads’ bottom lines.
No one group is at fault in the misunderstandings about PTC; the responsibility needs to be shared.
Regulators and vendors have viewed PTC from their individual perspectives of safety and potential equipment market, respectively, and they have been discouraged by the minimal advancement of PTC over the past decade. Hence, they have been inclined to link business benefits with PTC with the hope of encouraging its deployment – just check out their websites as to how they discuss PTC.
From the railroads perspective, their message has been clear and well proven. That is, railroads are safe, and the cost of PTC is not justified on safety benefits alone. However, what has not been properly pursued by railroads is an industry-based wireless data network that can service both PTC and business benefits. That is, a wireless network that can improve the management of a railroad’s key resources including track time, locomotive utilization, crew deployment, yard availability, and the efficiency of infrastructure maintenance. Additionally, a network that can service the railroads collectively as an industry by providing the position and status of shipments and equipment across the industry regardless of ownership. Such a network could provide for unprecedented equipment maintenance and utilization as well as shipment security and maintaining an accurate chain of custody.
PTC is now mandatory with the signing of the Rail Improvement Act of 2008, and the railroads have responded quickly and vehemently. Some may say too vehemently in that the railroads have dedicated much of their technical resources to the challenges of making PTC interoperable across the railroads, i.e., permitting any PTC-equipped locomotive to perform properly in any railroad’s PTC territory.
Hence, the true cost of PTC will not only be the direct capital investment, but the opportunity cost (lost opportunity) of not pursuing the business benefits that a wireless data infrastructure (also used for PTC) could deliver NOW.
Strategic Railroading™ as an Answer
The bottom line is that railroads are not looking aggressively at their bottom line relative to the deployment of technologies, most specifically wireless data. A cultural hsitory of only seeing capital expenditure as a way to create raw capacity and not efficiency, makes railroad executives risk-adverse when it comes to spending money on anything that doesn’t lay more track or provide more equipment. The railroads have excellent technicians, but they don’t have technologists that can deliver the business cases for deploying technologies in a strategic fashion. That is, the railroads don’t have the resources in place with the required disciplines to pursue advancing their business operations via advancing technologies.
They lack the ability to do Strategic Railroading™.
Ron Lindsey offers a course that provides a full understanding of PTC as to its history, operation, relationship with traffic management, regulatory considerations, and issues regarding implementation. Additionally, the course includes a threshold perspective of Strategic Railroading and its alignment with PTC.
To learn more about PTC, overlay vs. vital, traditional and advance traffic management concepts, wireless implementation in the railroads, and Strategic Railroading, check out Ron Lindsey’s Railroad Engineering and Immersion Courses.
The History of Positive Train Control (PTC)
Improving the safety or rail operations through enhanced communication has always been a stated goal, and the ideas behind this goal have been around in many forms for many years. Unfortunately, the rail industry has failed to act and innovate over the years despite nosediving costs in telecommunication and exponential improvements in wireless technology.
In the 1980’s the Association of American Railroads (AAR) and the Railway Association of Canada (RAC) tried to leverage the recent developments in digital radio and microprocessors. They set-out specifications for the implementation of something called ATCS – Advanced Train Control System. Around the same time BNSF worked to develop the ARES or Advanced Railroad Electronic System. Both of these systems relied on data radio systems and new wayside equipment (replacing the old). ARES was slightly more ambitious than ATCS in that it also used GPS for train tracking. Despite being publicly lauded as technical successes, neither of these systems were actually ever adopted.
ARES and ATCS were an important first step, but the fact that they were “technical successes” is not entirely true. ARES and ATCS were not implemented because the technology was not capable of being deployed on a wide scale in an economical fashion. They were not really designed for enforcement as much as they were done to provide advanced traffic and resource management. Additionally, those system did not deal with non-signaled territory (a.k.a. dark territory). Though ATCS and ARES are in many ways a development step towards PTC, these technologies should not be confused with PTC.
The term “Positive Train Control” was first introduced in 1994, when the FRA delivered a report to Congress titled, “Railroad Communications and Train Control.” The report described PTC as a technology that could automatically (using digital communication) control the speed of or stop a train should it exceed its speed authority. In this same year, the AAR abandoned ATCS.
In 1997, the Railroad Safety Advisory Committee (RSAC), was ordered by the FRA to conduct a PTC workgroup. The RSAC established that the workgroup would set out universal objectives for Positive Train Control Systems. The results of the study were the defining objectives of PTC or the definition of Positive Train Control Systems.
The three core objectives of PTC systems are (1) prevent train collisions; (2) enforce speed restrictions; and (3) provide protection for roadway workers – RSAC Website
These objectives or definition of PTC were delivered to the FRA in a report titled, “Implementation of Positive Train Control Systems.” in 1999 along with a blueprint for the deployment of the “technology”. This report was later addressed in a letter to Congress in 2000.
The problem and sources of confusion around PTC should now be apparent. Unsure of the technology, rail authorities focused on safety objectives and avoided the technology and much of the implementation. Therefore Positive Train Control Systems is essentially defined as the above objectives, and the technology is only described as the on-board platform required to stop the train (enforcement) should it be in danger of exceeding its authority.
The backbone of all modern PTC systems really came from two sources –
(1) Amtrak’s Advanced Civil Speed Enforcement System (ACES), which used transponders on trains in the North Eastern Corridor (NEC).
ACSES, though for the most part very successful, did not fulfill all three objectives of PTC. This technology does not provide for protection of road way workers. In the Northeast corridor, trains have absolute priority and work gangs have to look out for trains.
Also, for railroads looking to emulate an existing PTC system, ACSES may not be the best model. ACSES requires a significant amount of upfront investment (if the signaling equipment and infrastructure is not already modernized and in place) and thus should only be reserved for heavily trafficked lines to ensure a positive NPV investment.
(2) CSX Transportation initiated an overlay PTC system in 1999 called Communication Based Train Management System (CBTM).
CBTM was developed for dark territory, which was the most difficult in that it required a means to track and routes train for which there was no means to do so at that point. Designers developed that capability by coming up with the concept of monitoring switch position. Once CBTM knew that the train had moved through the switch (via GPS), then CBTM could be certain which track the train was on. This design point was extremely critical because none of the other systems to date could determine absolutely which track a train was on in parallel track territories, whether signaled or dark territory, due to the lack of accuracy in GPS at the time. Again, this design point is a critical consideration when designing PTC overlays for older railroads.
Older railroads, which use manual token block apparatuses or other equipment that traditional signal engineers will have trouble relating to, need to take the lessons learned from CBTM into consideration. As a model, CBTM is better suited for older railroads or new railroad construction looking to curb unnecessary spending.
Most recently, the FRA has invested in the North American Joint PTC project (NAJPTC). This was an effort to deliver moving block including PTC. The project was an unfortunate failure which delayed the FRA from mandating PTC (to the relief of the Class I Railroads).
As noted in the FRA’s Notice of Proposed Rulemaking in the Federal Register, Vol 74, No. 138:
“Although the system did not prove viable as then conceived, the project hastened the development of PTC technology that was subsequently employed in other projects.”
Or on FRA.gov:
Unanticipated technical issues primarily associated with communications bandwidth limitations resulted in relocating the North American Joint Positive Train Control Project (NAJPTC) to the Technology Transportation Center (TTC) test facility in Pueblo, CO.
Other systems that are being developed in order to meet Positive Train Control objectives are:
CAS – The Alaska Railroad is in the progress of a multiyear, phased statewide implementation of their communications-based train control system called the Collision Avoidance System (CAS). Originally planned for completion by late 2008/early 2009, technical complications have delayed the estimated completion until 2010.
ETMS – BNSF just received approval to deploy ETMS over 300 miles (482.8 km) of signaled track in Texas and Oklahoma. It is an overlay system that enforces movement authority and speed restrictions for equipped trains. ETMS is only integratable with current systems.
V-TMS – is a vital train management system, a BNSF upgrade from ETMS that is capable of supporting deviations from existing methods of operations. It has not yet been deployed and has just started testing phase.
OTC – Norfolk Southern is planning on testing a non-overlay version of ETMS in 2009. It uses computer aided dispatch along with PTC to try and realize business efficiencies. Capital expenditure to apply this integrated system, built from the ground up, is extensive.
TRAIN SENTINEL – a safety overlay on existing non-signaled methods of operations. The OCRS Train Sentinel System is an adaptation of a PTC system previously implemented on the Panama Canal Railroad (PCRR) between Balboa and Panama City in the Republic of Panama. Initial testing of the OCRS version of Train Sentinel began in late 2008. Technical issues were discovered during U.S. field testing of the system.
METRA ETMS – Chicago METRA is implementing a CAD independent PTC system based on the ETMS technology. Plans for the METRA ETMS system will include eventual procurement, installation, and integration with an electronic CAD system. Initial system field testing of the system began in January 2009,
The problems many of these programs face resulting in a slow pace of development and implementation are two fold – either the programs are not (1) using existing systems efficiently or they are (2) attempting to reinvent the wheel and investing in expensive infrastructure. All of the ETMS-based pursuits incorporate and are a direct derivative of the fundamental concepts developed for CBTM.
These difficulties originate from a general lack of vision in the industry regarding wireless technologies and spectrums.
Positive Train Control (PTC) Regulation
Existing communication and systems regulations – Title 49 Code of Federal Regulations (CFR), Part 236 – did not support microprocessor-based PTC-type system designs. Thus in 2005 FRA, using RSAC, developed “Performance Standards for Processor-Based Signal and Train Control Systems”. Sometimes called the “PTC rule,” these regulations grandfathered PTC systems, and a limited allowance was made for systems under development at the time. All other PTC systems were required to comply with the PTC rule.
Like the RSAC working group conclusions and reports, these regulations are performance focused, any specifications on technology are notably absent. The previous regulation prescribed precise requirements for electromechanical and fixed electrical and electronic circuitry. The old regulations were so prescriptive, there was little to no room for innovation or technological advancement. The new rules allow greater freedom and flexibility when applying technologies.
The fundamental regulatory precept of the new PTC rule is that the new system must be at least as safe as the system it is replacing or augmenting. – Grady C. Cothen, Jr. “MassTransit”, Dec 2007
At first PTC adoption was completely voluntary. Now, however, Congress has mandated all Class I railroads adopt PTC systems by 2015. The ironic point is that nearly a decade after the release of the blueprint defining PTC implementation, very few railroads have embraced PTC other than supporting federally backed test programs.
Prior to October 2008, PTC systems were being voluntarily installed by various carriers. However, the Rail Safety Improvement Act of 2008 (RSIA) (signed by the President on October 16, 2008, as Public Law 110-432) has mandated the widespread installation of PTC systems by December 2015. – FRA.gov
In 2006 the FRA commissioned a study to investigate the cost benefit analysis behind PTC. According to this study the benefits from implementing PTC mainly accrue as net societal benefits (ranging from $3.3 billion to $7.1 billion per year) but given the lower return for the railroad (estimated at 2.3% to 11.76% of the net societal benefits) and the much higher cost – PTC did not seem like an attractive investment.
Implementation costs by the railroads for just 100,000 miles of track would likely require upfront capital outlays by the railroads in excess of $2.3 billion. – Grady C. Cothen, Jr. “MassTransit”, Dec 2007
There have been other studies by PTC suppliers and the FRA that instead tout amazing business efficiencies provided by PTC implementation. The problem with these studies or any overly optimistic report on PTC is that they often confuse the source of the benefits. PTC – as a safety objective that can automatically stop a train should it become a hazard – only provides efficiencies in that it can prevent accidents. Other benefits like greater track optimization and more efficient use of resources are benefits of a central control center that is able to have real time two-way digital data communication with its trains. PTC requires wireless data communication but it is only one-way communication. Taking a PTC wireless infrastructure and using it to control trains in real time is a separate step.
To learn more about PTC, vital versus over, traditional vs. advanced traffic management, wireless deployment, and Strategic Railroading, request a PTC course or request a subscription to Mr. Lindsey’s Quarterly Journal – Full Spectrum.