Positive train control

Positive train control (PTC) is a system of functional requirements for monitoring and controlling train movements to provide increased safety.

The American Railway Engineering and Maintenance-of-Way Association (AREMA) describes Positive Train Control as having these primary characteristics:

• Train separation or collision avoidance
• Line speed enforcement
• Temporary speed restrictions
• Rail worker wayside safety.

Overview

The main concept in PTC (as defined for North American Class I freight railroads) is that the train receives information about its location and where it is allowed to safely travel, also known as movement authorities. Equipment on board the train then enforces this, preventing unsafe movement. PTC systems may work in either dark territory or signaled territory and may use GPS navigation to track train movements. The Federal Railroad Administration has listed among its goals, "To deploy the Nationwide Differential Global Positioning System (NDGPS) as a nationwide, uniform, and continuous positioning system, suitable for train control."

Various other benefits are sometimes associated with PTC such as increased fuel efficiency or locomotive diagnostics; however, these are benefits that can be achieved by having a wireless data system to transmit the information, whether it be for PTC or other applications.

In the 1990s, Union Pacific Railroad had a partnership project with General Electric to implement a similar system known as "Precision Train Control." This system would have involved moving block operation, which adjusts a "safe zone" around a train based on its speed and location. The similar abbreviations have sometimes caused confusion over the definition of the technology. GE later abandoned the Precision Train Control platform.

Conspiracy Theories

Certain members of the United States of America public firmly believe that this system is being pushed into use by the government so that they can continue to move weapons around North America with minimal fuel even in a severe state of civil unrest. These views are widely held by those working in the rail industry and backed by the Government's own documentation.

U.S. Rail Safety Improvement Act of 2008

Background

Starting in 1990 the National Transportation Safety Board (NTSB) counted PTC among its "Most Wanted List of Transportation Safety Improvements." At the time, the vast majority of rail lines relied on the human crew for complying with all safety rules, and a significant fraction of accidents were attributable to human error.

In September 2008, Congress considered a new rail safety law that sets a deadline of December 15, 2015, for implementation of positive train control (PTC) technology across most of the U.S. rail network. The bill, ushered through the legislative process by the Senate Commerce Committee and the House Transportation and Infrastructure Committee, was developed in response to the collision of a Metrolink passenger train and a Union Pacific freight train September 12, 2008, in California, which resulted in the deaths of 25 and injuries to more than 135 passengers.

As the bill neared final passage by Congress, the Association of American Railroads issued a statement in support of the bill. President George W. Bush signed the 315-page Rail Safety Improvement Act of 2008 into law on October 16, 2008.

Provisions of the law

Among its provisions, the law provides funding to help pay for the development of PTC technology, limits the number of hours freight rail crews can work each month, and requires the Department of Transportation to determine work hour limits for passenger train crews.

Implementation

To implement the law, the Federal Railroad Administration (FRA) published final regulations for PTC systems on January 15, 2010.

In December 2010 the U.S. Government Accountability Office (GAO) reported that Amtrak and the major Class I railroads have taken steps to install PTC systems under the law, but the work may not be complete by the 2015 deadline. The railroads and their suppliers are continuing to develop software to test various system components, which could delay equipment installation. GAO also suggests that publicly funded commuter railroads will have difficulty in obtaining funds to pay for their system components.

As of January 2012, the U.S. Congress is considering bills that would extend the 2015 deadline of the Rail Safety Improvements Act, possibly granted the railroads an extension of several years. The AAR has indicated its support of the extension; at least one commuter rail operation, the SCCRA's Metrolink, has indicated opposition to any extension.

The Federal Railroad Administration (FRA) proposed amendments to its published rules on December 11, 2012.

Controversy

There is some controversy as to whether PTC makes sense in the form mandated by Congress. Not only is the cost of nationwide PTC installation expected to be as much as US$10 billion, there are questions to the reliability and maturity of the technology for all forms of mainline freight trains and high density environments. The PTC requirement could also impose startup barriers to new passenger rail or freight services that would trigger millions of dollars in additional PTC costs. The unfunded mandate also ties the hands of the FRA to adopt a more nuanced or flexible approach to the adoption of PTC technology where it makes the most sense or where it is technically most feasible.

While the FRA Rail Safety Advisory Committee identified several thousand "PPAs" (PTC preventable accidents) on U.S. railroads over a 12-year period, cost analysis determined that the accumulated savings to be realized from all of the accidents was not sufficient to cover the cost of PTC across the Class I railroads. Therefore, PTC was not economically justified at that time. The FRA concurred with this cost assessment in its 2009 PTC rulemaking document.

The reason behind the lack of economic justification is that the majority of accidents are minor and FRA crash worthiness standards help mitigate the potential loss of life or release of hazardous chemicals. For example in the 20 years between 1987 and 2007 there were only two PTC preventable accidents with major loss of life (16 deaths in the Chase, Maryland wreck (1987) and 11 in the 1996 Silver Spring, Maryland train collision and in each case the causes of the accidents were addressed through changes to operating rules.

Basic operation

A typical PTC system involves two basic components:

• Speed display and control unit on the locomotive
• A method to dynamically inform the speed control unit of changing track or signal conditions.

Optionally, three additional components may exist:

• An on board navigation system and track profile database to enforce fixed speed limits
• Bi directional data link to inform signaling equipment of the train's presence
• Centralized systems to directly issue movement authorities to trains

PTC infrastructure

There are two main PTC implementation methods currently being developed. The first makes use of fixed signaling infrastructure such as coded track circuits and wireless transponders to communicate with the on board speed control unit. The other makes use of wireless data radios spread out along the line to transmit the dynamic information. The wireless implementation also allows for the train to transmit its location to the signaling system which could enable the use of moving or "virtual" blocks. The wireless implementation is generally cheaper in terms of equipment costs, but is considered to be much less reliable than using "harder" communications channels. For example the wireless ITCS system on Amtrak's Michigan Line was still not functioning reliably in 2007 after 13 years of development, while the fixed ACSES system has been in daily service on the Northeast Corridor since 2002 (see Amtrak, below).

The fixed infrastructure method is proving popular on high density passenger lines where pulse code cab signaling has already been installed. In some cases the lack of a reliance on wireless communications is being touted as a benefit. The wireless method has proven most successful on low density, unsignaled dark territory normally controlled via track warrants, where speeds are already low and interruptions in the wireless connection to the train do not tend to compromise safety or train operations.

Some systems, like Amtrak's ACSES, operate with a hybrid technology that uses wireless links to update temporary speed restrictions or pass certain signals, with neither of these systems being critical for train operations.

Locomotive speed control unit

The equipment on board the locomotive must continually calculate the trains' current speed relative to a speed target some distance away governed by a braking curve. If the train risks not being able to slow to the speed target given the braking curve the brakes are automatically applied and the train is immediately slowed. The speed targets are updated by information regarding fixed and dynamic speed limits determined by the track profile and signaling system.

Most current PTC implementations use the speed control unit to also store a database of track profiles attached to some sort of navigation system. The unit keeps track of the train's position along the rail line and automatically enforces any speed restrictions as well as the maximum authorized speed. Temporary speed restrictions can be updated before the train departs its terminal or via wireless data links. The track data can also be used to calculate braking curves based on the grade profile. The navigation system can use fixed track beacons or differential GPS stations combined with wheel rotation to accurately determine the train's location on the line accurately within a few feet.

Centralized control

While some PTC systems interface directly with the existing signal system, others may maintain a set of vital computer systems at a central location that can keep track of trains and issue movement authorities to them directly via a wireless data network. This is often considered to be a form of Communications Based Train Control and is not a necessary part of PTC.

Trackside device interface

The train may be able to detect the status of (and sometimes control) wayside devices, for example switch positions. This information is sent to the control center to further define the train's safe movements. Text messages and alarm conditions may also be automatically and manually exchanged between the train and the control center. Another capability would be to allow maintenance foremen the ability to automatically give trains permission through their work zones via a wireless device instead of verbal communications.

Technical limitations

Even where safety systems such as cab signaling have been present for many decades, the freight railroad industry has been reluctant to fit speed control devices due to the often heavy-handed nature of such devices having an adverse effect on otherwise safe train operation. The advanced processor-based speed control algorithms found in PTC systems claim to be able to properly regulate the speed of freight trains over 5,000 feet (1,500 m) in length and weighing over 10,000 short tons (9,100 t), but concerns remain about taking the final decision out of the hands of skilled locomotive engineers. Improper use of the air brake can lead to a train running away, derailment, or unexpected separation.

Furthermore, an overly conservative PTC system runs the risk of slowing trains below the level at which they had previously been safely operated by human engineers. Railway speeds are calculated with a safety factor such that slight excesses in speed will not result in an accident. If a PTC system applies its own safety margin then the end result will be an inefficient double safety factor. Moreover a PTC system might be unable to account for variations in weather conditions or train handling and might have to assume a worst case scenario, further decreasing performance. In its 2009 regulatory filing, the FRA stated that PTC was in fact likely to decrease the capacity of freight railroads on many main lines. The European LOCOPROL/LOCOLOC project had shown that EGNOS-enhanced satellite navigation alone was unable to meet the SIL4 safety integrity required for train signaling.

From a purely technical standpoint, PTC will not prevent certain low speed collisions caused by permissive block operation, accidents caused by trains "shoving" in reverse, derailments caused by track or train defect, grade crossing collisions, or collisions with previously derailed trains. Where PTC is installed in absence of track circuit blocks it will not detect broken rails, flooded tracks, or dangerous debris fouling the line.

Wireless PTC implementations

Radio spectrum availability

The wireless infrastructure planned for use by all US Class I freights, most small freight railroads, and many commuter railroads is based on the use of data radios operating in a single frequency-band near 220 MHz. A consortium created by two freight railroads called PTC 220 LLC has purchased significant spectrum around 220 MHz, from previous licensees, for use in deploying PTC. Some of this spectrum is in the form of nationwide licenses and some is not. The consortium plans to make this spectrum available for use by the US freights but has indicated as recently as 2011 that they are unsure if they have enough spectrum to meet their needs. Several commuter railroads have begun purchasing 220 MHz spectrum in their geographic areas but there is widespread concern that the acquisition of enough 220 MHz spectrum may be difficult to accomplish because of a lack of availability, difficulties in negotiating complex multi-party deals to gain enough adjacent spectrum, and because the financial cost of the acquisitions may make the task impossible for some state agencies.

Many of the railroads have requested that the FCC reallocate parts of the 220 MHz spectrum to them. They argue that they must have 220 MHz spectrum to be interoperable with each other. However, the FCC has stated that there is no reallocation forthcoming, that the railroads are not justified in requesting spectrum reallocation because they have not quantified how much spectrum they need, and that the railroads should seek spectrum in the secondary 220 MHz markets or in other bands.

Radio band choice

There are no regulatory or technical requirements that demand that 220 MHz be used to implement PTC (if a PTC implementation is to use wireless components at all). However if wireless data transmission is necessary, there are a few advantages to the 220 MHz spectrum, provided it can be acquired at a reasonable cost. The first reason to consider using 220 MHz spectrum is PTC interoperability for freights and for some, but not all, commuter rail operations. Freight operations in the US often include the sharing of railroad tracks where one railroad's rail vehicles operate as a guest on another railroad's host tracks. To implement PTC in such an environment is most easily achieved by using the same PTC equipment and this includes radios and associated radio spectrum.

When a commuter railroad operation must operate on a freight railroad territory, the commuter will most likely be required to install PTC equipment (including a radio) on their rail vehicle that is compliant with the freight railroad's PTC system, and this generally means the use of 220 MHz radios and spectrum. If the commuter uses the same PTC equipment, radios, and spectrum on their own property they will be able to use it when their vehicles travel onto a freight's territory. From a practical standpoint, if the commuter instead elects to use another type of PTC on their own property, they will need to install a second set of onboard equipment so they can operate PTC on their own property while also operating PTC on a freight's property. If a multi-band radio, such as the current generation software defined radios, is not available, then separate radios and separate antennas will be necessary.

However, if a small freight or commuter railroad does not operate on another railroad territory then there is no interoperability-based reason that obligates them to use 220 MHz spectrum to implement PTC. In addition, if a small freight or commuter railroad only operates on their own territory and hosts other guest railroads (freight or other passenger rail), there is still no interoperability-based reason the host is obligated to use 220 MHz spectrum to implement PTC. Such a railroad could implement PTC by freely picking any radio spectrum they choose, and requiring the guest railroads to either install compliant PTC equipment (including radios) onboard their trains or provide wayside equipment for their guest PTC implementation to be installed on the host railroad property. An interesting case that highlights some of these issues is the northeast corridor. Amtrak operates services on two commuter rail properties it does not own, MNR (owned by NY and Connecticut) and MBTA (owned by Massachusetts). In theory Amtrak could have found themselves installing their own PTC system on these host properties (about 15% of the corridor) or worse, found themselves in the ridiculous position of trying to install 3 different PTC systems on each Amtrak train to traverse the commuter properties. However this was not the case. Amtrak had a significant head-start over the commuter rail agencies on the corridor in implementing PTC. They spent a considerable amount of time in research and development and won early approvals for their ACSES system on the northeast corridor with the FRA. They chose first to use 900 MHz and then later moved to 220 MHz in part because of a perceived improvement in radio system performance, and in part because Amtrak was using 220 MHz in Michigan for their ITCS implementation. When the commuter agencies on the corridor looked at options for implementing PTC, many of them chose to take advantage of the advance work Amtrak had done and implement the ACSES solution using 220 MHz. Amtrak's early work paid off and meant that they would be traversing commuter properties that installed the same protocol at the same frequency, making them all interoperable. {Actually most of the NorthEast Corridor is owned and operated by AMTRAK, not the commuter properties including the tracks from Washington DC to New York Penn Station and the tracks from Philadelphia to Harrisburg PA. The State of Massachusetts owns the tracks from the Rhode Island state line to the New Hampshire state line, but AMTRAK 'operates' these lines. Only the line between New York City and New Haven Connecticut is actually owned and operated by a commuter line.]

One other perceived reason to consider 220 MHz for PTC may be PTC compatible radio equipment availability. Radio equipment specifically targeted toward PTC is only currently available from a limited number of vendors and they are focused only on 220 MHz. One radio vendor in particular is able to support the I-ETMS PTC protocol with a 220 MHz radio. The vendor, Meteorcomm, is owned by several of the Class I freights and some in the industry have indicated that using their 220 MHz radio, and associated equipment, will be done on a per site licensing basis. Recurring fees may be associated with this process too. There is further concern that the 'buy in' and licensing fees will be significant and this has led some to speculate that the owners of Meteorcomm (the freights) may have legal exposure to anti-trust violations . For many railroads, there is no other practical option to meet the federal mandate than to install PTC at 220 MHz using I-ETMS with the Meteorcomm radios. On the northeast corridor another radio vendor, GE MDS, is able to support the Amtrak ACSES protocol with a 220 MHz radio. It should be stressed that the number one concern among the freights regarding the PTC deadline is the availability of PTC equipment. Meteorcomm does not have a lot of experience producing radios in the quantities that will be required to meet the needs of PTC and there is concern that they will not be able to respond to the needs of the industry in the tight time frames associated with the 2015 deadline. The company will likely be outsourcing the manufacturing of the majority of the radios, probably with off-shore suppliers -- a challenging business model when the demand is so high and the timeline is so short. With an eye to anti-trust issues and ready radio availability, Meteorcomm radio designs have been second sourced to CalAmp radios. This all may mean that there is not enough 220 MHz PTC radio equipment available for all of the railroads that must implement PTC. In that case, 220 MHz may actually be a poor choice for implementing PTC. That remains to be seen.

To be sure, other bands besides 220 MHz will support PTC and in fact have been used to win approvals from the FRA for PTC. When Amtrak received their initial approval, Amtrak initially planned to use 900 MHz frequencies for ACSES. BNSF won their first FRA PTC approvals for an early version of ETMS using a multi-band radio which included 45 MHz frequencies, 160 MHz frequencies, 900 MHz frequencies and WiFi. A small freight or commuter that selects one or more of these bands, or another one such as 450 MHz, may find it easier to acquire spectrum. However, they will need to research spectrum issues, radio equipment, antennas and protocol compatibility issues to successfully deploy PTC.

Interoperability requirements

There is no single defined standard for "interoperable PTC systems". Several examples of interoperable systems illustrate this point. First, the UP and BNSF are interoperable across their systems. They are both implementing I-ETMS and will use different radio frequencies in different locations. In the second example, Amtrak is interoperable with Norfolk Southern in Michigan. Amtrak uses ITCS while Norfolk Southern uses I-ETMS. To interoperate, two 220 MHz radios are installed in each wayside location and they both interface with a common PTC system through an interface device (similar to a network gateway or protocol converter) at each wayside location. One radio talks to freight trains using I-ETMS and one radio talks to passenger trains using ITCS. In this case interoperability stops at the wayside and does not include the wireless segment out to the rail vehicles or the onboard systems. In the third example, similar to the first, Metrolink, the commuter rail agency in Los Angeles, is implementing I-ETMS and will use the same PTC equipment as both the UP and BNSF. Metrolink is procuring their own 220 MHz spectrum so that trains on Metrolink territory (commuter and freight) will use other channels than those used by the UP and BNSF. Interoperability is achieved by directing the onboard radio to change channels depending on location. For SEPTA, the commuter operation in and around Philadelphia, Ansaldo is implementing ACSES, the Amtrak northeast corridor PTC protocol. All ACSES PTC transactions will be handed to CSX at the SEPTA back office, and CSX will be responsible for deploying I-ETMS infrastructure that they will use to communicate with their freight trains. The SEPTA interoperability model is very similar to that of the public safety radio community wherein different radio systems that use different frequencies and protocols are cross-connected only in the back office to support system to system communications.

Multi-band solutions

For the major freight railroads and Amtrak the answer seems to be that one frequency band is sufficient. However, these rail operations measure on-time performance on a much more coarse scale than commuters do so their tolerance for delay is greater and has less impact on train schedules. In addition, the PTC implementations deployed by commuter operations will be running much closer to the performance envelope than that of either Amtrak or the freights. For commuters in particular there is therefore some concern that implementing PTC with a single frequency band may not be sufficient. The single frequency-band approach to supporting real-time train control has a history of being difficult to use for such applications. This difficulty is not unique to train control. Interference, both man-made and natural, can at times affect the operation of any wireless system that relies on one frequency band. When such wireless systems are employed for real-time control networks it is very difficult to ensure that network performance will not sometimes be impacted. CSX encountered this problem when it experienced propagation ducting problems in its 900 MHz Advanced Train Control System (ATCS) network in the 1990s. The ATCS protocol, which the Association of American Railroads (AAR) had recommended the FCC consider as PTC in 2000 (when AAR sought a nationwide 900 MHz "ribbon" license), can support train control operation at both 900 MHz and 160 MHz. However, to date the latter frequency band is only used for ATCS on a few subdivisions and shortlines. More recently, the industry had been moving toward a more robust multi-band radio solution for data applications such as PTC. In 2007, BNSF first won FRA approval for their original ETMS PTC system using a multi frequency-band radio. In addition, in mid-2008, an FRA sponsored effort by the AAR to develop a Higher Performance Data Radio (HPDR) for use at 160 MHz actually resulted in a contract being awarded to Meteorcomm for a 4-band radio to be used for voice and data. These more recent multi-band radio efforts were shelved in late 2008, after the Rail Safety Improvements Act became law, and the freights decided to pursue PTC using 220 MHz alone, in a single frequency-band configuration. Amtrak and most commuter operations quickly followed suit, selecting 220 MHz.

Suitability of wireless PTC for commuter rail

Soon after the Rail Safety Improvements Act was passed, many commuter railroads chose not to develop their own PTC protocol and instead decided to save time and money by using a protocol developed for either freight or long haul passenger (Amtrak) operations. Deploying such a protocol for urban commuter operation, where it will be necessary to support numerous, small, fast-moving trains, will be a challenge. It remains to be seen whether the performance envelope of PTC protocols developed and optimized for less numerous, slower and/or larger trains can support a more complex operational scenario, such as that of a commuter rail operation, without impacting on-time performance. Detailed and exhaustive protocol simulation testing can ease the risk of problems, however, there are too many variables, especially when the wireless component is considered, to guarantee before hand that under certain worst-case operational profiles in certain locations, train operations will not be impacted. In fact, during system acceptance testing, such worst-case operational profiles may not even be tested because of the effort involved. One need only consider what it would take to identify the PTC protocol train capacity limitations at each interlocking of a large commuter rail operation when a train is broken down at the interlocking and 10-20 other trains are within communications range of a single wayside location. Such a what-if scenario may be tested at a few interlockings but not at the 30 or more interlockings on a large commuter property.

Open standards

A large group of industry experts from the federal government, manufacturers, railroads, and consultants are participating in a study group sponsored by the IEEE 802.15 working group, to look at using lessons learned in protocol development in the IEEE 802 suite to propose a comprehensive solution to the wireless component of PTC. While this effort may not significantly change the current United States PTC efforts already underway, an open standard could possibly provide a way forward for all of the railroads to eventually deploy a more interoperable, robust, reliable, future-proof, and scalable solution for the wireless component of PTC.

Upgrade costs

The railroad industry, like the process control industry and the power utility industry, has always demanded that the return on investment for large capital investments associated with infrastructure improvements be fully realized before the asset is decommissioned and replaced. This paradigm will be applied to PTC as well. It is highly unlikely that there will be any fork-lift upgrades to initial PTC deployments within even the first 10 years. However, the calculation for return on investment is not a simple one and some railroads may determine, for instance after five years, that an upgrade of certain components of PTC may be justified. An example could be the radio component of PTC. If an open standard creates a less expensive radio product that is backwards compatible to existing systems and that perhaps improves PTC system performance and also includes improvements that save on operational costs, then a railroad would be prudent to consider a plan for replacing their PTC radios.

Areas where in use

Various types of Collision Avoidance Systems have been implemented across the globe. Most if not all of these operate differently than PTC in North America, as described above.

KLUB-U

The Russian KLUB-U train control system is similar to Positive Train Control for its integration of GLONASS satellite-based train location, electronic track map distribution and digital radio (GSM-R or TETRA) usage for track-releases as well as remote initiation of train stops. GE Rail has cooperated with the Russian VNIIAS manufacturer on this system. The KLUB-U system is used widely in the Russian Federation including high-speed rail for the Sapsan.

ERTMS (Europe)

Some form of Automatic Train Protection (ATP) has been operational in Europe for over one hundred years like the Automatic Train Control (ATC) system. In 1956 Automatic Warning System (AWS) was introduced in the United Kingdom whilst today the rail network is fitted with Train Protection & Warning System (TPWS). Some of the first systems implementing full ATP functionality were designed for the dedicated high speed rail lines such as the French TVM, German LZB and Italian SCMT. Continuing with the success of ATP systems, Europe is today transitioning to one ATP standard, the European Rail Traffic Management System (ERTMS), which is well evolved as a result of many years of European ATP experience and development. Although a major driver for the implementation of ERTMS is European interoperability, many non-European countries such as Australia, China, India, Saudi Arabia, South Korea and Libya are introducing ERTMS as the ATP system of choice.

The two main components of ERTMS are the European Train Control System (ETCS), a standard for in-cab train control, and GSM-R, the GSM mobile communications standard for railway operations. The equipment can further be divided between on-board and infrastructure equipment. There is also a low-cost variant ERTMS Regional developed by Banverket and the UIC. The ITARUS-ATC is a hybrid of the Russian KLUB-U in-cab signaling and the Italian ERTMS Level 2 GSM-R block control.

The system authority for ERTMS is the European Railway Agency.

Alaska Railroad (ARRC)

Wabtec is working with the ARRC to develop a collision-avoidance, Vital PTC system, for use on their locomotives. The system is designed to prevent train-to-train collisions, enforce speed limits, and protect roadway workers and equipment. Wabtec's Electronic Train Management System, (ETMS) is also designed to work with the Wabtec TMDS dispatching system to provide train control and dispatching operations from Anchorage.

Data between locomotive and dispatcher is transmitted over a digital radio system provided by Meteor Communications Corp (Meteorcomm). An onboard computer alerts workers to approaching restrictions and to stop the train if needed.

Amtrak

Alstom's and PHW's Advanced Civil Speed Enforcement System (ACSES) system is installed on Amtrak’s Northeast Corridor between Washington and Boston. ACSES enhances the cab signaling systems provided by PHW Inc. It uses passive transponders to enforce permanent civil speed restrictions. The system is designed to prevent train-to-train collisions (PTS), protection against overspeed and protect work crews with temporary speed restrictions.

GE Transportation Systems' Incremental Train Control System (ITCS) is installed on Amtrak's Michigan line, allowing trains to travel at 110 mph (180 km/h).

BNSF

Wabtec's Electronic Train Management System, (ETMS) is installed on a segment of the BNSF Railway. It is an overlay technology that augments existing train control methods. ETMS uses GPS for positioning and a digital radio system to monitor train location and speed. It is designed to prevent certain types of accidents, including train collisions. The system includes an in-cab display screen that warns of a problem and then automatically stops the train if appropriate action is not taken.

CSX

CSX Transportation is developing a Communications-Based Train Management (CBTM) system to improve the safety of its rail operations. CBTM is the predecessor to ETMS.

New Jersey Transit

Ansaldo STS USA Inc's Advanced Speed Enforcement System (ASES) is being installed on New Jersey Transit commuter lines. It is coordinated with Alstom's ACSES so that trains can operate on the Northeast Corridor.

Union Pacific (UP)

A team of Lockheed Martin, Wabtec, and Ansaldo STS USA Inc installed a PTC system on a 120-mile segment of UP track between Chicago and St. Louis. An Indian IT Major software company Mahindra Satyam is also one of the strategic IT partners in development of PTC systems.

Canadian Pacific (CP)

A team of Wabtec and an Indian IT major Infosys is in the process of implementing PTC interfaces and equipments.

Kansas City Southern (KCS)

Wabtec's Electronic Train Management System, (ETMS) will provide PTC solutions in conjunction with Wabtec's Train Management and Dispatch System (TMDS), which has served as KCS's dispatch solution since 2007, for all U.S. based rail operations along the KCS line.

See also

• Train protection system

References

• NTSB Symposium on Positive Train Control Systems (2005). Agenda and Presentations.
• Vantuono, William (2004). "BNSF starts positive train control trial - North American Viewpoint". International Railway Journal. Simmons-Boardman. ISSN 0744-5326. {{cite journal}}: Unknown parameter |month= ignored (help)

External links

• NTSB Safety Recommendation regarding 1996 Silver Spring accident (August 28, 1997)
• BNSF promotional video on ETMS
• "Communications-Based Signaling (CBS) – Vital PTC", Paper presented at AREMA C&S Technical Conference May 22, 2007