View source for Positive train control

{{Short description|Type of train protection system}}
{{Use mdy dates|date=November 2023}}
[[File:PTC, Metrolink 891, ARTIC, night.jpg|thumb|A [[Metrolink (California)|Metrolink]] locomotive decal on an [[MPI MPXpress#MP36PH-3C|MP36PH-3C]] stating that it is equipped with positive train control technology]]

'''Positive train control''' ('''PTC''') is a family of [[automatic train protection]] systems deployed in the United States.<ref name="PTC_DOT_Top">{{cite web |title=Positive Train Control |url=https://www.fra.dot.gov/ptc |publisher=U.S. Federal Railroad Administration (FRA) |location=Washington, D.C. |access-date=12 February 2018}}</ref> Most of the United States' [[national rail network]] mileage has a form of PTC. These systems are generally designed to check that trains are moving safely and to stop them when they are not.<ref name="PTC_DOT">{{cite web |title=PTC System Information |url=https://www.fra.dot.gov/Page/P0358 |publisher=FRA |access-date=12 February 2018}}</ref>

Positive train control restricts the train movement to an explicit allowance; movement is halted upon invalidation. A train operating under PTC receives a ''movement authority'' containing information about its location and where it is allowed to safely travel. PTC was installed and operational on 100% of the statutory-required trackage by December 29, 2020.<ref>{{cite web |title=Steps Toward Full PTC System Implementation of Mandated Positive Train Control Systems; Based on Railroads' Self-reported Progress as of December 29, 2020 |url=https://explore.dot.gov/t/FRA/views/PTCImplementationStatusReport/Overview |publisher=FRA |date=2020-12-29}}</ref>

== Overview ==
The [[American Railway Engineering and Maintenance-of-Way Association]] (AREMA) describes positive train control systems as having these primary functions:
* Train separation or collision avoidance
* Line speed enforcement
* Temporary speed restriction enforcement
* Rail worker wayside safety
* Blind spot monitoring.<ref>{{cite web |title=Meeting the Communication Challenges for Positive Train Control |url=http://www.arema.org/files/library/2009_Conference_Proceedings/Meeting_the_Communication_Challenges_for_Positive_Train_Control.pdf |date=2009 |publisher=American Railway Engineering and Maintenance-of-Way Association (AREMA) |location=Lanham, MD |id=AREMA 2009 Annual Conference & Exposition, Chicago, IL |archive-url=https://web.archive.org/web/20110809150021/http://www.arema.org/files/library/2009_Conference_Proceedings/Meeting_the_Communication_Challenges_for_Positive_Train_Control.pdf |archive-date=2011-08-09}}</ref>

== History ==
===Background===
In the late 1980s, interest in train protection solutions heightened after a period of stagnant investment and decline following [[World War II]]. Starting in 1990, the United States [[National Transportation Safety Board]] (<abbr>NTSB</abbr>) counted <abbr>PTC</abbr> (then known as positive train separation) among its "Most Wanted List of Transportation Safety Improvements."<ref name="ntsb_changes">National Transportation Safety Board (<abbr>NTSB</abbr>), Washington, <abbr>DC</abbr> (2010). [https://www.ntsb.gov/Recs/mostwanted/modifications-1990-on.pdf "Modifications to <abbr>NTSB</abbr> Most Wanted List; List of Transportation Safety Improvements after September 1990."] {{webarchive |url=https://web.archive.org/web/20080916130726/https://www.ntsb.gov/Recs/mostwanted/modifications-1990-on.pdf |date=16 September 2008 }}</ref><ref><abbr>NTSB</abbr> (2010). [https://www.ntsb.gov/Recs/mostwanted/index.htm "<abbr>NTSB</abbr> Most Wanted List of Transportation Safety Improvements – Implement Positive Train Control Systems."] {{webarchive |url=https://web.archive.org/web/20021007103657/https://www.ntsb.gov/Recs/mostwanted/index.htm |date=7 October 2002 }}</ref><ref>{{Cite web |url=https://www.ntsb.gov/news/events/Pages/2013_Train-Control_FRM.aspx |title=Positive Train Control Systems |date=27 February 2013 |publisher=NTSB |access-date=30 May 2016 |quote=positive train separation (which was renamed positive train control in 2001) was first placed on the Safety Board's Most Wanted List }}</ref> At the time, the vast majority of rail lines in US relied upon crew members to comply with all safety rules, and a significant fraction of accidents were attributable to human error, as evidenced in several years of official reports from the [[Federal Railroad Administration]] (FRA).<ref>{{cite web |title=Office of Safety Analysis |url=https://safetydata.fra.dot.gov/OfficeofSafety/ |date=2023-08-11 |publisher=FRA}}</ref>

In September 2008, [[United States Congress|Congress]] considered a new law that set a deadline of December 15, 2015 for implementation of <abbr>PTC</abbr> technology across most of the <abbr>US</abbr> rail network. The bill, ushered through the legislative process by the [[United States Senate Committee on Commerce, Science, and Transportation|Senate Commerce Committee]] and the [[United States House Committee on Transportation and Infrastructure|House Transportation and Infrastructure Committee]], was drafted in response to the [[2008 Chatsworth train collision|collision]] of a [[Metrolink (California)|Metrolink]] [[passenger train]] and a [[Union Pacific Railroad]] [[freight train]] at September 12, 2008, in [[Los Angeles]], 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]] (<abbr>AAR</abbr>) issued a statement in support of the bill.<ref>Association of American Railroads, Washington, <abbr>DC</abbr> (2008-09-24). [http://www.aar.org/NewsAndEvents/Press-Releases/2008/09/092408_Statement_on_railsafety_bill.aspx "Statement by Edward R. Hamberger, President and <abbr>CEO</abbr> Association of American Railroads on Passage of the Comprehensive Rail Safety Bill."] Press release.</ref> President [[George W. Bush]] signed the 315-page [[Rail Safety Improvement Act of 2008]] into law on October 16, 2008.<ref>U.S. Rail Safety Improvement Act of 2008, {{USPL|110|432}}, {{USStat|122|4848}}, {{USC|49|20101}}. Approved 16 October 2008.</ref>

===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 [[United States Department of Transportation|Department of Transportation]] to determine work hour limits for passenger train crews.

===Implementation===
{{Update|section|date=June 2021}}
To implement the law, the FRA published initial regulations for PTC systems on January 15, 2010.<ref>FRA (15 January 2010). "Positive Train Control Systems; Final rule." ''Federal Register.'' {{USFR|75|2598}}</ref> The agency published amended regulations on August 22, 2014.<ref>FRA (2014-08-22). "Positive Train Control Systems (RRR)." {{USFR|79|49693}}</ref>

In December 2010, the [[Government Accountability Office]] (GAO) reported that [[Amtrak]] and the major {{nowrap|Class I}} railroads had taken steps to install PTC systems under the law, but [[commuter rail]] operators were not on track for the 2015 deadline.<ref name="GAO 2010">{{cite report |title=Federal Railroad Administration Should Report on Risks to the Successful Implementation of Mandated Safety Technology |date=December 2010 |url=http://www.gao.gov/new.items/d11133.pdf |publisher=U.S. Government Accountability Office |location=Washington, DC |id=GAO-11-133}}</ref> {{As of|2015|June}}, only seven commuter systems (29 percent of those represented by APTA) were expecting to make the deadline. Several factors have delayed implementation, including the need to obtain funding (which was not provided by Congress); the time it has taken to design, test, make interoperable, and manufacture the technology; and the need to obtain radio spectrum along the entire rail network, which involves FCC permission and in some cases negotiating with an existing owner for purchase or lease.<ref name="npr_2015">{{cite news |url=https://www.npr.org/2015/06/03/411464396/most-commuter-rails-wont-meet-deadline-for-mandated-safety-systems |title=Most Commuter Rails Won't Meet Deadline For Mandated Safety Systems |work=NPR |date=3 June 2015 |access-date=4 February 2016}}</ref>

The [[Metrolink (California)|Metrolink]] [[commuter rail]] system in [[Southern California]] is planning to be the first US passenger carrier to install the technology on its entire system.  After some delays,<ref>Weikel, Dan (24 January 2014) [http://www.latimes.com/local/la-me-0124-metrolink-control-system-20140124,0,3514855.story "Metrolink to replace contractor to avoid train control project delays"] ''Los Angeles Times''</ref> demonstration PTC in revenue service began in February 2014; the system is expected to be completed in late summer 2015.<ref>{{cite web|url=http://www.metrolinktrains.com/agency/page/title/ptc|title=An Introduction to Positive Train Control |website=Metrolink |publisher=Southern California Regional Rail Authority |location=Los Angeles, CA |access-date=3 June 2015}}</ref>

In the [[Chicago metropolitan area]], the [[Metra]] system expected it will not be fully compliant with the PTC mandate until 2019.<ref name="npr_2015" />

In October 2015, Congress has passed a bill extending the compliance deadline by three years, to December 31, 2018. President [[Barack Obama]] signed the bill on October 29, 2015.<ref>{{cite magazine |last=Morris |first=David Z. |title=All aboard after Congress votes to avert threatened train shutdown |url=https://fortune.com/2015/10/29/legislators-extend-deadline-smart-trains/ |date=29 October 2015 |magazine=Fortune}}</ref><ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |title=Obama signs short-term transportation bill |url=https://www.washingtonpost.com/politics/obama-signs-short-term-transportation-bill/2015/10/29/f2c84e86-7e7d-11e5-bfb6-65300a5ff562_story.html |archive-url=https://web.archive.org/web/20190308081512/https://www.washingtonpost.com/politics/obama-signs-short-term-transportation-bill/2015/10/29/f2c84e86-7e7d-11e5-bfb6-65300a5ff562_story.html |url-status=dead |archive-date=8 March 2019 |newspaper=Washington Post |date=29 October 2015}}</ref> Only four railroads met the December 2018 deadline; the other 37 got extensions to December 2020, which was allowed under the law for railroads that demonstrated implementation progress.<ref>{{cite news |last=Wallace |first=Gregory |title=Most US rail systems miss safety deadline |url=https://www.cnn.com/2019/01/01/politics/positive-train-control-deadline/ |date=1 January 2019 |work=CNN}}</ref> On December 29, 2020, it was reported that the safeguards had been installed on all required railroads, two days ahead of the deadline.<ref>{{cite news|url = https://www.washingtonpost.com/local/trafficandcommuting/positive-train-control-/2020/12/29/5e90f978-4a0d-11eb-839a-cf4ba7b7c48c_story.html|title = Automatic brake system installed on U.S. railroads ahead of federal deadline|last = George|first = Justin|date = 29 December 2020|accessdate = 10 September 2021|newspaper = [[The Washington Post]]}}</ref>

===Criticism===
{{Update|section|reason=at least nine US train accidents with fatalities since 2012. See [[List of American railroad accidents#2010s]]|date=June 2021}}
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 {{nowrap|US$6–22&nbsp;billion}}, most all of it borne by U.S. freight railroads,<ref name="Atlantic">{{cite news |title=The Billion-Dollar Technology That May or May Not Prevent the Next Big Train Crash |author=Eric Jaffe |url=http://www.theatlanticcities.com/jobs-and-economy/2013/07/billion-dollar-technology-may-or-may-not-prevent-next-big-train-crash/6378/ |newspaper= The Atlantic |date=31 July 2013 |access-date=28 August 2013}}</ref> there are questions as to the reliability and maturity of the technology for all forms of mainline freight trains and high density environments.<ref>FRA (21 July 2009). "Positive Train Control Systems; Notice of proposed rulemaking." ''Federal Register.'' {{USFR|74|35950}}</ref> 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.<ref name="Atlantic" />

While the FRA Rail Safety Advisory Committee identified several thousand "PPAs" (PTC preventable accidents) on US 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 {{nowrap|Class I}} railroads. Therefore, PTC was not economically justified at that time.<ref>Resor, Randolph R. (2004). [http://transportation.northwestern.edu/docs/2004/2004.04.13.Resor.Presentation.pdf "The Business Benefits of PTC."] {{Webarchive|url=https://web.archive.org/web/20090920094555/http://transportation.northwestern.edu/docs/2004/2004.04.13.Resor.Presentation.pdf |date=20 September 2009 }}{doubtful} Northwestern University Transportation Center, Evanston, IL.</ref> 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 in the United States (16 deaths in the [[1987 Maryland train collision|Chase, Maryland wreck]] (1987) and 11 in the [[1996 Maryland train collision|Silver Spring, Maryland wreck]] (1996)), and in each case, the causes of the accidents were addressed through changes to operating rules.{{citation needed|date=December 2020}}

The cost of implementing PTC on up to 25 commuter rail services in the United States has been estimated at over $2&nbsp;billion and because of these costs, several services are having to cancel or reduce repairs, capital improvements, and service.{{citation needed|date=December 2020}} Other services simply do not have the funds available for PTC and have deferred action assuming some change from Congress.{{citation needed|date=December 2020}} Railroads that operate lines equipped with [[cab signalling]] and existing [[Automatic Train Control]] systems have argued that their proven track record of safety, which goes back decades, is being discounted because ATC is not as aggressive as PTC in all cases.<ref name="WSJValueOfLife">{{cite news|last=Mann|first=Ted|url=https://www.wsj.com/articles/SB10001424127887323582904578485061024790402 |newspaper=Wall Street Journal |title=Rail Safety and the Value of a Life |date=17 June 2013}}</ref>

=== PTC Preventable Crashes ===
The number of PTC preventable crashes has increased in recent years. In 2013, a [[December 2013 Spuyten Duyvil derailment|Metro-North crash]] in the Bronx killed four people and injured 61. This crash was caused by excess speed, something PTC is capable of guarding against. In 2015, an Amtrak crash Philadelphia killed eight and injured 185.<ref>{{Cite news |last=III |first=Ashley Halsey |date=2019-04-18 |title=Fifty years later, a lifesaving technology that could have saved over 300 lives inches toward completion |url=https://www.washingtonpost.com/local/trafficandcommuting/fifty-years-later-a-lifesaving-technology-could-have-saved-over-300-lives-inches-toward-completion/2019/04/17/43d3f12e-4f39-11e9-a3f7-78b7525a8d5f_story.html |access-date=2024-01-06 |work=Washington Post |language=en-US |issn=0190-8286}}</ref> In this crash the train accelerated beyond safe speed due to actions of a distracted engineer of the [[Amtrak]] train. According to the NTSB, this crash could have been prevented by a PTC system that would have enforced the 50 mile per hour speed limit and prevented the overspeed and subsequent crash of the train.<ref name="NTSB 2016">{{Cite web |last=National Transportation Safety Board |date=May 27, 2016 |title=Derailment of Amtrak Passenger Train 188 Philadelphia, Pennsylvania May 12, 2015 |url=https://www.ntsb.gov/investigations/AccidentReports/Reports/RAR1602.pdf |access-date=January 6, 2024 |website=National Transportation Safety Board}}</ref> In 2017, another [[2017 Washington train derailment|Amtrak crash]] near [[DuPont, Washington|Dupont, Washington]] killed three and injured 62. The engineer mistook the trains current location, and therefore was not following proper restrictions for the length of track the train was currently in, failing to notice signage that should have indicated the speed restrictions in the area the train was currently in. The NTSB learned safety improvements had recently been made to the track, except for the PTC section of the improvements. It was ultimately concluded that the engineer's error in train location lead to the crash. [[Sound Transit]], the owner of the section of railway where the accident occurred, was in the process of installing PTC, but it was not operational at the time of the accident.<ref name="NTSB 2016"/> In 2018, another [[Cayce, South Carolina train collision|crash]] occurred when Amtrak train rammed a stationary freight train in [[Cayce, South Carolina|Cayce, S.C]]., killed two crew members and injured 116 others. Chairman of the NTSB, [[Robert L. Sumwalt (U.S. government official)|Robert Sumwalt]], stated that "an operational PTC is designed to prevent this type of incident."<ref>{{Cite web |title=NTSB: Crash-preventing safety system was being installed when Amtrak, CSX trains collided |url=https://www.jacksonville.com/story/news/accident/2018/02/05/ntsb-crash-preventing-safety-system-was-being-installed/15311565007/ |access-date=2024-01-06 |website=The Florida Times-Union |language=en-US}}</ref>

==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.<ref name="Olson">Olson, R.T., Jr. (2007). [http://www.arema.org/eseries/scriptcontent/custom/e_arema/library/2007_Conference_Proceedings/Incremental_Train_Control_System_2007.pdf "Incremental Train Control System On Amtrak's Michigan Line."] Presentation at AREMA Annual Conference, 9–12 September 2007, Chicago, IL.</ref>
Optionally, three additional components may exist:
* An on-board navigation system and track profile database to enforce fixed speed limits
* A 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 [[Cab signaling|coded track circuits]] and [[Balise|wireless transponders]] to communicate with the onboard 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 [[Block signaling#Moving block|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. {{As of|2007}}, for example, the wireless ITCS system on Amtrak's Michigan Line was still not functioning reliably after 13 years of development,<ref name="Olson" /> while the fixed ACSES system has been in daily service on the [[Northeast Corridor]] since 2002 (''see'' [[#Amtrak|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.<ref name="Vogler">Vogler, John (2005). [http://www3.ntsb.gov/events/symp_ptc/presentations/05_Vogler.pdf Symposium on Positive Train Control Systems] {{webarchive|url=https://web.archive.org/web/20110604140641/https://www.ntsb.gov/Events/symp_ptc/presentations/05_Vogler.pdf |date=4 June 2011 }}</ref> The wireless method has proven most successful on low density, unsignaled [[dark territory]] normally controlled via [[track warrant]]s, 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 train's 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 also use the speed control unit to 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 (railroad)|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 within a few feet.

===Centralized control===
While some PTC systems interface directly with the existing signal system, others may maintain a set of [[Safety critical|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 [[railway switch|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 allow the employee-in-charge (EIC) to give trains permission to pass 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 because the often heavy-handed nature of such devices can have 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 {{convert|5000|ft|m}} in length and weighing over {{convert|10000|ST|t}}, but concerns remain about taking the final decision out of the hands of skilled [[railroad engineer]]s. Improper use of the [[Railway air brake#Limitations|air brake]] can lead to a train running away, [[derailment]] or to an unexpected separation.{{Citation needed|date=September 2009}}

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 [[Murphy's law|worst-case scenario]], further decreasing performance.<ref>Amtrak Employee Timetable #3, Northeast Region, Jan, 18th, 2010, p.351</ref> 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.<ref>{{cite web|last=Roskind|first=Frank D|title=Positive Train Control Systems Economic Analysis|url=http://www.fra.dot.gov/downloads/PTC_%20RIA_%20Final.pdf|publisher=Federal Railroad Administration|access-date=1 December 2011|archive-url=https://web.archive.org/web/20090724184036/http://www.fra.dot.gov/downloads/PTC_%20RIA_%20Final.pdf|archive-date=24 July 2009|url-status=dead}}</ref> The European [[LOCOPROL|LOCOPROL/LOCOLOC]] project had shown that [[EGNOS]]-enhanced satellite navigation alone was unable to meet the [[Safety Integrity Level|SIL4 safety integrity]] required for train signaling.<ref name="locoloc">Rousseau, Michel, et al. (2004).[http://esamultimedia.esa.int/docs/NavigationProjects/Locoloc_final_presentn_dec04%20.pdf "LOCOLOC Project: Final Presentation."] Noordwijk, December 2004.</ref>

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

==Wireless implementations==
{{essay-like|section|date=February 2022}}

===Radio spectrum availability===
The wireless infrastructure planned for use by all US {{nowrap|Class I}} freights, most small freight railroads, and many commuter railroads is based on data radios operating in a single frequency band near {{nowrap|220 MHz}}. A consortium created by two freight railroads called PTC 220 LLC has purchased significant spectrum around {{nowrap|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 {{nowrap|220 MHz}} spectrum in their geographic areas, but there is widespread concern that the acquisition of enough {{nowrap|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. However, research suggests that dynamic spectrum allocation can solve the spectrum allocation problem at 220&nbsp;MHz bandwidth.<ref name="wireless_bw">{{cite journal |last1=Bandara |first1=Damindra|last2=Abadie|first2=Andre|last3=Melaragno|first3=Tony|last4=Wijesekara|first4=Duminda |date=2014 |title=Providing Wireless Bandwidth for High-speed Rail Operations |journal=Procedia Technology |volume=16 |pages= 186–191  |doi=10.1016/j.protcy.2014.10.082 |doi-access=free}}</ref>
<ref name="cell planning">{{cite book |last1=Bandara |first1=Damindra|last2=Abadie|first2=Andre|last3=Wijesekara|first3=Duminda |date=2015 |title= 2015 Joint Rail Conference|doi=10.1115/JRC2015-5805 |chapter=Cell Planning for High-Speed Train Operations in USA|isbn=978-0-7918-5645-1}}</ref>

Many of the railroads have requested that the FCC reallocate parts of the {{nowrap|220 MHz}} spectrum to them. They argue that they must have {{nowrap|220 MHz}} spectrum to be interoperable with each other. 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 {{nowrap|220 MHz}} markets or in other bands.<ref name="FCC Public Comments">{{cite news|last=2012 PTC World Congress, Arsenault|first=Richard|title=Chief Council, FCC Mobility Division|date=1 March 2012}}</ref>

===Radio band===
There are no regulatory or technical requirements that demand that {{nowrap|220 MHz}} be used to implement PTC (if a PTC implementation is to use wireless components at all). If wireless data transmission is necessary, there are a few advantages to the {{nowrap|220 MHz}} spectrum, provided it can be acquired at a reasonable cost. The first reason to consider using {{nowrap|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. Implementing PTC in such an environment is most easily achieved by using the same PTC equipment, and this includes radios and the 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 {{nowrap|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 radio]]s) is not available, then separate radios and separate antennas will be necessary. With the complexity of track geometries, PTC requires a variable amount of the spectrum in a time critical manner. One way to achieve this is to extend the PTC software-defined radios, such that it has the intelligence to allocate the spectrum dynamically. Adding the intelligence to the radio also helps to improve the security of the PTC communication medium.<ref name="cr">{{cite book |last1=Bandara |first1=Damindra|last2=Melaragno|first2=Tony|last3=Wijesekara|first3=Duminda|last4=Costa|first4=Paulo |date=2016 |title= 2016 Joint Rail Conference|doi=10.1115/JRC2016-5784 |chapter=Multi-Tiered Cognitive Radio Network for Positive Train Control Operations|isbn=978-0-7918-4967-5}}</ref>

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 {{nowrap|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 obliged to use {{nowrap|220 MHz}} spectrum to implement PTC. Such a railroad could implement PTC by freely picking any radio spectrum and requiring the guest railroads to either install compliant PTC equipment (including radios) on board 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: [[Metro-North Railroad]] (owned by New York and Connecticut) and [[Massachusetts Bay Transportation Authority]] (MBTA) (owned by Massachusetts). In theory, Amtrak could have found themselves installing their own PTC system on these host properties (about 15 percent of the corridor), or worse, found themselves in the ridiculous position of trying to install three different PTC systems on each Amtrak train to traverse the commuter properties. 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 {{nowrap|900 MHz}} and then later moved to {{nowrap|220 MHz}}, in part because of a perceived improvement in radio-system performance and in part because Amtrak was using {{nowrap|220 MHz}} in Michigan for their ITCS implementation.<ref name="Public Comments">{{cite news|last=2012 PTC World Congress, Holtz|first=Keith|title=Deputy Chief Engineer, Communications and Signals|date=29 February 2012}}</ref>  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 {{nowrap|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, D.C.]] to [[Pennsylvania Station (New York City)|New York Penn Station]] and the tracks from Philadelphia to [[Harrisburg, Pennsylvania]]. 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 {{nowrap|220 MHz}} for PTC may be PTC-compatible radio equipment availability. Radio equipment specifically targeted toward PTC is currently only available from a limited number of vendors, and they are focused only on {{nowrap|220 MHz}}. One radio vendor in particular, Meteorcomm LLC, is able to support the I-ETMS PTC protocol with a {{nowrap|220 MHz}} radio. Meteorcomm is jointly owned by several of the {{nowrap|Class I}} freights, and some in the industry have indicated that using their {{nowrap|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. {{citation needed|date=January 2013}} For many railroads, there is no other practical option to meet the federal mandate than to install PTC at {{nowrap|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 {{nowrap|220 MHz}} radio. It should be stressed that the main concern among the freights regarding the PTC deadline is the availability of PTC equipment.<ref>{{cite news|title=2012 PTC World Congress Survey|date=29 February 2012}}</ref>  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 {{nowrap|220 MHz}} PTC radio equipment available for all of the railroads that must implement PTC. {{citation needed|date=January 2013}}

There are also issues with the use of these frequencies outside the US; in Canada, {{nowrap|220 MHz}} remains part of the [[amateur radio|radioamateur]] [[1.25-meter band|1.25-metre band]].<ref name="rac">{{cite web|url=https://www.rac.ca/en/rac/services/bandplans/220/|title=220 MHz Band Plan|author=Radio Amateurs of Canada|publisher=rac.ca|access-date=10 June 2014|archive-url=https://web.archive.org/web/20140307163709/https://www.rac.ca/en/rac/services/bandplans/220/|archive-date=7 March 2014|url-status=dead}}</ref><ref name="rac2">{{cite web|url=https://www.rac.ca/en/amateur-radio/operating-technical/vhf-uhf-microwave/220mhz/|title=220 MHz (1.25m) Information|author=Radio Amateurs of Canada|publisher=rac.ca|access-date=10 June 2014|archive-url=https://web.archive.org/web/20140307163358/https://www.rac.ca/en/amateur-radio/operating-technical/vhf-uhf-microwave/220mhz/|archive-date=7 March 2014|url-status=dead}}</ref>

Other bands besides {{nowrap|220 MHz}} will support PTC, and have been used to win approvals from the FRA for PTC. When Amtrak received their initial approval, they planned to use {{nowrap|900 MHz}} frequencies for ACSES. [[BNSF Railway]] won its first PTC approvals from the FRA for an early version of ETMS using a multi-band radio that included {{nowrap|45 MHz}} frequencies, {{nowrap|160 MHz}} frequencies, {{nowrap|900 MHz}} frequencies and WiFi. A small freight or commuter that selects one or more of these bands or another one such as {{nowrap|450 MHz}} might find it easier to acquire spectrum. They will need to research spectrum issues, radio equipment, antennas, and protocol compatibility issues to successfully deploy PTC. {{citation needed|date=January 2013}}

===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.{{citation needed|date=January 2013}} In the second example, Amtrak is interoperable with [[Norfolk Southern]] in Michigan. Amtrak uses ITCS, while Norfolk Southern uses I-ETMS. To interoperate, two {{nowrap|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 {{nowrap|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.{{citation needed|date=January 2013}} For [[SEPTA]], the commuter operation in and around [[Philadelphia]], [[Ansaldo STS|Ansaldo]] is implementing [[Advanced Civil Speed Enforcement System|ACSES]], the Amtrak northeast corridor PTC protocol. For [[CSX]] all the 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. {{citation needed|date=January 2013}}

===Multi-band solutions===
For the major freight railroads and Amtrak the answer seems to be that one frequency band is sufficient. 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.{{citation needed|date=January 2013}} 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.{{citation needed|date=January 2013}} 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 {{nowrap|900 MHz}} [[Advanced Train Control System]] (ATCS) network in the 1990s.<ref>{{cite web|last1=Williams |first1=Duard R. |last2=Metzger |first2=Barry R. |last3=Richardson |first3=Gregory R. |title=Spec 200 Radio Code Line Ducting – Cause and Effect |year=2001 |url=http://www.arema.org/files/library/2001_Conference_Proceedings/00050.pdf}} AREMA.</ref> The ATCS protocol, which the AAR had recommended the FCC consider as PTC in 2000 (when AAR sought a nationwide {{nowrap|900 MHz}} "ribbon" license),<ref>A "ribbon" license authorizes use of radio frequency spectrum in a specified geographic area, e.g. along a railroad right-of-way. Federal Communications Commission, {{cite web|title=In the Matter of Petition of Association of American Railroads (AAR) for Modification of Licenses For Use in Advanced Train Control Systems and Positive Train Control Systems |date=15 February 2001 |url=http://transition.fcc.gov/Bureaus/Wireless/Orders/2001/da010359.doc}}</ref> can support train control operation at both {{nowrap|900 MHz}} and {{nowrap|160 MHz}}.<ref>{{cite book|title=Manual of Recommended Standards and Practices Section K-II Railway Communications |year=2002 |publisher=Association of American Railroads|pages=K–II–16 Section 3.1.3.7.1.1}}</ref> 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.<ref>{{Cite web|url=http://meteorcomm.blogspot.com/|title=MeteorComm Official Blog|website=meteorcomm.blogspot.com}}</ref> In addition, in mid-2008, an FRA sponsored effort by the AAR to develop a Higher Performance Data Radio (HPDR) for use at {{nowrap|160 MHz}} actually resulted in a contract being awarded to Meteorcomm for a 4-band radio to be used for voice and data.<ref>{{Cite web|url=https://www.pr.com/press-release/97424|title=MeteorComm Wins Next Generation Railroad Voice/Data Radio Development Project|website=PR.com}}</ref> 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 {{nowrap|220 MHz}} alone, in a single frequency-band configuration. Amtrak and most commuter operations quickly followed suit, selecting {{nowrap|220 MHz}}.{{citation needed|date=January 2013}}

===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 beforehand 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. {{citation needed|date=January 2013}}

===Open standards===
A large group of industry experts from the federal government,{{which|date=September 2018}} manufacturers, railroads, and consultants are participating in a study group sponsored by the [[IEEE]] [[IEEE 802.15|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. {{citation needed|date=January 2013}}

===Upgrade costs===
The railroad industry, like the process 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 major upgrades to initial PTC deployments within even the first 10 years. 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.<ref>{{cite magazine|last=Kenton|first=Malcolm|title=After PTC|url=|magazine=[[Trains (magazine)|Trains]]|pages=34–41|issue=February 2021|publisher=[[Kalmbach Media|Kalmbach]]}}</ref>

==Deployment==

=== Alaska Railroad ===
[[Wabtec]] is working with the [[Alaska Railroad]] 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.<ref>{{cite web|url=http://alaskarailroad.com/Portals/6/pdf/projects/2012_01_04_Positive_Train_Control_FS_PROJ.pdf|title=Alaska Railroad|access-date=4 February 2016|url-status=dead|archive-url=https://web.archive.org/web/20120405191356/http://alaskarailroad.com/Portals/6/pdf/projects/2012_01_04_Positive_Train_Control_FS_PROJ.pdf|archive-date=5 April 2012}}</ref>

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.<ref>{{cite news |title=Alaska Railroad to install positive train-control system |url=http://www.progressiverailroading.com/freightnews/article.asp?id=3021 |publisher=Progressive Railroading |date=27 August 2003 |access-date=19 June 2007}}</ref>

=== Amtrak ===
[[Alstom]]'s and PHW's [[Advanced Civil Speed Enforcement System]] (ACSES) system is installed on parts of Amtrak's [[Northeast Corridor]] between [[Washington, D.C.|Washington]] and [[Boston, Massachusetts|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.<ref name="alstom.com">{{cite web|title=ACSES II -Advanced Civil Speed Enforcement System|url=http://www.alstom.com/Global/US/Resources/Documents/ACSES_April_16_2013.pdf |access-date=23 December 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131224094921/http://www.alstom.com/Global/US/Resources/Documents/ACSES_April_16_2013.pdf |archive-date=24 December 2013 }}</ref><ref>{{cite web|title=PHW Inc. Positive Train Control Products|url=http://www.phwinc.com|work=Positive Train Control|access-date=20 April 2019|archive-url=https://web.archive.org/web/20080414002956/http://www.phwinc.com/|archive-date=14 April 2008|url-status=dead}}</ref>

[[GE Transportation|GE Transportation Systems]]' Incremental Train Control System (ITCS) is installed on Amtrak's [[Chicago–Detroit Line|Michigan line]], allowing trains to travel at {{convert|110|mph|abbr=on}}.<ref>{{cite news|title=AGE's Positive Train Control Technology is Full Speed Ahead on Amtrak's Michigan Line |url=http://www.getransportation.com/na/en/docs/919677_2005_10_ITCS.pdf |publisher=General Electric press release |date=11 October 2005 |access-date=21 September 2007 |archive-url=https://web.archive.org/web/20071025071323/http://www.getransportation.com/na/en/docs/919677_2005_10_ITCS.pdf |archive-date=25 October 2007 |url-status=dead }}</ref>

The [[2015 Philadelphia train derailment]] could have been prevented had positive train control been implemented correctly on the section of track that train was travelling.  The overspeed warning/penalty commands were not set up on that particular section of track although it was set up elsewhere.<ref>{{cite web|url=http://www.democracynow.org/2015/5/14/as_train_crash_death_toll_reaches|access-date=14 May 2015|publisher=Democracy Now!|date=14 May 2015|title=As Train Crash Death Toll Reaches 7, GOP Votes to Cut Amtrak Budget by $250M & Delay Safety Upgrades}}</ref>

=== Burlington Northern and Santa Fe (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.<ref>{{cite news|title=FRA Approves Positive Train Control System at BNSF |url=http://www.apta.com/passenger_transport/thisweek/070122_4.cfm |publisher=American Public Transportation Association |date=22 January 2007 |access-date=19 June 2007 |archive-url=https://web.archive.org/web/20070927220547/http://www.apta.com/passenger_transport/thisweek/070122_4.cfm |archive-date=27 September 2007 |url-status=dead }}</ref>

=== 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.<ref>{{cite magazine |title=Advances At CSX Intermodal
 |url=https://www.forbes.com/2006/07/13/csx-train-truck-intermodal-cx_rm_0713csx.html |magazine=Forbes |date=13 July 2006 |access-date=28 July 2008}}</ref>

=== 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. In January 2015, KCS began training personnel on PTC at its TEaM Training Center in Shreveport, La., with an initial class of 160 people.<ref>{{cite magazine |url=http://www.rtands.com/index.php/freight/class-1/kcs-ptc-update-data-surveying-and-training-underway.html?channel=275 |title=KCS PTC update: Data surveying and training underway |author=<!--Staff writer(s); no by-line.--> |date=12 January 2015 |magazine=Railway Track & Structures |access-date=13 January 2015}}</ref>

=== Massachusetts Bay Transportation Authority (MBTA) ===
Most MBTA Commuter Rail locomotives and [[cab car]]s, except for the 1625–1652 series Bombardier control cars and the (now retired) 1000–1017 series [[F40PH]] locomotives, are equipped with the PTC compliant [[ACSES]] technology which is installed on the Amtrak [[Northeast Corridor]]. All MBTA trains traveling on any segment of the Northeast Corridor must be equipped with functioning ACSES onboard apparatus, which affects trains on [[Providence/Stoughton Line]], [[Franklin/Foxboro Line]] and [[Needham Line]] routings. The MBTA shut down some lines on weekends in 2017 and 2018 to meet a December 2020 federal deadline for full-system PTC.<ref>{{cite web |url=http://www.mbta.com/uploadedfiles/About_the_T/Board_Meetings/K.%20%20%20FINAL%20FMCB%20PTC%20WE%20Suspension%20Comm%20Plan%203-27-17.pdf |title=Commuter Rail Positive Train Control (PTC): Update and Communications Plan for Suspension of Weekend Service |publisher=Massachusetts Bay Transportation Authority |date=27 March 2017 |page=6 |access-date=30 March 2017 |archive-date=31 March 2017 |archive-url=https://web.archive.org/web/20170331205623/http://www.mbta.com/uploadedfiles/About_the_T/Board_Meetings/K.%20%20%20FINAL%20FMCB%20PTC%20WE%20Suspension%20Comm%20Plan%203-27-17.pdf |url-status=dead }}</ref>

=== Metropolitan Transportation Authority (MTA) ===
In November 2013 the New York [[Metropolitan Transportation Authority]] signed a $428&nbsp;million contract to install positive train control on the [[Long Island Rail Road]] and the [[Metro-North Railroad]] to a consortium of [[Bombardier Transportation]] Rail Control Solutions and [[Siemens Mobility|Siemens Rail Automation]].<ref>{{cite web|title=Siemens, Bombardier pair on NYMTA PTC|url=http://www.railwayage.com/index.php/ptc/siemens-bombardier-pair-on-nymta-ptc.html |access-date=23 December 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131219192208/http://www.railwayage.com/index.php/ptc/siemens-bombardier-pair-on-nymta-ptc.html |archive-date=19 December 2013 }}</ref><ref>{{cite web|title=Bombardier Strengthens Presence in North American Rail Control Sector|url=http://www.bombardier.com/en/media-centre/newsList/details.bombardier-transportation20131114bombardierstrengthenspresencein.html |access-date=23 December 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131224095459/http://www.bombardier.com/en/media-centre/newsList/details.bombardier-transportation20131114bombardierstrengthenspresencein.html |archive-date=24 December 2013 }}</ref> The LIRR and Metro-North installations will include modifications and upgrades of the existing signal systems and the addition of [[ACSES]] II<ref name="alstom.com"/> equipment. Siemens stated that the PTC installation will be completed by December 2015, but missed that deadline,<ref>{{Cite news |last=Coyne |first=Matt |url=http://www.poughkeepsiejournal.com/story/news/local/2016/08/22/metro-north-making-little-progress-positive-train-control-report-shows/89126258 |title=Metro-North making little progress on positive train control, report shows |date=2016-08-22 |work=Poughkeepsie Journal}}</ref> and did not complete the installation until the end of 2020.<ref>{{cite web |title=MTA Railroads Announce All Trains Operating in Positive Train Control, Critical Safety Technology |date=December 23, 2020 |publisher=MTA |url=https://new.mta.info/MTA-Railroads-Announce-All-Trains-Operating-in-Positive-Train-Control-Critical-Safety-Technology |access-date=2022-02-25}}</ref>

=== New Jersey Transit (NJT) ===
[[Ansaldo STS|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.<ref name="Vogler" />

=== Norfolk Southern (NS) ===
[[Norfolk Southern Railway]] began work on the system in 2008 with [[Wabtec]] Railway electronics to start developing a plan to implement [[Positive Train Control]] on NS rails. NS has already implemented PTC on 6,310 miles of track with plans to achieve it on 8,000 miles of track. NS has requested an extension on the time to have PTC active on its miles of track due to the need to work more on areas with no track signals, as well as making provisions for smaller railroads that the company does business with to be PTC capable. NS keeps experiencing issues with the system and wants to take the proper time to fix the system to ensure the safety of its employees and all others using their tracks. NS has been adding and updating its locomotives with PTC capable computers to allow those locomotives for use on mainlines. 2,900 locomotives out of the almost 4,000 the company has have been fitted with the PTC capable computers. NS plans to put at least 500 locomotives into storage using precision NS has been updating it trackside equipment such as radio towers and control point lighting to assist in PTC operations on the railroad. With the new computers on the locomotives it allows the locomotives to interact with each other and trackside systems. Norfolk Southern's [[General Electric]] Transportation locomotives are equipped with [[GPS]] to aid in the use of PTC. All of NS's locomotives are equipped with Energy Management a computer system that provides real time data on the locomotive. The system can also control train speed and brake systems on board. The EM system allows the locatives to use less fuel and be more efficient. NS's final goal is completely autonomous operations of their trains. This system will be used alongside Auto-router used to route train movements with little to no human interactions. With these two systems integrated with PTC it allows for more precise movement and train control across the railroad. NS, [[Union Pacific]], [[CSX Transportation|CSXT]], [[BNSF]], and [[Virginia Railway Express]] have been testing interoperation to make sure each companies PTC systems work with each other to ensure safe railroad travel. For this a NS train on [[CSX Transportation|CSXT]] tracks has to act like a [[CSX Transportation|CSXT]] train would or vice versa. That requires the railroads to use the same communications and radio frequencies for everything to operate smoothly. Nearly 3,000 locomotives have been fitted with the PTC capable computers.<ref>{{Cite web |url=http://www.nscorp.com/content/nscorp/en/about-ns/government-relations/where-we-stand/positive-train-control.html |title=Positive Train Control |website=Government Relations |publisher=Norfolk Southern |access-date=2023-08-20}}</ref><ref>{{Cite web|url=https://www.progressiverailroading.com/ptc/article/On-a-high-tech-trek-Norfolk-Southern-notes-progress-in-its-quest-to-become-a-technology-enabled-railroad-of-the-future--55310|title=Rail Insider-On a high-tech trek: Norfolk Southern notes progress in its quest to become a 'technology-enabled railroad of the future'. Information For Rail Career Professionals From Progressive Railroading Magazine|website=Progressive Railroading}}</ref><ref>{{Cite magazine|url=http://trn.trains.com/railroads/abcs-of-railroading/2018/02/what-is-positive-train-control|title=What is positive train control ... and will it work?|magazine=Trains|access-date=November 13, 2019|archive-date=November 13, 2019|archive-url=https://web.archive.org/web/20191113003242/http://trn.trains.com/railroads/abcs-of-railroading/2018/02/what-is-positive-train-control|url-status=dead}}</ref><ref>{{Cite web|url=https://www.railwayage.com/freight/class-i/at-norfolk-southern-automation-is-driving-information/|title=At Norfolk Southern, automation is driving information|date=12 December 2018|website=Railway Age}}</ref>

=== Peninsula Corridor Joint Powers Board (Caltrain) ===
[[Caltrain]]'s Communications Based Overlay Signal System (CBOSS) has been installed but not fully tested along the Peninsula Corridor between San Francisco, San Jose and Gilroy, California.<ref name=CHNS-170306 /> Caltrain had selected Parsons Transportation Group (PTG), who had been working on a similar system for Metrolink in Southern California, to implement, install, and test CBOSS in November 2011.<ref name=PR-111122>{{cite press release |url=https://www.parsons.com/Media%20Library/11-11-ptg-caltrain-cboss-ptc.pdf |archive-url=https://web.archive.org/web/20130901005646/http://www.parsons.com/Media%20Library/11-11-ptg-caltrain-cboss-ptc.pdf |url-status=dead |archive-date=1 September 2013 |title=Parsons Selected by Caltrain for Communications-Based Overlay Signal System Positive Train Control |author=<!--Staff writer(s); no by-line.--> |date=22 November 2011 |publisher=Parsons News |access-date=31 March 2017 }}</ref> In February 2017, Caltrain's board canceled the contract with PTG for failure to meet the scheduled 2015 deadline.<ref>{{cite press release |url=http://www.caltrain.com/about/MediaRelations/news/Caltrain_Terminates_Contract_with_Parsons_Transportation_Group__PTG_.html |title=Caltrain Terminates Contract with Parsons Transportation Group (PTG) |author=<!--Staff writer(s); no by-line.--> |date=24 February 2017 |publisher=Peninsula Corridor Joint Powers Board |access-date=25 March 2017 |archive-url=https://web.archive.org/web/20170320130109/http://www.caltrain.com/about/MediaRelations/news/Caltrain_Terminates_Contract_with_Parsons_Transportation_Group__PTG_.html |archive-date=20 March 2017 |url-status=live}}</ref> PTG and Caltrain would go on to file lawsuits for breach of contract.<ref name=CHNS-170306>{{cite news |url=https://www.courthousenews.com/caltrain-safety-contractor-trade-lawsuits/ |title=Caltrain, Safety Contractor Trade Lawsuits |author=Renda, Matthew |date=6 March 2017 |newspaper=Courthouse News Service |access-date=6 April 2017}}</ref><ref name=SJMN-170301>{{cite news |url=http://www.mercurynews.com/2017/03/01/caltrain-quietly-fires-contractor-before-testing-of-new-safety-system-is-completed/ |title=Caltrain fires contractor before testing of new safety system is completed |author=Baldassari, Erin |date=1 March 2017 |newspaper=San Jose Mercury News |access-date=4 April 2017}}</ref> At its board of directors meeting on 1 March 2018, Caltrain announced that it will be awarding a contract to Wabtec for implementation of I-EMTS.<ref>{{cite web|url= http://www.caltrain.com/Assets/__Agendas+and+Minutes/JPB/Board+of+Directors/Presentations/2018/2018-03-01+JPB+Wabtec+presentation.pdf |title=Caltrain PTC Program Status & Wabtec Contract Award  |author=<!--unknown--> |date=1 March 2018 |publisher=Caltrain |access-date=5 March 2018}}</ref>

=== Regional Transportation District (RTD) ===
Positive Train Control (PTC) and vehicle monitoring system technologies have been developed for the [[Denver-Aurora, CO Combined Statistical Area|Denver Metro Area]]'s new commuter train lines that began opening in 2016.<ref>{{cite web|url=http://www.rtd-fastracks.com/media/uploads/ep3/11Commuter_Rail_Fact_Sheet.pdf |title=Electric Commuter Rail Vehicle |website=Rtd-fastracks.com |access-date=4 February 2016}}</ref> After the [[University of Colorado]] [[A Line (RTD)|A Line]] opened on 22 April 2016 between [[Denver Union Station]] and [[Denver International Airport]], it experienced a series of issues related to having to adjust the length of unpowered gaps between different overhead power sections, direct lightning strikes, snagging wires, and crossing signals behaving unexpectedly.<ref name="CPR what's causing A Line Delays">{{cite web|url=http://www.cpr.org/news/story/whats-causing-delays-rtds-line-dia|title=What's Causing Delays With RTD's A Line To DIA?|access-date=27 February 2017|archive-date=February 28, 2017|archive-url=https://web.archive.org/web/20170228084347/http://www.cpr.org/news/story/whats-causing-delays-rtds-line-dia|url-status=dead}}</ref> In response to the crossing issues, Denver Transit Partners, the contractor building and operating the A Line, stationed crossing guards at each place where the A line crosses local streets at grade, while it continued to explore software revisions and other fixes to address the underlying issues.<ref name="DBJ 90-day extension">{{cite web|url=http://www.bizjournals.com/denver/news/2016/11/02/rtd-gets-90-day-extension-from-feds-to-fix-airport.html|title=RTD gets 90-day extension from feds to fix airport-train crossing gates|access-date=27 February 2017}}</ref> The FRA required frequent progress reports, but allowed RTD to open its [[B Line (RTD)|B Line]] as originally scheduled on 25 July 2016,<ref name="FasTracks B Line Opening">{{cite web|url=http://www.rtd-fastracks.com/nw_84|title=B Line to Westminster opens July 25|access-date=27 February 2017}}</ref> because the B Line only has one at-grade crossing along its current route.<ref name="DBJ 90-day extension" /> However, FRA halted testing on the longer [[G Line (RTD)|G Line]] to [[Wheat Ridge, Colorado|Wheat Ridge]] – originally scheduled to open in Fall 2016 – until more progress could be shown resolving the A Line crossing issues.<ref name="Post G Line Delayed Again">{{cite web|url=http://www.denverpost.com/2017/01/09/more-delay-for-debut-of-rtd-g-line-to-arvada-wheat-ridge/|title=RTD G-Line to Arvada, Wheat Ridge will be delayed — again|date=10 January 2017|access-date=27 February 2017}}</ref> G Line testing resumed in January 2018, though the A Line continued to operate under a waiver.<ref name="Denver7 A Line deadline">{{cite web |last1=Boyd |first1=Kirsten |title=RTD says it will meet feds' deadline for A Line crossing fix to avoid possible service disruption |url=http://www.thedenverchannel.com/rtd-says-it-will-meet-feds-deadline-for-a-line-crossing-fix-to-avoid-possible-service-disruption |website=TheDenverChannel.com |publisher=Scripps TV Station Group |access-date=21 February 2019 |date=14 December 2018}}</ref> The G Line opened to passenger service on 26 April 2019.<ref>{{cite news |last=Wingerter |first=Meg |date=April 1, 2019 |title=RTD: Long-delayed G-Line from Denver to Wheat Ridge will open April 26 |url=https://www.denverpost.com/2019/04/01/rtd-g-line-opening/ |work=The Denver Post |access-date=April 1, 2019}}</ref>

=== Sonoma-Marin Area Rail Transit (SMART) ===
Positive train control has been implemented at [[Sonoma–Marin Area Rail Transit]]'s 63 crossings for the length of the initial {{convert|43|mi|km|adj=mid}} passenger corridor which began regular service on 25 August 2017 after the FRA gave its final approval for SMART's PTC system.<ref>{{cite news|title=SMART Train Looking for a Windsor Stop|url=http://www.ksro.com/smart-train-looking-for-a-windsor-stop/|access-date=15 June 2016|agency=KSRO|date=14 April 2016|archive-url=https://web.archive.org/web/20160809012602/https://www.ksro.com/smart-train-looking-for-a-windsor-stop/|archive-date=9 August 2016}}</ref> SMART uses the E-ATC system for its PTC implementation.<ref>{{cite press release|title=FRA Awards More Than $200 Million for PTC Implementation|agency=Federal Railroad Administration|date=24 August 2018|access-date=27 February 2020|url=https://cms7.fra.dot.gov/newsroom/fra-awards-more-200-million-ptc-implementation|archive-date=February 28, 2020|archive-url=https://web.archive.org/web/20200228000003/https://cms7.fra.dot.gov/newsroom/fra-awards-more-200-million-ptc-implementation|url-status=dead}}</ref>

=== Southeastern Pennsylvania Transportation Authority (SEPTA) ===
SEPTA received approval from the FRA on 28 February 2016 to launch PTC on its [[SEPTA Regional Rail|Regional Rail]] lines.<ref name=inq22816>{{cite news|last=Laughlin|first=Jason|title=Feds approve new SEPTA train-control safety system|work=The Philadelphia Inquirer|date=28 February 2016|url=http://articles.philly.com/2016-02-28/news/71006423_1_regional-rail-trains-warminster-line-septa|access-date=22 May 2016}}</ref> On 18 April 2016, SEPTA launched PTC on the [[Warminster Line]], the first line to use the system.<ref name=inq22816/><ref>{{cite web|title=Positive Train Control Update|publisher=SEPTA|date=28 April 2016|url=http://www.septa.org/service/rail/ptc/2016-04-28-ptc-update-warminster.html|access-date=22 May 2016}}</ref> Over the course of 2016 and into 2017, PTC was rolled out onto different Regional Rail lines. On 1 May 2017, the [[Paoli/Thorndale Line]], [[Trenton Line (SEPTA)|Trenton Line]], and [[Wilmington/Newark Line]] (all of which run on Amtrak tracks) received PTC, the last of the Regional Rail lines to receive the system.<ref>{{cite web|title=Positive Train Control Update|publisher=SEPTA|date=1 May 2017|url=http://www.septa.org/service/rail/ptc/2017-04-update.html|access-date=17 May 2017}}</ref>

=== Southern California Regional Rail Authority (Metrolink) ===
[[Metrolink (California)|Metrolink]], the Southern California commuter rail system involved in the [[2008 Chatsworth train collision]] that provided the impetus for the [[Rail Safety Improvement Act of 2008]], was the first passenger rail system to fully implement positive train control.<ref>{{cite web |url= http://www.metrolinktrains.com/agency/page/title/ptc |title=Metrolink leads the nation with life-saving PTC technology |author=<!--Staff writer(s); no by-line.--> |publisher= Southern California Regional Rail Authority |access-date=7 April 2017}}</ref> In October 2010, Metrolink awarded a $120&nbsp;million contract to PTG to design, procure, and install PTC.<ref>{{cite news |url=http://www.railwayage.com/index.php/news/metrolink-parsons-first-out-of-the-gate-with-ptc.html |title=Metrolink, Parsons first out of the gate with PTC |author=Vantuono, William C. |date=27 October 2010 |newspaper=Railway Age |access-date=7 April 2017}}</ref> PTG designed a PTC system that used GPS technology informing position to on-board train computers, which communicate wirelessly with wayside signals and a central office.<ref name=MetroPTC /> Metrolink anticipated placing PTC in revenue service by summer 2013.<ref name=MetroPTC>{{cite web |url=https://www.parsons.com/projects/pages/metrolink-ptc.aspx |title= Metrolink PTC |author=<!--Staff writer(s); no by-line.--> |publisher=Parsons |access-date=|archive-url = https://web.archive.org/web/20170408083837/https://www.parsons.com/projects/pages/metrolink-ptc.aspx |archive-date = 8 April 2017}}</ref> However, Parsons announced the FRA had authorized Metrolink to operate PTC RSD using Wabtec's I-ETMS in revenue service on the San Bernardino line in March 2015.<ref>{{cite press release |url=https://www.parsons.com/media-resources/news/Pages/15-03-ptg-metrolink-ptc.aspx |title=Parsons' Positive Train Control to Launch on Metrolink's San Bernardino Rail Line |author=<!--Staff writer(s); no by-line.--> |date= 5 March 2015 |publisher=Parsons |access-date=7 April 2017}}</ref> Metrolink announced PTC had been installed on all owned right-of-way miles by June 2015, and was working to install the system on tracks shared with Amtrak, freight, and other passenger rail partners.<ref>{{cite news |url=http://www.latimes.com/local/lanow/la-me-ln-positive-train-control-20150624-story.html |title=Safety system for Metrolink trains advances |author=Weikel, Dan |date=24 June 2015 |newspaper=Los Angeles Times |access-date=7 April 2017}}</ref>

=== Union Pacific (UP) ===
In the 1990s, Union Pacific Railroad (UP) 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.<ref>Lindsey, Ron (7 December 2010). [http://strategicrailroading.com/2010/12/really-you-gotta-let-it-go/ "Really! You Gotta Let It Go."] ''Strategic Railroading.''</ref>

In 2008, a team of [[Lockheed Martin]], [[Wabtec]], and [[Ansaldo STS|Ansaldo STS USA Inc]] installed an ITCS subsystem on a 120-mile segment of UP track between Chicago and St. Louis. Other major software companies, such as [[PK Global]], [[Tech Mahindra]], are also some of the strategic IT partners in development of PTC systems.<ref>{{cite news |title=Positive train control in transition |url=http://www.progressiverailroading.com/ptc/article/Positive-train-control-in-transition--13239 |publisher=Progressive Railroading |date=October 2007 |access-date=21 December 2016}}</ref>

{{As of|2017|12|31}}, Union Pacific Installed 99 percent, or more than 17,000 miles, of total route miles with PTC signal hardware. Union Pacific has partially installed PTC hardware on about 98 percent of its 5,515 locomotives earmarked for the same technology and have equipped and commissioned 4,220 locomotives with PTC hardware and software.  Union Pacific has also installed 100 percent of the wayside antennas needed to support PTC along the company's right of way.<ref>{{Cite web |url=http://www.up.com/up/media/media_kit/ptc/about-ptc/index.htm |title=Positive Train Control |publisher=Union Pacific |access-date=2023-08-20}}</ref>

==References==
{{Reflist}}

==Further reading==
* [http://www.fas.org/sgp/crs/misc/R42637.pdf Positive Train Control (PTC): Overview and Policy Issues], [[Congressional Research Service]]
* [https://purl.fdlp.gov/GPO/gpo44726 Positive Train Control: Additional Authorities Could Benefit Implementation"], Report to the Chairman, Committee on Commerce, Science, and Transportation, U.S. Senate, [[Government Accountability Office]]
* [https://web.archive.org/web/20080830034149/http://grouper.ieee.org/groups/railtransit/wg2/Archive%20Other/2007%20AREMA%20CBS%20paper%20Vital%20PTC%20V2.pdf "Communications-Based Signaling (CBS) – Vital PTC"], Paper presented at AREMA C&S Technical Conference 22 May 2007
* [http://www.smartrailworld.com/white-papers-and-research "Integration and Alignment of PTC Track Data with Legacy Dispatch Data to Reduce PTC Implementation Cost and Safety Risks"], Paper presented at PTC World Congress 22 March 2016 Washington, D.C. Andrew Brant & Ken Xu

==External links==
* [https://railroads.dot.gov/research-development/program-areas/train-control/ptc/positive-train-control-ptc Positive Train Control  – Federal Railroad Administration]

{{Railwaysignalling|state=collapsed}}

[[Category:Railway safety]]
[[Category:Railway signalling block systems]]
[[Category:Train protection systems]]