Positive train control
"[5][6][7] 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).
[12] In December 2010, the Government Accountability Office (GAO) reported that Amtrak and the major 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.
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.
[citation needed] 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.
The first makes use of fixed signaling infrastructure such as coded track circuits and wireless transponders to communicate with the onboard speed control unit.
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[broken anchor].
The fixed infrastructure method is proving popular on high-density passenger lines where pulse code cab signaling has already been installed.
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 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.
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.
[citation needed] 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.
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.
[31] 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.
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.
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.
Meteorcomm is jointly 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.
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] 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.
[citation needed] For SEPTA, the commuter operation in and around Philadelphia, Ansaldo is implementing ACSES, the Amtrak northeast corridor PTC protocol.
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] 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.
[45] 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.
[47] Data between locomotive and dispatcher is transmitted over a digital radio system provided by Meteor Communications Corp (Meteorcomm).
NS, Union Pacific, 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.
[65] 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.
[76] Positive train control has been implemented at Sonoma–Marin Area Rail Transit's 63 crossings for the length of the initial 43-mile (69 km) passenger corridor which began regular service on 25 August 2017 after the FRA gave its final approval for SMART's PTC system.
[83] 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.
[84] 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.
[87] In 2008, a team of Lockheed Martin, Wabtec, and Ansaldo STS USA Inc installed an ITCS subsystem on a 120-mile segment of UP track between Chicago and St. Louis.
[89] Union Pacific had also equipped steam locomotive 4014 with its own PTC system in July 2024, mounting the necessary hardware in a new compartment of the tender.
