Making Synapses · Bringing Knowledge to Mankind
RailwayPositive Train Control: the Train That Stops Itself
Twenty flashcards on PTC, the federal safety system now running on every required U.S. main line.
Free to startYour progress here is temporary and is lost when you close this page. Install Making Synapses free to keep it, with spaced repetition.
20 cards
- What four kinds of accidents must PTC be designed to prevent?
- Train-to-train collisions, over-speed derailments, incursions into work zones and trains passing switches left in the wrong position.
- Which law first required PTC?
- The Rail Safety Improvement Act of 2008 (Oct. 16, 2008).
- Which freight lines must have PTC?
- Main lines carrying poison- or toxic-by-inhalation hazardous materials with five million or more gross tons of annual traffic.
- Which passenger lines must have PTC?
- Main lines with regularly provided intercity or commuter rail passenger service.
- What was the deadline for PTC on all required main lines?
- December 31, 2020.
- How many route miles do PTC-mandated main lines cover?
- Nearly 58,000 route miles nationwide.
- When did FRA announce full PTC implementation?
- On December 29, 2020, on all PTC-mandated main lines.
- How many host railroads are directly subject to the mandate?
- 35: 7 Class I, 23 intercity passenger or commuter, and 5 Class II or III, short line or terminal railroads.
- How many railroads did FRA count under the mandate at the end of 2020?
- 41, of which six are tenant-only commuter railroads.
- What does PTC interoperability mean?
- Locomotives of host and tenant railroads on the same main line talk to and obey the same PTC system, even across property lines.
- How many interoperable host-tenant relationships existed in December 2020?
- 209.
- How many types of PTC systems run in the U.S.?
- Five.
- Which PTC system did the Class I freight railroads implement?
- I-ETMS, the Interoperable Electronic Train Management System.
- Which PTC system runs on most of the Northeast Corridor, and which does Amtrak use in Michigan?
- ACSES II (or ASES II) on the Northeast Corridor; the Incremental Train Control System in parts of Michigan.
- How are PTC radio messages protected?
- All wireless messages between office, wayside and onboard parts must have cryptographic integrity and authentication.
- Which over-speed derailments must PTC prevent?
- Including those from civil engineering speed restrictions, slow orders and excessive speed over switches and turnouts.
- How does PTC protect track workers?
- It prevents entry into work zone limits without authority from the dispatcher or roadway worker in charge.
- What extra rule applies to PTC above 90 mph?
- The system must meet fail-safe criteria and block entry from non-PTC tracks with split-point derails or equivalent.
- What must a PTC system above 125 mph also detect?
- Incursions into the right-of-way, including vehicles leaving nearby roads and bridges, where conditions warrant.
- How did FRA's 2021 rule change PTC performance reports?
- From annual to biannual, adding positive performance data, not just failures.
Official sources
Federal Railroad Administration (FRA), via GovInfo
Positive Train Control Systems, final rule, 86 FR 40154 (July 27, 2021)
Federal Railroad Administration (FRA), via eCFR
49 CFR Part 236 Subpart I: Positive Train Control Systems
Making Synapses is not affiliated with, sponsored by or endorsed by the Federal Railroad Administration or any railroad. Agency names and regulations are named only to describe the content.