49 CFR § 236.1003 - Definitions.
(a) Definitions contained in subparts G and H of this part apply equally to this subpart.
(b) The following definitions apply to terms used only in this subpart unless otherwise stated:
After-arrival mandatory directive means an authority to occupy a track which is issued to a train that is not effective and not to be acted upon until after the arrival and passing of a train, or trains, specifically identified in the authority.
Associate Administrator means the FRA Associate Administrator for Railroad Safety/Chief Safety Officer.
Class I railroad means a railroad which in the last year for which revenues were reported exceeded the threshold established under regulations of the Surface Transportation Board (49 CFR part 1201.1-1 (2008)).
Cleartext means the un-encrypted text in its original, human readable, form. It is the input of an encryption or encipher process, and the output of an decryption or decipher process.
Controlling locomotive means Locomotive, controlling, as defined in § 232.5 of this chapter.
Host railroad means a railroad that has effective operating control over a segment of track.
Interoperability means the ability of a controlling locomotive to communicate with and respond to the PTC railroad's positive train control system, including uninterrupted movements over property boundaries.
Limited operations means operations on main line track that have limited or no freight operations and are approved to be excluded from this subpart's PTC system implementation and operation requirements in accordance with § 236.1019(c);
Main line means, except as provided in § 236.1019 or where all trains are limited to restricted speed within a yard or terminal area or on auxiliary or industry tracks, a segment or route of railroad tracks:
(1) Of a Class I railroad, as documented in current timetables filed by the Class I railroad with the FRA under § 217.7 of this title, over which 5,000,000 or more gross tons of railroad traffic is transported annually; or
(2) Used for regularly scheduled intercity or commuter rail passenger service, as defined in 49 U.S.C. 24102, or both. Tourist, scenic, historic, or excursion operations as defined in part 238 of this chapter are not considered intercity or commuter passenger service for purposes of this part.
Medium speed means, Speed, medium, as defined in subpart G of this part.
NPI means a Notice of Product Intent (“NPI”) as further described in § 236.1013.
PTC System Certification means certification as required under 49 U.S.C. 20157 and further described in §§ 236.1009 and 236.1015.
Restricted speed means, Speed, restricted, as defined in subpart G of this part.
Safe State means a system state that, when the system fails, cannot cause death, injury, occupational illness, or damage to or loss of equipment or property, or damage to the environment.
Segment of track means any part of the railroad where a train operates.
Temporal separation means that passenger and freight operations do not operate on any segment of shared track during the same period and as further defined under § 236.1019 and the process or processes in place to assure that result.
Track segment means segment of track.
Train means one or more locomotives, coupled with or without cars.