IEEE 1698-2009 pdf download IEEE Guide for the Calculation of Braking Distances for Rail Transit Vehicles
2.Definitions,acronyms,and abbreviations
2.1 Definitions
For the purposes of this document, the following terms and definitions apply. The IEEE StandardsDictionary: Glossary ofTerms & Definitions should be referenced for terms not defined in this clause.
brake assurance: A function in the automatic train protection (ATP) system that monitors the actualachieved braking rate, and, ifless than a predetermined value, applies emergency brake.
brake build-up: The time to achieve full commanded braking rate, beginning from the point at which atypical value of 10% of the commanded rate has been achieved.
braking rate: The deceleration of the train, resulting from the retarding effort of the braking apparatus, butexcluding train resistance and grade or curvature effects.
curvature: The measure of the amount by which the track does not run in a straight line (i.e.. is nottangent).
dead time: The time from a point at which the instantaneous accelerating tractive effort is zero untilbraking rate has reached a typical value of 10% of the commanded value.
entry point: The civil position of a train at which it enters territory wherein a more restrictive speed limitapplies (i.e., a signal boundary or transponder location).
entry speed: The speed of the train at the entry point that is allowed by the signal system or by governingrules and procedures. This speed may include allowable speed and wayside/vehicle equipment tolerances.
equipment reaction time: The time from passage of an entry point until the carborne equipment hasdetected, processed, and indicated the existence of a more restrictive speed.
full service application: A service brake application of sufficient amount to obtain the maximum servicebrake rate obtainable.
grades: Civil changes in track elevation; the tangent of the angle formed by the algebraic value of the risedivided by the horizontal component of the run, typically expressed as a percent.
gradient; The horizontal run over which one unit of rise occurs.
jerk rate limit: The limit to the rate of change of acceleration designed into the propulsion, automatic trainoperation(ATO).and/or braking apparatus.
maximum attainable speed: An entry speed, commonly used with trip-stops with wayside signals, whichis the highest speed that a train can achieve at the entry point of the braking model while operating inaccordance with the rules of the authority having jurisdiction.
maximum authorized speed: The highest speed at which a train is allowed to operate in the absence ofany condition requiring a lesser speed
operator reaction time: The time from passage of an entry point until an operator has performed adefinitive action in recognition of the existence of a more restrictive speed limit.