encyclopedia

STOCHASTIC PROCESS

A process that involves random variables and a nonreproducitible output. Also see Deterministic Process. (TRB)

STOCHASTIC TRIP ASSIGNMENT

A probabilistic trip assignment technique that allocates trips with deviation from the minimum time route on the basis of differences in travel times. (TRB)

STOCK RAIL

The rail against which the point of a switch, derail, or movable point frog rests.

STOP AND PROCEED

A signal indication to stop and then proceed with certain cautions not to exceed a designated speed. Also see Operating Modes (Light Rail). (NTSC)

STOP SIGNAL

A signal which displays the most restrictive aspect indicating stop. (NTSC)

STOPPED TIME

Time on a trip spent stationary because of the stoppage of other traffic. (TRB)

STORAGE LOCATION

An operator’s regular work, consisting of one uninterrupted assignment paying eight ours or more.