encyclopedia

INDEFINITE LEAVE

A leave of absence of a duration over ninty (90) days.

INDEFINITE-QUANTITY CONTRACT

A contract that provides for an indefinite quantity, within written limits, of specific supplies or services to be furnished during a fixed period, with deliveries to be scheduled by placing orders with the contractor. The contract requires the MTA to…

INDEPENDENT ASSURANCE

Activities that are an unbiased and independent evaluation of all the sampling and testing (or inspection) procedures used in the QA program.

INDEPENDENT FAILURE

A failure which occurs without being related to the failure of any associated item.

INDEPENDENT SAMPLE

A sample taken without regard to any other sample that may also have been taken to represent the material in question.

INDEXED SEQUENTIAL FILE

A file format in which records are organized and can be accessed according to a pre-established key that is part of the record.

INDICATION

The information conveyed by the aspect from a fixed signal, a cab signal, or a hand signal as viewed by a train operator.

INDICATION LOCKING

Electric locking of control circuits which prevents actions that would result in an unsafe condition for a train movement if a signal, switch, or if the operative unit fails to make a movement corresponding to a control command. (NTSC)

INDICATION POINT

The point at which the train control or cab signal impulse is transmitted to the rail vehicle apparatus from the track element. (TRB)