encyclopedia

HACKER

An individual who maliciously attempts to gain unauthorized access to a computer system.

HAND BRAKE

Device for applying/releasing brakes on cars or locomotives separately from the air brakes, usually used like a parking brake to secure unattended equipment; a train braking device manually applied to prevent vehicle movement, or to provide emergency braking.

HAND SIGNAL

A manual signal used to govern the movement of trains. See also Signal, Hand.

HAND THROWN SWITCH

A switch which can only be operated manually. See also Switch, Hand Operated. (NTSC)

HANDICAPPED

People who have physical or mental impairments that substantially limit one or more major life activities. In the context of transportation, the term usually refers to people for whom the use of conventional transit facilities would be impossible or would…

HANDICAPPED ACCESSIBILITY (FULL ACCESSIBILITY)

The extent to which facilities are free of barriers and usable by mobile handicapped people, including wheelchair users.

HANDICAPPED, NONAMBULATORY

Handicapped people who are unable to move about without assistance, for example, those confined to a wheelchair. (TRB)

HASH TOTAL

The total of any numeric data filed on a document or computer file. This total is then checked against a control total of the same field to facilitate accuracy of processing.