Stop indication board:
Stop Indicator A rectangular board with red and white bands. It is mounted on a post with alternating red and white bands. At night the sign is illuminated by two red lamps. This is used for temporary or permanent engineering restrictions which call for trains to come to a dead stop before proceeding.
Some stop indicators are used to mark the spot beyond which a locomotive must not proceed when a signal ahead is at danger. These include vertical poles with 'STOP' spelled out in black on yellow, or rectangular...
more... yellow boards with 'STOP' on them in black. The poles usually have horizontal yellow and black stripes. A single white lamp may appear within the sign. These signs may appear on the right or on both sides of the track. At stations these stop signs are used to position the train correctly along the platform. (Sometimes, an indication board (see below) is used instead, with a message (black on yellow) such as 'Stop here when main signal is at danger', or 'Engine stop here'.)