MCH 1969
Issue A
Traffic Control System Design (Compendium of Examples)
Annex A
Glossary
December 2003
A-9
portable signal
A traffic signal designed to be moved from place to
place
PROM
Programmable Read Only Memory
push button
A button which may be pressed to register a demand
push button box
A housing containing a push button. Also "push
button unit"
reflector
A curved polished device mounted behind a lamp to
focus the light through the lens
regulatory sign
A sign indicating a traffic regulation (such as a
prohibited movement)
relay
An electrical switch using a coil and solenoid which
makes or breaks contacts when the coil is energised.
Other types of equipment having the same function
SA
Speed Assessment. A VA control strategy for high
speed roads which affects the changing of the signals
according to the speed of approaching vehicles
SDE
Speed Discrimination Equipment. A VA control
strategy for high speed roads which discriminates
vehicles travelling above a give speed threshold
segmented arrow
An arrow signal where the head and shaft of the
arrow are separated to improve legibility of the arrow
direction
signal pole
A pole installed at a traffic signal installation to
solar cell
A light sensitive device mounted on signals to initiate
dimming of the lamps during darkness
solid state relay
A device having the isolated switching functions of a
relay achieved by the use of solid-state electronics
rather than solenoids and physical switching contacts
stool
A framework installed below ground on to which a
housing is mounted
stud
A square or circular metallic or thermoplastic marker
installed on a road surface to indicate the line of a
pedestrian crossing
SVD
A detector which responds only to certain vehicles
identified by their characteristics or by an electronic
tag. (Selective Vehicle Detector)
tactile indicator
An indicator (typically a rotating cone) which
indicates the presence of a green signal for the benefit
of visually impaired pedestrians
tactile paving
A type of textured paving which can be identified by
visually impaired pedestrians to indicate the location
of a pedestrian crossing facility
temporary signal
A traffic signal using the same type of signal
equipment as permanent signals but which is installed
for a limited period of time ( e.g signals in barrels)