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Traffic control devices and traffic signs

Short answer

Traffic control devices must fulfil a need, attract attention, convey clear meaning, command respect, allow response time, be uniform, visible at night, maintained and properly located/enforced. Signs are regulatory (circular, red border; stop octagon, give way inverted triangle), warning (equilateral triangle, red border) and informatory (rectangular, blue or green background).

What are general requirements of traffic control devices? Explain the different types of traffic sign.

General requirements of traffic control devices

  1. Fulfil a need: each device must be justified by a real need based on a traffic study.
  2. Command attention: be conspicuous (size, colour, shape, retro-reflectivity).
  3. Convey a clear and simple meaning that can be understood at a glance.
  4. Command respect: be used only where needed, not over-used, so that drivers obey.
  5. Give adequate time for response: placed in advance of the hazard, with enough time to read and act.
  6. Be uniform: the same type of device, shape and colour everywhere in the country.
  7. Be legible and visible at night (reflectorised or illuminated).
  8. Be maintained: clean, repainted, repaired.
  9. Be properly located and enforced by traffic police.

Types of traffic signs

TypePurposeShape and colour
Regulatory (mandatory)Tell the driver what to do or not do (stop, give way, no entry, speed limit, no parking)Circular, red border, white background; STOP is an octagon, GIVE WAY an inverted triangle
Cautionary (warning)Warn of a hazard ahead (curve, steep descent, junction, school, narrow bridge)Equilateral triangle, red border, white background, black symbol
Informatory (guide)Give directions, place names, distances, facilities (hospital, parking, fuel)Rectangular; blue (facilities) or green (direction on highways) background, white letters

Subdivisions: informatory signs include direction signs, place identification, route markers, facility information and parking signs.

Placement: within the cone of clear vision, 3 m lateral clearance from the edge, with a mounting height of 2.0-2.5 m above the ground; legends in a size that can be read at the speed of the road.

 Regulatory      Warning        Informatory
  .-----.        /\            +---------+
 /  STOP \      /  \           | HOSPITAL|
 \  (red) /     / !  \          +---------+
  `-----'      /______\        blue/green
 circle/octagon  triangle       rectangle

✓ Answer checked by Claude Opus 5.5 (high effort)

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