Consider the following aspects of human vision which are important for a traffic engineer: 1.Field of vision 2.Visual acuity 3.Colour perception Which of the above aspects are correct?
- A1 and 2 only
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3Correct
Solution
Concept
Vision is the most important road user characteristic. Field of vision, visual acuity and colour perception all affect driver behaviour.
Step-by-step solution
1. Field of vision (peripheral vision) lets the driver see objects on the sides of the road. 2. Visual acuity is clear vision in a narrow cone (about 3° to 5°). It is needed to read signs and see hazards. 3. Colour perception is needed to recognise signal lights and colour-coded signs. 4. All three are important for a traffic engineer, so the answer is (D).
Explanation
Human vision is a key road user characteristic in traffic engineering. Field of vision, visual acuity, colour perception, depth perception and glare recovery are all studied when designing signs, signals and sight distances. So all three listed aspects are correct.
Why the other options are wrong
A, B and C each leave out one important aspect, but all three are important.
Shortcut
Vision factors = acuity + peripheral vision + colour + depth + glare recovery. All are important.
Common mistake
Thinking colour perception does not matter. In fact signals and signs depend on colour.
Correct answer: D) 1, 2 and 3