Road User Characteristics in Traffic Engineering

Road users have an important role in traffic. They take up the role of driver, pedestrians, cycles etc. The physical, mental and psychological factors are the main road user characteristics that govern the safe operation of the vehicle on the road.

Below described are the important road user characteristics studied in traffic engineering.

Road User Characteristics

The important road user characteristics are:

  1. Physical Characteristics
  2. Mental Characteristics
  3. Psychological Characteristics
  4. Environmental Characteristics

1. Physical Characteristics

Vision, hearing, strength and the reaction of the road user are the important physical characteristics that are studied in traffic engineering.


The field of vision includes acute or clear vision cone, fairly clear vision cone and peripheral vision cone as shown in the figure below.

Field of Vision
Fig.1. Field of Vision
  1. Acute or clear vision cone: This vision is around 3 to 10 degrees around the line of site.
  2. Fairly clear vision cone: This vision is at 10 to 12 degrees around the line of sight. A vision in this field can identify the color and shape.
  3. Peripheral Vision: This field of vision extends up to 90 degrees to the right and left of the centerline of the pupil, as shown in figure-1. It also extends above and below the line of sight by 60 and 70 degrees respectively. A peripheral vision does not show stationary objects. It only detects the movement of objects within this field.


Hearing characteristics is more important for pedestrians and cycles when compared with drivers.


This is a less important characteristic compared with others. The lack of strength makes it difficult to park heavy vehicles.

2. Mental Characteristics

The important mental characteristics of the road user include skill, intelligence, experience, knowledge and literacy. Proper knowledge on the vehicle characteristics, driving practices, rules of roads and traffic behavior is necessary for safe traffic operations.

3. Psychological Factors

Psychological factors affect the reaction of the road user to traffic situations. These reactions include anger, fear, superstition, impatience, anxiety, etc. This affects traffic performance.

4. Environmental Factors

Atmospheric conditions, traffic facilities, the traffic stream characteristics are the various environmental factors that govern the behavior of the road. The traffic stream can be heavy traffic or mixed traffic which may limit the ability to overtake. Hence, the behavior of the road user changes with the traffic streams.

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