Road user Characteristics (Traffic Characteristics)

Hi,

According to S.K.Khanna and S.E.G.Justo from book Highway Engineering, Traffic Engineering is the branch of engineering which deals with the improvement of the traffic performance of road networks and terminals.
 For achieving that we have to perform systematic traffic studies, analysis and then its engineering application.

First of the most important scientific study is the study of the traffic characteristics. Traffic can be classified into two classes:

1. Road Users.
2. Vehicular traffic.

In this post I will discuss the road user characteristics that effect the traffic performance.

• Road user characteristics

Human beings performing different roles in the traffic are most important elements of the traffic and so we have to study their characteristics and behavior. Various roles of human are such as driver, pedestrians, cyclists etc. The physical, mental and emotional characteristics of human beings affect their ability to operate motor vehicle safely or to service as a pedestrian. Hence it is important for a traffic engineer to study the characteristics and limitations of the road users.

The various factors which affect road user characteristics may broadly be classified under four heads:

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

• Physical characteristics: The permanent physical characteristics of the driver are vision, hearing, strength and the general reaction to the traffic situations. 

1. Vision include the acuity of vision, peripheral vision and eye movement; glare vision, glare recovery and depth judgement.  Field of accurate, clear vision is about a 3 degrees cone however the vision is fairly satisfactory up to 10 degrees in general and 20 degrees in horizontal plane.In vertical plane the vision may be limited to 2/3 of that in horizontal plane.
2. Hearing is helpful for drivers but of more important for the pedestrians and cyclists. 



Road users (Google images)

3. Strength is not an important factor in general , lack of strength may make parking maneuvers difficult, particularly for heavy vehicles.

• Mental Characteristics:  Knowledge, skill, intelligence, experience and literacy can affect the road user characteristics. Knowledge of vehicle characteristics, traffic behavior, driving practice, rules of roads and psychology of road users will be quite useful for safe traffic operations. 
• Psychological factors: These effect reaction to traffic situations of road users to a great extent. Attentiveness, anger, fear, anxiety, phobias, superstition, and impatience may effect the traffic performance to great extent. 
• Environment factors: The various environmental conditions affecting the behavior of road user are traffic stream characteristics, facilities to the traffic, atmospheric conditions and locality. The traffic stream may consist of mixed traffic or heavy traffic whereas facilities to overtake to the faster vehicles may be limited. The behavior of the driver varies from one traffic stream to another. 

Similarly the facilities of the traffic separators, multi-lanes etc will effect the performance. Surrounding environment effect the performance of the traffic because one will get slower at the market places and will be faster at the open places.