Contents

# Traffic Engineering

The basic objective of traffic engineering is to achieve free & rapid flow of traffic with least no of accidents. For this various studies are carried out. These studies are divided into

# Traffic Characteristics

In traffic characteristics, we generally study

2. Vehicular Characteristics
3. Breaking Characteristics

1. Physical: Vision, hearing, strength and General reaction to traffic situation.
2. Mental: Knowledge, skill, experience, intelligence.
3. Psychological: Fear, anger, impatience, maturity.
4. Environmental: Facilities to the traffic, atmospheric condition and locality.

### Vision

$$vision = \frac{x}{y}= \frac{\text{Actual distance}}{\text{Requried distance}}$$

6/6 Vision / Normal Vision: It is an ability of a person to recognize a letter of size 8.5 mm at a distance of 6m.

6/9 Vision / Poor Vision: This vision is poorer then normal vision because he can recognize at a distance of 6 m but a Normal person can recognize at a distance of 9 m.

NOTE: Concept of 6/6 and 6/9 vision used to design of location of sign board.

## B. Vehicular Characteristics

In vehicular characteristics, we generally study

1. Dimension
3. Power of Vehicle
4. Speed of Vehicle

### Dimension

• Length of vehicle affects turning radius, extra widening, parking design etc. (Maximum length 18 meter)
• Width of vehicle affects lane width, shoulder width and parking design.  (Maximum width 2.44 meter)
• Height of vehicle affects height of bridges, height of pole, etc. (Maximum height 4.75 meter)

Weight affects design gradient & thickness of pavement. ### Power of Vehicle

It affects limiting & design value of gradient.

### Speed of Vehicle

It affect all geometrical element & traffic control devices.

## C. Breaking Characteristics

At least two of the following three parameters are needed during the breaking test in order to determine skid resistance of pavement. • initial speed (u m/s)
• length of skid distance (L meter)
• Time of break application (t sec)

### ⇒ Retardation

v-u = at

(v=o)

-u= at

-a= u/t

Retardation =$$\frac{\text{initial speed}}{\text{time}}$$

### ⇒ Skid Distance

$$L=ut+\frac{1}{2}at^{2}$$.

$$a=\frac{-u}{t}$$.

$$L=ut+\frac{1}{2}\frac{-u\cdot t^{2}}{t}$$.

$$L=ut-\frac{1}{2}ut$$.

$$L=\frac{1}{2}ut$$.

$$\text{Skid distance} = \frac{1}{2}\times \text{initial speed}\times \text{time}$$.

### ⇒ Skid Resistance

v2 = u2 +2aL (v=0)

u2= -2aL

$${L=\frac{u^{2}}{-2a}}$$…..(i)

Δ KE = workdone

$$-\frac{1}{2}mu^{2}=-m\cdot g\cdot f\cdot L$$.

$$L=\frac{u^{2}}{2gf}$$…..(ii)

from eq  i & ii.

(-a)= gf

$$f=\frac{-a}{g}$$.

$$\text{Skid Resistance} = \frac{\text{Retardation}}{\text{accelaration due to gravity}}$$

### ⇒ Breaking Efficiency

$$\eta _B= (\frac{f_\text{obtained}}{f_\text{max}}\times 100)$$.

$$f_\text{obtained} =\frac{u^{2}}{2gL}$$

### 2 thoughts on “Traffic Engineering – Traffic Characteristics”

1. AKASH SUNDRIYAL

sir please ab phle Environment engineering cover kr degea. or uske baad fluidkyuki inka weightage jada h

1. sorry bhai mai akela person hu es liye time lg jata h

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