Chapter 3, Problem 1P

To determine

The five characteristics of visual reception relevant to transportation engineering.

Explanation of Solution

The five characteristics of visual reception relevant to transportation engineering are:

(1) Visual Acuity

(2) Peripheral Vision

(3) Color Vision

(4) Glare Vision and Recovery

(5) Depth Perception

1. Visual Acuity:

Visual Acuity is used to find very small particles of an object which reflects individual sight distance of the person to their line of vision. This is measured in united states using a Snellen eye chart. This is the standard form of a length of an exam room, which is the length in the United States.

2. Peripheral Vision:

Peripheral Vision is the capability of people to see the objects beyond the hollow surface for the clearest vision. When the driver sees a vehicle coming near to his vehicle from the side, it is known as peripheral vision. Although the object may not be clear but using the hollow surface the object can be seen up to an angle depending upon the speed of the vehicle.

3. Color Vision:

Color vision is used to differentiate from one color to another color, but inefficiency to do so is referred to as color blindness. In this color combination test, black and white and black and yellow is tried on a person eyes. These color combinations are sensitive, and are usually used in regulatory traffic signals and in warnings.

4. Glare Vision and Recovery:

Direct and specular are the two types of glare vision.

When directly bright light falls on drivers' eye like a headlight shining in the eyes of the driver than direct glare occurs. When a bright light is reflected by the image in the field of vision example windshield reflected by the sun than specular glare occurs.

When the light source is passed through the effects of glare than the time required for a person for recovery of the effects is called glare recovery.

5. Depth Perception:

It is the ability to estimate distance, speed and to see the object in three-dimensional views. It is used during turning and passing man oeuvres of a two-lane highway.