Briefly describe the five characteristics of visual reception relevant to transportation engineering.

Question

What will be an ideal response?

Answer 1

Visual acuity: the ability to see fine details of an object. It can be represented by the visual angle, which is the reciprocal of the smallest pattern detail in minutes of arc. The ability to resolve a pattern detail with a visual acuity of 5’ of arc (1/12 of a degree) is considered the normal vision acuity (20/20 vision).
Peripheral vision: the ability of people to see objects beyond the cone of clearest vision. Although objects can be seen within this zone, details and color are not clear.
Color vision: the ability to differentiate one color from another. Deficiency in this ability, usually referred to as color blindness, is not of great significance in highway driving because other ways of recognizing traffic information devices (e.g., shape) can compensate for it.
Glare vision and recovery: there are two types of glare vision: direct and specular. Direct glare occurs when relatively bright light appears in the individual’s field of vision and specular glare occurs when the image reflected by the relatively bright light appears in the field of vision. Both types of glare result in a decrease of visibility and cause discomfort to the eyes.
Depth perception: affects the ability of a person to estimate speed and distance. It is particularly important on two-lane highways during passing maneuvers, when head-on crashes may result from a lack of proper judgment of speed and distance.