Factors affecting visibility of road at night time are:
i)Amount and distribution of light: The distribution should be downwards so that high percentage of light is utilized for illuminating the pavement and the adjacent area.
ii) Size of object: Small objects are less visible as compared to big objects with the reflection of light.
iii) Brightness of object: When the brightness of the object is less than the background, object appears darker than the road surface. Therefore, brightness of the object should always be more than the background.
iv) Brightness of background: Brightness of the background should be less than the brightness of the object.
v) Reflecting characteristics of pavement surface: Usually concrete roads are preferred over bituminous roads because of its good reflecting property.
vi) Glare on the eyes of driver: Artificial lights of the car, direct sunlight causes difficulty and gives impair vision.
vii) Time available to see the object: To perceive an object, the physical and mental condition of driver plays a vital role.