Correct option is C
Pavement surface characteristics:- For safe and comfortable driving four aspects of the pavement
surface are important:
1. The friction between the wheels and the pavement surface,
2. An unevenness of the road surface.
3. The light reflection characteristics of the top of the pavement surface, and
4. Drainage to water.
Friction:- Friction between the wheel and the pavement surface is a crucial factor in the design of
horizontal curves and thus the safe operating speed. Further, it also affects the acceleration and
deceleration ability of vehicles. Lack of adequate friction can cause the skidding or slipping of vehicles.
• Skidding happens when the path travelled along the road surface is more than the circumferential
movement of the wheels due to friction.
• Slip occurs when the wheel revolves more than the corresponding longitudinal movement along the road.
Unevenness:- The Unevenness index is a measure of unevenness which is the cumulative measure of
vertical undulations of the pavement surface recorded per unit horizontal length of the road.
• An unevenness index value less than 1500 mm/km is considered as good, a value less than 2500 mm/km is satisfactory up to a speed of 100 kmph, and values greater than 3200 mm/km are considered as uncomfortable even for 55 kmph.
Light Reflection:- White roads have good visibility at night but caused glare during day time.
• Black roads have no glare during the day but have poor visibility at night
• Concrete roads have better visibility and less glare
• It is necessary that the road surface should be visible at night and the reflection of light is the factor that answers it.
DRAINAGE:- The pavement surface should be absolutely impermeable to prevent seepage of water
into the pavement layers. Further, both the geometry and texture of the pavement surface should help in draining out the water from the surface in less time
