The correct answer is: D. half the longitudinal gradient.
Camber is the slope of a road from the center to the sides. It is designed to help water drain off the road and to keep cars from hydroplaning. The amount of camber is typically between 0.5% and 2%.
Longitudinal gradient is the slope of a road from one end to the other. It is typically expressed as a percentage, such as 1%. A 1% gradient means that the road rises 1 foot for every 100 feet of horizontal distance.
The camber of a road should be approximately equal to half the longitudinal gradient. This helps to ensure that water drains off the road evenly and that cars do not hydroplane.
If the camber is too high, water will not drain off the road properly and cars may hydroplane. If the camber is too low, water will pool on the road and create a hazard for drivers.
The camber of a road is typically designed by engineers based on the road’s location, the type of traffic it will carry, and the climate in which it is located.