What does crown (camber) refer to in road design?

The correct answer is that crown, or camber, refers to the road slope that falls from the center to the edges. This design feature is crucial for effective water drainage. By having a slope, rainwater can flow off the road surface towards the edges, reducing the risk of water pooling in the middle of the roadway, which can lead to hydroplaning and decreased traction for vehicles. Proper camber not only enhances safety by improving visibility and control for drivers but also prolongs the life of the road by minimizing water damage and erosion.

The other options do not accurately reflect the definition of crown in road design. For instance, while the area designated for bicycles is a consideration in road planning, it does not describe the road's cross-section or slope. The height of a road above sea level pertains more to elevation and doesn't relate to the crown's function in water drainage. Lastly, the material used in road construction is about the physical components that make up the roadway, not the slope or angle of the surface itself. Understanding crown in terms of its role in drainage helps ensure safer driving conditions and better road longevity.