The pebbled, uneven surface is easier to see.
Work Step by Step
Light from your headlights reflecting back to your eyes lets you see the road. As Figure 28.10 illustrates, diffuse/specular reflection from a rough surface is more likely to bounce back toward the light source. This partially explains the difficulty of driving a rainy night, when the road is covered with water and reflects light like a mirror does. The mirror-smooth surface reflects your headlights forward, mostly annoying oncoming drivers, and not helping you see the road.