Define "cross slope" in road design.

Cross slope in road design refers to the intentional slope constructed across the road surface to promote effective drainage of water. This design feature is critical because it helps direct water away from the roadway and into adjacent drainage systems or ditches, thereby reducing the risk of water accumulation, which can lead to hydroplaning and surface damage over time.

The appropriate cross slope is essential in maintaining roadway safety and integrity, as it actively helps in minimizing issues related to excessive water on the road, such as erosion or reduced friction. This function of cross slope is a fundamental principle in civil engineering and roadway design, ensuring that highways remain safe and durable under various weather conditions.