How does properly designed drainage benefit highway construction?

Answer: B — It prevents soil erosion and maintains road stability

Properly designed drainage is crucial in highway construction because it effectively prevents soil erosion and maintains road stability. When rainwater is not adequately channeled away from the roadway, it can saturate the soil around and beneath the pavement. This saturation can lead to erosion, which compromises the structural integrity of the road, potentially causing surface failures such as cracking, potholes, and buckling. Additionally, by managing water runoff efficiently, drainage systems help to maintain the compactness of the underlying soil. This is essential for the stability of the roadway, as unstable base conditions can lead to further complications, including alignment issues and the need for costly repairs. The overall longevity and safety of the roadway are improved as a result of effective drainage management, ensuring that the highway performs reliably under various weather conditions. In contrast to alternatives like reducing construction costs, allowing for parking, or causing traffic jams, the primary function of drainage in highway construction revolves around safeguarding the road structure from water-related damage. Proper drainage directly influences the highway's durability and safety, making it clear why maintaining effective drainage solutions is vital.