What is a primary advantage of creating roadways parallel to the slope?

Creating roadways parallel to the slope provides several advantages, among which improved drainage is particularly significant. When roads are aligned with the natural contours of the slope, they can facilitate the natural movement of water, allowing for effective runoff management. This alignment helps in directing the flow of water away from the roadway, reducing the risk of erosion and water accumulation on the road surface.

Additionally, by following the slope's gradient, these roadways may align better with surrounding topography, which can further enhance drainage systems and minimize issues related to water pooling or flooding. In contrast, roadways built across slopes can lead to drainage challenges, where water collects rather than flows away, potentially causing damage to the roadway and surrounding areas.

While options such as building height, access between roads and bridges, and the necessity for retaining walls have their own considerations, the primary benefit associated with creating roads in harmony with slopes is the effective management of drainage, ensuring the longevity and safety of the roadway system.