What primarily determines the alignment of roads on a site?

The alignment of roads on a site is primarily determined by site topography. The natural contours, slopes, and elevation changes of the landscape are critical factors that influence how roads can be designed and positioned. Roads need to follow the terrain to ensure safe and efficient travel; this includes considerations such as minimizing steep grades, avoiding erosion, and maintaining proper drainage.

Topography also impacts the costs associated with road construction. For example, building a road on a flat surface generally requires fewer resources and results in less disruption compared to constructing a road on a steep hillside. Additionally, the topography will influence sightlines and visibility for drivers, which are essential for safety.

While local vegetation patterns, proximity to commercial areas, and historical land use can all play roles in the planning process, they are often secondary to the more fundamental requirements set by the site’s topographical characteristics. Vegetation may be preserved or cleared based on how the roads are aligned, and commercial areas may dictate routing decisions, but those decisions are frequently constrained or shaped by the land's physical features.