What are the three terrain types typically considered in road design?

What are the three terrain types typically considered in road design?

• A. Level, Rolling, Mountainous
• B. Level, Flat, Mountainous
• C. Flat, Hilly, Mountainous
• D. Urban, Suburban, Rural

Answer: (A)

Terrain category is used to shape how a road is planned and built, affecting grades, sight distance, and the amount of earthwork and drainage required. The three typical types are Level, Rolling, and Mountainous. Level terrain is almost flat, so grades are small and alignment is straightforward, with minimal earthwork and simple drainage. Rolling terrain has gentle to moderate undulations, which means more attention to grades and vertical curves as the road climbs and descends along the terrain. Mountainous terrain features steep slopes and rapid elevation changes, driving tighter sight distances, steeper grades, numerous curves, and greater earthwork, slope stabilization, and drainage challenges. Some choices mix terms that describe land use or overlap with other terms (like flat or urban/suburban/rural), but they don’t represent the standard terrain categories used for design decisions.

Terrain category is used to shape how a road is planned and built, affecting grades, sight distance, and the amount of earthwork and drainage required. The three typical types are Level, Rolling, and Mountainous. Level terrain is almost flat, so grades are small and alignment is straightforward, with minimal earthwork and simple drainage. Rolling terrain has gentle to moderate undulations, which means more attention to grades and vertical curves as the road climbs and descends along the terrain. Mountainous terrain features steep slopes and rapid elevation changes, driving tighter sight distances, steeper grades, numerous curves, and greater earthwork, slope stabilization, and drainage challenges. Some choices mix terms that describe land use or overlap with other terms (like flat or urban/suburban/rural), but they don’t represent the standard terrain categories used for design decisions.