What are some examples of roadside elements requiring horizontal clearance?
Curbs, walls, barriers, piers, sign and signal supports, mature trees, landscaping items, and power poles are primary examples of the type of features that can affect a driver’s speed or lane position if located too close to the roadway edge. Other specific examples can be found in the Cross Section Elements, Local Roads and Streets, Collector Roads and Streets, Rural and Urban Arterials, Freeways, and Intersections chapters of the Green Book. The AASHTO A Policy on Design Standards – Interstate System also contains a discussion on horizontal clearance in the section Horizontal Clearance to Obstructions.
