University of California Institute of Transportation Studies

Many rural county road networks were created at a time when funding was greater and rural populations were often larger than they are today. Eventually, surface treatments such as chip seals or thin asphalt were applied to many of these gravel roads to provide them with an all‐weather surface. These treated surfaces were also desirable because conventional gravel roads are dusty, often develop wash boarding quickly, and have high rates of gravel loss—which result in unsafe and uncomfortable conditions and greater damage to vehicles and crops. A solution to this problem is called ‘unpaving using engineered gravel roads’.