Why talk about roads?

While there are already many good publications available on this subject, I felt the need to highlight some of the commonly overlooked and neglected issues that plague our gravel and soil surface roads here in western Oregon. I believe that a properly maintained road will function better and cost less in the long run than rehabilitating a neglected road.

What is a road?

The definition of a road may seem elementary, but it is extremely important to understand and recognize the characteristics of a “good” road. A road is a roof designed to support the movement of vehicles and equipment over the earth. I use the term “roof” to emphasize the need of a road to deal with water. In some parts of the world water may not be a big factor in road design, but in western Oregon most of the problems I see with roads are water related.

How does a road act like a roof?

First, by controlling the geometric shape of the road surface, shoulder and ditch. Crown, outslope and inslope are the three main geometric road designs used to get water off the road. This water must then be directed to a ditch or down away from the road. The ditch acts as a gutter does on a roof, and culverts are akin to downspouts.

Second, the road surface must be effective at shedding water and not absorb it.

How do we support the movement of vehicles and equipment?

Gravel, but not just any gravel. To determine what gravel we first must understand its functions. First, gravel provides a medium for tires to grip and propel a machine. Second, gravel distributes the weight of a tire over a larger area. Third, the gravel acts as a roofing material, shedding water. On dirt roads we are generally limited to traffic only during dry periods.

Please see my other road pages for more information on ditches, potholes, corrugation, gravel, and maintenance.