THE STATE-OF-THE-PRACTICE IN NORTH CAROLINA--PART II

This paper outlines current state-of-the-practice for pavement design in North Carolina. Normal pavement design for rigid pavement is an 8-in. (20-cm) continuously reinforced concrete pavement with a one-directional cross-slope toward the outside. A continuous drain is used along the low side of the pavement that contains perforated pipe. The material surrounding the perforated pipe is subdrain fine aggregate--concrete sand. Flexible pavement installations are used only in sag vertical curves. The drainage installation may be located on one or both sides of the pavement, depending on whether there is a crown cross-section or one-directional cross-slope. In the case of a paved shoulder, the drain is moved out to the edge of the paved shoulder. Underdrain systems for the purpose of intercepting subsurface drainage are used rather extensively in wet areas to drain subsurface water. Interceptor drains have been very effective in intercepting water that comes down from the cut before it reaches the roadway section.