Improving Performance Through Consideration of Terrain Conditions: Soils, Drainage, and Climate

Inadequate drainage of surface and subsurface water can have significant impact on pavement behavior and long-term maintenance costs. Interception of water before it infiltrates into the pavement foundation is essential unless the soils are truly free draining. Even then, there can be potential damage by frost action. Identification of seepage zones and surface runoff characteristics based on terrain conditions such as soils and geology can aid in the selection of a suitable road alignment and design to minimize future problems. However, most moisture–soil-related pavement performance problems are observed and corrected after construction of the facility. Case history examples of moisture damage were examined that relate to seepage from culverts, perched water tables, weathered zones in sedimentary rock, permeable glacial deposits, and ponded water. Construction defects and the effect of soil suction and exudation of water into the pavement structure were evaluated. With emphasis on inadequate surface and subsurface drainage conditions, ideas relating to improvements needed to correct deficiencies were developed.