Geotechnical and transportation engineering research at Washington State University merges geotechnics and pavement mechanics to provide solutions to infrastructure problems. The geotechnical engineering research program encompasses both traditional and emerging topics in the fields of geomechanics and geology and focuses on the behavior of natural materials in engineered systems. This active program involves fundamental and applied research using analytical, numerical, and experimental methods. The pavement engineering research program focuses on developing innovative, economical, and reliable technologies for highway and airport pavements. It involves characterizing and modeling the entire pavement structure from surface to base course and incorporating various paving materials including asphalt material, concrete material, aggregates, recycled materials, and subgrade soils. Emphasis is given to both fundamental theories and practical applications in design, construction, and rehabilitation of the transportation infrastructure. Geotechnical and transportation engineering research programs have been supported by funds from the National Science Foundation, US Geological Survey, US Department of Transportation (DOT), Washington State DOT, Federal Highway Administration (FHWA), National Cooperative Highway Research Program (NCHRP), US Department of Energy, and private industries.