Introduction -- Geophysical methods -- Information sources and general responses -- Agency practice-Methods and applications -- Agency practice-budgeting, costs, and contracting -- Agency project experience -- Conclusions and future research needs -- Glossary -- References -- Topical bibliography -- Appendices.

Geophysical methods provide a means to rapidly and economically characterize subsurface conditions and infer soil properties over a spatial extent that is not possible with conventional methods. The TRB National Cooperative Highway Research Program's NCHRP Synthesis 547: Advancements in Use of Geophysical Methods for Transportation Projects evaluates the current state of practice in the use of geophysical methods by state transportation agencies. Challenges and obstacles remain that must be overcome if routine implementation of geophysical methods for transportation projects is to be realized. Uncertainties associated with insufficient or poor site characterization can lead to overly conservative designs, increased risk of poor performance, cost increases attributable to changed conditions, and project delays.

"This circular offers an overview of 12 geotechnical geophysical methods that are commonly applied to transportation projects. Geotechnical geophysics is the application of geophysics to geotechnical engineering problems; such investigations normally extend to total depths of less than 300 ft. Geotechnical geophysical surveys are performed on the ground surface, within boreholes and water, and from the air. Using illustrations and brief examples, commonly employed geotechnical geophysical methods are described."--Page 1.