Geophysical Applications for Highway Infrastructure, a Retrospective-PPT Presentation

PPT Presentation

Pdf Summary

The presentation reviews how geophysical methods have improved highway site characterization, focusing on Caltrans experience and the national push to adopt underused exploration tools.<br /><br />Through the Federal Highway Administration’s Every Day Counts initiative, the Advanced Geotechnical Methods in Exploration (A-GaME) toolbox promotes methods that can reduce uncertainty, optimize subsurface investigations, and accelerate project delivery. Geophysics can complement boreholes by mapping conditions between them, extending information into unexplored areas, and helping target conventional sampling. These methods provide larger investigation coverage, denser and more continuous measurements, and useful estimates of properties such as shear-wave velocity, rippability, elastic moduli, and liquefaction potential.<br /><br />Better subsurface information can support less conservative design, more reliable cost estimates, and fewer construction surprises, while improving bids, claims defense, and construction quality control.<br /><br />The San Francisco–Oakland Bay Bridge East Span illustrates this approach. Its extensive investigation combined offshore borings and cone penetration tests with borehole logging, 2D and 3D seismic reflection, bathymetry, and sonar surveys. The geophysical data helped characterize subsurface formations and map the distribution of paleochannel sediments.<br /><br />Caltrans has progressively expanded its use of geophysics since the 1990s and incorporated guidance into its 2017 Geotechnical Manual. The presentation concludes that selective use of geophysical services can improve investigation quality and produce significant savings. In-house expertise makes routine services more cost-effective, and growing national engagement is helping advance geophysics as a standard part of infrastructure exploration.

Keywords

geophysical methods

highway site characterization

Caltrans

A-GaME toolbox

Federal Highway Administration

subsurface investigation

seismic reflection

shear-wave velocity

Bay Bridge East Span

infrastructure exploration