ENGINEERING GEOLOGY’S ROLE IN REOPENING VERMONT’S TRANSPORTATION INFRASTRUCTURE IN RESPONSE TO CLIMATE CHANGE

The increasing intensity of weather impacts in Vermont is increasing the stress to the aging transportation infrastructure system. Rock slides, debris flows, embankment failures and flooding and other geohazards are producing more damage, causing extended closures, delaying emergency responders, and inconveniencing the traveling public. Heavy, intense rainfall events and more extreme freeze-thaw cycles are two forms of weather-related stress that increasingly affect the stability of rock and soil slopes. To reopen these corridors, engineering geology plays a vital role in supporting emergency response to reopen the roadways (temporarily or partially), to develop initial mitigation alternatives, select a permanent design and support construction of that design. Basic engineering geology field skills are vital to support these tasks; a thorough understanding of a combination of structural geology, surficial geology, geohazards, geotechnical engineering, mineralogy, petrology, hydrogeology, meteorology, and physics are necessary for each response. The process involves using several mapping tools, ranging from structural geologic mapping to aerial drone inspection to 3D terrestrial/airborne LiDAR data analysis to evaluate potential mitigation strategies, followed by more detailed mapping and analysis to develop a final design and provide support during construction. Four recent slope failures due to intense rainfall and freeze-thaw events in Vermont highlight the skills, tools and processes used to reopen the roadway infrastructure.