Semi-Annual "Program Progress Performance Report (PPPR)" from the US DOT Tier 1 University Transportation Center for Underground Transportation Infrastructure (UTC-UTI) covering work done during the period April 2018 to September 2018. The report summarizes the status of our research and our accomplishments in terms of student activities, outreach, leveraging US DOT funding, faculty and researchers' accomplishments, products such as publications and websites, participants and collaborators, and the impact of our work.