This research project, "Dynamic Bridge Substructure Evaluation and Monitoring, " was sponsored by the Federal Highway Administration (FHWA) under contract number DTFH61-96- C-00030. The research was funded to investigate the possibility that by measuring and modeling the dynamic response characteristics of a bridge substructure, one could determine the condition and safety of the substructure and identify its foundation type (shallow or deep). Determination of bridge foundation conditions with this approach may be applied to quantify losses in foundation stiffness caused by earthquake, scour, and impact events. Identification of bridge foundation type may be employed to estimate bridge stability and vulnerability under dead and live load ratings, particularly for unknown bridge foundations. Chapter 2 introduces the research project scope and presents the results of a literature review of related topics. Chapter 3 describes the bridges in Texas that were selected for modal vibration tests during the research.