A study to collect and analyze field measurements of bridge scour is being conducted by the U.S. Geological Survey in cooperation with the Federal Highway Administration. The primary objective of this study is to collect measurements of bridge scour as it occurs during floods to improve the ability to understand and predict scour processes. Scour measurements are classified as limited or detailed depending on the range of information to be collected. Many scour measurements were obtained during floods in 1990. A data-base system is being developed to assist in documentation, compilation, and analysis of these data. Scour measuring instrumentation and techniques have been and continue to be developed in this study. The study will provide data needed to improve the understanding and prediction of scour processes.