The objective of this study is to provide FHWA and professional practice in the United States with timely information on four key topics related to roundabouts: Quantifying the effectiveness of RRFBs in providing accessible crossings for pedestrians with vision disabilities at roundabouts; collecting data from a large national sample to calibrate and/or update capacity models for assessing the operational performance of roundabouts; assessing tools to evaluate environmental performance of roundabouts; and evaluating fatal and severe injury crashes at roundabouts to determine potential contributory factors.