NCHRP Report 672 Roundabouts: An Informational Guide Second Edition

• Published by:  NCHRP
• Authored by:  L. Rodegerdts

TRB’s National Cooperative Highway Research Program (NCHRP) Report 672: Roundabouts: An Informational Guide – Second Edition explores the planning, design, construction, maintenance, and operation of roundabouts. The report also addresses issues that may be useful in helping to explain the trade-offs associated with roundabouts.

Publication of the FHWA Roundabout Guide in 2000 has fostered acceptance of the roundabout as a viable alternative for intersection design, leading to more than 2,000 roundabouts across the United States. Extensive use of the Roundabout Guide and completion of national and state research efforts identified many possible improvements. Recognizing this, the NCHRP and the FHWA jointly funded an NCHRP project to update the Roundabout Guide. In NCHRP Project 3-65A, Kittelson & Associates, Inc., reviewed the literature and research conducted since the publication of the FHWA Roundabout Guide. They then conducted focus groups of practitioners to identify concerns with the original guide and ideas for improvements. After achieving consensus with the project oversight panel on an outline, they developed the new guide and refined it through an extensive review process. The Second Edition of Roundabouts: An Informational Guide will be useful to anyone interested in evaluating or building a roundabout. The experience of the research team, coupled with the extensive review, has led to an authoritative, but not prescriptive, guide on roundabouts.