Roundabout Design

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Truckee Roundabout Photo
Roundabout in Truckee


Caltrans Highway Design Manual Topic 405.10 - Roundabouts

Roundabout intersections on the State highway system must be developed and evaluated in accordance with National Cooperative Highway Research Program (NCHRP) Report 672 entitled “Roundabouts: An Informational Guide, 2nd ed.” (NCHRP Guide 2) dated October 2010 and Traffic Operations Policy Directive (TOPD) Number 13-02. See also Index 401.5 for general information and guidance. See Figure 405.10 Roundabout Geometric Elements for nomenclature associated with roundabouts. Signs, striping and markings at roundabouts are to comply with the California MUTCD.

Caltrans Traffic Operations Policy Directive (TOPD) Number 13-02

This directive updates the evaluation procedures used to:

  • Justify the installation of traffic signal systems, yield-control (roundabouts), and multi-way stop
    control at state highway intersections and interchanges.
  • Identify effective intersection traffic control strategies and alternative treatments, strategies and
    configurations for particular conditions.
  • Estimate the relative effectiveness, impacts and utility of specific control strategies.

National Cooperative Highway Research Program (NCHRP) Report 672 “Roundabouts: An Informational Guide

This report updates the FHWA’s Roundabouts: An Informational Guide based on experience gained in the United States since that guide was published in 2000. The report addresses the planning, design, construction, maintenance, and operation of roundabouts. It also includes information that will be useful in explaining to the public the trade-offs associated with roundabouts. This 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.


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Updated: September 8, 2015