This technical summary is designed as a reference for State and local transportation officials, Federal Highway Administration (FHWA) Division Safety Engineers, and other professionals involved in the design, selection, and implementation of roundabouts. Its purpose is to provide an overview of safety considerations in the design, implementation, and operation of roundabout intersections in urban, suburban, and rural environments where design considerations can vary as a function of land uses, travel speeds, volumes of traffic by mode (e.g., car, pedestrian, or bicycle), and many other variables. This technical summary explores the characteristics of modern roundabouts while reinforcing the need to apply a principles-based approach to design. It provides readers with an overview of the key considerations for planning, analysis, and design of single-lane and multilane roundabouts. Section 1 of this document summarizes the characteristics of roundabouts. Section 2 presents benefits of roundabout intersections compared to traditional signalised and/or stop-controlled intersections. Sections 3-6 provide an overview of user, location, operational and design considerations respectively. The information presented in this summary outlines the principles described in the FHWA document Roundabouts: An Informational Guide and the forthcoming 2nd Edition of that document (hereafter referred to as the Roundabout Guide), which is in progress at the time of this writing and due to be published in 2010. Specific considerations for mini-roundabouts are summarized in a separate FHWA document titled Mini-Roundabouts Technical Summary. Figures are from the Roundabout Guide unless otherwise noted. This publication does not supersede any publication; and is a Final version. (Author/publisher)
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