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. This report updates the U.S. Federal Highway Administration's Roundabouts: An Informational Guide, based on experience gained in the United States since that guide was published in 2000.

This report examines the quality of state crash information; the activities states undertook using 411 grant funds to improve their traffic safety data systems, and the progress they made using the grant funds; and NHTSA's oversight of the grant program

"The Highway Safety Manual (HSM) is a resource that provides safety knowledge and tools in a useful form to facilitate improved decision making based on safety performance. The focus of the HSM is to provide quantitative information for decision making. The HSM assembles currently available information and methodologies on measuring, estimating and evaluating roadways in terms of crash frequency (number of crashes per year) and crash severity (level of injuries due to crashes). The HSM presents tools and methodologies for consideration of 'safety' across the range of highway activities: planning, programming, project development, construction, operations, and maintenance. The purpose of this is to convey present knowledge regarding highway safety information for use by a broad array of transportation professionals"--p. xxiii, vol. 1.

The manual provides guidance to State and local agencies for developing and implementing a highway safety improvement program which best suits their capabilities and needs. The manual should be beneficial to Federal, State, and local highway engineers and other professionals involved in a highway safety improvement program. The manual describes how to: 1. Implement a highway safety improvement program which complies with Federal-Aid Highway Program Manual 8-2-3 and which contains the following components and processes: Planning (collect and maintain data, identify hazardous locations and elements, conduct engineering studies and establish project priorities) Implementation (schedule and implement projects) Evaluation (determine the effect of safety improvements) 2. Select the most appropriate procedures based on an agency's particular goals, objectives, resources, and highway system. 3. Utilize current information concerning reporting requirements, funding sources, and practices of other highway agencies.