NEW! NCHRP Research Report 875: Guidance for Evaluating the Safety Impacts of Intersection Sight Distance is a resource for practitioners involved in the planning, design, operations, and traffic safety management of stop-controlled intersections. It provides information on how to estimate the effect of intersection sight distance (ISD) on crash frequency at intersections and describes data collection methods and analysis steps for making safety informed decisions about ISD.
Documents of type: NCHRP
TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 488: Roundabout Practices summarizes roundabout policies, guidance, and practices within state departments of transportation (DOTs) as of 2015. The synthesis may be used as a reference for state agencies that are creating or updating their roundabout and intersection control policies.
Project: Project Information
TRB’s National Cooperative Highway Research Program (NCHRP) Report 780: Design Guidance For Intersection Auxiliary Lanes expands on guidance provided in A Policy on Geometric Design of Highways and Streets (the Green Book), published by the American Association of State Highway and Transportation Officials (AASHTO). This report highlights information regarding bypass lanes, channelized right-turn lanes, deceleration and taper length, design and capacity of multiple left-turn lanes, and alternative intersection designs.
TRBs National Cooperative Highway Research Program (NCHRP) Report 650: Median Intersection Design for Rural High-Speed Divided Highways explores common safety issues at median intersections on rural divided highways, and examines innovative geometric and operational treatments for addressing those issues. The report includes ten case studies that illustrate how various treatments have been applied in the field.
This report classifies access management techniques and presents methods for estimating the safety and operational effects of the different techniques. For some techniques, quantitative assessment was not practical and case studies are presented to demonstrate good and poor practice. This report will be very useful to those developing access guidelines and policy and those analyzing specific access situations.
TRB's NCHRP Synthesis 348: Improving the Safety of Older Road Users examines programs and policies in place across the country to improve the safety and mobility of older road users. The report documents a range of strategies and related programs under way in roadway engineering, driver licensing, public information and education, and enforcement and adjudication.
Washington, S., I. Van Schalkwyck, S. Mitra, M. Meyer, E. Dumbach, and M. Zoll. NCHRP Report 546: Incorporating Safety into Long-Range Transportation Planning, Transportation Research Board of the National Academies, (2006)
Rose, D., J. Gluck, K. Williams and J. Kramer, NCHRP Report 548: A Guidebook for Including Access Management in Transportation Planning, Transportation Research Board of the National Academies, Washington, D.C. (2005)
Potts, I. B., D. W. Harwood, D. J. Torbic, K. R. Richard, J. S. Gluck, H. S. Levinson, P. M. Garvey, R. S. Ghebrial, NCHRP Report 524: Safety of U-Turns at Unsignalized Median Openings, Transportation Research Board of the National Academies, Washington, D.C. (2004)
Williams, K., NCHRP Synthesis of Highway Practice 304: Driveway Regulation Practices, Transportation Research Board of the National Academies, Washington, D.C., (2002)
This synthesis is a detailed assessment of driveway regulation practices in the U.S. it includes numerous case examples and information on all aspects of driveway regulation for access management.
Dowling, R., et.al., NCHRP Report 616, Multimodal Level of Service Analysis for Urban Streets, TRB, Washington DC, (2008)
This report presents recommended improvements for the geometric design and safety performance of at-grade intersections on expressways. In general, the operational and safety performance of these multi-lane divided highways nearly matches those of rural interstates. However, because expressways allow for stop-controlled at-grade crossings, increases in both major and minor roadway traffic volume have had a significant impact on intersection safety in recent years. The study investigated alternate safety improvements and indentified their relative effectiveness and focused on reduci
These guidelines do not establish ramp and interchange spacing standards. Rather they provide a process and criteria for assessing spacing in a given context to assist planners and designers in considering the feasibility of new or rebuilt interchanges and ramps. Interchange spacing is defined as the distance between the centerlines of successive crossroads with interchanges on a freeway.
Butorac, M., and J. Wen, NCHRP Synthesis 332: Access Management on Crossroads in the Vicinity of Interchanges, Transportation Research Board of the National Academies, Washington, D.C. (2004)
This study documented practices and standards relative to access location and design on the crossroads in the vicinity of interchanges, both for new interchanges and retrofit of existing interchanges. It provides guidance relative to factors that may be considered when assessing crossroad and mainline spacing near interchanges.
This document became the first national guide focused specifically on driveway design since the publication of AASHTOs An Informational Guide for Preparing Private Driveway Regulations for Major Highways in 1959. Since 1959, the transportation system and its needs have changed drastically, and this report addresses the need for a comprehensive driveway design guide that accounts for vehicles, pedestrians, and bicyclists. The report identifies more than 90 design elements that directly or indirectly affect the geometric design of a driveway or access point.
S. Smith. NCHRP Report 435: Guidebook for Transportation Corridor Studies: A Process for Effective Decision-Making, Transportation Research Board of the National Academies, Washington, D.C. (1999)
Williams, K., NCHRP Synthesis 337: Cooperative Agreements for Corridor Management, Transportation Research Board of the National Academies, National Academy Press: Washington, D.C. (2004)
This report reviews the state of the practice in developing and implementing cooperative agreements for corridor management, elements of such agreements, and best practices or lessons learned. It includes several case examples of cooperative agreements. Below are a few excerpts from the report relative to effective agreements.
The objective of this synthesis was to summarize the key findings of various geometric design research efforts published in the 1990s. In the decade following the publication of the 1990 edition of AASHTOs A Policy on Geometric Design of Highways and Streets (also known as the Green Book), the research community conducted a large amount of research with potentially significant implications on safety and operations. The primary goal of this synthesis was to capture and distribute that information for consideration in the development of the 2004 edition of the Green Book.
TRBs 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.