TRANSPORTATION RESEARCH Number E-C110 January 2007 Geometric Design Strategic Research TRANSPORTATION RESEARCH BOARD 2006 EXECUTIVE COMMITTEE OFFICERS Chair: Michael D. Meyer, Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta Vice Chair: Linda S. Watson, Executive Director, LYNX–Central Florida Regional Transportation Authority, Orlando Division Chair for NRC Oversight: C. Michael Walton, Ernest H. Cockrell Centennial Chair in Engineering, University of Texas, Austin Executive Director: Robert E. Skinner, Jr., Transportation Research Board TRANSPORTATION RESEARCH BOARD 2006 TECHNICAL ACTIVITIES COUNCIL Chair: Neil J. Pedersen, State Highway Administrator, Maryland State Highway Administration, Baltimore Technical Activities Director: Mark R. Norman, Transportation Research Board Christopher P. L. Barkan, Associate Professor and Director, Railroad Engineering, University of Illinois at Urbana–Champaign, Rail Group Chair Shelly R. Brown, Principal, Shelly Brown Associates, Seattle, Washington, Legal Resources Group Chair Christina S. Casgar, Office of the Secretary of Transportation, Office of Intermodalism, Washington, D.C., Freight Systems Group Chair James M. Crites, Executive Vice President, Operations, Dallas–Fort Worth International Airport, Texas, Aviation Group Chair Arlene L. Dietz, C&A Dietz, LLC, Salem, Oregon, Marine Group Chair Robert C. Johns, Director, Center for Transportation Studies, University of Minnesota, Minneapolis, Policy and Organization Group Chair Patricia V. McLaughlin, Principal, Moore Iacofano Golstman, Inc., Pasadena, California, Public Transportation Group Chair Marcy S. Schwartz, Senior Vice President, CH2M HILL, Portland, Oregon, Planning and Environment Group Chair Leland D. Smithson, AASHTO SICOP Coordinator, Iowa Department of Transportation, Ames, Operations and Maintenance Group Chair L. David Suits, Executive Director, North American Geosynthetics Society, Albany, New York, Design and Construction Group Chair Barry M. Sweedler, Partner, Safety & Policy Analysis International, Lafayette, California, System Users Group Chair TRANSPORTATION RESEARCH CIRCULAR E-C110 Geometric Design Strategic Research Transportation Research Board Geometric Design Committee Operational Effects of Geometrics Committee January 2007 Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 www.TRB.org TRANSPORTATION RESEARCH CIRCULAR E-C110 ISSN 0097-8515 The Transportation Research Board is a division of the National Research Council, which serves as an independent adviser to the federal government on scientific and technical questions of national importance. The National Research Council, jointly administered by the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine, brings the resources of the entire scientific and technical communities to bear on national problems through its volunteer advisory committees. The Transportation Research Board is distributing this Circular to make the information contained herein available for use by individual practitioners in state and local transportation agencies, researchers in academic institutions, and other members of the transportation research community. The information in this Circular was taken directly from the submission of the authors. This document is not a report of the National Research Council or of the National Academy of Sciences. Design and Construction Group L. David Suits, Chair Design Section Elizabeth Hilton, Chair Geometric Design Committee Brian L. Ray, Chair Reza Amini James L. Gattis, II Basil M. Psarianos Don T. Arkle Elizabeth Hilton Jennifer A. Rosales James O. Brewer Karen B. Kahl Norman H. Roush Salvatore Cafiso Joel P. Leisch Joe Wilson Ruffer Richard C. Coakley David R. McDonald, Jr. John Francis Smart Daniel L. Dawson John M. Mason, Jr. Larry Francis Sutherland Karen Dixon Rebecca L. Mowry Mark B. Taylor Eric T. Donnell Mousa Nazif Barton A. Thrasher Ingrid B. Potts Stephen F. Maher, Senior Program Officer Michael DeCarmine, Senior Program Associate Operational and Maintenance Group Leland D. Smithson, Chair Operations Section Daniel S. Turner. Chair Operational Effects of Geometrics Committee Raymond A. Krammes, Chair Nicholas D. Antonucci Douglas W. Harwood Richard J. Porter Geni B. Bahar Joseph E. Hummer Wendel T. Ruff James O. Brewer Kathleen A. King Karen S. Schurr Michael Dimaiuta Keith K. Knapp Larry J. Shannon Eric T. Donnell John J. Nitzel John Francis Smart Paul W. Dorothy Angelia H. Parham Richard W. Stafford Duane S. Eitel Karl Passetti Daniel S. Turner Kay Fitzpatrick Christopher Poe Richard A. Cunard, Senior Program Officer Freda R. Morgan, Senior Program Associate Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 www.TRB.org Jennifer Correro, Proofreader and Layout Contents Part 1: Background........................................................................................................................1 Part II: Research Implementation Plan.......................................................................................5 Part III: Research Problem Statements.......................................................................................8 Median Design and Barrier Considerations for High-Speed Divided Highways in Rural and Urban Areas ..........................................................................8 Performance-Based Geometric Design Analysis....................................................................11 Multimodal Design to Create “Complete Streets”..................................................................14 Investigation of Alternative Geometric Design Highway Design Processes: Strategic Research ..................................................................................................................16 Horizontal Curve Design Philosophy .....................................................................................26 Right-Turn Interactions and Channelized Right Turns ..........................................................28 Ramp and Interchange Spacing ..............................................................................................31 Transition Zones: Design from High-Speed to Low-Speed Rural Sections...........................32 Ramp Design as a System.......................................................................................................34 Safety and Operational Tradeoffs of Freeway Lane and Shoulder Widths............................36 Safety, Operations, and Usability Tradeoffs Between User Groups at Intersections.............38 Operational and Safety Impacts of Four- and Six-Lane Sections with Raised Medians Versus Two-Way Left-Turn Lanes..............................................................40 Superelevation Criteria for Steep Grades on Sharp Horizontal Curves .................................41 Geometric Design Guidelines for Major Intersection Alternatives to Accommodate Multimodal Users.......................................................................................43 Design, Safety, and Operation Considerations of Pedestrian Treatments at Intersections.....................................................................................................46 One- and Two-Way Ramp Loop Design................................................................................48 Effectiveness of Various Midblock Crossing Treatments......................................................50 Intersection Design to Accommodate Pedestrian Crosswalk Cross-Slope.............................52 Guidelines for the Provision of Sidewalks .............................................................................54 Safety Effects of Intersection Skew Angle.............................................................................56 Accommodating Bicycles on Rural Highways.......................................................................59 Operational and Safety Impacts of Angle Versus Parallel Versus Back-In Parking..............62 Appendix A: Combinations of Design Controls and Elements................................................65 Ingrid Potts, Midwest Research Institute Research Topics......................................................................................................................65 Related Research and Literature.............................................................................................65 Cross-Section Elements..........................................................................................................66 Horizontal Curve Design ........................................................................................................71 i Sight Distance.........................................................................................................................72 Breakout Group Notes............................................................................................................74 Appendix B: User and Vehicle Controls....................................................................................84 Douglas Harwood, Midwest Research Institute Design Controls Related to Human Operator Characteristics and Capabilities .....................84 Design Controls Related to Accommodating the Current Vehicle Fleet................................86 Multimodal Highway Design: Enhancing the Design Process to Balance the Needs of All Travel Modes in the Highway Right-of-Way................................88 Breakout Group Notes............................................................................................................89