RURAL EXPRESSWAY INTERSECTION SYNTHESIS OF PRACTICE AND CRASH ANALYSIS Sponsored by the Iowa Department of Transportation (CTRE Project 03-157) Final Report October 2004 Disclaimer Notice The opinions, fi ndings, and conclusions expressed in this publication are those of the authors and not necessarily those of the Iowa Department of Transportation. The sponsor(s) assume no liability for the contents or use of the information contained in this document. This report does not constitute a standard, specifi cation, or regulation. The sponsor(s) do not endorse products or manufacturers. About CTRE/ISU The mission of the Center for Transportation Research and Education (CTRE) at Iowa State Uni- versity is to develop and implement innovative methods, materials, and technologies for improv- ing transportation effi ciency, safety, and reliability while improving the learning environment of students, faculty, and staff in transportation-related fi elds. Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. CTRE Project 03-157 4. Title and Subtitle 5. Report Date Rural Expressway Intersection Synthesis of Practice and Crash Analysis October 2004 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. T. H. Maze, Neal R. Hawkins, and Garrett Burchett 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Center for Transportation Research and Education Iowa State University 11. Contract or Grant No. 2901 South Loop Drive, Suite 3100 Ames, IA 50010-8634 12. Sponsoring Organization Name and Address 13. Type of Report and Period Covered Iowa Department of Transportation Final Report 800 Lincoln Way 14. Sponsoring Agency Code Ames, IA 50010 15. Supplementary Notes This report is available in color at www.ctre.iastate.edu 16. Abstract This report presents a national synthesis of rural expressway, two-way stop -controlled (TWSC) intersection safety strategies and intersection designs and an analysis of Iowa expressway TWSC intersection crash characteristics. A rural expressway is a multi-lane highway with a divided median and with mostly at -grade intersections, although some intersections may be grade separated. The synthesis of intersection strategies is conducted in two parts. The first is a literature review and the second part is a national survey of strategies currently being applied by state transportation agencies. The characterization of crash patterns at TWSC expressway intersections is examined through the analysis of 5 years of crash data at 644 intersections. 17. Key Words 18. Distribution Statement crash characteristics—expressway—intersections— intersection design—traffic safety—safety performance functions No restrictions. 19. Security Classification (of this 20. Security Classification (of this 21. No. of Pages 22. Price report) page) Unclassified. Unclassified. 115 NA RURAL EXPRESSWAY INTERSECTION SYNTHESIS OF PRACTICE AND CRASH ANALYSIS Principal Investigator T. H. Maze Professor, Department Civil, Construction and Environmental Engineering Iowa State University Co-Principal Investigator Neal R. Hawkins Associate Director of Traffic Operations Center for Transportation Research and Education Iowa State University Research Assistant Garrett Burchett Center for Transportation Research and Education Iowa State University Center for Transportation Research and Education Iowa State University 2901 Loop Drive, Suite 3100 Ames, IA 50010-8632 Phone: 515-294-8103 Fax: 515-294-0467 www.ctre.iastate.edu Final Report October 2004 TABLE OF CONTENTS ACKNOWLEDGMENTS ..............................................................................................XIII EXECUTIVE SUMMARY .............................................................................................XV 1. INTRODUCTION .......................................................................................................... 1 1.1 Report Organization.................................................................................................. 1 2. LITERATURE REVIEW ............................................................................................... 3 2.1 Methodology............................................................................................................. 3 2.2 Expressway Intersection Design Policy Studies ....................................................... 4 2.3 Safety impacts of intersection features ..................................................................... 7 2.4 Intersection safety modeling studies....................................................................... 10 Three-legged Intersection Model.............................................................................. 14 Four-legged Intersection Model ............................................................................... 14 2.5 Special Designs: Treatments and Innovative Technology...................................... 15 Intersection Median Width........................................................................................ 15 Median Opening Widths............................................................................................ 16 Median Left-turn Acceleration Lanes ....................................................................... 16 Offset Right- and Left-Turn Lanes............................................................................ 18 Indirect Left-turns..................................................................................................... 18 Offset T-Intersection ................................................................................................. 21 Unconventional Intersection Designs ....................................................................... 22 Semi-Roundabout Intersection.................................................................................. 24 2.6 Technology to Assist in Intersection Safety........................................................... 25 Prince William County, Virginia .............................................................................. 25 Norridgewock, Maine................................................................................................ 27 Intersection Decision Support System ...................................................................... 29 v Summary Remarks..................................................................................................... 30 3. EXPRESSWAY INTERSECTION SURVEY ............................................................. 31 3.1 Methodology........................................................................................................... 31 3.2 Survey Responses by State Transportation Agencies............................................. 33 Alabama Department of Transportation .................................................................. 33 Arizona Department of Transportation ................................................................... 34 California Department of Transportation ............................................................... 34 Colorado Department of Transportation ................................................................. 36 Florida Department of Transportation .................................................................... 36 Illinois Department of Transportation ..................................................................... 37 Indiana Department of Transportation .................................................................... 38 Iowa Department of Transportation......................................................................... 38 Kentucky Transportation Cabinet ............................................................................ 44 Louisiana Department of Transportation and Development ................................... 45 Maryland Department of Transportation ................................................................ 45 Michigan Department of Transportation ................................................................. 46 Minnesota Department of Transportation................................................................ 47 Mississippi Department of Transportation .............................................................. 48 Missouri Department of Transportation .................................................................. 49 Nebraska Department of Roads ............................................................................... 51 New York State Department of Transportation ....................................................... 52 North Carolina Department of Transportation ....................................................... 53 North Dakota Department of Transportation .......................................................... 55 Oklahoma Department of Transportation ............................................................... 56 Oregon Department of Transportation .................................................................... 56 vi Pennsylvania Department of Transportation ........................................................... 57 South Carolina Department of Transportation ........................................................ 57 South Dakota Department of Transportation .......................................................... 59 Texas Department of Transportation ....................................................................... 60 Virginia Department of Transportation ................................................................... 60 Washington