Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA/TX-04/4538-1 4. Title and Subtitle 5. Report Date REVIEW AND EVALUATION OF INTERCHANGE RAMP September 2003 DESIGN CONSIDERATIONS FOR FACILITIES WITHOUT 6. Performing Organization Code FRONTAGE ROADS 7. Author(s) 8. Performing Organization Report No. James Bonneson, Karl Zimmerman, and Marc Jacobson Report 0-4538-1 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Texas Transportation Institute The Texas A&M University System 11. Contract or Grant No. College Station, Texas 77843-3135 Project No. 0-4538 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Texas Department of Transportation Research: Research and Technology Implementation Office September 2002 - August 2003 P.O. Box 5080 14. Sponsoring Agency Code Austin, Texas 78763-5080 15. Supplementary Notes Research performed in cooperation with the Texas Department of Transportation and the U.S. Department of Transportation, Federal Highway Administration. Research Project Title: Ramp Design Considerations for Facilities without Frontage Roads 16. Abstract Based on a recent change in TxDOT policy, frontage roads are not to be included along controlled-access highways unless a study indicates that the frontage road improves safety, improves operations, lowers overall facility costs, or provides essential access. Interchange design options that do not include frontage roads are to be considered for all new freeway construction. Ramps in non-frontage-road settings are more complicated to design than those in frontage-road settings for several reasons. Adequate ramp length, appropriate horizontal and vertical curvature, and flaring to increase storage area at the crossroad intersection should all be used to design safe and efficient ramps for non-frontage-road settings. However, current design procedures available in standard TxDOT reference documents are focused on ramp design for frontage-road settings. The objective of this research project is to develop recommended design procedures for interchange ramps on facilities without frontage roads. This report describes the findings from the first year of a two-year project. Current ramp design practices were reviewed, and the operational features of interchange ramps in non-frontage-road settings were evaluated. Both the diamond and partial cloverleaf interchange forms were considered. The findings from the evaluation of the field and simulation data indicate that a rational approach to interchange type selection and operational evaluation is feasible using the critical movement analysis approach. A procedure for using this approach is documented in the Appendix. 17. Key Words 18. Distribution Statement Highway Operations, Highway Design, Types of No restrictions. This document is available to the Interchanges, Ramps (Interchanges) public through NTIS: National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 19. Security Classif.(of this report) 20. Security Classif.(of this page) 21. No. of Pages 22. Price Unclassified Unclassified 144 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized REVIEW AND EVALUATION OF INTERCHANGE RAMP DESIGN CONSIDERATIONS FOR FACILITIES WITHOUT FRONTAGE ROADS by James Bonneson, P.E. Research Engineer Texas Transportation Institute Karl Zimmerman, P.E. Assistant Research Engineer Texas Transportation Institute and Marc Jacobson, P.E. Assistant Research Engineer Texas Transportation Institute Report 0-4538-1 Project Number 0-4538 Research Project Title: Ramp Design Considerations for Facilities without Frontage Roads Sponsored by the Texas Department of Transportation In Cooperation with the U.S. Department of Transportation Federal Highway Administration September 2003 TEXAS TRANSPORTATION INSTITUTE The Texas A&M University System College Station, Texas 77843-3135 DISCLAIMER The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data published herein. The contents do not necessarily reflect the official view or policies of the Federal Highway Administration (FHWA) and/or the Texas Department of Transportation (TxDOT). This report does not constitute a standard, specification, or regulation. It is not intended for construction, bidding, or permit purposes. The engineer in charge of the project was James Bonneson, P.E. #67178. NOTICE The United States Government and the State of Texas do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of this report. v ACKNOWLEDGMENTS This research project was sponsored by the Texas Department of Transportation and the Federal Highway Administration. The research was conducted by Dr. James Bonneson, Dr. Karl Zimmerman, and Mr. Marc Jacobson with the Texas Transportation Institute. The researchers would like to acknowledge the support and guidance provided by the project director, Ms. Patricia L. Crews-Weight, and the members of the Project Monitoring Committee, including: Mr. Robert L. Stuard, Mr. Bob Richardson, Ms. Rory Meza, Mr. Gerald Pohlmeyer, and Mr. Gilbert Gavia (all with TxDOT). In addition, the researchers would like to acknowledge the valuable assistance provided by Mr. George Balarezo and Mr. Ho Jun Son during the conduct of the field studies and the subsequent data reduction activities. The assistance provided by Dr. Montasir Abbas in the conduct of this research is also gratefully acknowledged. Finally, the authors would like to thank Mr. Joel P. Leisch for his thoughtful review of Chapter 2. His comments and advice are greatly appreciated. vi TABLE OF CONTENTS Page LIST OF FIGURES ......................................................... viii LIST OF TABLES ........................................................... ix CHAPTER 1. INTRODUCTION ............................................. 1-1 OVERVIEW ............................................................ 1-1 RESEARCH OBJECTIVE ................................................. 1-1 RESEARCH SCOPE...................................................... 1-2 RESEARCH APPROACH ................................................. 1-2 CHAPTER 2. REVIEW OF RAMP DESIGN PRACTICE ........................ 2-1 OVERVIEW ............................................................ 2-1 INTERCHANGE TYPES .................................................. 2-1 RAMP CONFIGURATIONS .............................................. 2-10 NON-FRONTAGE-ROAD RAMP DESIGN ISSUES ........................... 2-17 SYNTHESIS OF CURRENT RAMP DESIGN PRACTICE ...................... 2-34 CHAPTER 3. OPERATIONAL EFFECTS DATA COLLECTION PLAN ........... 3-1 OVERVIEW ............................................................ 3-1 CRITICAL FLOW RATIO MODEL DEVELOPMENT .......................... 3-1 DELAY PREDICTION MODEL DEVELOPMENT ............................ 3-15 DATA COLLECTION PLAN.............................................. 3-24 CHAPTER 4. DATA ANALYSIS ............................................. 4-1 OVERVIEW ............................................................ 4-1 SIMULATION SOFTWARE CALIBRATION.................................. 4-1 DELAY MODEL CALIBRATION........................................... 4-8 PROCEDURE FOR COMPARING ALTERNATIVE INTERCHANGE TYPES ...... 4-14 FORTHCOMING RESEARCH ............................................ 4-16 CHAPTER 5. SUMMARY OF FINDINGS ..................................... 5-1 OVERVIEW ............................................................ 5-1 REVIEW OF RAMP DESIGN PRACTICE.................................... 5-1 OPERATIONAL ANALYSIS OF ALTERNATIVE INTERCHANGE TYPES ........ 5-2 CHAPTER 6. REFERENCES ................................................ 6-1 APPENDIX: PROCEDURE FOR COMPARING ALTERNATIVE INTERCHANGE TYPES AND RAMP CONFIGURATIONS ................................. A-1 vii LIST OF FIGURES Figure Page 2-1 Typical Interchange Types............................................... 2-1 2-2 Distribution of Interchange Types Used in the U.S. ........................... 2-2 2-3 Interchange Types Commonly Used in Non-Frontage-Road Settings .............. 2-3 2-4 Operational Performance Comparison of Interchanges with Frontage Roads........ 2-8 2-5 Interchange Types Amenable to Various Facility Classes and Area Types .......... 2-9 2-6 Alternative Ramp Configurations ........................................ 2-10 2-7 Alternative Diagonal Ramp Configurations ................................ 2-12 2-8 Three Diagonal Ramp Alignment Options ................................. 2-13 2-9 Relationship between Loop Radius and Running Time ........................ 2-14 2-10 Effect of Ramp Volume on Crash Frequency at Exit Ramps ................... 2-16 2-11 Effect of Ramp Volume on Crash Frequency at Rural Exit Ramps .............. 2-16 2-12 Illustrative Parclo A Design Detail ....................................... 2-19 2-13 Design Speed Application to Exit Ramps.................................. 2-21 2-14 Ramp Length Components .............................................. 2-23 2-15 Discontinuous Ramp Alignment at Ramp/Crossroad Junction .................. 2-28 2-16 95th Percentile Queue Length for a Stop-Controlled Approach .................. 2-30 2-17 Minimum Storage Length for a Signalized Approach......................... 2-31 2-18 Alternative Right-Turn Channelization Designs............................. 2-31 2-19 Designs to Discourage Wrong-Way