Continuous Flow Intersection, J-Turn 19
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Alternative Intersections/Interchanges: Informational Report (AIIR) PUBLICATION NO. FHWA-HRT-09-060 APRIL 2010 Research, Development, and Technology Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, VA 22101-2296 FOREWORD Today’s transportation professionals, with the limited resources available to them, are challenged to meet the mobility needs of an increasing population. At many highway junctions, congestion continues to worsen, and drivers, pedestrians, and bicyclists experience increasing delays and heightened exposure to risk. Today’s traffic volumes and travel demands often lead to safety problems that are too complex for conventional intersection designs to properly handle. Consequently, more engineers are considering various innovative treatments as they seek solutions to these complex problems. This report covers four intersection and two interchange designs that offer substantial advantages over conventional at-grade intersections and grade-separated diamond interchanges. It also provides information on each alternative treatment covering salient geometric design features, operational and safety issues, access management, costs, construction sequencing, environmental benefits, and applicability. The six alternative treatments covered in this report are displaced left- turn (DLT) intersections, restricted crossing U-turn (RCUT) intersections, median U-turn (MUT) intersections, quadrant roadway (QR) intersections, double crossover diamond (DCD) interchanges, and DLT interchanges. Raymond Krammes Acting Director, Office of Safety Research and Development Notice This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document. Quality Assurance Statement The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. TECHNICAL DOCUMENTATION PAGE 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. FHWA-HRT-09-060 4. Title and Subtitle 5. Report Date Alternative Intersections/Interchanges: Informational Report (AIIR) April 2010 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Warren Hughes, Ram Jagannathan, Dibu Sengupta, and Joe Hummer Project 37769.19 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Vanasse Hangen Brustlin, Inc. (VHB) 8300 Boone Blvd., Suite 700 11. Contract or Grant No. Vienna, VA 22182-2626 DTFH61-05-D-00024 (VHB) Subconsultants: North Carolina State University; Persaud Lyon, Inc.; Task T-06-016 University of Missouri-Rolla 12. Sponsoring Agency Name and Address 13. Type of Report and Period U.S. Department of Transportation Technical Report Federal Highway Administration Office of Safety Informational Report 1200 New Jersey Ave., SE August 2006 to July 2009 Washington, DC 20590 14. Sponsoring Agency Code FHWA 15. Supplementary Notes The Federal Highway Administration (FHWA) Office of Safety Research and Development managed this study. The FHWA Office of Safety Research and Development Contract Task Order Manager was Dr. Joe Bared. Project focus group members contributed significantly to document organization, content, and exhibits. They included Tom Hicks and Saed Rahwanji from the Maryland State Highway Administration; Debbie Self from the Charlotte Department of Transportation; Ed Rice and Jon Obenberger from the U.S. Department of Transportation; Louis Thibault from the U.S. States Access Board; Robert Copp and Jerry Champa from the California Department of Transportation; and Mike Cynecki from the City of Phoenix. In addition, many FHWA staff members participated as focus group members and/or provided comments throughout the project including Neil Spiller, James Colyar, John Halkias, Wei Zhang, Tamara Redmon, Fred Ranck, Brian Chandler, Mary Stringfellow, William Prosser, and Scott Wainwright. The research team is grateful to James Young and the Ohio Department of Transportation for providing the real-world intersection example used in chapter 10. 16. Abstract Today’s transportation professionals are challenged to meet the mobility needs of an increasing population with limited resources. At many highway junctions, congestion continues to worsen. Drivers, pedestrians, and bicyclists experience longer delays and greater exposure to risk. Today’s traffic and safety problems are more complex and complicated. Conventional intersection/ interchange designs are sometimes found to be insufficient to mitigate transportation problems. Consequently, many engineers are investigating and implementing innovative treatments in an attempt to think outside the box. This report covers four intersection designs and two interchange designs that may offer additional benefits compared to conventional at-grade intersections and grade- separated diamond interchanges. The six alternative treatments covered in this report are displaced left-turn (DLT) intersections, restricted crossing U-turn (RCUT) intersections, median U-turn (MUT) intersections, quadrant roadway (QR) intersections, double crossover diamond (DCD) interchanges, and DLT interchanges. The information presented in this report provides knowledge of each of the six alternative treatments including salient geometric design features, operational and safety issues, access management issues, costs, and construction sequencing and applicability. 17. Key Words 18. Distribution Statement Alternative intersections, Alternative interchanges, CFI, XDL, DDI, DLT, No restrictions. DCD, MUT, Median U-turn, Diverging diamond, Displaced left-turn, Super street, Continuous flow intersection, J-turn 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 340 Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized SI* (MODERN METRIC) CONVERSION FACTORS APPROXIMATE CONVERSIONS TO SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometers km AREA in2 square inches 645.2 square millimeters mm2 ft2 square feet 0.093 square meters m2 yd2 square yard 0.836 square meters m2 ac acres 0.405 hectares ha mi2 square miles 2.59 square kilometers km2 VOLUME fl oz fluid ounces 29.57 milliliters mL gal gallons 3.785 liters L ft3 cubic feet 0.028 cubic meters m3 yd3 cubic yards 0.765 cubic meters m3 NOTE: volumes greater than 1000 L shall be shown in m3 MASS oz ounces 28.35 grams g lb pounds 0.454 kilograms kg T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") TEMPERATURE (exact degrees) oF Fahrenheit 5 (F-32)/9 Celsius oC or (F-32)/1.8 ILLUMINATION fc foot-candles 10.76 lux lx fl foot-Lamberts 3.426 candela/m2 cd/m2 FORCE and PRESSURE or STRESS lbf poundforce 4.45 newtons N lbf/in2 poundforce per square inch 6.89 kilopascals kPa APPROXIMATE CONVERSIONS FROM SI UNITS Symbol When You Know Multiply By To Find Symbol LENGTH mm millimeters 0.039 inches in m meters 3.28 feet ft m meters 1.09 yards yd km kilometers 0.621 miles mi AREA mm2 square millimeters 0.0016 square inches in2 m2 square meters 10.764 square feet ft2 m2 square meters 1.195 square yards yd2 ha hectares 2.47 acres ac km2 square kilometers 0.386 square miles mi2 VOLUME mL milliliters 0.034 fluid ounces fl oz L liters 0.264 gallons gal m3 cubic meters 35.314 cubic feet ft3 m3 cubic meters 1.307 cubic yards yd3 MASS g grams 0.035 ounces oz kg kilograms 2.202 pounds lb Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T TEMPERATURE (exact degrees) oC Celsius 1.8C+32 Fahrenheit oF ILLUMINATION lx lux 0.0929 foot-candles fc cd/m2 candela/m2 0.2919 foot-Lamberts fl FORCE and PRESSURE or STRESS N newtons 0.225 poundforce lbf kPa kilopascals 0.145 poundforce per square inch lbf/in2 *SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003) ii TABLE OF CONTENTS CHAPTER 1. INTRODUCTION ................................................................................................ 1 CHAPTER 2. DISPLACED LEFT-TURN INTERSECTION ................................................. 7 2.1 INTRODUCTION....................................................................................................... 7 2.2 GEOMETRIC DESIGN CONSIDERATIONS ..................................................... 12 2.3 ACCESS MANAGEMENT CONSIDERATIONS ................................................ 17 2.4 TRAFFIC SIGNALIZATION TREATMENTS .................................................... 20 2.4.1 Signal Design ............................................................................................... 22 2.4.2 Signing and Marking.................................................................................... 34 2.5 ACCOMMODATION OF PEDESTRIANS, BICYCLISTS, AND TRANSIT USERS ..........................................................................................................