Freeway Exit Lane Drops in Texas 6
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Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA/TX-94/ 1292- lF 4. Title and Subtitle 5. Report Date November 1993 FREEWAY EXIT LANE DROPS IN TEXAS 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Kay Fitzpatrick, Torsten Lienau, Michael Ogden, Marty Lance, Research Report 1292-lF and Thomas Urbanik II 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 Study No. 0-1292 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Texas Department of Transportation Final: Research and Technology Transfer Office September 1991 - August 1993 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 Study Title: Communicating Lane Drops to Motorists 16. Abstract This project determines how motorists interpret or respond to various sign and pavement marking alternatives they may or may not have experienced before. Motorist interpretation of signs and markings were obtained through surveys, while field observations were used to measure actual motorist responses to pavement markings. The results from both surveys indicate that motorists have a high level of understanding of the yellow EXIT ONLY panel. Drivers do not understand the use of the white arrow next to a yellow EXIT ONLY panel as well. Over one third of the participants incorrectly interpreted the meaning of the white arrows. Motorists prefer the use of diagrammatic signs as the first of several signs indicating an approaching exit lane drop and the use of the conventional black on yellow panel close to the exit lane drop. Texas motorists understand the meaning of the wide solid white line. The field studies demonstrate that the installation of lane drop markings can cause a shift in motorist lane change locations in advance of a lane drop. One site's data directly reveals while the other site's data indicates that drivers move into or out of the exiting lane further upstream of the lane drop in the period after markings were installed than in the period before markings were installed. For the 800 feet (244 m) immediately upstream of the gore at one site, fewer vehicles left the exit lane in the after period than in the before period, while in the area between 1700 and 1000 ft (518 and 305 m) upstream of the gore, more vehicles left the exit lane in the after period than in the before period. The before-and-after studies also reveal that the number of erratic maneuvers within the entire study segment decrease with the installation of markings. 17. Key Words 18. Distribution Statement Exit Lane Drops, Lane Drop Markings, Exit No restrictions. This document is available Only Signs, Surveys, Field Studies to the public through NTIS: National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 19. Security C!assif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 212 Form DOT F 1700.7 (8-72) FREEWAY EXIT LANE DROPS IN TEXAS by Kay Fitzpatrick, P.E. Assistant Research Engineer Torsten Lienau Assistant Research Scientist Michael Ogden, P.E. Assistant Research Engineer Marty Lance Graduate Research Assistant and Thomas Urbanik II, P.E. Research Engineer Research Report 1292-lF Research Study No. 0-1292 Study Title: Communicating Lane Drops to Motorists Sponsored by the Texas Department of Transportation In Cooperation With U.S. Department of Transportation Federal Highway Administration November 1993 TEXAS TRANSPORTATION INSTITUTE The Texas A&M University System College Station, Texas 77843-3135 IMPLEMENTATION STATEMENT This study demonstrates that motorists have a good understanding of exit lane drop markings and signs, except for the white down arrow located next to the yellow EXIT ONLY panel on two-lane exits with an option lane and an exit only lane. Findings also demonstrate that motorists move earlier out of a lane that is being dropped (i.e., further upstream of the exit) when lane drop markings are present. Consistent use of the standardized marking treatments provides several benefits, such as consistency in communicating lane drops on Texas freeways to drivers, and improved driver expectancy at lane drops. The improved driver expectancy encourages motorists to move out of or into a lane that is being dropped further upstream of the gore area. This behavior results in fewer erratic maneuvers. v DISCLAIMER The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Texas Department of Transportation or the Federal Highway Administration (FHWA). This report does not constitute a standard, specification, or regulation, nor is it intended for construction, bidding, or permit purposes. This report was prepared by Kay Fitzpatrick (PA-037730-E), Torsten Lienau, Mike Ogden (TX-77485), Marty Lance, and Tom Urbanik (TX-42384). vii ACKNOWLEDGMENTS Several individuals within the Houston, Fort Worth, and Dallas Districts assisted with this study. These people were extremely cooperative and helpful in scheduling equipment and personnel, installing equipment at the sites, providing and operating the bucket (crane) trucks during installation and removal of the video cameras, and arranging or installing the lane drop markings at the sites. The following individuals are acknowledged: Billy David, Wallace Ewell, Pete Laramon, Royce Newman, James Ward, Vernon Wallace, Virgil Wheat, and Dickie White of the Fort Worth District; James Elliot, Jerals Hancock, Pat Henry, Steve Levine, Dennis Milcek, Mark Montgomery, Ervin Ramirez, Debbie Rogers, Douglas Streetman, and Dennis Zimmerman of the Houston District; and J. W. Coey, Leo Donnahue, James McKinney, Allen McNeil, Lannie Sarrat, and Leroy Wallen of the Dallas District. The TxDOT 1292 advisory panel is also recognized for its time in providing direction and comments for this research. The authors would also like to recognize the undergraduate students (Yvette Felix, Deanne Simmons, Jed Sulak, Terry Turner, Nikki Wagner, and Stacy Wiatrek) who diligently watched several hours of video tapes to extract the necessary data for this project. This study was performed in cooperation with the Texas Department of Transportation and the U.S. Department of Transportation, Federal Highway Administration. Vlll TABLE OF CONTENTS Chapter Page LIST OF FIGURES . xiii LIST OF TABLES .......................................... xvii SUMl\'.[ARY . .xix 1 INTRODUCTION .......................................... 1 RESEARCH SCOPE AND OBJECTIVES ............................ 2 Survey ............................................... 2 Field Observations . 3 ORGANIZATION OF REPORT .................................. 3 2 LITERATURE REVIEW ..................................... 5 EXIT LANE DROP PROCEDURES IN THE MUTCDS ................... 5 Current Material on Signs ................................... 5 EXIT ONLY Panel Inclusion in the MUTCD . 8 Current Material on Markings . 9 Special Pavement Marking at Exit Lane Drops Inclusion in the MUTCD . 10 PREVIOUS RESEARCH ON EXIT ONLY SIGNS . 10 General Comments on Signs . 10 Exit Only Signs . 11 Black on Yell ow . 11 Diagrammatic Signs .................................... 12 PREVIOUS RESEARCH ON PAVEMENT MARKINGS . 12 OTHER RELATED STUDIES .................................. 15 OTHER STUDIES ON LANE DROPS ............................. 16 Geometric Considerations . 16 Operational Effects . 17 Safety ............................................... 18 3 SURVEYS .............................................. 19 DRIVER SURVEY--AUTO SHOW ............................... 19 Development of Survey .................................... 19 Experimental Plan . 20 Conduct Survey . 24 lX TABLE OF CONTENTS (continued) Chapter 3 SURVEYS (Con't) Findings . 24 Demographics . 24 Markings Only Questions . 26 One-Lane, Lane Drop Exit Questions ......................... 28 Two-Lane Exit with an Option Lane and an Exit Only Lane Questions ..... 30 Two-Lane, Lane Drop Exit with Markings Between One Set of Lanes Questions . 32 Two-Lane, Lane Drop Exit with Markings Between Two Sets of Lanes Questions . 34 Driver Preference Questions . 36 Interpretation of Findings . 36 DRIVING INSTRUCTOR SURVEY--MAILOUT SURVEY ................ 40 Development of Survey . 40 Selection of Questions . 40 Conduct Survey . 42 Findings . 43 Instructor Responses . 43 Student Responses . 4 7 Instructor Responses Versus Student Responses ................... 48 Interpretation of Findings . 49 4 OVERVIEW OF FIELD STUDIES .............................. 51 IDENTIFICATION OF CANDIDATE SITES ........................ 51 SELECTION OF SITES ...................................... 51 INSTALLATION OF MARKINGS ............................... 51 DATA COLLECTION ....................................... 52 Coordination with Districts . 54 Installation of Equipment ................................... 55 Recording of Data . 57 DATA REDUCTION ........................................ 58 Identification of Zones and Lanes .............................. 58 Creation of Templates . 58 Selection of Video Tapes to be Viewed . 59