An Investigation of Signs for Median Crossovers
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Scholars' Mine Doctoral Dissertations Student Theses and Dissertations Spring 1986 An investigation of signs for median crossovers Gillian M. Worsey Missouri University of Science and Technology, [email protected] Follow this and additional works at: https://scholarsmine.mst.edu/doctoral_dissertations Part of the Civil Engineering Commons Department: Civil, Architectural and Environmental Engineering Recommended Citation Worsey, Gillian M., "An investigation of signs for median crossovers" (1986). Doctoral Dissertations. 589. https://scholarsmine.mst.edu/doctoral_dissertations/589 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. AN INVESTIGATION OF SIGNS FOR MEDIAN CROSSOVERS BY GILLIAN MARY WORSEY, 1957- A DISSERTATION Presented to the Faculty of the Graduate School of the UNIVERSITY OF MISSOURI-ROLLA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY in T5270 CIVIL ENGINEERING Copy 1 177 Pages 1986 Advisor ii ABSTRACT This paper describes a study of advance warning signs for median crossovers on divided highways. Candidate crossover signs were identified from a literature review, survey of current State practices and discussions with FHWA personnel. Seven of these signs were selected for further testing in a laboratory study for legibility, understanding and driver preference. Sixty subjects representing a cross-section of drivers took part in the study, thirty at the Turner-Fairbanks Highway Research Center in McLean, Virginia and thirty at the Unversity of Missouri-Rolla in Rolla, Missouri. Two of the seven signs were word messages and five were symbolic signs. The results from both groups of subjects showed that the most appropriate word message sign would appear to be "Median Crossover". This sign was understood the best by the subjects to whom it was shown and "Crossover" was the word the majority of subjects thought best conveyed the intended meaning. The symbolic sign found to be the best out of those tested was one showing two median noses. This did well In legibility and understanding tests and was least confused with other signs. It was also the symbolic sign most preferred by the subjects and was the simplest of the symbolic designs. Legibility of the symbolic signs was much greater than that of the word messages and this symbolic design is the sign recommended to identify median crossovers. ill ACKNOWLEDGEMENTS Part of this study was funded by a Grants for Research Fellowship from the Federal Highway Administration. This enabled the author to work at the Turner-Fairbanks Highway Research Center for three months during the summer of 1985. The support of the Federal Highway Administration is gratefully acknowledged, particularly that of the staff of the Traffic Safety Research Division headed by Dr. Samuel Tignor. Special thanks are due to Richard Schwab and Howard Bissell for advice and guidance on this study and Juan Morales and Jim Kemper for help with computer analysis and sign design and slide preparation using the computer graphics system. Thanks are also due to King Roberts, John Walker, Beth Alicandri and Harry Lum for help with the experimental design and analysis. The author would particularly like to thank her advisor, Dr. Charles Dare and her committee for their help and support at the University of Missouri-Rolla. Thanks are also due to the Health Service for lending an eye chart, the Safety Office for lending a light meter and Auxiliary Services for lending a rear-projection screen for the experiment at the University of Missouri-Rolla. Special thanks are due to the thirty people who gave an hour of their time to take part in this experiment without payment. The help of Mr. R. N. Robertson and Mr. C. Morris of the Virginia Department of Highways and Transportation in providing information on the Virginia crossover sign is also acknowledged. Thanks go to the State Highway Departments which replied to the survey on median crossovers. iv TABLE OF CONTENTS Page ABSTRACT............................................................. ii ACKNOWLEDGEMENTS .................................................. lii TABLE OF C O N T E N T S ................................................... iv LIST OF ILLUSTRATIONS...............................................vi LIST OF TAB L E S ......................................................vii I. INTRODUCTION ............................................. 1 A. UNIFORM SIGNING ...................................... 1 B. MEDIAN CROSSOVER SIGNS ................................ 4 II. REVIEW OF L I T E R A T U R E ....................................... 12 A. RECOGNITION OF HIGHWAY SIGNS .......................... 12 1. L e g i b i l i t y ........................................... 12 a. Early S t u d i e s .....................................13 b. Other S t u d i e s .....................................13 c. Glance Legibility .............................. 19 2. V i s i b i l i t y ...........................................20 B. UNDERSTANDING OF HIGHWAY SIGNS ........................ 25 1. Speed Related Signs ................................ 23 2. Guide S i g n s ...........................................28 3. Symbol Versus Verbal Signs ........................ 31 4. Other Studies.........................................38 C. WORK ON MEDIAN C R O S S O V E R S .............................. 39 III. SURVEY OF STATES PRACTICES OF SIGNING AND DELINEATING MEDIAN CROSSOVERS ........................................ 40 A. SIGNING OF MEDIAN CROSSOVERS .......................... 41 1. Minor Road Crossovers................................ 41 V 2. Authorized Vehicle Crossovers ...................... 46 3. Commercial Development Crossovers .................. 47 4. Comments ............................................. 48 B. PAVEMENT MARKINGS AT MEDIAN CROSSOVERS ................ 49 C. GEOMETRIC DESIGN OF MEDIAN CROSSOVERS ................ 52 1. Designs for Deceleration............................. 52 2. Designs for Acceleration............................. 55 IV. METHODOLOGY................................................. 56 A. VIRGINIA EXPERIMENT .................................. 58 1. Subjects ............................................. 58 2. Apparatus............................................. 60 3. Procedure............................................. 73 a. Legibility and Meaning............................. 73 b. Recognition ....................................... 74 c. Preference......................................... 74 B. DIFFERENCES IN MISSOURI EXPERIMENT .................... 75 1. Subjects ............................................. 75 2. Apparatus............................................. 75 3. Procedure............................................. 77 V. RESULTS......................................................79 A. VIRGINIA................................................. 79 1. Legibility ........................................... 79 2. Understanding......................................... 84 3. Recognition........................................... 89 4. Preference ........................................... 92 B. MISSOURI................................................. 99 1. Legibility 99 vi 2. Understanding........................................ 104 3. Recognition.......................................... 109 4. P r e f e r e n c e .......................................... 112 C. COMPARISON OF THE VIRGINIA AND MISSOURI RESULTS .... 117 1. L e g i b i l i t y .......................................... 117 2. Understanding........................................ 119 3. Recognition.......................................... 122 4. Preference .......................................... 124 VI. CONCLUSIONS.................................................127 BIBLIOGRAPHY........................................................ 134 V I T A ................................................................ 143 APPENDICES A. SURVEY OF STATES PRACTICES OF SIGNING AND DELINEATING MEDIAN CROSSOVERS SENT TO STATE TRAFFIC ENGINEERS .......... 144 B. DESIGNS FOR MEDIAN CROSSOVERSCONSIDERED BUT NOT TESTED . 151 C. INSTRUCTION AND DATA COLLECTION SHEETS USED IN MEDIAN CROSSOVER SIGN EXPERIMENT ............................... 161 vii LIST OF ILLUSTRATIONS Figure Page 1. Virginia crossover sign ...................................... 6 2. MUTCD crossover s i g n ............................................. 10 3. Most common signs used on divided highway approaches to minor road c r o s s o v e r s ................................................. 42 4. Most common signs used on minor approaches to minor road crossovers....................................................... 43 5. Most common signs used in median at minor roadcrossovers . 45 6. Most common pavement markings used on divided highway approaches at crossovers................................................... 50 7. Permissive U turn sign suggested by FHWA office of traffic operations....................................................... 61 8. "Crossover” Sign suggested by South Carolina .................. 62 9. "Median opening" sign suggested by FHWA p e r s o n n e l .............. 63 10. Crossover nose sign suggested by FHWA p e r s o n n e l ................. 64 11. Nose plus arrows sign adapted from