Alternative Information Signs: an Evaluation of Driver Comprehension and Visual Attention
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ALTERNATIVE INFORMATION SIGNS: AN EVALUATION OF DRIVER COMPREHENSION AND VISUAL ATTENTION by David S. Hurwitz (PI) Oregon State University Michael Olsen (Co-PI) Oregon State University Justin Neill Oregon State University for Pacific Northwest Transportation Consortium (PacTrans) USDOT University Transportation Center for Federal Region 10 University of Washington More Hall 112, Box 352700 Seattle, WA 98195-2700 And Travel Oregon Park Place Building 250 Church Street ST SE, Suite #100 Salem, OR 97301 Disclaimer The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the U.S. Department of Transportation’s University Transportation Centers Program, in the interest of information exchange. The Pacific Northwest Transportation Consortium and the U.S. Government assumes no liability for the contents or use thereof. Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. 2013-S-OSU-0029 4. Title and Subtitle 5. Report Date 7/31/2015 Alternative Information Signs: An Evaluation of Driver Comprehension and Visual Attention 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. David S. Hurwitz, Michael Olsen, and Justin Neill 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) School of Civil and Construction Engineering 11. Contract or Grant No. Oregon State University (OSU) DTRT12-UTC10 101 Kearney Hall Corvallis OR 97331 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Research 7/1/2013-7/31/2015 Pacific Northwest Transportation Consortium (PACTRANS) 14. Sponsoring Agency Code University of Washington More Hall 112, Box 352700 Seattle, WA 98195-2700 15. Supplementary Notes 16. Abstract The effectiveness of a traffic sign is collectively influenced by the sign’s understandability, legibility distance, glance legibility, and learnability; however, understandability has been repeatedly identified as a one of the most important measures of effectiveness. This study contributes to best practices for evaluating traffic sign understandability by using a variety of online survey questions and driving simulation tasks to assess the understandability of alternative Tourist Information signs in Oregon. To achieve this goal, the understandability of five alternative Tourist Information signs were first tested in an online survey with 142 participants, resulting in the identification of the four best-performing alternatives. The understandability of these alternatives was then tested in the OSU Driving Simulator with 42 participants. The “INFO” Sign was found to be correctly understood by 95.7% of the driving simulator subjects. The two “i” Sign alternatives had the second and third highest comprehension rates for driving simulator subjects with 72.8% for signs without a circular border and 75.4% for signs with a circular border. There was a statistical difference, at the 95% level, between the comprehension results of the online survey and the driving simulator test of the “?” Sign. However, it is likely that comprehension rates for the “i" Sign will continue to increase in the future due to its prolific usage in a wide variety of contexts. 17. Key Words 18. Distribution Statement Information Signs, Traffic Signs, Driver Behavior, Driving Simulator No restrictions. Copies available from PACTRANS: www.pactrans.org 19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 86 ii Table of Contents List of Abbreviations v Acknowledgments vi CHAPTER 1 INTRODUCTION ......................................................................... 1 CHAPTER 2 LITERATURE REVIEW ................................................................ 3 2.1 Tourist Information Sign Standards ............................................................... 3 2.1.1 Information Signs and Symbols in Different Contexts .......................... 4 2.1.2 Relevant Traffic Sign Research ............................................................. 6 2.1.3 “i” Sign Research ................................................................................. 8 CHAPTER 3 METHODOLOGY ...................................................................... 10 3.1 Research Objectives ..................................................................................... 10 3.2 Online survey ............................................................................................... 11 3.3 Driving Simulator Study .............................................................................. 13 3.3.1 Driving Simulator ............................................................................... 13 3.3.2 Eye Tracking ....................................................................................... 14 3.3.3 Scenario Layout .................................................................................. 15 CHAPTER 4 RESULTS AND ANALYSIS ........................................................ 18 4.1 Online Survey .............................................................................................. 18 4.1.1 Open-Ended Survey Questions ........................................................... 18 4.1.2 Rating Task Survey Questions ............................................................ 21 4.2 Driving Simulator ........................................................................................ 23 4.2.1 Driver Comprehension during Simulated Driving ............................. 24 4.2.2 Visual Attention during Simulated Driving......................................... 27 4.2.3 Post Drive Survey Rating Task ........................................................... 28 4.3 Test Methods Comparison ........................................................................... 30 CHAPTER 5 DISCUSSION ............................................................................ 33 5.1 Driver Related Factors ................................................................................. 33 5.2 Traveler Information Sign Comprehension ................................................. 34 5.3 Traveler Information Sign Glance Patterns ................................................. 35 5.4 Experimental Design Influence on Comprehension .................................... 35 i 5.5 Comparison to Previous “i” sign research ................................................... 36 5.6 Study Limitations and Future work ............................................................. 37 CHAPTER 6 CONCLUSIONS ......................................................................... 38 BIBLIOGRAPHY ........................................................................................ 39 APPENDIX B : ............................................................................................ 49 B.1 Symbol vs. Word Signs.......................................................................... 53 B.1.1 Understandability ................................................................................... 53 B.1.2 Conspicuity ............................................................................................ 56 B.1.3 Reaction Time ........................................................................................ 56 B.1.4 Legibility ................................................................................................ 59 B.1.5 Learnability ............................................................................................ 60 B.1.6 “i” Sign Research Gaps .......................................................................... 61 B.2 Subject Testing Methods........................................................................ 63 B.2.1 Testing Standards ................................................................................... 63 B.2.2 Question design ...................................................................................... 63 B.2.3 Questionnaire Strategies ........................................................................ 65 B.2.4 Context ................................................................................................... 66 B.2.5 Questionnaire Design Framework ......................................................... 67 ii List of Figures Figure 2.1: UNWTO recommended and MUTCD required Tourist Information signs ................ 4 Figure 2.2: Example information signs and symbols from alternative contexts ........................... 5 Figure 2.3: Critical sign characteristics and their relation between studies over time .................. 7 Figure 3.1: Example images of comprehension (a) and rating (b) questions for the “i” Sign ..... 11 Figure 3.2: Views from a) outside the simulator and b) from inside the OSU Driving Simulator and c) subject wearing eye-tracking device. ......................................................................... 14 Figure 3.3: Driving simulator track (not to scale) and example “i” sign presented in the simulator ............................................................................................................................... 15 Figure 4.1: Sign comprehension scores from the rating task ....................................................... 22 Figure 4.2: Driving simulator task averages with confidence intervals ...................................... 27 Figure 4.3: Sign comprehension scores from the rating task ......................................................