MODELING OF GUIDE SIGN ILLUMINATION AND RETROREFLECTIVITY TO IMPROVE DRIVER’S VISIBILITY AND SAFETY by MOHAMMED SAID OBEIDAT B.A., Jordan University of Science and Technology, 2004 M.S., Jordan University of Science and Technology, 2008 AN ABSTRACT OF A DISSERTATION submitted in partial fulfillment of the requirements for the degree DOCTOR OF PHILOSOPHY Department of Industrial and Manufacturing Systems Engineering College of Engineering KANSAS STATE UNIVERSITY Manhattan, Kansas 2015 Abstract This dissertation is the result of studying different methods of increasing guide sign visibility and legibility to drivers during nighttime, to increase safety on roadways. It also studies intersection lighting to indicate the lighting benefits on nighttime crash frequency reduction. From a survey conducted, practices related to overhead guide sign illumination and retroreflectivity in United States were summarized. A laboratory experiment was conducted to compare light distribution of five light sources: Metal Halide, Mercury Vapor, High Pressure Sodium, induction lighting, and Light Emitting Diode (LED). Cost analysis of the five light sources was performed. Combining results of the laboratory experiment and the cost analysis, induction lighting was recommended for states that want to continue external sign illumination. A retroreflectivity experiment was conducted to compare three types of retroreflective sheeting: Engineering Grade (type I), Diamond Grade (type XI), and High Intensity (type IV), to determine the sheeting that best increases visibility and legibility. Diamond Grade (type XI) was found to be the optimal sheeting that increases visibility and legibility to drivers during nighttime. A glare experiment was conducted to expand the retroreflectivity experiment results. Four sheeting-font combinations of High Intensity (type IV) and Diamond Grade (type XI) materials and Series E (Modified) and Clearview fonts were compared. Results revealed an optimal sheeting-font combination of Diamond Grade (type XI) sheeting and Clearview font which increases the visibility and legibility of guide signs to drivers under presence of oncoming glare source. The Highway Safety Information System (HSIS) database was used to study the effect of intersection lighting on the expected crash frequency. Illuminated intersections showed 3.61% and 6.54% decrease in the expected nighttime crash frequency as compared to dark intersections in Minnesota and California, respectively. In addition, partial lighting at intersections decreases the expected nighttime crash frequency by 4.72% compared to continuous lighting in Minnesota. The recommended sheeting-font combination for Departments of Transportation was Diamond Grade (type XI) and Clearview. This combination will increase signs’ visibility and legibility to drivers, and consequently increase safety on roadways. Adding partial lighting at intersections will reduce the expected nighttime crash frequency, and increase safety on roadways. MODELING OF GUIDE SIGN ILLUMINATION AND RETROREFLECTIVITY TO IMPROVE DRIVER’S VISIBILITY AND SAFETY by MOHAMMED SAID OBEIDAT B.A., Jordan University of Science and Technology, 2004 M.S., Jordan University of Science and Technology, 2008 A DISSERTATION submitted in partial fulfillment of the requirements for the degree DOCTOR OF PHILOSOPHY Department of Industrial and Manufacturing Systems Engineering College of Engineering KANSAS STATE UNIVERSITY Manhattan, Kansas 2015 Approved by: Major Professor Malgorzata J. Rys Copyright MOHAMMED SAID OBEIDAT 2015 Abstract This dissertation is the result of studying different methods of increasing guide sign visibility and legibility to drivers during nighttime, to increase safety on roadways. It also studies intersection lighting to indicate the lighting benefits on nighttime crash frequency reduction. From a survey conducted, practices related to overhead guide sign illumination and retroreflectivity in United States were summarized. A laboratory experiment was conducted to compare light distribution of five light sources: Metal Halide, Mercury Vapor, High Pressure Sodium, induction lighting, and Light Emitting Diode (LED). Cost analysis of the five light sources was performed. Combining results of the laboratory experiment and the cost analysis, induction lighting was recommended for states that want to continue external sign illumination. A retroreflectivity experiment was conducted to compare three types of retroreflective sheeting: Engineering Grade (type I), Diamond Grade (type XI), and High Intensity (type IV), to determine the sheeting that best increases visibility and legibility. Diamond Grade (type XI) was found to be the optimal sheeting that increases visibility and legibility to drivers during nighttime. A glare experiment was conducted to expand the retroreflectivity experiment results. Four sheeting-font combinations of High Intensity (type IV) and Diamond Grade (type XI) materials and Series E (Modified) and Clearview fonts were compared. Results revealed an optimal sheeting-font combination of Diamond Grade (type XI) sheeting and Clearview font which increases the visibility and legibility of guide signs to drivers under presence of oncoming glare source. The Highway Safety Information System (HSIS) database was used to study the effect of intersection lighting on the expected crash frequency. Illuminated intersections showed 3.61% and 6.54% decrease in the expected nighttime crash frequency as compared to dark intersections in Minnesota and California, respectively. In addition, partial lighting at intersections decreases the expected nighttime crash frequency by 4.72% compared to continuous lighting in Minnesota. The recommended sheeting-font combination for Departments of Transportation was Diamond Grade (type XI) and Clearview. This combination will increase signs’ visibility and legibility to drivers, and consequently increase safety on roadways. Adding partial lighting at intersections will reduce the expected nighttime crash frequency, and increase safety on roadways. Table of Contents List of Figures ............................................................................................................................... xii List of Tables ............................................................................................................................... xiii Acknowledgements ....................................................................................................................... xv Dedication .................................................................................................................................... xvi Chapter 1 - General Issues Related to Elderly Drivers ................................................................... 1 Introduction ................................................................................................................................. 1 The Importance of Driving for Older Populations ...................................................................... 2 Working and Retiring Behavior in the U.S. ................................................................................ 3 Older Population Statistics .......................................................................................................... 4 Age-Driving Related Issues ........................................................................................................ 5 Visual Acuity ........................................................................................................................... 6 Increasing Reaction Time ........................................................................................................ 9 Physical Limitations .............................................................................................................. 10 Cognitive Functions ............................................................................................................... 10 Possible Solutions for Improving Roadways to Enhance Population Safety ............................ 12 Reducing the Impact of Vision Decline ................................................................................ 12 Improving Intersections to Overcome Physical Changes ...................................................... 12 Making Roadway Navigation Easier ..................................................................................... 13 Chapter 2 - Overhead Guide Signs and Senior Drivers ................................................................ 15 Introduction ............................................................................................................................... 15 The Observation Angle ............................................................................................................. 16 Retroreflective Traffic Sign Sheeting Materials ....................................................................... 17 Guide Signs ............................................................................................................................... 19 MUTCD 2009 Standards Regarding Guide Signs .................................................................... 19 Standardization of Guide Sign Location ............................................................................... 20 Lettering Style and Size on Conventional Road Guide Signs ............................................... 20 Lettering Style and Size on Freeway and Expressway Guide Sign Standards ...................... 22