TUNNEL ROAD SAFETY: A LOOK AT OLDER DRIVERS’ PERFORMANCE AND SIGHT IMPAIRMENT A Thesis presented to the Faculty of California Polytechnic State University, San Luis Obispo In Partial Fulfillment of the Requirements for the Degrees Master of City & Regional Planning Master of Science in Engineering (Transportation Planning Specialization) by Edith Lopez Victoria March 2014 © 2014 Edith Lopez Victoria ALL RIGHTS RESERVED Page ii COMMITTEE MEMBERSHIP TITLE: Tunnel Road Safety: A Look at Older Drivers’ Performance and Sight Impairment AUTHOR: Edith Lopez Victoria DATE SUBMITTED: March 2014 COMMITTEE CHAIR: Dr. Cornelius Nuworsoo, Associate Professor City & Regional Planning Department COMMITTEE MEMBER: Dr. Anurag Pande Assistant Professor Civil Engineering Department COMMITTEE MEMBER: Chris Clark, JD, Lecturer City & Regional Planning Department Page iii ABSTRACT Tunnel Road Safety: A Look at Older Drivers’ Performance and Sight Impairment Edith Lopez Victoria In California, there is an observed trend in which collisions cluster in and around tunnels. The break in road continuity created by the tunnels disturbs traffic flow that can lead to collisions. One of the main contrasts between open roads and tunnel roads occurs in lighting. Drivers with sight deficiencies are unable to adapt their sight to the change in the lighting environment and may crash due to misperception of road alignment, vehicle’s speed and other physiological reactions, such as tension. The suspect population group of crashes occurring under the influence of tunnels conditions is older drivers. The literature suggests that sight and driving performance deteriorate with age. This research attempted to validate this claim by performing a study that looked at driver and crash characteristic of injury and fatal collisions that occurred in and around tunnels. The expectation was that a greater proportion of the older population, 60 years and older, would be represented in the crash data. However, this study found that it is young drivers and not older drivers who are more likely to crash in and around tunnels. This finding may be explained by the State of California’s vision requirements for the issue of a driver’s license, and the voluntary retirement of drivers that feel that they can no longer drive safely. Page iv A second explanation may be that high-risk taking behavior exhibited in younger drivers overcompensates for the physical impairments exhibited in older drivers. Page v ACKNOWLEDGMENTS I would like to dedicate this thesis to my thesis committee, thank your for all your help. A special thank you goes for Professor Nuworsoo for guiding me throughout the process and for being patient and supportive every time I explored a different thesis topic. Additionally, thank you to my family and friends who supported me throughout my thesis writing process. Page vi TABLE OF CONTENTS !"#$%&'%()*+,#%-----------------------------------------------------------------------------------------------------------------%.% !"#$%&'%/"012,#%-------------------------------------------------------------------------------------------------------------%."% 3-%45$2&617$"&5%------------------------------------------------------------------------------------------------------------%3% 1.1. Statement of the Problem ........................................................................ 1 1.2. Statement of Purpose .............................................................................. 3 1.3. Relevance of Study .................................................................................. 4 8-%!"$,2)$12,%9,:",;%--------------------------------------------------------------------------------------------------%<% 2.1. Physical Factors ....................................................................................... 7 2.1.1. Sunlight Glare ...................................................................................... 7 2.1.1.1. Sunlight Glare Mitigation .......................................................................... 9 2.1.2. Lighting .............................................................................................. 10 2.1.2.1. Flickering and Rhythmic Lighting ........................................................... 11 2.1.3. Ventilation .......................................................................................... 11 2.2. Human Factors ....................................................................................... 12 2.2.1. Age .................................................................................................... 12 2.2.1.1. Crash Severity ........................................................................................ 13 2.2.1.2. Driving Behavior and Performance ........................................................ 13 2.2.1.3. Vision ..................................................................................................... 15 2.2.1.4. Physiological and Psychological Factors ............................................... 22 =-%>$16?%@,$A&6&+&0?%----------------------------------------------------------------------------------------------%8B% 3.1. Data .......................................................................................................... 25 3.1.1. Data Source ...................................................................................... 25 3.1.2. Data Limitations ................................................................................. 27 Page vii 3.2. Analytic Framework ............................................................................... 28 3.2.1. Site Selection .................................................................................... 29 3.2.1.1. Tunnels .................................................................................................. 30 3.2.1.2. Age Cohorts ........................................................................................... 36 3.2.1.3. Age Cohort Determination ...................................................................... 37 A,%B3(*=#"#%(34%7+#/*$#%,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,%;C% 4.1. Expectations ........................................................................................... 38 4.2. Crash characteristics ............................................................................. 39 4.2.1. Temporal Distribution ........................................................................ 39 4.2.1.1. Yearly ..................................................................................................... 39 4.2.1.2. Monthly ................................................................................................... 40 4.2.1.3. Hourly ..................................................................................................... 41 4.2.1.4. Tunnel Location – Entrance, In Tunnel and Exit .................................... 45 4.2.1.5. Collision Type ......................................................................................... 48 4.2.2. Driver and Party Characteristics ........................................................ 50 4.2.2.1. Sex ......................................................................................................... 50 4.2.2.2. Old Drivers vs. Young Drivers ................................................................ 51 4.2.2.3. Involvement ............................................................................................ 54 4.2.2.4. Violation Category .................................................................................. 58 4.2.2.5. Sobriety .................................................................................................. 59 @,%D&35*/#"&3%(34%7+5&EE+34($"&3#%,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,%F6% 5.1. Concluding Observations ...................................................................... 62 5.2. Recommendations ................................................................................. 63 5.3. Further Investigation .............................................................................. 65 G")*"&.0(H?=%,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,%FF% Page viii BHH+34"5+#%,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,%:I% A. Population Projections ............................................................................. 80 B. Crash Characteristics ............................................................................... 81 C. Driver and Party Characteristics ............................................................. 87 D. Population Proportion Analysis .............................................................. 92 Page ix LIST OF TABLES Table 1. Mean Minimum Speed (km/h) Reached During Hazard. ....................... 14! Table 2. Information Provided in Crash Records ................................................ 26! Table 3. Tunnel Characteristics (2002-2011) ...................................................... 35! Table 4. Tunnel Location: Chi-Square Frequency (2002-2011) .......................... 47! Table 5. Age Distribution of Percent Involve in Crash and Age Percentage ....... 52! Table 6. Crash Severity – Chi-Square Frequency (2002-2011) .......................... 57! Table 7: Sobriety – Chi-square Frequency (2002-2011) ..................................... 61! Page x LIST OF FIGURES Figure 1. Cluster