Date of Award

2005

Degree Type

Dissertation

First Advisor

Jyh-Hone Wang

Abstract

This research presents a study that assessed drivers' responses to and comprehension of variable message sign (VMS) messages displayed in different ways with the intent to help enhance message display on VMSs. Firstly, a review of literatures and current practices regarding the design and display of VMS messages is presented. Secondly, the study incorporates three approaches in the assessment. Questionnaire surveys were designed to investigate the preferences of highway drivers. Lab experiments were developed to assess drivers' responses to a variety of VMS messages in a simulated driving environment. Field studies were set up to study drivers' response to VMS in real driving environment. Thirty-six subjects, from three age populations (20-40, 40-60, above 60 yrs old) with balanced genders, were recruited to participate in both questionnaire surveys and lab experiments while eighteen of them participated in field studies. Survey results suggest that VMS messages should display specific, unabbreviated messages. Results additionally indicate that static (one-frame) messages with no flashing or one-line flashing displayed in amber or green-amber color combination are most preferred by drivers. Flashing effect, color combination and their interaction were found to significantly affect a subject's response time to comprehend a message. Age effect was found throughout all test conditions. Older subjects responded slower with lower accuracy than younger subjects. No significant difference was found between male and female subjects. Results from lab experimentation supported the finding found from the survey and field studies, helping to validate lab simulation experiments in this research area. In addition, it found that there existed a positive, linear, and strong correlation between lab experiment and field study results, indicating that stable individual differences are reflected in both sets of results. Based on this strong correlation, a model was developed using results obtained from simulated driving lab experiment to predict drivers' response in real driving.

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