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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/11912

Title: Experimental evaluation of fog warning system
Authors: Al-Ghamdi, A.S.
Keywords: Alarm systems; Codes (standards); Data structures; Fog dispersal; Highway traffic control; Vehicles
Issue Date: 2007
Publisher: Published by Elsevier Ltd.
Citation: Accident Analysis and Prevention Volume 39, Issue 6, November 2007, Pages 1065-1072
Abstract: Highway safety is a major concern to the public and to transportation professionals, so the number of crashes caused by poor visibility due to fog form an alarming statistic. Drivers respond to poor visibility conditions in different ways: some slow down; others do not. Many drivers simply follow the taillights of the vehicle ahead. Accordingly, hazardous conditions are created in which speeds are both too high for the prevailing conditions and highly variable. Findings are presented from a study of traffic crashes due to fog in the southern region of Saudi Arabia. The primary objective was to assess the effectiveness of fog detection and warning system on driver behavior regarding speed and headway. This warning system includes visibility sensors that automatically activate a variable message sign that posts an advisory speed when hazardous conditions due to fog occur. The system was installed on a 2 km section of a two-lane, rural highway. A data set of 36,013 observations from both experimental and control sections at two study sites was collected and analyzed. The data included vehicle speed, volume, and classification; time headway, time of day, and visibility distance. Although the warning system was ineffective in reducing speed variability, mean speed throughout the experimental sections was reduced by about 6.5 kph. This reduction indicates that the warning system appeared to have a positive effect on driver behavior in fog even though the observed mean speeds were still higher than the posted advisory speed. From relationships found in the literature between mean driving speed and number of crashes, a speed reduction of only 5 kph would yield a 15% decrease in the number of crashes. © 2007.
URI: http://hdl.handle.net/123456789/11912
ISSN: 00014575
Appears in Collections:College of Engineering

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