Road Weather Management Program
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Best Practices for Road Weather Management Version 2.0


Experimental Evaluation of Fog Warning System


This paper presents findings 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 a fog detection and warning system on driver behavior regarding speed and headway. The warning system includes visibility sensors that automatically activate a dynamic message sign that posts an advisory speed when hazardous conditions due to fog occur. Although the warning system was ineffective in reducing speed variability, mean speed throughout the experimental sections was reduced by about 6.5 kph. This speed reduction could yield a 15 percent decrease in the number of accidents.


King Saud University (Saudi Arabia). For a copy of this resource, please direct your request to

Date: NA




Motorist warning system
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