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Caltrans Urges Motorists: Prepare For Fog Season
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During the winter months, San Joaquin, Stanislaus and Merced counties are plagued by extremely dense fog which poses a severe hazard to drivers. Typically the fog season begins during the month of November and continues through February. Despite this predictable seasonal occurrence, multi-vehicle accidents are commonplace due to the combination of fog, excessive speeds and traffic congestion.

The California Department of Transportation (Caltrans) implemented what is now known as Caltrans Automated Warning System (CAWS) as part of the annual Operation Fog campaign aimed at helping drivers get safely through the winter months. The CAWS consists of 48 Changeable Message Signs (CMS), 44 weather stations and 160 speed monitor locations along Interstate 5 and State Routes 99, 120, 152, 205, 156 and 580.

The CAWS system is fully automated; visibility sensors provide reduced visibility information and the speed monitors detect slow and stopped traffic. Working together, these components provide the data necessary to display the appropriate message on the CMS. “Low Visibility Reduce Speed” and “Slow Traffic Ahead” are only two of the helpful and informative messages displayed for motorists.

The California Highway Patrol (CHP) has implemented pace units that work on major highways between Modesto and Merced on foggy days to slow vehicles down when visibility is less than 500 feet.

For up-to-date information, motorists should tune in to local radio and television stations. Motorists can get information on specific highway conditions from the Caltrans website or by telephone at 1-800-427-ROAD (7623).

A Caltrans News Flash video highlighting Operation Fog is available on You Tube at

For the safety of workers and other motorists, remember to slow for the cone zone and for more information visit