The Fog Detection and Warning System (FDWS), a pilot project, uses high-tech equipment to help you find your way when the going gets tough on Central California freeways. There are roadside weather stations and visibility meters, electronic message signs and low-powered AM radio stations that gather information and alert you in advance of foggy conditions. Signs that estimate road visibility and a 3-2-1 countdown pattern of one way clear reflective pavement markers to assist motorists in locating exit ramps in heavy fog.