United States. Department of Transportation. Federal Highway Administration. Offices of Research and Development
Abstract
DOT-FH-11-9328The program objective was to develop a system capable of detecting snow, ice, frost, or slush over a highway bridge deck area greater than 4 x 2 feet (1.2 x 0.6 m) and generate a valid alarm signal to warn motorists of a hazard. The detection system selected was a microwave radiometer operating at 10 GHz which continuously samples a reference noise source and internal amplifier noise to provide measurement corrections of radiated power received from the road surface being observed. Principal radiometer components are: rectangular horn antenna; sensitive receiver; and signal processor/alarm unit. The successive program phases were: (1) design optimization and system tradeoffs; (2) breadboard model laboratory and field tests; and (3) prototype model design, fabrication and test. Test results on asphalt and concrete roadway simulators, as well as actual asphalt roads, correlated with previously published radiometric temperatures for similar surfaces. The following road conditions were detectable: dry/warm; dry/cold; wet; slush; ice layer (0.1 cm. minimum); and snow layer (1 cm. minimum). All road hazard detection objectives were met except for frost detection. Descriptions of recommended additional effort are presented, including detailed evaluation of the prototype model; advanced alarm logic; self-test techniques; and a scanning antenna to cover increased road areas
