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OCR for page 25
25 "streamer" or "pencil" nozzles or just holes in the spray bar ABRASIVES be used to apply "strips" of chemical to the surface. The The primary function of abrasives is to provide temporary spacing of nozzles or holes should be in the range of 8 in. traction (friction) improvement on snow/ice surfaces. It should There have been rare circumstances when using a liquid be realized that snow/ice covered roadways that have been chemical has resulted in slippery conditions in the absence of treated with abrasives provide friction values that are far less precipitation or freezing pavement temperature. This phe- than "bare" or "wet" pavement. The application rate for abra- nomenon seems to be related in many instances to the com- sives varies considerably among maintenance agencies. Appli- bined effect of relative humidity, pavement temperature, and cation rates for most agencies fall within the 500 lb/LM to chemical type. The untreated areas between strips should 1,500 lb/LM range with the overall average centering around help minimize the potential for this type of slipperiness. 800 lb/LM.