NCJ Number
29980
Date Published
Unknown
Length
74 pages
Annotation
THIS REPORT PRESENTS RECOMMENDED STANDARDS FOR EMERGENCY VEHICLE WARNING LIGHTS, SIRENS, AND VEHICLE MARKING PATTERNS.
Abstract
THIS REPORT PREPARED BY THE LAW ENFORCEMENT STANDARDS LABORATORY AT THE NATIONAL BUREAU OF STANDARDS DISCUSSES THE CURRENT STATE OF THE ART OF VEHICULAR WARNING DEVICES: LIGHTS, SIRENS AND CONSPICUOUS MARKINGS. THE AUTHORS CONTEND THAT THE VARIETY OF WARNING DEVICES CURRENTLY USED AND THE LACK OF UNIFORMITY WITHIN INDIVIDUAL COMMUNITIES MAKES IT DIFFICULT FOR TRAVELERS, TRUCK DRIVERS, AND OTHERS MAKING LONG DISTANCE TRIPS TO KNOW HOW TO RESPOND APPROPRIATELY TO AN APPROACHING EMERGENCY VEHICLE. BASED ON TESTS CONDUCTED BY LESL, THE AUTHORS RECOMMEND A WARNING LIGHT SYSTEM COMPRISED OF ALTERNATING RED AND WHITE FLASHING (OR ROTATING) LIGHTS HAVING A FLASHING RATIO OF 20% ON TO 80% OFF, COMBINED WITH A RELATIVELY LOW INTENSITY BLUE LIGHT (FLASHING RATIO OF 50-70% ON, WHICH IS SENSED AS FLASHING OFF RATHER THAN FLASHING ON). THE RED AND WHITE FLASHING SIGNALS WOULD BE USED FOR EMERGENCY VEHICLES OPERATING AT HIGH SPEED. THE BLUE SIGNAL WOULD INDICATE AN EMERGENCY VEHICLE NOT OPERATING IN AN EMERGENCY MODE, BUT ON ROUTINE PATROL OR PARKED OFF THE ROAD. STANDARDS FOR SIRENS ARE ALSO REPORTED. FOR A SIREN OR PAIR OF SIRENS THE STANDARD REQUIRES THE A-WEIGHTED (A STANDARD MEASURE OF SOUND) SOUND LEVEL TO BE AT LEAST 132DB ON THE FORWARD (LONGITUDINAL) AXIS AND AT LEAST 128DB IN THE DIRECTIONS AT PLUS OR MINUS 45 DEGREES FROM THE FORWARD AXIS. THESE LEVELS MUST BE REACHED AT A DISTANCE OF TWO METERS FROM THE SOUND SOURCE. THE CONSPICUITY OF VEHICLE PAINTING SCHEMES IS ALSO DISCUSSED. THE STANDARD RECOMMENDS THAT EMERGENCY VEHICLES BE PAINTED IN A 'HARLEQUIN' PATTERN (CONSISTING OF VERY LARGE SQUARES OF CONTRASTING COLORS) FOR MAXIMUM CONSPICUITY. THIS PATTERN ENSURES THAT THE VEHICLE WILL STAND OUT REGARDLESS OF THE IMMEDIATE BACKGROUND.