Speed Enforcement Policies and Practice

1970PDFResearch PaperWitheford, David K.Eno Foundation for Highway Traffic ControlEno Foundation for TransportationUnited StatesTraffic speed measurementSpeed limitsPolice traffic servicesSurveysSpeed limits enforcementDrivingSpeedData collectionIn 1903, New York City Police Commissioner William McAdoo introduced what was perhaps the first modern speed enforcement technique. As described in "Traffic is a Monster,"' "The system, put to work along the Hudson drives, consisted of three dummy tree trunks set up at one-mile intervals along the roadside. A policeman equipped with a stopwatch and a telephone was concealed inside each fake tree. "When a car sped past the first station, the policeman telephoned the exact time to the officer in the next tree. The second officer set his watch accordingly. When the car went by his post, be computed its speed for the mile. If this was above the limit, he telephoned the policeman in the third tree, who lowered a pole across the road and stopped the car." Though time and distance measurements are often still essentials, policies and techniques in speed enforcement have come a long way since then. Speed limits at that time were typically from eight to ten miles per hour in cities, and fifteen miles per hour on rural roads. Today, 70 mile per hour speed limits are common, and radar devices and electronic computers do the work of calculating speeds for police officers. Some things have not altered, however. The principal reasons for controlling vehicle speeds are the same: protection of life and property against the hazards of highway travel, and efficient use of street and highway systems. Vehicle speed, either high or low, may in itself be a cause of accidents; it is clearly a factor in determining the severity of accidents. Speed is also a factor in determining a highway's capacity to move traffic. There is, therefore, an interest in speed control from the viewpoint of safeguarding not only the public welfare but also the public investment in highway systems. As travel growth has been accompanied by higher tolls in accidents and increasing levels of highway investment, this concern has grown.95