Use of Radar Devices in Road Traffic Surveys

The Department of Roads and Transportation of Polytechnic University of Bari owns CW radar devices for road traffic surveys. The radars can be used to measure traffic volumes and vehicle lengths and speeds. Radar’s manual suggests to refer to measures of length to install the devices. To verify the reliability of such measures , an experimental survey has been carried out. The results of the survey have been used to study the errors of instruments when they are installed following the proposed (by the manufacturer) installation procedure as best as a meticulous operator without topographic helps could do in situ. Then the sensitivity of errors to changes in installation parameters have been analysed. The paper concludes that is very difficult to avoid bias in length measures and that small deviations from the suggested angle of installation (30°) causes noteworthy increase in errors if the angle is slightly greater than the recommended one.