One freeway and one surface street arterial site were chosen in each of three states to test and evaluate alternative traffic detector technologies. The states were selected to be representative of extremes in climatic conditions. Accordingly, Minnesota was chosen for its cold winter environment; Florida for its summer thunderstorms, lightning, and humidity; and Arizona for its dry desert summer heat. Sites were located on roadways that had high traffic density and suitable structures for mounting the overhead detectors. The detector technologies evaluated were ultrasonic, microwave radar, infrared laser radar, imaging and nonimaging passive infrared, video image processing with visible spectrum imagery, acoustic array, high sampling rate inductive loop, conventional inductive loop, microloop, and magnetometers. Approximately 5.9 GBytes of digital and analog vehicle detection data and more than three hundred video tapes of the corresponding traffic flow were recorded. The detector outputs were time tagged and recorded on 88 MByte replaceable magnetic cartridges by using a data logger specifically designed and built for this project. Data analysis software was written to convert the data into an easily accessible Paradox data base format compatible with a Windows personal computer operating system. Traffic volume ground truth data, obtained by counting vehicles in the recorded video imagery, were compared with the counts from the detector outputs. Speed ground truth data, obtained by driving probe vehicles through the field of view of the detectors and noting the vehicle speed as measured by the vehicle instrumentation, were compared with the speed measurement from the detectors.