UC Irvine Institute of Transportation Studies

The Tracer system consists of any number of mobile extensible data collection units (EDCU) communicating wirelessly in real time with a base station server. The mobile EDCUS store speed, longitude, latitude, and timestamp readings from a global positioning system (GPS) antenna. They also transmit these readings wirelessly, in real time, over a cellular digital packet data (CDPD) modem. A small pilot study with four vehicles was conducted to test the system. Three vehicles have collected over 100 days worth of data, and the one other vehicle has collected over 70 days worth of data. The operational experience gained from this wireless data collection implementation is documented here. The results demonstrate that long-term wireless data collec tion is feasible, but that the CDPD link's instability can add errors to the data stream.