California Partners for Advanced Transportation Technology

This report describes a cost-effective data collection system for Caltrans 170 traffic signal controller. The data collection system is based on TCP/IP communication over existing low-cost mobile communication networks and Motorola® iDEN1 mobile handsets. An adaptive wireless flow control protocol is developed to ensure reliable continuously communication over unstable wireless link. The system is fully integrated with Caltrans 170 signal controllers and its CTNet server program. Lab testing shows that with the adaptive flow control protocol, each handset can deliver data fetched from signal controllers at a period of 200ms continuously over 95% of the time. One set of data collection device costs less than $100 and its monthly cost can be as low as $10.