Sensate Roadbeds


We are building a prototype infrastructure for real-time collection and distribution of comprehensive information about road traffic and conditions on a network of streets. Small (2 cm diameter) cylinders placed just under the road surface count passing vehicles by detecting magnetic-field disturbances. Periodically, these sensors transmit an updated count by radio to a regional repeater, which relays them to a central processing station. Each package, which costs about $40, is powered by a single lithium battery, and can be installed in a few minutes without tearing up the road. The central station uses the sensor data to compute queue-length and departure-rate statistics for each road segment, and uses Little's Formula to assign a time in seconds to each road link. This database is published once a minute on the Internet. Vehicles will use CDPD or a similar wireless network standard to download the relevant sections of the database, and plan optimum (shortest-time or least-fuel) routes through the road network, informing the driver of suggested route changes in real time. We will also explore adding other minimally expensive sensors to this package, such as piezo pickups for detecting road vibration, and perhaps accident signatures and temperature and humidity sensors to determine local road conditions.