Southern California drivers are using the first solar-powered devices to pay automatically for road tolls. The California Department of Transportation (Caltrans, Sacramento, CA) has introduced pocket-sized devices, known as transponders, as part of the FasTrak system for collecting tolls electronically on Orange County's 51 miles of public toll roads, which handle 200,000 trips a day.
Solar-powered transponders are estimated to last up to 11 years, or twice as long as battery-powered units currently in use. The transponders are mounted on vehicle windshields and automatically deduct tolls from prepaid accounts when drivers pass under overhead readers on toll roads.
The solar-powered transponders alternate between sunlight and a lithium battery for power. About 5,000 solar transponders will be distributed on a first-come basis to customers. Each transponder is marked with a unique ID number to track the device's performance over time.