The devices will use GPS to track when, how far and on which roads the drivers use their vehicles in their daily lives. Leibel said participants will be paid $895 - $300 up-front, $40 a month for eight months and $275 at the end of the project.
The survey will test not only the technology but also behavioral reactions and attitudes about the concept. Leibel said researchers hope to put together a broad cross section of the population, including people of varying education and individuals who have privacy concerns.
Kuhl, the project leader, said the electronic systems are perhaps the least uncertain part of the experiment. Similar GPS-based systems are already up and running in Europe.
Leibel compared the system to other, more familiar technologies that can pinpoint a vehicle's location at a given time - such as EZ-Pass, individually owned GPS units and cell phones.
The distinction is that the use of those technologies - like participation in the study - is voluntary and can be avoided on any given day. Any widely adopted road use fee scheme would likely involve mandatory participation in order to drive on public roads.
Kuhl acknowledged that such a system would raise privacy concerns and force "hard choices" about how to replace fuel taxes in the future.
"There's concern that the gas tax has been around for 70 years and it's pretty invisible and pretty ingrained," he said.
While Kuhl insisted that any eventual system could include safeguards to ensure that no precise locational information would be reported to authorities, the privacy center's Coney was less sanguine.
"The GPS signal will be associated with a vehicle or the owner of a vehicle," she said.
Coney said she would be concerned that a system adopted to collect revenue would be subject to "mission creep" - future pressure to expand its use by government agencies with other agendas.
While not flatly opposing the concept, Coney said any system that can track locations would have to be designed with strict safeguards - including criminal sanctions - to ensure that future events won't drive how the system is used.
"The inevitable emergency is going to happen," she said, adding that law enforcement and national security officials will want the same type of access to information they have received from phone companies.
One of the dangers, Coney said, is that such a system would let authorities track who is associating with whom and draw their own, potentially erroneous conclusions. She gave the example of a person joining in a highway cleanup with a church group including members who oppose the death penalty - a reference to the recent revelation that the Maryland State Police had put death penalty opponents under surveillance and added some of their names to a terrorist watch list.
Doug Hecox, a spokesman for the Federal Highway Administration, admitted that there are still concerns about such a system that have not been resolved.
"How do you get around the fact that the government would be riding around in your car? I don't know," he said.
Information about participating in the study can be found at roaduserstudy.org. or by calling a toll-free number, 866-363-1975.
