However, Dina Katabi and Omid Abari at MIT realized that anyone could prod a transponder to emit its signal, simply by asking nicely. They have developed a small solar-powered unit called Caroake that can measure the position and speed of up to 20 nearby vehicles that are equipped with E-ZPass transponders. Each Caroake unit currently costs around $100, although that figure would drop significantly if the units where produced in volume, say the researchers.
By putting Caroakes on every urban streetlight, the researchers envisage tracking the occupancy of every parking space, counting how many cars are waiting at every traffic light, and perhaps even catching every speeding vehicle. They are about to deploy six readers on public streets in Cambridge, Massachusetts to learn local traffic and parking patterns.
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