>> about 90% accurate. >> reporter: nathaniel runs the city's transportation agency and he says te $20 million project entirely federally funded, is about trying to ease congestion. >> that helps us speed up our transit system, helps us with greenhouse emissions in terms of automobiles circling around. >> reporter: the app has been downloaded more than 12,000 times but there's real concern about whether or not it's creating another problem, california has a no texting law while behind the wheel, and driving while using the app, surely doesn't seem safe. >> we do not encourage people and it's not necessary to constantly look down at your device, looking for a parking spot. >> reporter: still considered a pilot project, the city installed sensors in 7,000 of the city's 24,000 metered parking spaces and 12,000 more in city owned garages. if it works, look for it to expand here and another big cities. dan simon, cnn, san francisco. >> all right. so right 134 some of the time,