In Traffic? Next Time, Use an App - NYTimes.com

Crowdsourcing traffic data

"The ideal solution would be to gather live information on the speed and location of most vehicles on the road, and then to transmit the relevant traffic conditions to drivers so that they can avoid problems ahead. A sampling of three services suggests that this is finally starting to happen with improved accuracy, thanks to the growing popularity of in-car telematics and — perhaps more important — the pervasive use of smartphones.
The basic idea is to gather information from drivers on the road through in-dash or smartphone GPS and cellular connections. It’s a mutually beneficial arrangement. To receive traffic alerts, drivers allow the services to collect anonymous information on their own speed and location."

In Traffic? Next Time, Use an App - NYTimes.com