Google Traffic works by analyzing the GPS - determined locations transmitted to Google by a large number of mobile phone users. By calculating the speed of users along a length of road, Google is able to generate a live traffic map. Google processes the incoming raw data about mobile phone device locations, and then excludes anomalies such as postal vehicles which make frequent stops. When a threshold of users in a particular area is noted, the overlay along roads and highways on the Google map changes color.
where does google maps get the traffic information from
the GPS - determined locations transmitted to Google by a large number of mobile phone users