Google has added real-time traffic data for several major cities to its mapping service, the company said Wednesday.
The traffic information is integrated with Google Maps and is available in more than 30 American cities, including San Francisco, Dallas, Chicago and New York.
The data is provided for major highways and is color-coded to signify traffic conditions: green means no congestion; yellow is for minor holdups; and red means significant slowdowns.
According to Google product manager Carl Sjogreen, the data is aggregated from several sources, including road sensors, as well as car and taxi fleets.
As a result, Sjogreen said, there is sometimes not enough data to report road conditions. In that case, the roads appear gray.
For the time being, he added, Google will provide traffic data only for major highways, but it may expand the offering eventually.