Google Maps for Mobile users become traffic beacons

This week, Google is expanding the traffic layer in Google Maps to cover all US highways, and to determine the flow of traffic, its own users are anonymously supplying the data.

In Google Maps for Mobile with "My Location," phones with GPS (excluding iPhones) send their speed data to Google so it can determine the overall speed at which traffic is flowing. Traffic flow is not uploaded in a social way. That is to say, a single user does not simply flick on his GPS to show other users that he's stuck in traffic. Rather, Google pulls the speed data off of every phone with Google Maps and GPS and combines it to arrive at an average.

"We understand that many people would be concerned about telling the world how fast their car was moving if they also had to tell the world where they were going, so we built privacy protections in from the start," Dave Barth, Product Manager for Google Maps wrote in the company's blog today.

"We only use anonymous speed and location information to calculate traffic conditions, and only do so when you have chosen to enable location services on your phone," Barth continued. "We use our scale to provide further privacy protection: When a lot of people are reporting data from the same area, we combine their data together to make it hard to tell one phone from another. Even though the vehicle carrying a phone is anonymous, we don't want anybody to be able to find out where that anonymous vehicle came from or where it went -- so we find the start and end points of every trip and permanently delete that data so that even Google ceases to have access to it. We take the privacy concerns related to user location data seriously, and have worked hard to protect the privacy of users who share this data -- but we still understand that not everybody will want to participate."