How GPS devices are being used to detect and avoid traffic

This is relevant to the discussion about congestion pricing, mesh networks and avoiding traffic jams, a topic that I am getting interested in as you could see from this previous post.

[… snip] Now help is at hand. As satellite-navigation devices become more widely used, networking effects are making them more powerful. This is because vehicles themselves are starting to relay real-time traffic data—and he more that do so, the more accurate traffic information will become. [snip…] (from The Economist)

Read the whole article and you will see that it's more than just GPS devices that are being called to duty: cell phones as well as verbal reports can get integrated together into an overall picture of where the traffic is and how to avoid it.