How Traffic Apps Use Others Drivers' Data to Help You Pick a Better Route

DOWNTOWN — Do you ever wonder how your phone knows that traffic is snarled and you should probably reroute?

There aren't traffic sensors on every Chicago street, right?

Turns out, drivers ahead of you are lending a hand in tipping off your phone to the best route.

Michael DeKrell, senior manager of traffic incident processing at HERE, said the mapping company collects real-time data from drivers with GPS-enabled phones and connected in-dashboard navigation systems. That data helps HERE compute "current flow, current current congestion, and current travel times."

"We don't track individual vehicles," DeKrell said. "We track a point, a path so that we know where something is going and how fast it's going."