This is how Google Maps knows which route is the fastest at any given moment

A couple of days ago, I was driving to a concert on the other side of the state, a trip that was intermittently soundtracked by Google Maps' turn-by-turn directions. I was coasting down the interstate on-ramp, when the Maps voice said "You are on the fastest route and your route is clear." But how does Google Maps know that? According to Tech Insider, it's a combination of the number of people who are currently using the service, its database of historical traffic data and a few technological tricks it has absorbed from other companies.

Everyone who uses Google Maps is helping the app become a little more accurate — and a little more indispensable — for the rest of us. When the app is open, it is constantly sending information back to Google, providing data about the route being traveled and what the traffic patterns and average speeds are like at any given time of day. All of that information (and the number of users who use the app on a regular, if not daily, basis) has given Google a huge database of traffic data, which allows it not only to monitor what's happening now, but also to more accurately predict what will happen as you continue on that particular route.

Amanda Leicht Moore, Google Maps' lead product manager, told Tech Insider:

"It's not just what [traffic] is right now, but how do we expect it to change over the next hour or two hours. We can tell you if the traffic jam ahead — is that going to add five minutes to your trip? Or 10 minutes to your trip? Or 40 minutes to your trip? There’s a lot of modeling and a lot of smarts that go into trying to anticipate how traffic will change."

Part of the app's "smarts" are provided by Waze, the traffic and navigation app that Google purchased in 2013. Waze relies on its users who supply real-time traffic information and accident reports during their commutes — and then that information is also used to make route recommendations (or to alert you of upcoming delays) in Google Maps. If the app does change your route, telling you to take an exit you might've otherwise driven by or sending you on a two-lane county road, it has started to let you know why.

On the night of the concert, Google Maps told me that I would arrive at 8:03. I pulled into the parking lot at 8:02. I was slightly late, but that wasn't Google's fault.