Something you probably take for granted — I know I do — is that your favorite navigation app will plot routes with traffic in mind, and warn you whenever a jam is brewing. It’s essential for driving, or more lately, riding a high-end PEV. I used to live in Austin, Texas, where a jam on MoPac or I35 could mean the difference between getting somewhere in 30 minutes or over an hour. When there’s an alternative, no one in their right mind takes I35 during rush hour.
Where do Apple Maps and Google Maps actually get their traffic data from, though? And how reliable is it? The quick answer is that they share similar sources, and that reliability can vary wildly, especially when it comes to incident reporting. Always prepare for a worst-case scenario when a trip is urgent.
The secret to Apple and Google traffic data
You are the radar
At the core of both Apple and Google’s apps is the same technique: crowdsourcing. As you drive, your phone (or car) naturally needs to communicate with a remote server, unless you’re relying on offline maps. At the same time, it uploads your anonymized GPS location, which gives a rough sense of where you’re headed and how fast.
On its own, your personal info is useless. But if you aggregate that with the data of hundreds or thousands of other drivers, a bigger picture starts to emerge. In fact, the more people there are using your app of choice, the more likely it is to even out any discrepancies, such as someone waiting to pick up a friend, or pulling into a drive-through for coffee.
Google, at least, also uses aggregated content to make predictions. If a particular stretch tends to slow from 50 to 30mph at the same time every day, that can be factored into calculations. This does have to be properly balanced against real-time data, naturally. In Austin, for example, visitors and road closures during SXSW can bring otherwise fast roads to a crawl. A rule of thumb is that the further out your destination is, the more historical data is used for modeling.
To improve things further, both companies license data from outside parties. The list of Apple Maps partners is huge, and it’s even bigger for Google Maps. You’ll notice that a lot of these parties are government agencies. They’re not necessarily sharing traffic material — but given that governments record it for their own purposes, and make a lot of it public, it would be crazy for Apple and Google to ignore the opportunity when it arises. The two private groups Apple relies on most are TomTom (of dash unit fame) and OpenStreetMap. Google pulls much of its crowdsourcing from Waze, but that’s not an outside party anymore. Google bought the firm way back in 2013.
The last piece in the puzzle is user-submitted incident reports. Each app lets you flag not just congestion, but specific causes, such as crashes, construction, flooding, police, or stalled vehicles. This isn’t necessarily taken as gospel, since drivers do make mistakes. Much as with general traffic, though, a large enough reporting sample helps. Apple notes that it doesn’t display warnings on other users’ devices until there’s a “high level of confidence” in a particular hazard. Google presumably does the same, since it’s constantly prompting you to confirm whether an issue is still active.
How much should you trust an app’s traffic data?
Good news, with edge cases
In my own testing across Canada and the US, I’ve found Apple and Google Maps to be reasonably accurate under most circumstances. Sometimes the ETAs they provide are uncanny, no more than a minute or two off from the original route prediction. And as you travel, both apps constantly refine their estimates based on your own position and cumulative info.
This can break down, as you’re probably aware. A dependence on crowdsourcing rather than true mass surveillance means that there’s always going to be a slight delay between when congestion builds and when it’s actually reported. You may find yourself in a jam even though an app claims it’s all clear.
This is even more true when it comes to user-reported incidents. It may take several reports before a hazard appears on your map, and these can easily be misplaced. Drivers are, after all, trying to tap a screen while careening at dozens of miles per hour, and may not notice something until they’re right on top of it. Apple and Google also have no quick way of knowing whether a hazard has been cleared — when I lived in Edmonton, it was common for Google Maps to claim ongoing construction when it had long since been moved out of the way.
Yet another factor to consider is the popularity of a platform. While iPhones are dominant in North America, many owners still use Google’s app instead of Apple’s, and the combination of that with the presence of Android phones can give Google an edge. In other regions, it’s often Android that reigns supreme. There might only be a few Apple Maps drivers on some roads, if any, particularly as you venture into rural areas. I’d definitely recommend against relying on Apple Maps for a cross-country tour of China.
