February 3, 2016 7:00 am
Updated: February 3, 2016 4:21 pm

Does your phone help build Google’s traffic maps? (And is that bad?)

WATCH: Have you ever wondered how Google Maps is able to show you traffic patterns?

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Google’s traffic maps paint an extraordinary picture of a big city’s movements.

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In Toronto, a mouse click or two recently showed that the southbound lanes of Toronto’s Don Valley are bumper-to-bumper, but the northbound lanes are moving well – those drivers can indulge the complacent glance we save for someone else’s traffic jam. Green lines on a road are good, red is bad, black is seething misery.

Zoom in, and you see traffic patterns on smaller streets, in a startling level of detail. Red lines show that traffic is slow around Broadview and Danforth, where road work has drivers moving cautiously. Zoom further in, and thin coloured lines show traffic, such as it is, on quiet residential streets.

Out in the country, thin green lines show that traffic is moving well on lonely sideroads.

It’s by far the best traffic data available – it makes the traffic helicopters and traffic reports of old seem last-century.

Where does all that data come from in the first place?

Well, some of it may come from the phone beside you in the car.

READ MORE: Our digital privacy coverage

It’s a simple concept – if you know where someone is, and if their location is updated often, you can tell how fast they’re moving as well as where they are. If lots of drivers’ phones participate, you can tell fairly accurately how fast the road is moving.

As traffic grinds to a halt, many of the phones around you in many of the cars around you are telling Google about it, and presently the road turns red, or worse yet black, on the map. Other, more fortunate drivers frown at their maps and change their plans.

“All iPhones that have Google Maps open, and Android phones that have location services turned on, send anonymous bit(s) of data back to Google, and this allows us to analyze the total number of cars on the road, how fast they’re going on a given road at a given time,” explains Aaron Brindle, a spokesperson for Google in Canada.

By the time it reaches Google, identifying data has been delinked from the position reports – Google has chosen to know that a phone has moved in a certain way across the city, but not whose phone that is. As well, data about the beginning and ending of trips are deleted.

“For what we’re trying to achieve here, user data is not necessary,” Brindle says.

“What we need to know is the number of cars on the road and how fast they’re moving.”

Pedestrians can be screened out of the data because of their different speed and because the geolocation is precise enough to see that they’re mostly on the sidewalks:

“They will move with a different kind of cadence, and they will also typically not be on the roads themselves. We can really tell where data is coming from, even between lanes and that sort of thing.”

Brindle would not say how many devices were participating in Canada.

READ MORE: Every move you make: Privacy expert wary as insurers track drivers

“This is anonymized data, it’s not personal, it’s not reflecting any one user account. We respect our users’ privacy, and one of the ways we do that is by making it very clear in our privacy agreement what data is being used, and that you don’t have to share that data.”

Brindle could not say how often phones reported their location, but did say that “ … we can tell when traffic is speeding up or slowing down, and that’s pretty much instantaneous.”

From Google’s point of view, everybody who lets their device contribute to Google Traffic has clearly consented.

“It’s in the privacy terms – it’s clearly outlined there.”

IMG_9424 An Android device warns its user that their location will be sent to Google.

Google Traffic encapsulates a lot of the issues with our digital privacy and the quiet conversations our devices have with databases far away. It’s a high-quality free service, it’s ingenious, contributor consent may range from fully informed to ambiguous and it involves trusting a company with personal data that you may or may not realize is being collected in the first place.

There’s also the view that if you’re benefiting from data it’s reasonable to ask you to let your device contribute to gathering it. The issue in this case is visualizing what consent means, and realizing that you’re trusting Google to self-limit its ability to track your comings and goings, as they say they do.

“When a company is simply crowdsourcing information collection with no controls, there’s a very real chance that privacy can be invaded,” says Brenda McPhail, a privacy expert at the Canadian Civil Liberties Association.

“The whole model of consent, in the online age, is not serving us really well, because the issue of what can happen to your data is so complicated, and the way that it gets put out into the system and can be used for so many things, without your knowledge, means that you either have to have very great trust in a company that says ‘we will only use your data for this purpose,’ or you sort of just let it go.”

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