GPS users map the nation's most congested cities

A California traffic jam

The company that makes Tom Tom global positioning system - or GPS - navigation devices says it's getting some of the most complete and up-to-date information ever on roads in the U.S.

And now, it's ranking them.

"There's some surprises," says Margot Dologne, a spokeswoman for Tele Atlas, a digital map company and subsidiary of Tom Tom. "I mean, you would never think Seattle would be the most congested city in the continental United States, or for that matter Minneapolis -St Paul would be down at the number 30 spot."

The company ranked 30 metropolitan areas in the US with populations over half a million.

Here's how the system works: Using satellite location data, Tom Tom devices drop the equivalent of a digital "breadcrumb" into an onboard database every five seconds, marking where the device goes.

When users connect the units to desktop software, most of them also allow their devices to upload the anonymous "breadcrumbs" onto the company's servers.

The company applies algorithms and GIS software to the data from thousands of users and comes up with a map. The software can compare posted speed limits on any given stretch of road with how fast the Tom Tom devices traveled through the area.

Tele Atlas says that with millions of GPS units out traveling around, the company has daily data on every major road in the US. Tele Atlas can analyze the information and push the data back out to GPS users to alert them to traffic trends in their area.

"What we're seeing now is GPS devices that have live information in them, historic information in them," Delogne says. "It's using a lot of intelligence and imagery and a lot of other content to give you the best possible experience and the fastest possible route."

And the company still digging deeper into the user data it is collecting.

"This data is actually revealing all kinds of things to us. You know, some of the things we're pulling from the data are like, where is the American autobahn? Where are the fastest drivers in the country, i.e., those that are going way above the speed limit. I don't personally know the answer right now, but what we're finding actually in some of the data is that the fastest drivers are people who have the slowest speed limits."

That kind of detailed information that just hasn't been around before, according to David Schrank.

He'a a co-author of the annual Urban Mobility Report from the Texas Transportation Institute at Texas A & M. His study is considered a gold standard of traffic scholarship.

"Over the last three, four, five years, the majority of this GPS data was on fleet vehicles, whether it was trucks or utility vehicles or perhaps transit vehicles. But it was not necessarily passenger cars," Schrank says. "But just in the last year or two, they have started getting more and more passenger car data. So they're starting to mine
that data, too."

But more data isn't necessarily good data.

Schrank says many of the commercial GPS providers look at only a single factor when considering congestion: speed.

Traffic scholars, though, say that transportation is more complex than simply how fast the vehicles are going down a stretch of road at any given time.

Some cities, for instance, restrict freeway entrances with ramp meters. Traffic may be moving swiftly on the road itself, but motorists could be facing long delays to get to the interstate.

The volume of vehicles on the road is also a key factor in traffic delays and what the Texas Transporation Instiute bases its estimates on.

All that may explain why the Transportation Institute's reports are different from GPS data.

In their annual report, for instance, Seattle barely cracked the top 20 for most hours of delay per year and more than a dozen urban areas rank better than the Twin Cities.

But Schrank says crowd-sourcing with GPS still has a lot of potential.

Stephen Collwell says he thinks GPS devices are where phones were earlier this decade, poised to be a breakout technology.

Colwell is a founder of GPS World, one of the industry's leading trade journals.

After years of innovation in geography, meteorology and oceanography, Colwell says location based services are becoming a uniquely human phenomenon.

He says social media and wireless networks may soon pinpoint real-time images and data, phone numbers and even menus and store inventories, in the real landscape.

"We're really beginning to realize just what it is we can do with all this GPS stuff. We're moving into the Golden Age."

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