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Tuesday, November 26, 2013

Tracing the World's Most Complicated Roadways With GPS Data

As reported by The Atlantic Cities: Who knew GPS could be so beautiful?  The intricate highway interchange is always easier to appreciate from above. Take away the congestion, the last-minute mergers, the tail-pipe exhaust, the conflicting road signs and the vertigo, and a perfect cloverleaf really starts to look like a marvel of engineering.


Perhaps you've seen photos like these that capture the most complex Interstate overpasses as interlocking ribbons of asphalt. The above image, though, presents some of this same information in a quieter, more beautiful way, reducing interchanges – in this case, the intersection of I-70 and the I-465 beltway around Indianapolis – to their simplest geometry.
That picture comes from a layer of GPS traces on OpenStreetMap, where it's now possible to visualize the open-source mapping project's vast, ever-updating GPS database. The traces come from individual contributors, often driving their own cars, creating their own data streams via something as simple as an app on their smartphones. Such data can correct imprecise maps or validate earlier edits. But GPS data also produces a compass byproduct: Using it, we can verify the direction of a one-way street captured from a moving car, or unravel the elaborate logic of a four-way stacked overpass in a way that's not possible from a satellite photo.
Forget the old two-toned picture of road traffic: red for tail lights and white for head lights. This map, courtesy of MapBox and the OpenStreetMap Foundation, paints moving GPS traces with the full color wheel at right. Eric Fischer, who worked on the project, explained the method this way by email:
The resulting map of the world portrays every traced road by both location and direction. The highway interchanges, though, pop out as some of the most compelling parts of our infrastructure when viewed this way. With the help of Fischer, we pulled out some of our favorites below.
Consider this a more zen appreciation of highway infrastructure than what you'll undoubtedly experience on the roads this week heading to and from Thanksgiving.
The famous Spaghetti Junction outside of Birmingham
in the United Kingdom

A four level interchange in Los Angeles.

The confluence of I-90, I-190 and I294 outside of O'Hare International Airport
in Chicago.

New Jersey from I-95 and I-495

Arc de Triomphe in Paris

A particularly heavily traveled cloverleaf in Moscow.