Animated Map Shows How Paved Roads Spread Across L.A. County

Is the L.A. of 2014 driving around on a road network built for the L.A. of the 1980s? That's one conclusion two researchers at Arizona State University draw from their above data visualization, which uses building records from the Los Angeles County Assessor's Office to infer the age of the metropolis' roads. Green represents the oldest roads, red the newest.

The animation by doctoral student Andrew M. Fraser and professor Mikhail V. Chester tracks the steady growth of L.A.'s road infrastructure through the city's prewar boom and its postwar suburbanization. After 1955—the cutoff point between green/yellow and orange/red—the growth slows. It then more or less stops by 1990, when the county was home to nearly one million fewer people. In an email message, Chester alludes to that disconnect:

By the late 1980s nearly 99% of all lane miles that exist in LA County today had been deployed. Demand (measured in Vehicle Miles of Travel, VMT), however, continued to increase until the the early 2000s. This rise in demand without equivalent increases in the supply of transportation infrastructure may have contributed to the growing levels of congestion experienced in Los Angeles.


That's not earth-shattering news to anyone who's spent a long afternoon on the 405, but the pair's research could provide a data-driven rationale for rethinking how Angelenos get around. Chester continues:

We are investigating whether the saturation of infrastructure supply has contributed to the leveling off of VMT in the region over the last decade. In short, the roadway infrastructure in Los Angeles may have reached a capacity limit for vehicle travel which, combined with population growth, may lead to decreasing levels of personal mobility if the current transportation and land use paradigm remain [emphasis added].

Check out Fraser's and Chester's full report for more, including an explanation of their methodology.

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