Several examples here at CityLab, and an analysis of the disaster that never seems to happen. As with Vancouver’s Burrard Bridge bike lane in early 2009, the doomsday howling about Carmageddon and chaos arrives like clockwork whenever motordom’s asphalt is threatened.

But life goes on, it seems. The dire prophecies are rarely true, and the pundits rarely pilloried for their false prophecies.

Joe Cortright in CityLab looks at Atlanta, where part of I85 (a major freeway) caught fire. Yes, the usual noise filled the airwaves, but Carmageddon and its attendant chaos did not arrive.

So what’s going on here? Arguably, our mental model of traffic is just wrong. We tend to think of traffic volumes, and trip-making generally as inexorable forces of nature. The diurnal flow of 250,000 vehicles a day on an urban freeway like I-85 is just as regular and predictable as the tides. What this misses is that there’s a deep behavioral basis to travel. Human beings will shift their behavior in response to changing circumstances. If road capacity is impaired, many people can decide not to travel, change when they travel, change where they travel, or even change their mode of travel. The fact that Carmageddon almost never comes is powerful evidence of induced demand: people travel on roadways because the capacity is available for their trips, and when the capacity goes away, so does much of the trip making.

I wonder — is there a real Carmageddon?  As illustrated below, is it the endless expansion of asphalt-covered land to the benefit of motordom, and to the exclusion of every other mode of transportation?