Carmageddon in Atlanta -- or maybe not, because "predictions of terrible traffic in the wake of even major disruptions to the road system are almost never realized."

To hell with facts -- we need more traffic lanes!

Carmaggedon stalks Atlanta, by Joe Cortright (City Observatory)

Why predicted gridlock almost never happens and what this teaches us about travel demand

It had all the trappings of a great disaster film: A spectacular blaze last week destroyed a several hundred foot-long section of Interstate 85 in Atlanta. In a city that consistently has some of the worst traffic congestion in the country, losing a key link its freeway system could only mean one thing: Carmageddon ...

 ... The prospect of gridlock makes for great headlines and local TV news stories, but as it turns out, predictions of terrible traffic in the wake of even major disruptions to the road system are almost never realized.

One of the most famous instances of this phenomena was in Los Angeles. In 2011 and 2012, the state highway department closed a 10 mile stretch of Interstate 405 on several weekends to rebuild overpasses. The media was awash in predictions of Carmaggedon. But surprisingly, nothing of the kind happened. As Brian Taylor and Martin Wachs explain in an article in Access, people mostly avoided taking trips in the area, or chose alternate routes, with the effect that traffic was actually much lighter than normal. They report that “Rather than creating chaos, the first closure greatly reduced traffic congestion.” Taylor and Wachs explain that “crying wolf” about likely gridlock depressed trip-taking in the affected area, but that effect faded as travelers realized things were nowhere as bad as predicted ...