Carmageddon?

This past weekend, a ten-mile section of the I-405 freeway which links western Los Angeles to the San Fernando Valley through the Sepulveda Pass was completely closed for construction. Although there was much worry that the closure of this vital stretch of highway would lead to a "carmageddon" of traffic gridlock in the Los Angeles area, the freeway was reopened ahead of schedule and the feared calamity of paralyzed traffic never came to pass.

A couple of thoughts:

1. What does it say about the cultural gravity of Los Angeles that the closure of 405 was the weekend's biggest national news story? I know LA is the nation's second-largest metropolitan area as well as the country's entertainment center. But it nevertheless seemed a bit strange that a closure of a section of freeway in this city appeared to be the top story of several major media websites, ahead of arguably more important items such as the ongoing debt ceiling negotiations in Washington or a tabloid scandal in Britain that threatens to bring down an entire media empire. Last year The Atlantic's Conor Friedersdorf wrote about "The Tyranny of New York," whereby the city dominates America's media such that everything that happens there becomes national news. Perhaps we can speak of "the tyranny of Los Angeles" as well?

2. Motorists are not water molecules. We describe traffic as analogous to fluid: the movement of vehicles is referred to as "traffic flow." Areas of recurring congestion due to merges and lane closures are referred to as "bottlenecks." As such, there's always a fear that the closure of a major section of roadway will cause massive traffic backups, much as the closure of a valve on a pipe causes water to back up.

However, at the wheel of every vehicle is a human being who makes choices as to where to drive or to drive at all. If motorists are made aware of a major closure - the 405's shutdown was well-publicized - they will choose alternate routes to get to their destination or decide not to make the trip at all. That obviously happened in Los Angeles this past weekend, as there was reported to be 65% fewer automobiles on the LA freeway network than on a normal weekend (the fact that the closure occurred over the weekend also probably helped, although as anybody who's been to Los Angeles knows, heavy traffic is just as frequent on Saturdays and Sundays as it is during the work week).

This is why traffic nightmares did not occur in Manhattan after the West Side Highway was shut down in 1973 or in San Francisco after the Embarcadero Freeway was demolished following the Loma Prieta earthquake in 1989: people were aware of the closures and simply altered their travel habits accordingly. (This, incidentally, is also one of the reasons why widening a freeway does not, in the long term, relieve traffic congestion: people become aware of the added capacity of the widened freeway and begin using it for their trips, and the new capacity is eventually completely absorbed by all those new motorists.)

Another closure of the 405 is scheduled for next year. It will likely be just as much of a non-event as this weekend's closure was, and hopefully the rest of the nation won't be subjected to constantly hearing about it.