Revelations on Carmageddon

In the summer of 2011, with the 405 through Sepulveda Pass set to close for construction, there were so many dire warnings of epic traffic jams that a new portmanteau, Carmageddon, was born. When the congestion failed to materialize, Streetsblog took a victory lap and declared that it was now apparent that LA doesn’t need so many freeways. Now, it’s Randal O’Toole’s turn to gloat, asserting that the BART strike has revealed the system to be unnecessary. (Although since it’s O’Toole, you have to consider the possibility that he had that post finished the day before the strike and so all he’d have to do is hit “publish”.) There are other similar examples of closures that were not known quite as far in advance: the closure of the 10 and the 14 after Northridge, the MBTA Green Line getting flooded, and so on. Why don’t the traffic prophesies bear out?

The answer is pretty simple. Cities are dynamic systems and people adjust. The predictions are silly because they assume a static system. The interesting thing to me is the apparent lack of curiosity about the knock-on effects of those adjustments.

Example: I’m right-handed; so let’s say I break my right hand. The static analysis says that my work and blogging productivity will go to zero because I can’t type, and that in a couple weeks I’ll starve to death because I can’t eat. Now obviously, that’s not going to happen. I’m going to type and eat with my left hand. I’ll type slower and I’ll probably spill coffee on myself, though I will get a little better with time.

There are two important takeaways here. One, the fact that I survive breaking my right hand does not mean that it is useless. Really, that reveals nothing about its utility for my survival. Its utility is shown by all the things I use it for when I have the ability to use it. Likewise, the utility of transportation is demonstrated by the people using it. Just because a city survives having a piece of infrastructure closed, it does not mean the infrastructure is useless. There is plenty of useless infrastructure in the United States, and it is self-evident because it is there and it has no users.

Second, even though I survive, there are still negative effects, because I get less work done and I ruin some of my clothes with coffee stains. In the case of cities, these losses are social and economic, manifest through lost economic activity, additional commuting time, etc. The losses diminish with time as people adjust, but the shadow can be very long. If I lose my right hand, I’ll recover some of my abilities in time, but I’ll never be able to do everything I could if I had both. The effects can be cumulative – if enough city infrastructure is broken and not replaced, the city will decline.

Finally, it is worth noting that there are cases where the loss of infrastructure does result in crippling traffic jams. This occurs when the disruption was not foreseen or when its magnitude was misunderestimated. The most common example is snowstorms, but even then, the system adjusts – if the roads are still blocked the next day, no one goes out. Likewise, if I order a steak for dinner and then discover I have somehow broken my hand splitting a dinner roll, I’m going to be pretty screwed that night because I won’t be able to cut my steak. But the next night, I’m not going to order another steak, knowing going in that I won’t be able to cut it.

We’re getting another experiment today with the 5 freeway closed at the interchange with the 2 due to the gas tanker spill and fire. Here’s betting that traffic won’t be as bad on Monday, since people have had time to plan ahead, as it was on Saturday, when everyone was caught off-guard. But remember, no matter what happens, it won’t tell us very much about the long-term effects of changes to the transportation network.

Like I said, I find it interesting that people seem relatively uninterested in those effects, because if you’re going to talk about eliminating infrastructure, that’s what matters.


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