Who Would Have Thought?
Lance on Sep 19 2007 at 5:44 pm | Filed under: Lance's Page, Urban planning and development
One of the more irritating aspects of debates on urban planning is the denial of what should be obvious. More people per square mile relative to the number of miles of roads means more traffic congestion. Yet “Smart Growth” and “New Urbanist” planners continue to act as if mass transit, urban design and increasing density can change this relationship. Amusingly they typically describe for we rubes Los Angeles as the hell we are all supposed to avoid.
There are two problems with that prescription. Los Angeles is the densest metropolitan area in the US and has the fewest per capita road miles. Unsurprisingly they lead the nation in congestion! Los Angeles isn’t an argument for increased density and allocation of resources away from increased road capacity, they are proof such a strategy doesn’t work! The latest report from the Texas Transportation Institute makes that clear as cities who have neglected road construction in favor of light rail and other solutions saw congestion increase faster than those which did not (small pdf.)
Funny how supply and demand works.
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Here in Austin the smart growthers argue that new roads cause development, which in turn causes traffic congestion. When you point out that by their logic one could argue that the sale of cat food causes traffic congestion, they just look at you funny.
yours/
peter.
I’m not sure exactly how this graph demonstrates how light rail makes congestion happen. Or what it’s depicting at all. Care to elaborate?
It seems to me that basic common sense shoots this down. DC congestion is terrible, and they have as many roads as you could possibly cram into the area. If you removed the Metro, it would go from terrible to catastrophic collapse. If LA does badly on road miles per person, it’s probably because of an upper limit on how many miles of roads are physically possible to cram into the geography.
You are wrong on both DC and Los Angeles as to potential road capacity. Also, while light rail demonstrably reduces congestion less than spending the dollars on road capacity, I was not attacking light rail (though there is much to attack. The first point is that cities which do less to increase road capacity versus places that do not, whether they use the money on light rail or otherwise (It doesn’t seem to matter because so little traffic is carried on the light rail it amounts to a rounding error) have worse congestion problems. If you look at the underlying data it has little to do with the size of the cities. Some big cities do worse than others depending on that one metric.
The second point is that cities which increase density do not reduce congestion, whether they spend money on light rail and other options or not. Yet, this is often claimed as a way to reduce congestion. Every city which has tried the growth boundary/high density/fewer roads/Transit Oriented Development model has seen congestion increase faster than cities which do not. That doesn’t mean the model is bad (though I have problems with it) but that this particular claim fails. As far as I can tell it has failed in every instance to accomplish this particular stated aim.
One problem is clear from cities which have aggressively utilized this model such as Portland. By increasing density they have both made it difficult to build roads while simultaneously increasing the need for roads. Transit, despite receiving huge subsidies has barely made a dent.
The interesting thing is Portland knew that. Not at first, but when their planners studied what the effect of their plans were, right on the heels of screaming to get their plans approved to keep them from becoming Los Angeles, found that Los Angeles actually was a lot like what they were trying to accomplish from a density, transit and roads standpoint. Instead of questioning that goal they quietly slipped the findings in and admitted Los Angeles had a desirable development pattern. Now I am no LA hater, and think it is unfairly criticized, but it isn’t what they were selling people on, and the planners need to start being straight with themselves and people that they are trying to accomplish things which may be fine and dandy but will not solve problems such as pollution, congestion or lead to more affordable housing. We have seen time and again they make each worse. The other goals may be laudable enough to overcome those issues, but my guess is they don’t think the public will buy if they knew the truth. So they lie to themselves and/or others.