Tuesday, October 18, 2011

A remedial lesson in urban form and economics (part 2)

Continuing from last week with excerpts from Phil Hayward's amazingly insightful paper on urban form and economics. (again the bold highlighting is mine)
Platitudes like “we must locate people close to where they work”, or “we must locate jobs close to where people live”, have little basis in reality.
Ultimately, green planning will phase out cheap urban land, undermining this sector and destroying jobs in the process.
The Los Angeles urbanized area (the census bureau’s functional definition of “urban” that includes a central city and all of the surrounding land above 1,000 people per square mile) has increased in density from barely over 4,000 people per mile to over 7,000 people per square mile, making it the densest urban area in the United States. It is this increasing density, not sprawl, together with the fact that Los Angeles has one of the lowest provisions of freeway miles per capita in the nation, that has led to increasing traffic congestion in Los Angeles. This has happened despite the fact that Los Angeles has one of the most extensive transit systems and lowest car ownership rates in the country today. One of the things that all of these erroneous preconceptions about sprawl demonstrate is the complexity of urban systems and the way that in these complex systems almost every cause is also an effect and vice versa. Thus, rather than say, as many people do, that the automobile was a principal cause of sprawl in the twentieth century, it would probably be at least as accurate to say that a desire for lower density living was the reason automobile makers were able to transform themselves from a small industry turning out luxury products to an enormous industry making a product that has become a standard fixture in affluent households worldwide.
Eric A. Morris says, in “Los Angeles Transportation Facts and Fiction”:
“.......by the standards of U.S. cities, Los Angeles is not sprawling, has a fairly extensive transit system, and is decidedly light on freeways. The smog situation has vastly improved.....“........Los Angeles’s traffic woes stem from the fact that it doesn’t sprawl enough and has overinvested in costly rail transit at the expense of developing its undersized freeway network.....”
Although many people like to observe that Europeans still drive less than Americans, in fact the upward trajectory of automobile ownership and automobile use have increased in Europe in almost exactly the same way as in the United States, simply with a time lag due to a lag in affluence.
The term “dense sprawl” has recently been coined to describe LA. This also describes the cities of Australia and NZ. With all the successful infill development that has taken place, we have ended up with much higher traffic congestion, because our provision of road space has not kept up with the population increase.
Planners might have hoped that mode shift to public transport would negate the effect of higher density on road congestion, but this has never happened anywhere in the world, to sufficient extent to actually negate the congestion negative externalities. The very wrong assumption underlying our modern planning fashions is that increases in density might lead to direct reductions in car use. In fact, it perfectly logically leads to increases in car use per square mile/ square kilometer of the urban area, and increased congestion.

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At 9:03 PM, October 21, 2011, Blogger Alon said...

Freeway lane-miles per capita have weak correlation with congestion per capita and an anemic regression coefficient, and zero correlation once you control for the size of the urban area.

See my analysis of TTI data in the following two posts:

At 7:40 PM, October 24, 2011, Anonymous awp said...

it is increased congestion (increasing cost of travel) that causes density (living closer to where you want to go=>less travel).

There is a new study out by duranton and turner in American Economic Review that claims to show that growth in roadway provision is matched one for one by growth in travel. Haven't read it yet.

At 8:04 PM, October 24, 2011, Blogger Tory Gattis said...

It seems pretty straightforward to me. As long as mobility is available (i.e. growing with population), core job centers continue to grow and draw employees from the growing suburbs. When they reach their limits, prices go up in the core (since people can't live in the cheaper suburbs with better schools and still have a reasonable commute) and the job centers slowly stop growing. Employers either move to the suburbs, or new employers start there, to access the affordability and commutes for their employees. But the metro area fragments. Employees no longer have as many employers to choose from (commute limitations) and employers have a smaller potential employee base to draw on. That's harmful to both sides - lower productivity and salaries + higher unemployment. Core tax base stagnates.


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