Urban Form and Sustainability

I ran across an article on the Atlantic, which claimed new research showed that density of cities had little to no effect on sustainability. The article was based on computer modeling future development of three regions in the UK, and concluded that building these areas more densely would not significantly affect people’s behavior – only reducing the amount of vehicle traffic by ~5% as compared to diffuse, market-driven suburban development. Of course this flies in the face of prevailing thought, but it struck me as problematic for deeper reasons.

Link to Atlantic Article

Link to Original paper

If I were to re-write the headline of the article, I would say “New Research Finds Urban Form <u>By Itself</u> Plays Little Role in Sustainability”

My biggest problem with the models presented in the paper is that they analyze density as an <b>isolated</b> goal. This makes sense scientifically – it’s easier to measure one variable at a time instead of considering multiple, interacting variables – but it’s just not how the real world works. In the real world multiple, complementary, policy goals must be pursued at once in order to be effective. I think of compact development not as a single policy, but as a pre-cursor to other policy goals.

One example: In the conclusion section of the paper, it says “Achieving the targets on reducing CO2 emissions…can also be achieved by substantial behavioral changes such as shifting from the automobile to public transport.”

So the paper treats “compact development” and “shifting from the automobile to public transport” as two separate variables. But anyone who has visited New York and Los Angeles (sorry, I’ve never been to UK and can’t comment on the areas studied) knows that improved public transit and compact development go hand in hand. It is very difficult to develop successful public transit in Los Angeles, because the density just doesn’t support it. But the more dense a city becomes (like New York) the more impact a single new train or bus line can have. Therefore density is not a goal unit itself, it is a way to enable practical use of public transit.

The paper then seems to wave away this idea with a single sentence – “…[shifting from the automobile to public transit] demands strong incentives or penalties to make a significant difference, which would have a detrimental effect on some of the social and economic indicators.”

I’m sure this is true – but again, only if density is analyzed as an isolated policy. Expecting people to drive cars in a more compact city WILL lead to more congestion – and creating penalties such as fuel taxes, road pricing or reduced parking will only make people’s lives harder – and NOT change their behavior.

But yet again, this is an unrealistic idea. In the real world we can develop these two goals together – improve public transportation at the same time as we encourage compact development. Why stop at 2 policy goals? As commentator Chris_Mackenzie said earlier, what about mixed use development? What about innovative programs such as car-sharing that let people have access to a car without owning one, which makes it easier to live a transit based lifestyle with the convenience of a car when needed.

In my opinion, this paper is only valid within a very small conceptual box. It proves that increased density alone does not impact sustainability, but no sane planner would pursue density as a goal by itself. Density is a not an end in itself – it is the means to an end, which makes other urban development possible.

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