Green Design

How Affordable is that Subdivision, Really?

How much of your monthly budget you pay for transportation is largely influenced by where you live.

Live in a compact community, and your mere choice of residence vaporizes trips, because the things you need are close-by, and we all know that the most sustainable form of transportation is not having to go anywhere in the first place. But should you have to travel some distance, you're more likely to be able to car share or take transit (since density makes transit cost-effective).

Live out in McMansion Land, though, are your choices are basically drive or spend hours and hours in inconvenient transit, if it can be found at all. So auto dependent are most new suburbs, that they're hazardous to the health of the people who live there.

All that driving gets expensive as well. The median household expenditure or transportation in the U.S. is 19.1% of its budget. That percentage rises sharply in suburban households, and, I'd expect, skyrockets in exurban developments where, on the extreme end, 3.5 million Americans now commute more than three hours a day, and spend more than 40% of their income on transportation.

We've covered the Housing and Transportation Affordability Index before, but now Worldchangers Erica Barnett and Eric de Place have both blogged elsewhere about the Center for Neighborhood Technology's new interactive mapping site, which graphically illustrates the connection.

Here's how Eric explains it:

This map combines both housing and transportation costs. The result is maybe a bit surprising. In-city areas tend to look pretty good, while far-flung suburbs -- where you get a lot of square footage (and lawnage) for your money -- don't look so good at all. It makes a little clearer the tradeoff between floor space and travel costs, which tend to be higher than buyers imagine. Especially these days.

In the maps below, the pale areas show places where housing + transportation are 45 percent or less of median income. It's higher than 45 percent -- and therefore not "affordable" by this definition -- in the blue areas.

Erica takes on "the argument most commonly used for anti-growth management, pro-suburban land use policies—middle-class people have to live somewhere; the suburbs, and exurbs, just provide them an affordable place to do it."

One factor that often doesn’t get considered in discussions of Seattle’s rising prices is transportation costs. It makes sense that if you have to “drive until you qualify,” as one common justification of living in the suburbs puts it, the cost of that driving ought to be considered as part of the cost of living far outside the city. Generally, though, it isn’t—allowing pro-suburban, anti-regulation, anti-density pundits and politicians to claim that Seattle’s housing prices are “out of control” and that the suburbs are the only “affordable” alternative.

According to CNT’s analysis of the Seattle region, the most affordable parts of our region are actually inside city limits—once transportation costs are factored in.

This is a really brilliant piece of map hackery, one which clearly illustrates a basic principle in contemporary urban planning through a simple portrayal of real numbers. In the process it shows why smart growth is good for regular people. Bravo, CNT!

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(Posted by Alex Steffen in Columns at 5:33 PM)