Advanced Search

Please click here to take a brief survey

How Affordable is that Subdivision, Really?
Alex Steffen, 14 Apr 08
Article Photo

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!

Bookmark and Share


The one problem with transportation costs, and this has been touched on by others, is that often the fixed costs of owning an automobile far outweigh the variable costs, even with gasoline prices in excess of $3. Things like time-based depreciation, insurance, parking (or the implicit opportunity cost of one's own garage), non-fuel taxes that go to pay for infrastructure, registration and title fees, and financing costs are all fixed, with insurance having some small reductions possible with reduced driving demand (depending on the insurer). On top of that, insuring a vehicle in a more dense urban environment in and of itself is usually more expensive than in a less dense area, and even more so without secure, covered parking.

So without the ability to go without a car entirely, there's fairly substantial diminishing returns on reducing auto use, which varies with the age of one's vehicle.

On the number for exurban extreme commuters, could you possibly link to the source of that? Thank you.

Posted by: p on 14 Apr 08


Good points. There's a whole world of intelligent incentivization to explore here.

The numbers cited are from the story linked to in that paragraph, by the way...


Posted by: Alex Steffen on 14 Apr 08

P comments that fixed costs of car ownership make the cost differences smaller. That has not been my experience.
When we lived in the Seattle neighborhood of Wallingford, one car was plenty for two people. Out in the country now, we have to have two. (Fortunately we don't have to have a pickup truck as well, because we can borrow a neighbor's.) Depreciation is different as well. In Wallingford, a car would go 12-15 years. Now 5 is doing well.

Posted by: T on 15 Apr 08

Someone made a a valid point about fixed costs, and it is true that once you have paid big bux into a car, you want to make the most of your investment, ie drive more. How useful would it be if car insurance were paid by the day, or by the distance travelled? So every morning you would have to decide - is it worth calling up and putting another -say $5 - on the insurance to go to the mall today, or do I wait? This would also be fairer, more economical for those who do own a car but do not drive very much.

Posted by: Ted Syp on 15 Apr 08

I would love if there was one of these interactive maps for Australian cities. Even better would be incorporating some of the findings from such an analysis into housing and development policy..

Posted by: Bond on 15 Apr 08

1. concerning renting: 850 square feet in Ravenna neighborhood (2br 2 bath): 1500 dollars. 1300 square feet in shoreline (3br 2bath) 1500 dollars. to charactarize the decision to gain 35% of space for the same price by going ten miles north as "McMansion land" is at best insulting.
2. concerning buying: a recent study by economists at University of Washington (sorry, can't find link right now) found that the growth management act is responsible for as much as 200,000 added to the price of a home. e.g. 2br 1 bath home in Ravenna is as much as 500,000. 3000 sq ft can go for 1.5 million or more. young people like myself, already crushed by student loan debt, cannot afford to even live in the suburbs, let alone the city.
3. concerning transit: seattle has no subway. only 2 bridges go across the lake. going from shoreline to bellevue on the bus: 2 hours. In a car with no traffic, 15 minutes. in a car with heavy traffic, 1 hour.
going from downtown to shoreline on the bus(north edge of king county): 1 hour. going downtown to shoreline in a car with no traffic, 15 minutes. in heavy traffic, 30-40 minutes.
that one can live without a car here is fantasy. try taking your supermarket shopping for a family of three on a crowded bus. take your haul from Costco on the bus? impracticable.
4. Map uses median income. what is the mean? in a stratified place like seattle, a few have money and own expensive homes. many others struggle. the median used on the map may be enticing, but probably does not describe the circumstances of most residents.

Posted by: wcs on 15 Apr 08

I poked around the Seattle area and one thing I've noticed is that the map seems to be highlighting neighborhoods with lower property values.
These property values are lower for a reason.
To be really meaningful they'd have to cross reference the housing and transportation data with some crime stats, school quality, and access to services.

Posted by: dillenger69 on 15 Apr 08


The study you're referring to has been thoroughly debunked.

There are plenty of people who live in Seattle without cars: I've heard 40% of Seattle residents either don't own a car or can't drive.

It would seem to me that median income is a much smarter figure to use for determining affordability than mean. But if you have a plausible argument the other way I'd be glad to hear it.

Posted by: Alex Steffen on 15 Apr 08

Bravo for including non World Changing links in a post. I'm frequently frustrated by that.

Posted by: Anonymous on 15 Apr 08

wcs, while I agree with you about shopping on the bus, taking a cab is often a good option. When I used to live in Toronto, we paid $150 for parking, about $150 for insurance - that's $300 a month not including gas, maintenance, the cost of the car. While we usually took the bus (about $75 each for a bus pass), we did not think twice about taking a cab when we needed to - like getting groceries.

Posted by: Andrew on 15 Apr 08

For the curious, 15% of households in the city of Seattle have no vehicle, 55% of commuters drive to work alone, and 10% carpool.

Posted by: p on 15 Apr 08

wcs: A few points regarding the problems of shopping and not having a car.

First, there are services like ZipCar which can mitigate the worst inconveniences of public transit. I'm not sure if they exist in Seattle, but I imagine they, or a competitor, do. Or if not, there are taxis. The up-front costs look unpleasant, but when all the costs of owning a car beyond gas (maintenance, inspections, etc) are considered, going this route can lead to significant savings.

Secondly, instead of going to a massive retailer in a strip-mall, it's often possible to shop closer to home. Often this can have the side-effect of supporting local businesses too. Obviously, this is less effective in the suburbs, but we're talking about living more urbanly.

Finally, rather than taking a large shopping trip once a week, you can shop more frequently and buy in smaller quantities. This has the added benefit that you don't have to plan as much in advance (if you dont want to ;-). Your produce and baked goods are fresher, too.

Posted by: joeyo on 15 Apr 08


I'm not sure that those statistics actually run counter to the ones I quoted above.

The percentage of people who drive for their commute is a poor evaluation of the percentage of people who drive, since a sizable fraction of people don't work for pay (students, the elderly, homemakers). Similarly, many people in households with a car do not themselves own a car. I think the 40% carless/ don't drive stat is probably pretty much right.

Posted by: Alex Steffen on 15 Apr 08

If moving to the suburbs were merely a housing + transportation cost question then the above analysis, which seems correct in its main drift, would alter decisions on where to live.

But, this is not the whole story, there are obviously many other important variables, particularly trying to find a "good" -- often defined as providing the best chance of upward mobility-- environment for kids to grow up in....avoiding the presumed undermining influences in many city center areas. Similarly networking opportunities and access to economic opportunities (read: jobs) also tend to be somewhat spatially differentiated, though one is not sure if the central cities or the suburbs are better -- it is probably patchy, and depends on one's individual situation rather than being a simple dichotomy.

These factors apply even in Toronto, Canada, where urban "problems" affecting children's perceived chances of mobility are somewhat tame compared to some U.S. cities ... or so we think.

All this said, I think the work is useful, and does help quantify one factor that may contribute to both individual housing decisions and policy. It just should not be represented as being a valid "total model" of the household location decision, which usually involves a number of other significant variables.

Posted by: Mathew on 16 Apr 08

There is a start towards this with green mortgages. Where they will, for example, take into account the reduced cost to heat a home if it has above average insulation or solar. An analogous example is in the IT world where vendors will try to sell you a more expensive up-front product, but claim that requires much less technical support so the "Total Cost of Ownership" (TCO) is much less in the long run (this was one of Microsoft's arguments for buying its product over Linux).

Posted by: Scott on 16 Apr 08

There is a start towards this with green mortgages. Where they will, for example, take into account the reduced cost to heat a home if it has above average insulation or solar. An analogous example is in the IT world where vendors will try to sell you a more expensive up-front product, but claim that requires much less technical support so the "Total Cost of Ownership" (TCO) is much less in the long run (this was one of Microsoft's arguments for buying its product over Linux).

With all of the mortgage defaults now would be a great time to push for a better qualification criteria that includes transportation and home energy costs to get a little help from the market in reining in energy waste

Posted by: Scott on 16 Apr 08

A -

The intent was not to run counter to the number you provided but rather to give some numbers which have a high degree of certainty to them, and which can be easily compared with other cities. What's interesting is to see the distribution of no-car households in Seattle. Three-quarters of them are one-person households, so it ends up pulling down the percentage of people without access to a vehicle in their household to around 10% from that 15% of households level.

What's also interesting is that 88% of the car-free households are rental properties.

The original comment about it being a "fantasy" to live without a car in Seattle is clearly wrong, but the numbers seem to indicate, especially when comparing with similar cities, that relatively few people in Seattle are without access to a motor vehicle in the household.

Lumping in dependents, especially children, to arrive at some percentage doesn't seem to get at the angle of being voluntarily car-less, since these children have high access rates to household vehicles, it's just that they aren't the ones doing the driving. One could extend the same thought to other dependents who may be disabled in some manner and/or advanced in age, precluding them from being able to drive.

Even including children below the age of 16 only adds up to 14% of Seattle's population in any case.

Posted by: p on 16 Apr 08

Interesting article. I've been looking for research and hard data on this topic. I would appreciate any suggestions on more places to check.

There is certainly a correlation between suburban sprawl and GHG emmissions. I encourage everyone to read the work of Reid Ewing called "Growing Cooler".

There is also some research out there on the health effects of suburban sprawl on children. A good place to start is an article called "Think of the Children" in the May/June 2007 issue of Another good read is "Last Child in the Woods" by Richard Louv.

Posted by: blutown on 17 Apr 08



MESSAGE (optional):

Search Worldchanging

Worldchanging Newsletter Get good news for a change —
Click here to sign up!


Website Design by Eben Design | Logo Design by Egg Hosting | Hosted by Amazon AWS | Problems with the site? Send email to tech /at/
Architecture for Humanity - all rights reserved except where otherwise indicated.

Find_us_on_facebook_badge.gif twitter-logo.jpg