John Thacker points us to a study of California (registration required, but free). I've only browsed it but the introduction states:
In September 2008, the California state legislature passed the first state law (Senate Bill 375) to include land use policies directed at curbing urban sprawl and reducing automobile travel as part of the state’s ambitious strategy to reduce greenhouse gas (GHG) emissions. The legislature recognized that cleaner fuels and more fuel-efficient vehicles would not be sufficient to achieve the state’s goal of reducing GHG emissions to 1990 levels by 2020. The bill requires the state’s 18 metropolitan planning organizations to include the GHG emissions targets established by the state Air Resources Board (ARB) in regional transportation plans, and to offer incentives for local governments and developers to create more compact developments and provide transit and other opportunities for alternatives to automobile travel to help meet these targets. ARB currently estimates that reductions in vehicle miles traveled (VMT) resulting from these actions will contribute only about 3 percent of the 2020 targets–an estimate that reflects uncertainties in the state of knowledge about the impacts of more compact development patterns on travel and the short time horizon involved.
In other words, the environmental benefits of checking pro-suburb subsidies are real, but they are smaller than many people think. That's from the National Academy of Sciences and the authors are no haters of the environment. If you check out p.59, you'll see that a forty percent increase in population density decreases vehicle miles traveled by less than five percent. pp.131-132 offer a summary of the study's conclusions and quantitative estimates.
The authors conclude that density-friendly policies are a good idea, and I agree, but still these are not overwhelming effects. Keep in mind that current trends are strongly pointing toward population dispersion, so to reverse those trends and see greater density would take some doing. We're not close to that margin.
There are many other interesting parts of the report, including case studies of Portland and Arlington.
I don’t have time to read the report now, but it strikes me that a large part of the reason for the limited carbon emission reduction is that the current sprawl would remain, so the impact would be marginal but so too would be the change in the total number of housing units in CA before 2020.
Compact development and mass transit also have positive health effects, as sprawl is positively correlated with obesity. See http://www.springerlink.com/content/x57848u7t83v004r/
People living in walkable communities are likely to walk (and bike and jog) much more than lazy suburban land whales. More density, well planned, will lead to svelte, athletic urbanites exercising all the time on their way to the organic grocery, the hip independent coffeeshop cum bookstore, and their luxe creative class offices where they manipulate symbols all day.
The ultimate result is that they will be eating more and more edamame, grass fed beef, sprouted wheat germ, and that kind of peanut butter they like where the oil separates.
All that walking and jogging is less efficient than motor vehicles once you include the petrochemical fertilizers, shipping farm to market, farm machinery, packaging, advertising, and other costs of feeding the urbanites all those extra calories.
In fact, walkable urbanism is a likely a net energy consumer once we consider feeding active urbanites. I bike to work and eat 3500+ kcalories a day (yes, I’m skinny). And that doesn’t mention the depredations on farmland that could be restored to nature.
I’m a libertarian, but I have to say it’s sad to see so much underutilized space in American inner cities. I’ve driven in downtown Baltimore and seen tons of row houses which sit empty while sprawling suburban development gets built elsewhere. Its the same story in Atlanta, New York, and many other cities across the nation.
In the 1950′s, Detroit had the busiest pedestrian intersection in the nation, busier than any corner in New York. Now downtown Detroit is a ghost town. It all goes back to chronic mismanagement of inner-city schools and police departments starting in the 1960′s and hopefully the management will get better as it has in Atlanta recently, encouraging more people to move back in from the suburbs.
The problem preventing people from moving back into cities is not the policies or the infrastructure, but the people who live in them.
OK, a fine suggestion, but the paper does include figures estimating the result up to 2050 as well, which addresses several of the objections here. The research claims that if 75% of all housing (new construction and replacement) is built at double the current density everywhere, it would only reduce VMT by only 8 to 11 percent by 2050.
From that abstract, there were “small but significant associations.” As we know from statistics, even if the p value is very small, so that we’re quite likely that there’s something there, if the size of the effect is very small, as it is in your paper, it’s still not very important.
It’s the same issue in the obesity paper as with VMT from the NAS paper. Sure, the effect is probably real. But the size of the effect is a lot smaller than you might think.
Brian,
You owe me a new keyboard.
Only 5% for a 40% increase in density? Wow, thats horrible.
For my family, living in a denser neighborhood decreased miles traveled by about 40%, and I got rid of one car.
I moved from Highland, Indiana to Oak Park, Il. Simply not driving to the train and walking to public transportation every day saved me about 3000 miles a year. 12 * 250 = 3000, then my wife apparently puts on about 2000 miles less a year.
Not typical, but it really depends on having robust PT and a walkable community. If we take plainfield, Il and make it 40% more dense, there is no benefit. But if we take make Evanston, Il more dense, it would make a huge difference. Simply increasing density doesn’t help that much.
Plus, glad to see you are addressing the former paucity of posts about land usage!
Here is some related info:
Disturbingly, this simply isn’t true. I started by pulling out various numbers on the energy used per passenger mile of various forms of transportation. These numbers can be found in places like the U.S. government bureau of transportation statistics figures and the Dept. of Energy Transportation Energy Data Book (Especially table 2-12). I’ve also found tables broken down per city.
http://www.templetons.com/brad/transit-myth.html
http://cta.ornl.gov/data/index.shtml
It doesn’t have to be, and you’ll never sell it to people with that tag line. Denser housing can have smaller yards, less space between houses, or involve multilevel buildings. In some areas, “luxury” townhomes and apartments/condos are quite large.
Thanks for the clarification, John. Much as I’d like to read through every interesting-sounding report that comes my way, in this case all I had to respond to was what was in Tyler’s post.
Also, of course denser housing doesn’t *have* to be smaller, but it’s an empirical fact that on average it is. As for ‘selling it’ to people, I imagine there are lots of people who would like to buy a more affordable apartment rather than a less affordable detached home. And the locational amenities of denser areas are of course very different. There are a lot of tastes not catered to by the predominantly low-density nature of current development patterns.
Jim,
I haven’t read the study so they might touch on this, but VMT reductions wouldn’t be the only environmental impact of denser development. Denser housing will tend to be smaller, and apartments, semi-detached or terraced housing are more energy efficient, so energy use for heating tends to decline with density.
Reducing housing size would be a cost to consumers who prefer bigger housing. Substituting apartments, semi-detached housing or terraced housing for detached housing would be a cost to consumers who prefer detached housing. You can’t simply look at the benefits of a change in housing policy and ignore the costs.
And, as with VMT, it’s not really clear that any feasible densification policy would produce more than trivial savings in energy consumption or emissions through smaller housing sizes or more energy-efficient housing designs. It may not produce any savings at all. Denser housing would tend to involve taller buildings. Taller buildings tend to require more energy for construction and operation per square foot than shorter buildings, because of the need for stronger building materials to support the weight of lower floors, and energy required for things like elevators and water pumps.
The impact on VMT of a shift in development patterns would presumably also get larger over time, so the estimate of a small impact by 2020 isn’t that surprising.
The report’s MOST OPTIMISTIC densification scenario, which would require 75% of new construction to be built at twice the current average density, projects fuel and CO2 emissions savings from VMT reduction of only 8-11% by 2050. That’s 41 years from now. Since passenger transportation accounts for only about 20% of total energy consumption and emissions, this would be a total savings of just a few percentage points. And that’s for the most optimistic scenario. For the report’s “moderate” scenario, the total savings would be just a fraction of a percentage point. It’s negligible. You could achieve the same effect as projected for the most optimistic densification scenario, without any reduction in VMT, by increasing average automobile fuel efficiency by around 2 mpg (about 10%).
There is no serious argument for densification on energy efficiency or emissions grounds. It would require a huge and absurdly implausible change in current building practises to achieve just trivial savings in energy use and emissions.
jim: “There are a lot of tastes not catered to by the predominantly low-density nature of current development patterns.”
Sorry, but I disagree. Unless by a lot of tastes you mean the desire of high density advocates to restrict the choices of those who prefer low density living.
All across Dallas – Fort Worth, one can find both high density and low density residential development. The market is providing the type of housing both groups desire. What it is not providing is enough demand for high density housing so that retailers are catering to the high density dwellers. So residents of high density housing still, for the most part, have to travel to low density neighborhoods to obtain groceries, to repair vehicles, to purchase TV’s, etc.
The reason retailers are locating near low density residential neighborhoods is very simple: that’s where most of their customers prefer to live.
“the environmental benefits of checking pro-suburb subsidies are real, but they are smaller than many people think… you’ll see that a forty percent increase in population density decreases vehicle miles traveled by less than five percent.”
Increasing density to reduce VMT by 5 percent will not reduce carbon emissions by 5 percent. Increased density will simply lead to higher traffic congestion. Stop-and-go driving in congested areas consumes much more gasoline per mile driven than does the free flowing driving common in low density suburbs.
If you are an environmentalist, sprawl – or the reduction of pollution-causing congestion – is your friend. Walkable living environments for 300 million Americans is, of course, an unattainable fantasy.
I suspect that at some point there will be a sort of back-fill of some of the urban centers and this would match the history of cities much older than exist in North America (except Mexico, DF).
I don’t know what you mean by leaving out México. We’re currently rebuilding on many abandoned lots in the center where there were collapses in 1985. Central city population (Delegación Cuauhtémoc and around) is growing again.
Hey!
As a drunk Scottish economist I think you guys are really missing the point. When you are building a new housing estate you are able to incorparate the latest environmental building techniques along with localized and acceptable local power development from the onsett so people know what they are buying into. This has a much larger affect than just how much gas it takes to buy a nice frappachino.
Well, There are number of factors that we should consider upon to reduce GHG and it can only be achieved by social awareness of the people and some legislative Laws passed by the goverment….
Even if all growth were into suburban densities, it would still result in a higher density for population centers. Remember 100 years ago 75% of the country lived in rural areas and many of those on farms. To talk my home county in Missouri as an example: in the 1920 census it had a population of 20,000, now it is 6,500. However, in that time the population of the actual 3 towns in the county never changed.
While the suburban form of population density is slightly less (or lets say equal) to small towns, it is still more than the overall population density of rural ares when rural was the majority of the population. However, the explosion of suburban population has had the effect to spread the density of the small towns (as if the small towns in my county grew to cover the entire county resulting in a population of likely several hundred thousand). This has occurred over the last hundred years, resulting in 75% of the US population living in suburbs, roughly 20%+ in urban and 3% in rural. Urban centers have gone down in density, but overall density has gone up because of the growth of the suburbs. New Jersey has a population density matching NW Europe. That is the future for population in this country.
The report does not look at co-benefits, which can strengthen the advantage of a more dense housing market. Additionally, these benefits grow slowly, as new development only adds a small portion of the total built environment each year, and less than usual over the past year due to the economy. However those small portions add up over time and they are also last for 50 to 100 years.
Dan H: “It would be interesting to come up with a good congestion pricing scheme, perhaps coupled with automated GPS-based billing, and see if that alone solves the ‘urban sprawl’ problem over time.”
Sorry, but I don’t understand how congestion pricing would “solve” urban sprawl.
As I see it happening today, sprawl is the solution to urban congestion. Companiess such as J.C. Penney, EDS, Burlington Northern Santa Fe, and Frito Lay have relocated headquarters from congested urban locations to the far suburbs of Dallas-Fort Worth. As they did so, they removed thousands of employees’ vehicles from center cities.
Geographic dispersion of workplaces and residences is how Americans have chosen to deal with urban congestion. Urban congestion pricing is not going to get people out of cars and into mass transit. All it will do is hasten geographic dispersion.
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