Junk Science Week: #2 – Density & Congestion

I’ve previously discussed the myth that density relieves congestion, yet it persists. Most recently, planners in Fairfax County, Virginia say they want to put thousands of high-rise apartments in Tysons Corner in an effort to increase the density and relieve congestion around proposed rail stations.

Planners claim that Ballston, a rail station on the DC Orange line, proves that this strategy is successful. The opening of the Ballston station in 1979 led to a lot of transit-oriented development, and today many people in the area walk or take transit to work.

However, planners fail to mention that a major freeway, I-66, opened at about the same time, and it probably did more to stimulate development than the rail line. At least, other stations that were not close to new freeway interchanges failed to develop as planners hoped.

The myth that density can reduce congestion goes at least as far back as 1973 with publication of a book titled Compact City: A Plan for a Livable Urban Environment. The book called for high-rise housing projects, but suggested that Jane Jacobs’ “lively streets” model could work as well.

The year before, Edwin Mills’ models of urban economies had already proven than density only increased congestion because large increases in density would only produce small reductions in per-capita driving. But Mills was not a popular writer (except among economists), and his work was ignored by planners.

The modern smart-growth concept of density came from the LUTRAQ research program sponsored by 1000 Friends of Oregon. Based largely on hypothetical data, LUTRAQ found that density, pedestrian-friendly design, and improved transit service would lead to small reductions in per-capita driving. 1000 Friends equated such reductions with reductions in congestion — the two are not at all the same — and convinced the state of Oregon to require all major cities in the state to adopt such policies with the aim of reducing per-capita driving by 10 to 20 percent.

USC Professor Genevieve Giuliano pointed out that most of the driving reductions projected by LUTRAQ came not from density or land-use patterns but from an assumption that all employers and retailers would charge for parking and employers would give all their employees free transit passes. As far as I know, no city has dared require retailers or employers to charge for parking; instead, they focus on less effective (and counterproductive) practices like density and transit-oriented developments.

The Ballston story, and many similar stories, suffer from the problem of self selection. Even if it is true that people who live near Ballston drive less, it is largely because people who want to drive less choose to live near transit lines. This does not mean that putting people who drive a lot in high density transit-oriented developments will reduce driving. By extension, it does not mean that increasing the density of an urban area will reduce overall driving in that area.

One of the most striking examples of this can be seen in a study by junk scientists in the Sierra Club, Surface Transportation Policy Project, and other advocacy groups. The paper (abstracted here) claimed to prove that higher densities, pedestrian-friendly design, and intensive transit service led to less driving.

To reach this conclusion, the junk scientists looked at individual neighborhoods in the San Francisco, Chicago, and Los Angeles urban areas. But they also ranked each of these three urban areas, and San Francisco had the highest density, most intensive transit service, and (by their measures) twice the pedestrian friendliness of the other urban areas.*

Guess which urban area had the most per-capita driving? Yep, San Francisco. It also had the most vehicles per capita. (This information is from table one in their paper.) And not just slightly more driving either: San Francisco was supposed to have nearly 10 percent more per-capita driving and 20 percent more cars per capita than L.A. and close to 20 percent/40 percent more than Chicago.

On a neighborhood scale, urban design may correlate with driving, but this is due to people choosing their neighborhoods according to their transport preferences. On an urban scale, if there is any correlation at all, it is that more density means more driving, or at least no less. And even if per-capita driving were the same or slightly less in a denser area, it would mean more congestion and more air pollution.

As long as planners say “less congestion” when they mean “less per-capita driving,” planning will be a junk science.

* According to Census Data, Los Angeles has a higher density than the San Francisco-Oakland urban area. The Sierra Club-STPP study used the “San Francisco urban area,” which presumably includes only the west Bay Area (San Francisco and San Mateo).

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14 thoughts on “Junk Science Week: #2 – Density & Congestion

  1. DE

    Yet another straw man. In 2 years of planning school and all my time practicing planning, I have never heard a reputable planner use “reduction in congestion” as a rationale for density. Unless someone bulldozed the sprawl, the source of congestion remains the same. The argument may be that density will result in less congestion than a comparable addition of sprawling housing units, but you don’t need all that analysis to show that adding density will, if anything, increase congestion. The catch is, with density and transit, more people are able to get around easily despite congestion. Congestion is irreversible over the long term.

  2. msetty

    Holtzclaw et al never claimed that congestion would be reduced by higher densities and less per capita driving overall. As for the “self selected” who prefer walkable neighborhoods, apparently this ia is large, and growing, percentage of suburbanites, even in places like Atlanta, where they are 35%-40% of the population, if you believe the “SMARTRAQ” surveys (Oh, I’m sure you’ll hate THAT name…)

    Congestion” is also a tertiary concern in my book, compared to problems like global warming and peak oil. Oh I forgot…these latter two concerns are something you consider to be “junk science” too. I suppose you’ll see the Atlanta surveys the same way.

  3. Tad Winiecki

    Good example of learning too much from an experiment, Randall.
    I lived in San Diego when the first light rail line to San Ysidro started. It had some unique features – the local government bought an existing rail line for a very low price; the federal government was not involved at all; the route had high traffic both directions end-to-end most of the day everyday.
    Later lines in San Diego County and almost everywhere else in the USA didn’t have these features and were much less successful. There is still debate, however, about whether buses wouldn’t be more economical than trains on the San Ysidro route.

  4. JimKarlock

    DE: Yet another straw man. In 2 years of planning school and all my time practicing planning, I have never heard a reputable planner use “reduction in congestion” as a rationale for density.
    JK: No, they just say that density will reduce driving, leaving people to conclude that it will reduce TOTAL driving instead of per person driving. They lie by deliberately leaving a false impression. I actually saw this here in Portland: The guy went on about how TODs reduce auto usage – all the usual crap. I asked if that means that there will be less congestion after building the apartment farm. He was honest enough to admit that congestion would increase.

    DE: Unless someone bulldozed the sprawl, the source of congestion remains the same.
    JK: Huh?? A direct cause of congestion is density, not sprawl. To cure congestion, you bulldoze density, not sprawl. Or simple add road capacity at the same rate as you add people.

    DE: The argument may be that density will result in less congestion than a comparable addition of sprawling housing units,
    JK: No, because you are putting more trips in the same area. It does appear to slightly decrease trips per capita, but increase in the capita results in dramatically more congestion. See http://www.DebunkingPortland.com/Smart/DensityCongestion.htm

    DE: but you don’t need all that analysis to show that adding density will, if anything, increase congestion.
    JK: I think the point here is to get rid of the “if anything”. There is NO IF – DENSITY IS A CAUSE of congestion.

    DE: The catch is, with density and transit, more people are able to get around easily despite congestion.
    JK: What? Long trip times are (almost?) always associated with density. Travel to work times are usually much longer in dense areas.

    DE: Congestion is irreversible over the long term.
    JK: Where do you get this stuff? All you have to do is add capacity to keep up with demand.

    Thanks
    JK

  5. JimKarlock

    DS: Gee. Not everyone wants to live in the suburbs
    JK: The problem in Portland is that the planners are FORCING density on the unwilling. Even after we voted against increased density by probably 85%. See http://www.DebunkingPortland.com/Smart/MetroDensityVote.htm

    DS: and be forced to drive everywhere, like some ideologies profess.
    JK: Feel free to walk and bike on paths that you pay for, but if you use transit be aware that you are using welfare. In Portland taxpayers are paying 80% of your transportation expense – welfare.

    Thanks
    JK

  6. JimKarlock

    DE: In 2 years of planning school and all my time practicing planning,
    JK: Since you are the expert, let me ask if you believe that planners are planning for what people really want or what planners want people to want? How do you tell what people really want?

    Thanks
    JK

  7. DE

    “He was honest enough to admit that congestion would increase.”
    Yeah, and so am I. Stop blaming us for idiots reading too much into our words.

    “Even after we voted against increased density by probably 85%.”
    PROBABLY 85%!? Probably? I clicked on that link and read how they got from 65% to 85%. That SURELY belongs in a blog about junk science. It’s got to be the least scientific means of determining public opinion EVER. In reality, we ARE forced into sprawl. Our investment in transportation and infrastructure has resulted in very affordable sprawl and comparably expensive urban living, pricing many who would otherwise live in the city out. I met a major developer of suburban housing in Philadelphia who left Toll Brothers to start his own booming company doing “new urbanism.” [Don’t get me started, I’m not a fan.] He explained his rationale: all of our best market research shows that 35% of Americans would choose denser, walkable communities if given the choice, but fewer than 10% of housing starts fit this segment of the market because developers aim for the “safe” 65% crowd. In other words, I am providing a product that is over 50% undersupplied!” And he’s doing very well with it.

    “There is NO IF – DENSITY IS A CAUSE of congestion.”
    I apologize profusely for my vague sentence construction. I concur that density is a cause of congestion. That said, planners like me favor density that puts people in walking or transit distance to work. This does in fact result in more people being able to get from point A to B faster and with more ease. Go have coffee at Starbucks from 7-9am and see how stressed out people look getting to work, or to the grocery store. They’re not, and I’m not when I walk/MAX to work, to the store, to the movies, etc. My commute is always the same time, there’s no such thing as “congestion,” and frankly, I’m not all that concerned if some suburbanite’s trip gets longer from Hillsboro.

  8. JimKarlock

    DE said: “He was honest enough to admit that congestion would increase.”
    Yeah, and so am I. Stop blaming us for idiots reading too much into our words.
    JK; Well, you weren’t very clear about the connection either. I have then impression that planners KNOW that people don’t like congestion and are thus reluctant to be honest about their plans causing more congestion. For Portlander’s like of congestion see: http://www.DebunkingPortland.com/Polls/CongestionPolls.htm

    DE said: “Even after we voted against increased density by probably 85%.”
    PROBABLY 85%!? Probably? I clicked on that link and read how they got from 65% to 85%. That SURELY belongs in a blog about junk science. It’s got to be the least scientific means of determining public opinion EVER.
    JK; And that is why I put the qualifier, “probably” in there. But you have to admit to 65% because that is the actual count. Surely some voted for the citizen’s measure and not Metro’s. So we can pretty sure that the real number is above 65%. Would you buy 70% or 75% or 80%. Where would you guess the total to be?

    DE said: In reality, we ARE forced into sprawl.
    JK; Since when is people freely choosing to live is suburbs, forcing them?

    DE said: Our investment in transportation and infrastructure has resulted in very affordable sprawl
    JK; What;’s wrong with driver’s paying for roads that help people reduce the cost of living? And what is wrong with sprawl, it has been going on for over 2000 years.

    DE said: and comparably expensive urban living, pricing many who would otherwise live in the city out.
    JK; Are you claiming that the existence of suburbs drives UP the cost of living in the in the city? That claim defies logic. Care to give me details on how they repealed the law of supply and demand?

    JK: BTW, do you believe that planners are planning for what people really want or what planners want people to want? How do you tell what people really want?

    Thanks

  9. DE

    Sure, whatever, I’ll buy that 70-80% of people voted for one of the two measures. But I won’t accept the silly connection that their vote represents a repudiation of density. It means they reject mandatory government enforced density. Fine. Even plenty of people who love and choose density could agree to that. It’s not a sign that 70-80% of people reject the tenets of smart growth.

    “Since when is people freely choosing to live is suburbs, forcing them?”
    There are plenty of young people and families who would love to live in the city, but can’t afford the rent, so they’re in high density apartment complexes in Tualatin, with a $400/mo rent and a 50min commute.

    “Are you claiming that the existence of suburbs drives UP the cost of living in the in the city?”
    No, clearly not, I am saying that the investment in transportation out there allows a falsely “cheap” cost of living, compared with the city. And it’s not as simple as them paying for their own roads to support lower cost of living. The roads that make that possible are not the little streets, they are the major highways and freeways paid with all of our tax dollars. Us city dwellers are subsidizing them with our gas tax while we primarily use City of Portland roads (if driving at all) to get from home to work. Meanwhile we’re letting the suburbanites drive on our roads every day, which their taxes do not support. Meanwhile, let’s think about how many times the average Portlander is using Hillsboro roads…

    “Do you believe that planners are planning for what people really want or what planners want people to want? How do you tell what people really want?”

    First, I believe that different planners plan differently. A fundamental point that anti-planners fail to recognize. Planners in Portland plan very differently from planners in Phoenix or even Tigard. That’s why all those places look different and have different successes and problems. Second, I believe that planners plan the way their political and business leadership tell them to. It’s politics. Politicians will get canned if voters don’t like their planners; planners will get canned when those politicians feel the heat. It’s that simple. Unsurprisingly, Portland’s voters keeps voting in the leadership that has kept our city on everybody’s list as a great place to live.

  10. JimKarlock

    It’s that simple. Unsurprisingly, Portland’s voters keeps voting in the leadership that has kept our city on everybody’s list as a great place to live.

    AND

    Sure, whatever, I’ll buy that 70-80% of people voted for one of the two measures[to stop increasing density]

    JK: Maybe there some other reason we keep re-electing the same rascals. Perhaps it is the massive campaign donations from the people who profit from high density: Your buddies Homer & Gerdling (sp) and the gaggle of consultants architects etc.

    Thanks
    JK

  11. DE

    That is a good point… hmmm. I don’t know how to get around that one.

    OH, ok, how bout this! Francesconi took WAY more developer donations than Tom Potter, and yet, we STILL ended up with someone who’s pro-transit, pro-streetcar, pro-tram, and pro-planning. It didn’t matter who won, they were both pro-planning. Why? Because no one with any amount of money can make it past a primary when they are FUNDAMENTALLY OUT OF LINE WITH PORTLANDERS DESIRE FOR PROGRESSIVE PLANNING AND DEVELOPMENT POLICY.

  12. DE

    One more point. I think money is necessary to market candidates and ballot measures, such that anyone with too little (as a baseline rule, not relative to the other side)is likely to lose. However, that does not mean whoever has the most will always win. That’s why I’m not saying M37 and all your anti-sprawl measures win because they are so well funded. That said, if you believe Portland’s pro-planning establishment wins simply because of their massive developer-driven campaign war chests, you would have to concede that on that same logic, property rights and anti-sprawl measures that are heavily funded (with very little grass roots support) are also not representative of the public will. Can’t have it both ways…

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