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This is More Important: Setting the Density of Urban Centers in King County

2011 June 27
by Brock Howell

Citytank and other Seattle blogs have lit up recently with debates over the densities at the new Link Light Rail station areas, such as in the Roosevelt neighborhood. But there’s a more important fight happening, and few people are paying attention.

For the first time in two decades, the Growth Management Planning Council of King County is set to make the first major update of the “countywide planning policies” on June 27. These policies establish the framework for all local land use and transportation plans—serving as the foundation for how we approach everything from climate change to affordable housing.

At the intersection of the entire update are the minimum standards for “urban centers.”

With 724,000 people moving to King County in the next 30 years—a 37% increase—we need to design our cities to function much more efficiently. This means encouraging compact neighborhoods that support transit, bikes, and pedestrians and reduce the need for car trips. The result will be more vibrant and livable cities with thriving small businesses, active streetscapes, and more housing options.

Unfortunately, the staff recommendation on density for urban centers is woefully inadequate—the recommendation maintains the out-dated density of only 15 residential units per gross acre. That level of density is in the range of a typical townhouse development. Why would we set such a low target for neighborhoods like Northgate, Overlake, or South Center?

< Source: John Holtzclaw, Metropolitan Transportation Commission, “1990 Household Travel Survey” (1997) >

In 2009, Futurewise, GGLO, and Transportation Choices Coalition published the report Transit-Oriented Communities: A Blueprint for Washington State. Based on a synthesis of the best available information, the report proposed a set of recommendations for creating diverse, equitable communities in which people can meet most of their daily needs with relying on a personal automobile. And key among these was a minimum threshold for zoned capacity of 30 residential units per gross acre.

Numerous studies have documented that as densities rise from typical suburban densities towards 30 units per gross acre, the result  is a significant reduction in vehicle-miles-traveled and the associated greenhouse gas emissions. One study showed that 50 units per residential acre is an approximate tipping point at which transit or walking surpass car trips (see adjacent graph, and note that a conversion from “residential acres” to gross acres would reduce the density of the mode crossover by 25% or so).

This density is not Mumbai, Beijing, or Tokyo. Three to five story buildings can easily meet this standard. Urban center neighborhoods exceeding 30 residential units per gross acre can be composed of a diverse and functional mix of single-family homes, townhouses, and taller buildings.

Furthermore, these standards would not apply to all neighborhoods in the county—just to those designated urban centers that have already signed up to accommodate future residential and job growth.

While the debates at Roosevelt and the other Light Rail station areas are important, the update to the King County countywide planning policies presents a unique opportunity to have a much bigger impact. For the next week, let’s focus on the countywide planning policies and set minimum standards for functioning cities to handle the coming 724,000 people.

After all, given it took two decades for the first major update, this could easily be the last update for the next two decades. We cannot afford to miss our chance.

13 Responses leave one →
  1. Brian permalink
    June 27, 2011

    Zoning and planning is important but usually it is the minimum parking requirement that sets the density of urban development.

    Now then, as to your city comparisons, let’s check.

    You suggest 30 units per residential acre and say, “This density is not Mumbai, Beijing, or Tokyo.” In fact, Toyko proper has a residential density of about 30 units per acre. And Tokyo is filled with buildings of two to five stories. I believe that Beijing is similar but even lower height. There is no place in the world where high rise buildings make up a significant part of urban residences and such towers usually reduce density through mandated plazas, parking, and setbacks.

    • dan bertolet permalink*
      June 27, 2011

      What about Hong Kong?
      http://citytank.org/2011/05/17/how-much-density-is-too-much-density/

      Looking at gross densities across entire cities misses the point. The average housing unit density for the entire City of Seattle is 5 per acre. What matters is density within specific areas in the city, e.g. our “urban centers.” It would be safe to assume that there are neighborhoods in Tokyo with much higher gross densities than the citywide average.

      • wave permalink
        June 27, 2011

        Indeed, car and freeway proponents always like to point out that the LA metro area has a higher average density than the NY metro area. But the reason that everyone drives in LA is because there are not enough nodes of high density like NY has. It’s all about nodes and corridors, folks. High density nodes, that is.

  2. g_dub permalink
    June 27, 2011

    Thanks for pointing this out Brock. Yes – this is an important action that will cascade down to set the policy on how many land use and zoning decision in the Puget Sound region are evaluated for a number of years.

    I’m a huge GMA supporter in Washington, so it troubles me to note that we’re seeing a reaching of the limit of what GMA can accomplish on climate change / TOD / smart growth etc. An Act that was progressive 15 or so years ago is now kind of pedestrian in terms of the impact it can have on these issues. Under the GMA framework everything stems from regionally forcast growth targets, which inform County & City Comp plans and density targets like the one you mention. But it’s increasingly clear that the type of density and compactness many voices are calling for (especially in TOD) is totally detached from the targets assigned through the GMA-based forecasting system. Urban greens are calling for way more density than is supported by GMA targets. I see this boiling down to a legitimate claim by urban greens that the major cities should get a greater allocation of regionally forecasted growth. Macro forecasts are rarely off target so this could ultimately lead to a claim that the increased growth share for the ‘bigger’ urban places like Seattle should come out of the pocket of the more suburban and smaller cities. Obviously there are potentially explosive politics here. Hopefully this debate can evolve without GMA coming into the crosshairs again. (Let’s not forget it survived a major initiative challenge in 2006.) In my opinion it would be bad news if urban greens decide to go to the mat and at some point stop supporting the GMA framework.

  3. Ron B. permalink
    June 27, 2011

    Those population growth projections are FAR too high. There will not be employment growth to support “724,000 people moving to King County in the next 30 years”. That’s because MSFT, AMZN, and BA are in a mature, slow-growth phase and they will be adding employees in other states and countries, not here. The cost of adding employees here is too high. Moreover, the odds of one or more new major employers springing up here are low; lightning already struck twice here, and no way will it happen a third time. The problem with the large population growth forecasts used by density advocates is they are extrapolations from decades that had freakishly large employment growth patterns; that’s not going to happen again.

    • Matthew 'Anc' Johnson permalink
      June 27, 2011

      Why? Is the area suddenly going to lose it’s highly educated population? Is it going to suddenly sprawl out, losing the density that leads to innovation? Unless the setting that produced these ‘lightening strikes’ changes in the near future, I don’t see why one would think that no new industries or major firms will develop in the area.

      • Ron B. permalink
        June 27, 2011

        Density does not leads to innovation, and it sure does not lead to big employers around here.

        Bill Boeing’s plants weren’t set up along the shores of the Duwamish River in the 1930′s, and they are why when WWII spending started up we got big munitions payments. Those aircraft plants were there because of levees and dredging – not density. Density did not clue Trey Gates in to licensing rights from IBM so DOS could become the industry standard. Density here wasn’t why Bezos drove here from the analyst position on Wall Street.

        Density these days stifles innovation.

        • Steve permalink
          June 28, 2011

          Density stifles innovation? You think unwed graduates of top-tier colleges would go work for Amazon if it were based in Ellensberg?

        • Dan Staley permalink
          June 28, 2011

          Density does not leads to innovation, and it sure does not lead to big employers around here.

          Ron B. has debunked a segment of urban economics called ‘agglomeration economies’, right here in a blog comment! Years of study by economists, down the drain, right in front of our eyes. Most impressive, sir!

    • scot permalink
      June 27, 2011

      Fortunately we don’t rely on your big 3 the way Detroit relied on its big 3. We’ve also got F5 and other web infrastructure companies, Big Fish and other gaming companies, Dendreon and other biotech (plus the more traditional medical industry clustering around south Lake Union). And of course Amazon is reinventing itself as a publisher, so there may still be a next wave in that ‘mature’ company.

  4. Paul permalink
    June 30, 2011

    Two things worth adding to the conversation: First, it is important to note that the King County standard of 15 du/acre applies to the gross acreage of the urban center, which might include a variety of non-residential space, while the graph shown above is based on residential acreage. When applied across the gross acreage, 15 du/acre is surprisingly high.

    Second, if one is really concerned about ensuring that the centers of our growth, investments and economic development have sufficient density, take a look at the density standard for PSRC’s regional growth centers – it’s just 45 “activity units” per acre which is a calculation of people and jobs. http://www.psrc.org/assets/6454/rsc_agenda_061611.pdf

  5. Doug permalink
    July 11, 2011

    I think the problem with the designation is the “gross” acre component. This can really penalize an area that has a large amount of the Growth Center boundary dedicated to ROW and disguise the actual density needed. While the gross density may only be 15 DU/acre, the net effective density, once ROW and other undevelopable areas are factored in and an allowance is made for a percent of the parcels that are not likely to redevelop, you end up with a net effective density that is much higher. I recently did a study for one city considering adopting an urban center that had a net effective density of 67 DU/acre needed in order to meet the gross calculation.

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