An excellent and innovative study by AECOM for SPUR on future growth in the San Fran Bay area. I must declare an interest i’m an AECOM employee, however I am finishing off a book on new GIS based methods for allocating growth targets across regiona soi I do have some positive comments.
First the method. It divides the area into raster cells, called place types, on 1/2 mile width based on urban morphology/typology.
This reminds me of the Turley ‘typical urban areas’ approach used in the UK about 15 years ago. This was widely used and widely criticised and then dropped. It was based on historic built rates and projecting them forward rather than specific sites. The SPUR study is based on average estimates of future potential. For policy the key issue is the difference between build rates now and the impact of zoning on build rates in the future. Here I would like to see more evidence on how future build rates are estimated. The build rates for the dense urban mix implies a population density greater than the densest places on earth, such as parts of Shanghai and a 80 to 1+ FAR, which seems high to me.
Another point I would make is the use of square rasters, which makes modelling on travel times and accessibility hard. I would recommend the use of hex bins instead. As in the Planagon method I have been developing and used successfully on projects in several countries now.
The biggest criticism of the typology based approach was that it didn’t consider the potential of specific sites whether brownfield or greenfield and for that you need some means of measuring the sustainability of the individual cell.
What is striking looking at the above map is the lack of dense urban centres. They simply arnt where they should be such as Central San Jose or Fremont, or along the central valley to LA (which urban economics suggest would be the best place). We dont have dense corridors of urbanism or the kind of RT systems to serve them. Also large non protected areas which are potentially highly accessible (former railway lines) exist – such as the Rio Visat/Birds Landing area where you could fit a new Garden City twice the size of San Francisco. One problem with a pure upzoning scenairo is it happens, but slowly, and often too slowly to provide enough early and mid phase development. For that you will almost always need some greenfield sites and large ones at that. Its a stock/flow issue.
A thought provoking and excellently illustrated study which should lay the foundations for future thinking in the area.