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Rebuild Potrero development density survey

One of the hot topic discussed in Rebuild Potrero's community meeting on Tuesday is the development's density. People have asked how does the proposed project compares to other condo development such as The Potrero (Whole Food). Unfortunately the host do not have any information to answer this question.

In order to find out, I have set out to do a survey myself. I have gathered information on a number of large condo projects around Potrero Hill. I measured their area using satellite map. And then I ranked the density in the table below. It turns out Rebuild Potrero's density is among the low end of all development. It is just below Potrero Court (near General Hospital) and slightly above Sierra Height. Only Victoria Mews, which is built in 1978, has a much lower density.

Note that Bridge housing's plan has proposed the number of unit from 1,400-1,700. The ranking above uses the middle number 1,550. Obviously the final number can change. So the data is only useful for getting a rough idea of how the projects compares.

The chart below visualizes the data on two dimension. The height of each bar represents the density. The width represents the lot size. The area of each rectangle bar reflects the total number of units. Although Rebuild Potrero's density is among the low end, its size dwarf any other single project. On the other hand this project will be built in phases. And as we can see from the plan the project span may blocks. In time more detail data should be available such that we can access the density of each block individually. In that case the project will be shown as many narrow bars with varying height rather than one monolithic brown rectangle like below.

Measurement

The area are measure using Google's satellite view. All measurement are taken with best effort but their accuracy cannot be guaranteed. The measurement include the property area as well as a "fair share of street space". For properties that span the entire block, we include the area of two out of the four surrounding streets. For properties spanning less than an entire block, the street space is prorated. For example, in the picture below shows "The Potrero" condo's area includes the street space on the west and south side.

The reason we include "fair share of street space" is it makes measurement of a small area comparable to large area. Image we divide the city into tiles of street blocks, each includes the street on the south and west side. We can seamlessly join these tiles together like a jigsaw puzzle to form a large city area, with no gap or overlapping area in between. Therefore we can add the area of small blocks together and it will equal to measuring a large area as a single unit. For your information, this street space increase the footprint of a development by about 60%.

The Rebuild Potrero project's area is large and irregular. We made a best effort to measure its area by break it down into several roughly rectangular lots. The total comes out to be 36.6 acre. This is about 10% high than the 33 acre quoted from official source. The discrepancy is possibly due to the "fair share of street space" metric include some street area on the perimeter that is not reported in the official number.

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Comment by Evan Goldin on March 4, 2010 at 10:36: A lot of people probably saw this on the Yahoo group, but I thought it was a really intelligent comment by Daniel Connelly:

"Higher density areas don't necessarily have more car traffic. It depends on how well served the area is by public transit and local businesses. Since a greater population density can support local business, I view density as improving the livability of a neighborhood. The key is to manage vehicle density, not people density, and the two, while correlated, are not necessarily invariably coupled. That's where the focus needs to be."

Comment by Soren Peterson on February 28, 2010 at 20:47: Very clear presentation. Thank you!

Comment by Stacey Bartlett on February 26, 2010 at 11:25: Knowledge is power! Thanks for presenting the data so clearly Wai Yip!

Comment by Evan Goldin on February 26, 2010 at 8:02: Hey Wai Yip! This is so, so, so helpful. I live on the block immediately next to the Potrero Terrace — 900 Wisconsin — and one of the top concerns about the project (not mine, but felt strongly by some of my neighbors) is the concern that this project is too dense, at least in some parts. I'd never thought to compare the density of the rebuilt project to other developments around the Hill. For example, it's good to see that Sierra Heights, which will immediately border the Rebuild Potrero project, is just about equal in terms of density. Thanks for putting this together!

I'll

Comment by Audrey Cole on February 26, 2010 at 7:39: Wow! Thank you, Wai Yip, for doing all this. It's a great way to not only compare projects but to get quick visuals. Great work. Thanks again.

Audrey