Livable Green Lake

– Greater Awareness of the Impact of Growth in the Green Lake Community –

We think so.

The project is Green Lake Mixed Use, 419 NE 71ST St, currently under development. 419 will have 130 residential units and 106 parking stalls (including 5 ADA).

The numbers in question are from the project’s parking analysis, which can be found here on page 10.

First, a little background on traffic studies performed for development projects. The goal of these studies, which are funded by developers and reviewed by government agencies, is to assess the traffic and parking impact of the projects. A variety of tools are used to make this assessment, including parking statistics provided by the Institute of Transportation Engineers (ITE) Parking Generation manual, US Census data, surveys of similar projects that have already been built in the community (often, by the same developer), and, in the case of projects in Seattle and the surrounding area, the King County Right Size Parking Calculator.

The tools are often used together, employing methods and generating results that are sometimes difficult if not impossible to understand because the accompanying discussions are vague or leave out important details.

And that takes us back to the parking study conducted for 419. That, in its entirety, is here:

The Institute of Transportation Engineers Parking Generation, Fourth Edition, 2010, was used to determine parking demand for the proposed mixed use development at the Greenlake South Mixed Use project. Based upon Land Use Code 221 for a Low/Mid-Rise Apartment and Land Use Code 820 for a Shopping Center, direct application of published rates in Parking Generation were initially used to estimate the peak development parking demand (see Table 6). ITE rates however, do not consider time of day factors or shared used between on-site uses, and therefore, Shared Parking, Second Edition, Urban Land Institute, 2005, was reviewed for recommended time-of-day factors of residential and retail peak parking periods.

Based on the 2010 United States Census, approximately 21 percent of all households within Census Tract 36 have no vehicles (Attachment C), compared with an “all Seattle Metro Area households without auto” ownership of only 8 percent. In addition, the proximity of the Roosevelt Light Rail station, a reduction in reliance on automobile utilization of 20 percent for all transportation needs was also applied.

As such, when considering vehicle availability factors of similar residences within the neighborhood and the proximity of the Roosevelt LRT station, peak parking demand during the weekday (when commercial retail is at its peak) and evening hours (when residential uses are at their peak) is estimated at approximately 100 stalls and 83 stalls, respectively. Based on the proposed supply of 104 stalls, no on-street parking demand impacts is expected.

Here, roughly, is what the author’s doing:

  1. First, based on 419’s size and land use codes, he uses the ITE Parking Generation manual to conclude that the peak weekday residential parking demand is 120 stalls and the peak weekday retail parking demand is 37 stalls (top of Table 6)1
  2. Then, using US Census tract data and the proximity of the project to the future2 Roosevelt Light Rail station (LRT) he reduces the ITE estimate of 120 to 83 for a revised estimate of the average peak weekday residential parking demand (middle of Table 6)
  3. Finally, using time-of-day factors, he arrives at 62 for an estimate of the peak weekday residential parking demand during the day (bottom of Table 6)

And that reduction to 62 is important, because when it’s added to the peak weekday retail parking demand of 37 stalls during the day, it means that at most 99 stalls on a weekday will be required to accommodate daytime parking—less than the number of stalls the project is providing.

The problem for the public with this analysis is it provides virtually no understanding of how it produced its results. It provides no step-by-step discussion of how it calculated various parking demand estimates, first 120, then 83, and finally 62. It offers no explanation how the census data and LRT proximity were used together—let alone why they can be used together—to produce reasonable results. It provides no source for the 20 percent used for the LRT reduction.

Of course, the calculations should also have been a problem for Seattle DPD since they receive the same study the public does. So we emailed the individual at DPD who oversaw the 419 traffic study and asked him to explain the parking analysis they had approved, including the calculation of the parking demand estimate of 83 and the source for the 20% LRT reduction.

In fact, we did this twice, over a two-week period. We received no response to either inquiry.

We also contacted the engineer who prepared the study for the developer, Michael Read at Transportation Engineering NorthWest, to see if he could provide some clarification. Mr. Read, after a few brief responses, informed us he wouldn’t be able to respond much more unless we were a client.

And he is right of course, we’re not a paying client. On the other hand, we are taxpayers.

Why the focus on 419 at all, a project already under construction?

First of all, it’s connected to a nearby project currently awaiting MUP approval. In a correction notice for a proposed project at 417 NE 73rd St, Seattle DPD has requested that the developer “provide a cumulative on-street parking analysis, identifying any additional spillover parking demand within the study area generated by other development projects currently under review or construction.” That should include the spillover parking from 419.

However, we believe that 419’s parking analysis is suspect and that it understates the real impact of the project on neighborhood parking, perhaps significantly. It also doesn’t account for retail employees, who must park on the street.3 Without an accurate assessment of 419’s parking demand, an accurate cumulative parking analysis for 417 is impossible.

The second reason that 419 is important is it raises the broader question of Seattle DPD credibility. Traffic studies performed for new development need to be thorough, believable and documented so that the public can have confidence in their results. 419’s study is just one of several conducted for projects in the east Green Lake community that fail in this respect. The pattern reveals a troubling lack of oversight and due diligence by Seattle DPD.

And that, to us at least, would seem to be a problem that is much bigger than what typically goes before a hearing examiner.

1 These are, in fact, averages. The actual numbers could be much higher.
2 Scheduled for completion in 2021, five years after the completion of 419.
3 Parking studies typically ignore the impact of retail employees.

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