San Diego Affordable Housing Parking Study

276 Pages·2012·16.34 MB·English

San Diego Affordable Housing
Parking Study
December 2011
Submitted to
City of San Diego
Submitted by
Wilbur Smith Associates
In association with
AECOM
Michael R. Kodama Planning
Consultants
Richard Willson, PhD
National Data and Surveying
Services
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EXECUTIVE SUMMARY
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Purpose & Goals
Executive Summary
The purpose of the San Diego Affordable Housing Parking Study was to determine the links between
affordable housing variables (income levels, household age, transit accessibility, land use context, and
housing type) for use in developing a corresponding regulatory framework for parking requirements.
Organization & Process
The study was broken down into the following discrete related tasks addressed by a collaborative team
process.
• Stakeholder and Public Outreach • Best Practices and Case Studies
• Review of City Policies and Current Research • Applied Parking Model
• Data Collection Methodology & GIS Database • Policy Recommendations
• Statistical Analysis & Parking Demand Tool
Stakeholder & Public Outreach
A detailed public outreach strategy was developed including the use Project Working Group (PWG) that was
used to solicit advice and feedback on policy issues. Other key elements of the outreach included project
fact sheets, a public workshop and stakeholder focus groups.
Review of City Policies, Current Research & Best Practices
The city’s parking code and policies, recent industry research pertaining to affordable housing and parking
requirement adjustments, and best practices from similar communities were reviewed, revealing the
following:
1) There is a substantial gap between demand for affordable housing and the number of units that can
realistically be built in San Diego.
2) Affordable housing developments in San Diego are subject to a complex set of parking requirements
and potential modifications. But, it is not clear the current code provides modifications in a manner
consistent with a project’s likely parking demand.
3) In addition to increasing the price of housing by driving up construction costs, parking requirements
also impact site design; reducing the land available for residences.
4) While the costs created by excessive parking requirements affect all types of homeowners and
renters, their impact on lower income households is particularly disproportionate because low
income households consistently own fewer vehicles than their higher income counterparts.
Data Collection Methodology & GIS Database
GIS Database of Affordable Housing Sites: The consultant team developed a master list of affordable
housing project sites based on city records.1 The database contained 265 unique developments that were
coded with a series of “project” and “neighborhood” variables that captured key characteristics about each
development’s qualities and surroundings. The sites were further reduced to eliminate all sites with less
than 80% restricted units leaving 138 affordable sites available for data collection.
Site Selection Methodology: The 138 sites established a variable profile target for a future a data collection
sample. The goal for data collection was to select a minimum of 30 sites to survey that met the existing

1 The list maintained by SDHC, RDA, CCDC and SEDC included both rental and ownership developments and contains project types
ranging from senior housing, to transitional homes, to inclusionary units within larger market rate developments.
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project characteristic mix (existing population of affordable housing sites) and 20 of those sites to collect on-
Executive Summary
site parking occupancy data. The final selection was made by the city staff. Sources of data for the study are
summarized as follows:
• Household surveys –Household characteristics (e.g. size, income, # vehicles, parking behavior)
• Management surveys - Project characteristics, details and operations
• Field observations – Parking counts, land uses and parking restrictions.
A total of 2780 household surveys were distributed to 34 selected project sites with an overall 40% return.
One management survey was returned for every project site. Field observations were conducted at 21 sites
that maintained the original sample mix and also had a survey response rate of 20 percent or more.
Occupancy data was collected at each site both on and off-street between the hours of 12AM and 4AM to
measure peak resident parking demand. Property manager feedback was most helpful in the review of
tandem parking and parking assignment practices.
Parking Demand Analysis
The statistical analysis of the survey and field data provided a step-by-step examination of the primary
determinant of residential parking demand – household vehicle availability– considering both the level of
household vehicle availability and factors that affect it. The findings are summarized as follows:
1) Parking demand for affordable projects is about one half of typical rental units in San Diego; almost
half the units surveyed had no vehicle.
2) Parking demand varies with type of affordable housing (i.e., Family Housing versus SRO); higher
demand is also associated with larger unit size and higher income.
3) Household vehicle availability varies significantly with income; however, income may be correlated
with other project characteristics, such as project type and size.
4) Parking demand is less in areas with many walkable destinations and more transit service.
5) In all of the projects studied, the amount of peak overnight parking used was less than the amount
supplied.
Parking Model: A parking model was developed based upon the findings in the statistical analysis. It
provided empirically-based rates for four types of affordable housing: Family, Living Unit/SRO, Senior
Housing, and Studio - 1 Bedroom. The model’s predictions were compared with existing requirements and
supply patterns, to understand the alignment of those requirements with actual demand levels. The main
conclusion from these tests was that current requirements do not require significantly more parking than
the household survey-based parking model would suggest. Overnight parking occupancy in projects (where
data was available) was less than the current requirements and the model prediction, but overnight parking
counts did not account for visitor parking, overnight trips by residents, and some other aspects of demand.
Recommendations
It was recommended that the parking model be used to create a look up table of new affordable housing
parking requirements. The parking requirements are determined based on type of affordable housing and its
context in terms of transit availability and walkability. The parking requirements also include provisions for
visitor and staff parking and expected vacancy. The recommended parking requirements are summarized in
the following table.
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Type of project A. Total B. C. D. E. F. G. H. I. J. Total requirement with vacancy factor
units Studio 1 BR 2 BR 3 BR Subtotal Visitor Staff Subtotal w/ staff adjustment (I3*J2)
Executive SuLomw/Memd/ aLorw/Myed / Low/Med/ Low/Med/ for units parking parking + visitor Vacancy adj./no vacancy adj.
High High High High (sum B3 (G2*A1) (H2*A1) (F3+G3+H3)
– E3)
1. Units
Family 2. Rate N/A 1.0/0.6/ 1.3/1.1/ 0.5 1.75/1.4/0. 0.15 0.05 1.1/1.0
Housing 0.33 75
3. Spaces
Living 1. Units
Unit/
SRO 2. Rate 0.5/0.3/0.1 N/A N/A N/A 0.15 0.05 1.1/1.0
3. Spaces
Senior 1. Units
Housing
2. Rate 0.5/0.3/ 0.1 0.75/0.6/ 1.0/0.85/0.2 N/A 0.15 0.05 1.1/1.0
0.15
3. Spaces
Studio – 1. Units
1 bed-
room 2. Rate 0.5/0.2/ 0.1 0.75/0.5/ N/A N/A 0.15 0.05 1.1/1.0
0.1
3. Spaces
Special 1. Units
Needs
2. Rate 0.5/0.2/ 0.1 0.75/0.5/ N/A N/A 0.15 0.10 1.1/1.0
0.1
3. Spaces
Notes on Model & Parking Requirements:
1. Requirements should be developed based on the four housing types outlined in this table.
2. Requirements are based on mean (average) vehicle availability.
3. Requirements should be based on walkability/transit indices (Suburban, urban and core designations have been simplified to low, medium and high, respectively).
4. 10% base vacancy factor is adjustable if using unassigned parking. Unassigned parking is the preferred method.
5. Visitor parking = 0.15 spaces/unit, or zero for dense urban areas, or unassigned lots.
6. Staff Parking should be considered on a case by case basis, with 0.1 for staff intensive developments.
7. Parking management tools and travel demand management strategies should be considered for appropriate developments to supplement minimum requirements.
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CHAPTER 1.0 Introduction
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