Potential for Transit-Oriented Development in San Diego:
Where should agencies facilitate TOD and how can they collaborate?
Katie Lemmon
UP 206A, W11
Prof. Estrada
March, 2011
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Introduction
San Diego County has many transit options including trolley, bus rapid transit, commuter rail and regular
bus service. Bus rapid transit is one proposed solution to combat region-wide mobility issues in San
Diego. With this in mind, this project seeks to spatially analyze the City of San Diego to identify specific
areas that would be excellent locations for transit-oriented development. San Diego Association of
Governments (SANDAG) plans the region’s transit and yet the City has jurisdiction over approving
specific projects that would contribute to transit ridership. This project explores the following question:
Where should SANDAG and the City of San Diego work together to prioritize transit-oriented
development and what tools will help these agencies collaborate?
For this project I identified a few characteristics that need to be present for successful transit-oriented
development (TOD):
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high density of people,
access to transit and amenities
inhabitants who will actually take transit or non-car modes
Given these characteristics I also wanted to identify areas with a high potential for successful TOD within
¼ mile of bus rapid transit and express bus stops and routes. This includes a proposed bus rapid transit
line.
Methodology
To address the policy question, this project followed these steps:
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Identify express bus routes and stops in San Diego
Rank census tracts based on TOD demographics:
o Population density – weighted 1 because it’s an important component of TOD
o Workers who commute using alternatives to cars – weighted 2 because it is more
important than density
o Workers with no vehicles – weighted 2 because indicates transit need and is as
Within identified census tracts, create ¼ buffer around existing express bus stops and proposed
rapid route
Identify redevelopment areas, if any
Identify and create online tool for inter-agency collaboration
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Layout 1:
This layout shows an inset map locating the City of
San Diego and putting the study area in context.
The City of San Diego is on the coast in the
southwesternmost corner of the county.
Skills - Inset map, Geoprocessing (clipping)
Layout 2:
The second layout highlights the existing
express bus routes in the city. Location of
express bus routes is one of the components
that will be considered in answering the policy
question.
Skills - Attribute sub-set selection, selected
express bus routes and stops from dataset of all
transit modes
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Layout 3:
In this map I created an index of necessary
census tract characteristics for TOD. To do this,
I aggregated the alternative commuter modes
from census data into one field called
alternative means to work. The index gave
population density (number of people per
square mile – also a newly created field) a
weight of 1, alternative means to work a
weight of 2, and workers with no vehicles a
weight of 2. Census tracts that ranked higher in
the index are darker red in this layout. This
layout also includes the express bus routes so
the viewer can visually compare high-potential
tracts with express bus routes. Using the index,
the top 5 highest potential tracks are outlined
in bright green.
Skills - Aggregating attribute fields, Created index
Layout 4:
This layout focuses on the area determined as
having the highest potential for TOD by the
ranking index. It also shows the existing express
routes that go through the tracts and the
express stops. The yellow half circles show a
quarter-mile buffer around the existing stops
but within the census tracts.
Skills - Buffering – ¼ mile radius around express
bus stops, Geoprocessing – intersect tool to
show areas within census tracts that are ¼ mile
from express bus stops
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Layout 5:
This layout speaks to how the City can think
about its involvement in facilitating TOD. The
redevelopment areas for the City are shown.
Four out of five of the highlighted census tracts
fall within the same redevelopment area, MidCity. The fifth census tract is not within a quartermile of an express route stop and is not within a
redevelopment area so it is dropped from the
study at this point.
Skills - Attribute sub-set selection, Geoprocessing
Layout 6:
This layout is original data showing the proposed
bus rapid transit route and stops in the Mid-City
neighborhood of San Diego. Both the stops and
route shapefiles were drawn in ArcGIS. The
accompanying metadata is shown below.
Skills – Original Data, Metadata
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Layout 7:
Combining the original data from the previous
layout with the high priority census tracts and
existing express routes, this layout paints a
picture of the future rapid transit connectivity in
the Mid-City neighborhood. A quarter-mile buffer
around the proposed route is shown in light
green. The combination of this buffer and the
quarter-mile buffer around existing express stops
will show the priority area within which the City
should facilitate TOD.
Skills - Buffering – ¼ mile radius around proposed
route, Seven Layers
Layout 8:
The orange area shows the combined buffers
that represent the priority area for the two
agencies to collaborate on and encourage TOD.
Skills – Geoprocessing, intersect, merge, and
dissolve
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Layout 9:
Using the area created above, this layout shows
which parcels are within the priority area. This
is another way to think about how the City can
facilitate more TOD in the area.
Skills - Geoprocessing
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Collaboration Tool
Beyond identifying where TOD should be located in the City, given the relationship between land use
and transportation, interagency collaboration is also important to facilitate TOD. To this end, I created a
model to streamline the process of writing HTML code to create an online collaboration tool. The
following model took multiple layer files and converted them to KML files for use in the HTML code.
Steps to creating Google mash-up:
Model
1.
Create model to convert files to
KMZ
2.
Research for-sale parcels online as
of 3/14/11
3.
Geocode for-sale parcels
4.
Write html
5.
Display layers on Google map
6.
SANDAG and the City can share
maps
In addition to the data files from the layouts created, information on for-sale parcels was needed. Using
the online real estate website, Loopnet, I identified four for-sale properties within or near the priority
project area identified in the spatial analysis. The properties from this online search were included in the
HTML code to produce the resulting Google mash-up map.
Loopnet.com for location of for-sale properties
Google Mash-Up: Online Collaboration Tool
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Conclusion/Recommendations
The priority area identified by this spatial analysis is important information for agencies to determine
where to facilitate and encourage transit-oriented development. This development will support the
transit that serves it. Because the transit planning function and permit approval process are siloed in
different agencies, this is an opportunity for collaboration. One project can support the other. To
streamline collaboration and also potentially provide information to the private developers or the
public, a Google mash-up will aid SANDAG and the City of San Diego.
Sources
The data in this project is from the following sources:
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SANDAG
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SanGIS
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UCLA MapShare
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ESRI-TIGER
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American Community Survey
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US Census
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Bing maps
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Google maps
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