Rachel Cavin, ManagerJames Dodds, Assistant Manager

Taylor Dorn, GIS AnalystKyler McNew, GIS Analyst

Cartographic Modeling of Sidewalk Location Selection for

The City of San Marcos, Texas

Introduction San Marcos, Texas is a diverse and

growing community.

The city boasts numerous landmarks, including the river, outlet malls, and university.

Providing adequate access for all members of the community represents a challenge.

Introduction Residents have expressed desire for

improved pedestrian infrastructure.

Currently, no formal system for siting sidewalks exists.

To effectively meet citizen needs, a process for determining potential sidewalk locations is to be developed.

Objectives

Develop a model that hierarchically ranks potential locations for sidewalks based on criteria that are determined to generate pedestrian traffic.

Locate areas that are in need of sidewalks within the San Marcos City Limits.

Ensure this model can be used for future projects.

DataData Source

City Facilities

The City of San Marcos

Schools

Pedestrian CIP

Railroads

Sidewalk Inventory

Streets

Trails

Parks

Texas State University

Zoning

Projection: Lambert Conformal Conic

Data

Data Source

San Marcos City Limits The City of San Marcos

Low Income & Student Housing Census Bureau

Medical & Pharmacy Facilities

Google EarthGrocery Stores

Retail Centers

Public Transit Stops

Projection: Lambert Conformal Conic

Data

Limits• Data may not be current.• Data is not survey grade.• Google Maps and Earth may not be

accurate.• Errors may be present.

Methodology

Data Preparation• Create necessary data layers for additional

traffic generators.• Create a layer that shows gaps in the

sidewalk inventory by placing center points in the gaps of the present sidewalk inventory.

Methodology

Data Processing• Begin model development by editing data

to fit our scope.• Finalize factor ratings and weights for each

criteria.• Use buffers to associate gap center points

with the factors.• Transform associated data layers into raster

format for analysis.

MethodologyCriteria Factor Factor Rating Weight Value

City Facilities

Activity Center 9

1

Public Library 9City Hall 7Municipal Building 10Greenhouse Interpretive Center 4Dunbar Recreation 7Downtown Police Patrol 2Conference Center 7

SchoolsElementary Schools 10

2Middle Schools 10High Schools 8Private/Other Schools 8

Trails/ParksParks 10

1Greenspace 4Trailheads 7

Transit Texas State University-San Marcos Trams 8 1C.A.R.T.S. 8

University Texas State University-San Marcos 7 1

MedicalHospital 10

2Pharmacy 10

Physicians/Other Medical Offices 10

Retail Grocery 10 1Retail Centers 6

Low Income Low Income Housing 8 1Student Living Areas 8

All ratings and weights are tentative.

Methodology

Data Analysis• Continue model development, input all

factor ratings and weights.• Run all the factors through a weighted sum

function, this will calculate location scores. We will also run average factors through a

weighted sum function to compare outcome. • Locations with the highest scores will have

the greatest need for access to pedestrian traffic generators.

Methodology

Model Certainty Check• To assess our model’s sensitivity, we will run

it multiple times, each using different buffer radius lengths. Buffers with 50, 100, and 200 meter radius

lengths. • Adjustments will be made to the model to

correct any uncertainty.

Research/Results/Findings Quantitative ranking systems are

common in sidewalk locating (Pérez 2010, Zipf 2010)

It is difficult to determine how sidewalks should be sited, as access needs are hard to quantify.

The relative importance of factors to be ranked is always subjective, but tailoring the ranking to the local needs is crucial.

Research/Results/Findings Result of our project will be a model

the City of San Marcos can use to plan potential sidewalk development.

Our model will not be suitable for the actual locating of sidewalks, only as a conceptual guide to scout sites for surveying.

Final Deliverables At the conclusion of our project, The City of San

Marcos will receive the following:• Detailed Final Report (two copies)• Project Website• CD, two copies containing:

All data Metadata Proposal, Progress Report, and Final Report Poster PowerPoint Presentations Instructions on how to use the CD (readme file)

A poster will be produced for the Texas State Geography Department.

Timetable Phase 1: Data Collection

• February 5th - February 20th

• Reviewing available literature & collecting data

Phase 2: Data Processing • February 21st - March 25th • Data will be converted into proper format• Metadata will be checked to ensure accuracy

Phase 3: Data Analysis• March 26th - April 25th • Criteria ranking & weights will be integrated into our

model

Phase 4: Data Interpretation • April 26th – May 3rd • Develop visualizations for results

Key Dates

February 20th - Proposal PresentationMarch 25th - Progress PresentationMay 3rd – Final Product Delivered

Conclusion Our project will develop a model to rank

sidewalk development locations based on criteria such as schools and medical facilities.

We will produce maps using our model results that will illustrate locations within the San Marcos city limits in need of sidewalks.

Our model concept is based on research done by others, as well as GIS suitability modeling.

Conclusion Our hope is that our project will

provide a valuable resource for the City of San Marcos as pedestrian infrastructure developments are planned.

Allocating funds to the areas most in need of development is critical. We will endeavor to create as accurate and sensitive a model as possible.

Any Questions?

Thank you.