Creating a Walkability Surface for Maricopa County Parul Singh and Madison Davis ASU MAS-GIS students Co-Authors: Marc Adams, Jane Hurley, Lu Hao Funding Source #: R01CA198915
Overview Background on Walkability and WalkIT Arizona Study Five Components of the Walkability Index: Net Residential Density Intersection Density Transit Density Retail Floor Area Ratio Land Use Mix (Entropy) Results and Significance 2
Presentation Objective To share the the steps taken and tools used to create a geographic surface of walkability for Maricopa County 3
Why is Walkability important? Vice Admiral Vivek Hallegere Murthy, Surgeon General of the United States U.S. Department of Health and Human Services. September 2015 4
WalkIT Arizona Study to test the effectiveness of interventions using physical activity trackers, goal setting, motivational text messages, monetary incentives and health education to promote physical activity behaviors... Principal Investigator Marc Adams, PhD, MPH in high and low walkable communities 5
International Physical Activity and Environment Network (IPEN) Study IPEN GIS templates guided decisions to quantify built environment attributes for physical activity Templates include +100 pages of definitions, recommendations www.ipenproject.org Adams, Frank et al., 2015 Int l J of Health Geographics 6
Software ESRI ArcGIS for Desktop v. 10.3 Microsoft Excel SPSS 7
Calculating Walkability 5 components, each is a surface First find raw scores for each component Walkability Index = [ (z-score of net residential density) + (z-score of intersection density) + (z-score of transit density) + (z-score of retail floor area ratio) + (z-score of land use mix)] 8
Maricopa County 9
Focus Area North Scottsdale Suburban Phoenix Urban Core 10
Comparison Urban Core Suburban Same scale (resolution) 11
Preliminary Steps 12
Preliminary Steps Data Acquisition Maricopa County Assessor's Office Maricopa Association of Governments (MAG) Valley Metro U.S. Census Bureau Prep for use in context Projection: NAD 1983 HARN StatePlane Arizona Central FIPS 0202 (Meters) PUCs Reclassification (2251 down to 5) Main categories: residential retail office entertainment civic 13
PUCs Reclassification Residential single & multiple family,mobile home, dormitory exclude: hotels, motels, timeshared property Retail retail stores, shopping malls, banking, gas stations, food-related exclude: auto dealerships, big box mega stores ( >=300,000 sqf.) Office administration, nonprofit institutions, medical services exclude: warehouses, manufacturing offices, factories, 14
PUCs Reclassification Entertainment Civic/ institutional bars, night clubs, theaters, museums educational, religious, health, governmental, police, military facilities Multi-use codes (mixed-use) Store & Office/Apartment Office & Residence double/ triple counted 15
Unit of Analysis Census Block Groups Aligns with population estimate in IPEN templates 100 Meter buffer Captures walkability/built environment features on edges 16
Block Group Buffer Original Boundary 17
Walkability Components 1:Residential Density 18
Net Residential Density Ratio of residential housing units: residential land area in the buffer Residential= permanent, majority of the year, not easily moved housing/dwelling units Includes single and multi family use 19
Net Residential Density High Density = many units in area Low Density = units spread out 20 Imagery: Google, Map Data, Digital Globe, 2016
Net Residential Density Layer of all residential parcels ~1.3 million parcels Includes Land Area and Housing Unit count fields 21
Net Residential Density Assign parcels to buffered block groups 22
Net Residential Density = Count Area 23
Net Residential Density Urban Core Lowest Suburban Highest 24
Walkability Components 2:Intersection Density 25
Intersection Density Ratio of intersections : land area Intersection: 3 or more walkable road segments intersect High Density = Many walkable intersections Low Density = Few walkable intersections 26
Intersection Density Roads Included: Roads Excluded: Neighborhood Streets Interstate highway Byway - single lane of traffic in each direction Ramps Unpaved Roads Pedestrian Trail Limited Access Highways Pedestrian Passageway Freeways Rural Road Expressway City Streets 27
Intersection Density Nodes not included Dangling Nodes Pseudo Nodes 28
Intersection Density True Nodes 29
Intersection Density Assign Regular nodes to the Block group 30
Intersection Density Intersection Density = Count/ Area Summarize on Block group buffer Field 31
Intersection Density Urban Core Lowest Suburban Highest 32
Walkability Components 3:Transit Density 33
Transit Density Ratio of transit stops: land area Transit stops include bus and light rail Considered how many buses stop at each physical stop High Transit Density = many transit stops Low Transit Density = few transit stops 34
Transit Density Bus Stops Light-Rail stops 35
Transit Density Transit density = Count/Area Summarize on Block group buffer Field 36
Transit Density Urban Core Lowest Suburban Highest 37
Walkability Components 4:Retail Floor Area Ratio 38
Retail Floor Area Ratio A ratio of the sum of the retail floor area: land area of a parcel Average for block group buffer Retail includes clustered shops, strip malls, shopping malls, department stores, etc. Excludes big box stores/ uses of 300,000+ sq. feet (Specific inclusions/exclusions in templates) High Retail FAR indicates more retail space on a parcel Low Retail FAR typically indicates more parking 39
Retail Floor Area Ratio Create layer of retail parcels Verify Floor Area Data (approximate when missing) and Land Area Data Add field and calculate Retail FAR Retail FAR = Retail Floor Area Parcel Land Area Esri, HERE, DeLorme, MapmyIndia, OpenStreetMap contributors, and the GIS user community 40
Retail Floor Area Ratio 41
Retail Floor Area Ratio Avg. in buffer 42
Retail Floor Area Ratio Urban Core Lowest Suburban Highest 43
Walkability Components 5: Land Use Mix 44
Land Use Mix Calculation of entropy of land use types in block group buffer Raw Score always between 0 and 1 0 indicates only one land use present 1 indicates a perfectly even distribution of all land uses across the block group buffer 45
Land Use Mix Repeat merge and summarize processes described to get the sum of land or floor area in each block group 46
Land Use Mix 47
Land Use Mix Urban Core Lowest Suburban Highest 48
Walkability Index Walkability Index = [ (z-score of net residential density) + (z-score of intersection density) + (zscore of transit density) + (z-score of retail floor area ratio) + (z-score of land use mix)] 49
Z- Score Net Residential Density Intersection Density Transit Density Retail Floor Area Land Use Mix Lowest Highest 50
Z- Score Net Residential Density Intersection Density Transit Density Retail Floor Area Land Use Mix Lowest Highest 51
Z- Score Net Residential Density Intersection Density Transit Density Retail Floor Area Land Use Mix Lowest Highest 52
Z- Score Net Residential Density Intersection Density Transit Density Retail Floor Area Land Use Mix Lowest Highest 53
Z- Score Net Residential Density Intersection Density Transit Density Retail Floor Area Land Use Mix Lowest Highest 54
Walkability Surface Combine all of the components... 55
Walkability Surface Net Residential Density Intersection Density Transit Density Retail Floor Area Land Use Mix Lowest Highest 56
Walkability Urban Core Suburban 57
Advantages of using GIS Analysis on Macroscale Use existing data Map Creation Patterns are clearly observed Help to select neighborhoods to test the effectiveness of the physical activity intervention 58
Next Steps Virtual truth to make sure the surface makes sense Conclusion Able to target recruiting efforts to high and low walkable areas Gather participants for the WalkIT Arizona Research Study 59
Thank you! 60
Contacts Parul Singh psingh26@asu.edu Madison Davis mbdavis6@asu.edu Marc Adams, PhD, MPH marc.adams@asu.edu MAS-GIS 2015-16 61
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Data Versions: Maricopa County Block Groups, 2010 U.S. Census Parcels, Maricopa County Assessor s Office, 2015 Light Rail and Transit Stops, Valley Metro, 2015 (Month??) Roads, U.S. Census TIGER/Line, 2015 63