Table 1. Criteria used to Develop the Walking Accessibility Index.
Criteria Services
Description
Combined
Density of nonresidential parcels within a ¼ mile radius of the center of the grid cell (based on DOR code). Density of roadway intersections within a grid cell (excluding culs de sac and major roadways).
Network
Sidewalk Length
Total sidewalk length within a grid cell.
Subtract (Discount each by 50%)
Barriers
Subtract barrier index from above combination. Subtract sidewalk gap index from above combination Subtract average walking time to four closest adjacent cells.
Gaps in Sidewalk
Estimated Google Directions Walking Time
Table 2. Example Calculation for the Walking Accessibility Index
Example Values for Calculation *
Walking Accessibility Index Result
Services Criteria = 1 Network Criteria = 0 Sidewalk Length Criteria = .146 Barriers = .092 Gaps in Sidewalk = .515 Walking Time = .118 Weights for Each Criteria = 1,1,1,.5,.5,.5 Description: this cell had a high number of services within a close distance of the center, a high number of existing sidewalks, and low barriers.
((1*1+1*0+1*.146)-.5*.092-.5*.515-.5*.118) / (1+1+1+.5+.5+.5) = .174
.174 is >2.5 Standard Deviations and classified as High Potential
* All values are scaled to a range of 0 to 1 for combining.
The Cycling Accessibility Index (Table 3) examines the potential of study area residents to cycle to surrounding destinations and is calculated as follows. The density of services within a bikeable distance (1-mile radius) of the grid cell is added to network density, bike lane length, and the centerline length of local roads. The network density criterion largely reflects residential neighborhoods resulting from the denser connections of roads within those neighborhoods. The radius assumes that most individuals are able to cycle for one mile in one direction. Bicyclists may use local roads for travel, therefore the index accounts for local roads with a speed limit of 25 mph or less.
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