a one. When this gap is subtracted from the Walking Accessibility Index, areas with no sidewalks penalize the walking index more than areas with sidewalks.
Table 7. Criteria Used to Develop the Sidewalk Gap Index.
Criteria
Description
Divide roadway length by sum of sidewalk and roadway lengths. A value of 1 indicates no sidewalks.
Roadway
Centerline length of roadway within a grid cell. Length of sidewalk within a grid cell
Sidewalk
For the Sidewalk\Bike lane Gap Index (Table 8), the length of existing roadways within a cell is divided by the combined length of sidewalks, bike lanes, and roadways. A bicycle may use either a bike lane or sidewalk. Local roads were not included in the gap analysis but added in the Cycling Accessibility Index. This results in an index ranging from zero to one, where one indicates the absence of sidewalks or bike lanes, and lower values indicating the presence of more sidewalks or bike lanes than roadway centerline miles (i.e., both sides of the roadway). The lowest score is for areas with both bike lanes and sidewalks. Also, an area where the sidewalk covers only one side of a roadway is assigned a value of .5. Areas with no roadway are automatically assigned a one. When this gap is subtracted from the Biking Accessibility and Potential Index, areas with no sidewalks or bike lanes penalize the biking index more than areas with sidewalks or bike lanes.
Table 8. Criteria Used to Develop the Sidewalk and Bike Lane Gap Index
Criteria
Description
Divide roadway length by sum of sidewalk, bikelane and roadway lengths. A value of 1 indicates no sidewalks or bikelanes.
Roadway
Centerline length of roadway within a grid cell. Length of sidewalk within a grid cell
Sidewalk Bikelane
Length of bikelane within grid cell.
2.1.2 Categories
All indices ranged between -1 and 1. Indices are grouped by a maximum of 4 categories: no potential, low potential, moderate potential, and high potential. These categories are determined by the index’s standard deviations from the mean. Less than -0.5 standard deviation represents no potential, between -0.5 and 0.5 represents low potential. Between -0.5 and +2.5 standard deviation represents the average, and greater than 2.5 standard deviation represents high potential. These categorizations represent the relative potential for the area. These indices are relative to South County and are not transferrable for analysis in areas outside of the study area. For example, the classifications are relative to the high and low values within the study area; downtown Tampa has much higher road density and would have different potential than Ruskin.
13
Made with FlippingBook Learn more on our blog