CTwalk Map

Mapping Pedestrian (co)Accessibility

Pedestrian Accessibility

We use different walksheds to determine which places are within walking distance of each origin (i.e., homes). We employ buffers that correspond to 5- and 15-minute walking distances. We use the average walking speed of 1.26 m/s (i.e., the average of all age groups) to delineate these walksheds. Specifically:

[STEP 1] We represent the walkable street network as a graph. The edges of the graph represent streets, while the nodes represent the street intersections.

[STEP 2] We find the network node that is closest to the centroid (i.e., the geometrical center) of each grid cell. The generated node indicates a person’s estimated home location and serves as the starting point for further analysis.

[STEP 3] We measure pedestrian accessibility to various destinations by calculating walking trips from the origins, weighted by the length of each street segment, and taking into account the above-mentioned average walking speed.

[STEP 4] In this way, we compute the areas that can be reached on foot in 5 and 15-minute journeys and locate the places that are inside these areas.

Co-accessibility & age diversity metric

To calculate the degree of co-accessibility and the corresponding age diversity metric for each destination:

[STEP 1] We calculate the total number of people who have access to each destination within the 5 and 15-minute walksheds.

[STEP 2] We calculate how many of these people are in each age group.

[STEP 3] We use Shannon’s Equitability Index (EI) to determine the age diversity of everyone who has access to each destination:

$\mathrm{EI}=\frac{-\sum _{}^{}{{\ln }_P}^{}\times P_i}{{\ln }_k}$

[STEP 4] We label each place as Low (values lower than average), Average (values around average) , or High (values higher than average), depending on the age diversity (or the number of children or elderly citizens) of the people who can access to each destination.