Walkability Index

Both summarize walkability but differ in construction. The Frank index is a research measure that z-scores and sums net residential density, land-use mix (entropy), street connectivity (double-weighted), and retail floor-area ratio for a neighbourhood. Walk Score is a commercial product that scores an address mainly on the distance to nearby destinations across categories, with a street-connectivity adjustment. Studies have found the two correlate well, but the Frank index gives transparent components while Walk Score is a proprietary destination-access score.

Frank and colleagues found that intersection density — a measure of how connected and fine-grained the street grid is — was the strongest and most consistent correlate of walking among the components. A dense web of intersections shortens routes and turns nearby density and mixed uses into genuinely walkable trips, whereas superblocks and cul-de-sacs lengthen every journey. Doubling its z-score in the sum reflects that empirically stronger role.

It measures how evenly developed land is split across use categories such as residential, commercial, office, and institutional. Computed as normalized Shannon entropy, it equals zero when one use dominates and one when all categories are perfectly balanced. A higher value means more varied destinations within walking distance — somewhere to shop, work, and live close together — which gives people practical reasons to walk rather than drive.