Comparing walkability methods: Creation of street smart walk score and efficacy of a code-based 3D walkability index

Abstract Purpose Findings are reported from the original study that supported the creation and validation of the current road network-based (“Street Smart”) version of Walk Score. It shows how Street Smart Walk Score improved upon the former “airline” (Euclidean, crow-fly or straight-line) distance method. It further compares the ability to predict objectively measured physical activity between the original airline Walk Score and Street Smart Walk Score methods and a code-based composite three-dimensional “Walkability Index” of net-residential density, land use mix, street connectivity, and retail floor area ratio. Methods The three walkability approaches were linked with objective physical activity data from 2,199 participants in the Neighborhood Quality of Life Study and compared. Walk Score's classic airline-based distance method to assess proximity to destinations was dramatically enhanced to form the new network-based method. A road network method to measure distance was created. A non-linear distance decay function with distance-based weights was also developed for specific destinations. Inclusion of a link-node ratio measure of connectivity and removal of schools was advised. Findings were externally validated using similar data from another region. Results The code-based Walkability Index remained the best predictor of physical activity even after all of the enhancements were made to create a network-based Walk Score which was positively associated with moderate-to-vigorous physical activity (MVPA). Each step of the Walk Score calibration process further improved the strength of association with MVPA. Discussion Destination proximity used by Walk Score provides a useful measure of accessibility for a wide range of end-users. However, from a policy perspective, it is essential to measure features enforceable through development regulations. Components of these regulations are contained in the Walkability Index. Presence of shops, restaurants, and other destinations captured by Walk Score can be enabled but not mandated through these regulated features.