Walk score® and its potential contribution to the study of active transport and walkability: A critical and systematic review

The Walk Score (R) index has become increasingly applied in studies of walking and walkability. The index assesses the "walking potential" of a place through a combination of three elements: the shortest distance to a group of preselected destinations, the block length, and the intersection density around the origin. The Index links a gravity-based measure (distance accessibility), with topological accessibility (street connectivity) measured by two complementary indicators that act as penalties in the final score (R) (linearly expanded in the range 0-100). A systematic review of Scopus (R) and Web of Science was conducted with 42 journal articles eventually being evaluated. Research was primarily undertaken in North American urban geographies. Analysis of walk ability using Walk Score (R) is inconsistent. Twenty-nine papers do not exclusively relying on Walk Score (R) as a single measurement of walkability and add further estimates to better capture the multiple dimensions of walkability. In 33 studies the Walk Score (R) was used as an independent variable, and only once as a mediating-moderating variable. In eight papers (18%) the Walk Score (R) was a part of a bivariate correlation model. On no occasion was it used as a dependent variable. Results tend to only partly support the validity of Walk Score (R). The paper concludes that the Index is best understood as a surrogate measure of the density of the built environment of a specific neighborhood that indicates utilitarian walking potential. Implications for, and potential areas of, future research are discussed.