The tool uses a simple weighted scoring of distance to amenities such as shops, restaurants, schools, banking etc. to rank how walkable the address is. They have also produced a walkability Heat Map and ranked many US cities.
- walk-score does not appear to include distance to transit and its frequency in its calculations. It has a separate transit accessibility score (where transit agencies make data publicly available) but this is not included in the walk score. I believe this is a major flaw as the ability to access public transport to employment and major service hubs is a large contributing factor to improving the available amenities within 'walking' distance. Although you may use public transport it does reduce car dependence.
- Walk score does not include distance to employment opportunities.
- The application is dependent on information being available on the internet. Because of this the city-edge apartment I owned in Pietermaritzburg scored a lower Walk Score that my current mid-suburban home in Brisbane - because most of the amenities within walking distance of my previous apartment are not captured on the web.
- the assessment does not take into account what facilities are available for pedestrians. An address along a major road with no pedestrian facilities would score the same as one within similar distances to amenities but with pathways and crossing facilities.