A study on the effects of walkability and investment returns showed that, on a 100-point scale, a 10-point increase in walkability increased values by 1 to 9%, depending on property type. The value of more than 4,200 buildings across the United States was studied for the years 2001-2008.
Pivo, Gary, and Jeffrey D. Fisher. (2011). The walkability premium in commercial real estate investments. Real Estate Economics, 39(2), 185-219.