“Experts generally conclude that typical transit riders will walk up to a quarter-mile to a bus stop and a half-mile to a train station,” Land Use Impacts on Transport – How Land Use Factors Affect Travel Behavior, 15 April 2011, Todd Litman, Victoria Transport Policy Institute With Rowan Steele
“Reasonable walking distance can vary, based on such factors as topography, sense of safety and security, and presence of interesting activity along the route of walking, but it is generally understood that most people will walk from 5 to 15 minutes to get to or from a transit station stop. This walk time corresponds to approximately 1/4 mile to 1/2 mile.
The transit planning area should initially be defined based on walking distances of approximately 1/4 to 1/2 mile.” Transportation Research Board PLANNING FOR TRANSIT-FRIENDLY LAND-USE. A HANDBOOK FOR NEW JERSEY COMMUNITIES 1994-96
“Findings show that sites within one-quarter mile of a rail station have significantly higher rates of transit use than sites between one-quarter and one-half mile from stations. Transit use drops even further one-half mile from stations.” Transit Use and Proximity to Rail: Results from Large Employment Sites in the San Francisco, California, Bay Area Journal Transportation Research Record: Journal of the Transportation Research Board
“The 1983 National Personal Transportation Survey found that 70 percent of Americans will walk 500 feet for normal daily trips, 40 percent are willing to walk 1,000 feet, and 10 percent are willing to walk a half mile (U.S. DOT, 1986). In a study of travel behavior for nonwork trips, Hedel and Vance found that each additional walking minute to public transportation increases the probability of car use by 0.022 and kilometers driven by 0.15 per day (Hedel and Vance, 2006).” The Broader Connection between Public Transportation, Energy Conservation and Greenhouse Gas Reduction, Linda Bailey, Patricia L. Mokhtarian, Ph.D., Andrew Little
“The optimal walking distance between a transit station or stop and a place of employment is 500 to 1,000 feet. Residents are willing to walk slightly longer distances to get to transit, between a quarter- and a half-mile.”Dittmar, H., and G. Ohland, eds. The New Transit Town: Best Practices in Transit-Oriented Development. 2004. Island Press. Washington, D.C. p. 120.
From the Walkability Index: “Distance Decay Function… We use a polynomial distance decay function that gives full score or near full score for amenities that are within .25 miles of the origin. After this, scores decrease with distance smoothly(there are no “cliffs,” it is not a step function). At a distance of one mile, amenities receive only about 12% of the score they would have had if they were right next to the origin. After one mile, scores decrease less quickly with greater distance, until they reach 1.5 miles, after which they do not count towards the final score. Using the standard speed of 3mph, .25 miles is a 5-minute walk, 1 mile is 20-minute walk and 1.5 miles is a 30-minute walk. We think it is fair and accurate to have amenities receive full or close to full score within a 5 minute walk, receive very low scores after 1 mile and receive a score of zero after 1.5 miles. From the Walkability Index” Walk Score Methodology (pdf) Transit Score Methodology (pdf)