How Far Will People Walk to a Park?
One problem with assessing how far people will walk to use a park is that most walkability studies are focused on commuters rather than park users who have a mix of motivations. However, it does seem that the quarter-mile standard used to assess the walkability of transit stations is mostly applicable to parks as well:
"...research supports the validity of both quarter-mile and half-mile distance goals, depending on perceptions of the built environment, safety, and time constraints. Of course, people's preferences and habits are only part of the equation for planners, who must also take into account the cost effectiveness of expanding the park system versus improving current parks or focusing on connectivity."