I have to develop an article entitled as "GIS IN ASSESSMENT OF BUS TRANSIT SYSTEM ACCESSIBILITY CONSIDERING GRADES". I'm still at an early stage of development of the research project, but I have realized that there are very few methods to assess the accessibility of transit networks. The academic literature bring the distance of 400 m (5 minutes walk) as the maximum appropriate distance to be traveled by the user to walk to access the network.
However, there is no method to consider the grades of the land, reaching up to 100 m, depending on the inclination.
Based on the above, with the data, the idea would be create a kind of 400m buffer around each bus stop (but considering the slopes). Then add the uncovered areas and identify the area percentage that doesn't have service (disregarding any cutting centers and the like).
I have no ideia about how do it. Somebody can give me a light?