For a quick and relatively simple analysis of who has access to the transit stop, circular buffers can be drawn around them, capturing households and destinations. A standard size for buffers is 1/4 mile radius for bus stops and 1/2 mile radius for [[LRT]] or [[BRT]]. Drawing buffers offers quick analysis, but has some disadvantages. People or destinations just outside the buffer may be unnecessarily excluded. Buffers measure distance on a map, so barriers such as highways or railroad tracks
that are ignored, meaning some people are included that have no access to the stations, or for whom the station is much farther away than the 1/4 or 1/2 mile measured.When buffers are used, travel time can be estimated as an average. For example, one could say that people inside of a half mile buffer around a light rail station take 7 minutes on average to get to the station. This helps establish realistic accessibility expectations, but glosses over the fact that some people in the buffer only have a 1 minute walk to the station, while others might have a 12 minute walk, which drastically changes their total travel time.
===Using the street network===