Distribution of nine GIS-based measures in St. Louis.

a: shortest travel time (minutes);b: average travel time to the nearest five facilities (minutes);c: service density;d: spatial accessibility index from the model without weighting parameter;e: spatial accessibility index from the model with continuous weighting parameter;f: spatial accessibility index from the zonal weighted model with 3 time zones and quick decay weighting;g: spatial accessibility index from the zonal weighted model with 3 time zones and slow decay weighting;h: spatial accessibility index from the zonal weighted model with 6 time zones and quick decay weighting;i: spatial accessibility index from the zonal weighted model with 6 time zones and slow decay weighting.