Access Across America: Transit 2017 Methodology
Andrew Owen, Brendan Murphy
Report no. CTS 18-13
Accessibility is the ease of reaching valued destinations. It can be measured across different times of day (accessibility in the morning rush might be lower than the less-congested midday period). It can be measured for each mode (accessibility by walking is usually lower than accessibility by transit, which is usually lower than accessibility by car). There are a variety of ways to measure accessibility, but the number of destinations reachable within a given travel time is the most comprehensible and transparent as well as the most directly comparable across cities.
This report describes the data and methodology used in the Access Across America: Transit 2017 report, which examines accessibility to jobs by transit in 49 of the 50 largest (by population) metropolitan areas in the United States.
Rankings are determined by a weighted average of accessibility, giving a higher weight to closer jobs. Jobs reachable within ten minutes are weighted most heavily, and jobs are given decreasing weight as travel time increases up to 60 minutes.