Spatial Accessibility Analysis
Definition
Spatial accessibility analysis measures how easily people can reach services, jobs, or amenities given transport networks, time, cost, and capability. It goes beyond proximity by modeling travel times, schedules, capacity, and competition. Methods include isochrones, two‑step floating catchment area (2SFCA), gravity‑based measures, and cumulative opportunities. Accessibility is central to equity, public health, and economic inclusion.
Application
Cities evaluate access to clinics, groceries, parks, and transit. Universities analyze campus wayfinding and mobility services. Developers assess site value in relation to jobs. Disaster planners model shelter access under road closures and curfews.
FAQ
How does 2SFCA account for facility capacity compared with simple isochrones?
2SFCA divides each facility’s capacity by the demand within its catchment, then sums these ratios for each population location, weighting by travel cost. This captures crowding and competition that proximity alone misses.
What network details are critical for equitable results?
Walking speeds by slope, curb ramps, sidewalk gaps, transit frequency and transfer penalties, and fare costs. Ignoring these can overstate access for people with disabilities or low incomes.
How do you communicate accessibility without overwhelming users?
Use simple bands like 15‑minute access and pair with examples (‘X% of residents can reach a clinic in 15 minutes by transit’). Interactive maps allow deeper exploration while keeping the headline metric clear.
When should accessibility be dynamic rather than static?
During evacuations, events, roadwork, or when timetables change seasonally. Streaming GTFS‑realtime and traffic speeds keeps results aligned to lived experience.