Radial Distance Analysis
Definition
Radial distance analysis evaluates phenomena around a point using concentric rings or buffers at fixed radii. It is a simple, rapid method to approximate influence zones for stores, hazards, or amenities. However, it ignores network realities, barriers, and direction, so it should be used as an initial screen or where radial effects are genuinely isotropic (e.g., sound or radiation in open terrain). Results depend on the coordinate system and map scale; Euclidean distance in degrees is invalid. Combining radial analysis with demographic summaries, land use, or competing sites reveals market overlap or exposure. Analysts should present limitations openly and consider transitioning to cost- or network-distance models for decisions.
Application
Retail site selection uses 1/3/5-mile rings; regulators set blast or safety zones; urbanists assess park access; epidemiologists compute initial case-radius searches; telecoms analyze coverage approximations before detailed RF modeling.
FAQ
When is a radial approach misleading?
In street grids with rivers or highways, or in hilly terrain—true travel distance/time differs widely from straight-line circles.
How many rings are useful?
Keep to a few actionable radii tied to policy or business practice; too many rings clutter maps and add little insight.
Should rings be dissolved for multiple sites?
Yes when analyzing overall coverage; keep separate when exploring cannibalization or competition between sites.
What CRS should be used?
A local projected CRS in meters/feet to ensure accurate buffer radii; avoid geographic degrees.