Table 1.

McGrail and Humphrey’s rules to define the variable application of distance-decay to service catchments (Step 1)

Rule	Explanation	Outcome
1. Population within 10 minutes of the service	Initial (local neighbourhood) catchment without distance decay	No decay
2. Population linked to their nearest 25 services	Services likely to provide access to populations (beyond 10 minutes) that have few alternative options	No decay
3. Population <5000 and < 0.5 population of the Service town	Services in larger towns likely to provide access to significantly smaller nearby populations, but not vice-versa	No decay
4. All other scenarios	Services less likely to provide access to populations as distance increases.	Decay