Proposed features/Catchment

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Catchment Areas
Status: Draft (under way)
Proposed by: chrisb8
Tagging: boundary=catchment_area
Applies to: Relation
Definition: A tagging proposal for catchment areas
Rendered as: none
Drafted on: 2012-12-01


Lots of amenities have a catchment area (the area in which they provide their service(s)), but there is currently no way represent this information. We propose a tag to associate catchment areas with amenities.


Places that might have catchment areas:

  • Medical Facility
    • Hospitals
    • Dentists
    • Doctors’ Surgeries
  • Schools
  • Places of Worship
  • Postal Depots


A boundary relation should be created to describe the catchment area.

Relation tags

Key Value Discussion
type=* boundary This relation describes the boundary
boundary=* catchment_area The type of boundary, in this case the catchment area
catchment_type=* a catchment type Optional, the catchment area for some subjects is inferred from the tags on the subject, or it can be tagged with one, or many of the values in the table below.

Catchment Types

Type Description
ambulance_service Applies to a facility providing ambulances
vaccinations Applies to a facility providing vaccinations
school_bus Applies to the area served by the bus for a school
school_admission Applies to catchment area (for admissions) to a school

Relation members

Element Role Recurrence? Discussion
Way outer one or more The multiple ways that form the closed border
Way inner zero or more Enclaves of this border - the multiple ways that form the closed inner borders
Node Way Relation subject one or more Node representing the objects that this catchment area relates to


For a school tagged as a closed way with amenity=school, to represent the catchment area, a relation is created describing the catchment area using the outer and inner members, the school way is the subject member of the relation. If multiple schools share the same catchment are, multiple subjects can be added.

Medical Facility

For a medical facility, tagged with amenity=hospital, if the hospital has a catchment area, it is the subject of the relation. The boundary is then tagged by using the outer and inner members.


This feature has been explicitly requested by the US Peace Corps, as part of the Granular Health Mapping ( Random Hacks of Kindness ( problem. If implemented, the feature could quite possibly be used by many Peace Corps volunteers to analyse health problems and needs in developing countries.

Some of the use cases our contact person at the Peace Corps sent are:

1. „When developing a logistics plan for mosquito net distribution, since the head nurse of a clinic tends to be responsible for his/her area, it's useful to be able to see both the roads and the catchment areas to determine which villages are covered by whom (or which facility as it were). Often this logistics planning happens in a meeting, so I'm seeing printing out a map with roads, health facilities and their catchment areas overlaid.“

2. Analysis like: What percentage of the area of this catchment is more than 7km from the Hospital? How many people (joined with population data) are in the catchment of a certain hospital? This is valuable for e.g. journalists, health planners (staffing, resources), insurances, emergency response.