Ambulance stations — how this layer is made

What you are looking at

Each point is an ambulance station — a feature tagged `emergency=ambulance_station` in OpenStreetMap. 15,840 of them worldwide, drawn as a dot sized by the footprint of the building. At the closest zooms rather more than half are joined by their outline as it is mapped.

Click any station to see what OpenStreetMap records about it — the service that runs it, where a mapper noted that. Where it has a Wikipedia article, a short summary is fetched live and shown in your own language; and every station links to the OpenStreetMap object it came from.

Please read the blank areas carefully

Of every layer on HueMaps, this is the one most likely to mislead you, so the warning comes before anything else rather than at the bottom.

An empty region on this map does not mean there are no ambulances there. It usually means one of two things:

the ambulance has no building of its own. In much of the world an ambulance is based at a hospital, a health centre or a fire station, and there is nothing separate to tag. In Germany, Austria, the Netherlands and France the Rettungswache or caserne is a distinct site with its own address, so it gets its own object;
nobody has mapped it. The ordinary OpenStreetMap caveat, and a strong one for a building type that is rarely a landmark.

Set against population, this is the most unevenly distributed layer on the site. Counted crudely — features inside a bounding box, per million people — Germany has around 45, France 26, Australia 27, the United Kingdom 11 and the United States 7, against India 0.05 and Nigeria none at all. That is a ratio of roughly 800 to 1 between Germany and India, higher than any other layer here, including the windmills.

No country in that list is eight hundred times better served by ambulances than another. What the ratio measures is a tagging convention and a mapping effort, in that order.

Mapped, not modelled

Each station is an object a mapper drew, from survey, local knowledge or aerial imagery; nothing here is modelled, estimated or derived from any register of emergency services.

What counts, and what does not

Only the exact tag `emergency=ambulance_station`. That is deliberate and narrow.

The `emergency` key as a whole holds more than three million objects in OpenStreetMap, the vast majority of them fire hydrants, so it is never used as a whole. Neighbouring services have layers of their own or are on the way: fire stations and police stations are separate selections, and the composite emergency services layer will draw all four together.

A hospital with an ambulance bay is not here unless somebody has tagged the bay itself. Air ambulance bases appear only where they carry this tag rather than a heliport tag.

One colour, and why

Most layers on HueMaps colour their features by some property. This one does not, because OpenStreetMap records nothing about an ambulance station that could carry a legend — no consistent tag for the size of the station, the number of vehicles, or whether it is staffed around the clock.

Size carries the information instead, and the operator is in the panel when you click.

Size

Each symbol is sized by the footprint of the station, in square metres measured on the globe. Symbol area is proportional to that (radius to its square root), so a station four times the area draws twice as wide.

About 57% of stations are mapped as an outline rather than a bare point, and among those the median footprint is 411 m² — a garage for two or three vehicles with a crew room. The remaining 43% are recorded as a single point with no shape; those are drawn at a nominal small size rather than at the minimum, because being mapped as a point usually says something about the mapper's time rather than about the station.

84.8% carry a name, the highest share of any layer added in this batch. These are institutional buildings with a formal name, not landmarks somebody chose to record.

The largest features are not really ambulance stations

At the top of the size range are hospital campuses and Red Cross centres whose entire plot carries the tag — a Centro Polifunzionale near Milan at nearly nine hectares, a clinic site in Hamm, a combined fire, civil-protection and ambulance centre near Frankfurt. They are drawn very much larger than any real station.

There are few enough of these to be a tail rather than a pattern, and no rule that removed them would spare a genuine large regional centre, so they are left in and named here rather than quietly filtered.

A picture of the present

Today's map, not a history. OpenStreetMap is edited continuously; this copy is refreshed periodically. There is no year control, and a station closed some time ago may still be mapped until a mapper updates it.