Airport surfaces (runways, taxiways): ways vs. areas?

I’m new to editing OSM, and trying to understand some of the “philosophy” of why some things are done as they are.

Surfaces on airports - runways, taxiways, etc. - are a key issue for me right now. I see that they can be depicted as ways or areas, or - why not both? For my purposes, the areas are needed, as my use cases involve working around the runways on the ground, and the way depiction is insufficient.

For now, I’m leaving the way depictions alone and adding simple "area: surface = concrete (or as appropriate) for the surfaces, with the thought that I could later go back and convert them to “runway” or “taxiway” areas easily enough if it turns out that is more correct.

So: why not put both way AND area data in for things like runways and taxiways?

Routing engines are more comfortable with ways than with areas and most objects that are not clear areas and are usually traversed in a discrete manner (from A to B and not randomly across) are generally mapped as ways. Of course routing is not the most important aspect of airway mapping, but still for taxiways it can be very helpful.
I think both have a reason to be on OSM: the way to help routing across an airport, the areas to show limits of where you can go.

Thank you, that is quite helpful.

So I would imagine that the routing engines would select on the way for a runway, and ignore the area.

It’s certainly not a consistent thing. I do find plenty of runway areas, for example, at Reykjavik. It seems that having both ways and areas when possible would allow the consumer of map data to choose which fits a particular purpose.

For describing area highways there is a key area:highway, but i have not found anything for aeroways.

Routing engines usually do not do anything with areas. That’s on of the biggest problem with pedestrian areas, that routers don’t route over them. Usually there are still footways mapped in a pedestrian area.

The consistency issue is more an issue of “it is not mapped yet” and I would guess that large airports are usually better mapped than local small airstrips.

I would absolutely encourage mapping both.

Closed ways on aeroways are assumed to be areas so area:aeroway is unnecesseray.

Be careful though: I’ve seen airports where runways are mapped both with a way along its centerline and an additional area, both tagged as aeroway=runway. I think this is wrong since it would suggest that there are actually two runways (as there are two data objects in OSM). I would tag the area as area:aeroway=runway therefor in analogy how a highway can be mapped with highway=residential in the centerline and area:highway=residential for the area it’s covering.

The problem with mapping runways as areas is that it is much harder to programmatically extract direction and length from an area versus a way. My suggestion would be therefor to map them as both ways (with aeroway=runway) and a separate area (with area:aeroway=runway) .