The idea

This entry will describe one application of our GNIS matching program using a very narrow slice of the dataset.

While looking through the Populated Place feature class, I noticed a rather substantial number of names for mobile home parks. I was immediately reminded of the MapSwipe effort in coordination with YouthMappers and the ASU Knowledge Exchange for Resilience.

The full GNIS file has ~7000 entries that look like they will very likely be the location and name of a mobile home park. Running the GNIS Matcher against the ones in Arizona gives 516 places to check the map for either tagging improvement or new geometry.

You can check out the project here.

How to map

There is an amazing guide produced by ASU that has a huge amount of detail about mapping mobile homes. Definitely look it over.

Tagging

An area drawn to represent a mobile home park should have tagging like:

landuse=residential
residential=trailer_park
name=Estrella Villa Mobile Home Park

There is occasionally some confusion between this and a similar tag tourism=caravan_site. This tagging may also show up in places with trailers/RVs but the intent is for that to mark temporary stopping locations, similar to tourism=camp_site.

The matcher would also like a GNIS ID included. The appropriate tagging looks like:

gnis:feature_id=2669824

Drawing areas

In general, try to draw a boundary that encompasses all of the residences. There are often clues in aerial imagery that help delineate the specific park from other areas (guide). Look for fences, pavement differences, and road connectedness to guide your judgement. If there is high ambiguity, it may be helpful to leave a Note for local mappers.

Street side imagery from Mapillary or Bing Streetview is often helpful and has the appropriate license for OSM use.

Examples

No area found, needs mapping

Here’s three pictures from tasks showing GNIS data points that the matcher has not found an appropriate OSM object for. The correct thing is to add an area with appropriate tags as described and mark the task as “I fixed it!”. The matcher is somewhat conservative so may have missed the correct area. You should feel empowered to update an appropriate landuse=residential area if one already exists.

No area found, does not need mapping

The GNIS entries are not maintained and may point to areas that are no longer mobile home parks. In that case mark the task as “Not an issue”. Here’s an example:

Likely area found, needs tag updates

Some mobile home parks have already been mapped but may be missing some of the necessary tagging the keep the matcher happy. Check that the area is correctly drawn and add/modify the tags as appropriate and suggested by the matcher. Here’s two:

Area found but unlikely the correct area

While we try to keep false positives to a minimum, sometimes the matcher will make a guess that is incorrect. In that case, either map in the correct place or mark the task as “Too hard”. In the example below, the matcher has selected the incorrect area. It turns out this was because the correct area to the west was marked incorrectly as leisure=caravan_site.

Next steps

If you have any questions or would like to have a project created for another set of GNIS information please let us know!