[GIS] How to obtain road classification type at a point via nominatim

geocodingopenstreetmap

This is my first time posting here so please forgive me if i ask a trivial question. Is there a way of obtaining the type of road an object is settled in from a request via nominatim? (i have the geocoded sample)

For example:
http://nominatim.openstreetmap.org/reverse?format=xml&lat=52.5487429714954&lon=-1.81602098644987&zoom=18&addressdetails=1

does provide me with loads of info. yet, there is no info on the road the address is settled in. would like to obtain something like: rural road or even just grade*N* (where N stands for the level of hierarchy.) i hope what i'm looking for is understandable 🙂 thanks in advance!

Best Answer

The hierarchy of roads is reflected in OSM by the "highway" field. Possible values in hierarchical order are: motorway, trunk , primary, secondary, tertiary, unclassified, residential, service, track, path

See this wiki pages: http://wiki.openstreetmap.org/wiki/Highway:International_equivalence http://wiki.openstreetmap.org/wiki/Highway_tag_usage

highway=road is default for unknown classification (e.g. if only digitized by aerial photo).

BUT: It is allowed to change highway type in order to reflect the importance for routing purposes.

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[GIS] How to decrease size of geodatabase “Nominatim”

The speed of geocoding relies on two main points for a server that has the good capacities : increasing shared_buffers to 2Go in the postgresql.conf file and waiting for the index to complete : this can take much time. On my server with a test concerning the database of France only, geocoding went faster after 2 or 3 days.

If you want to index and leave the terminal session you can use the nohup command under unix like systems for example.

If you decrease the size of database as mentionned in the manual with the --drop argument, this will impact updates.

[GIS] Get road type by coordinates

It probably depend on what you want to do with these informations and on the number of points on which you want apply this.

1) If you have not many points you can maybe try to do this with the overpass API. Trying to get the closest road around your pair of coordinates. It might look like this :

[out:json];
way["highway"~"."](around:5,50.7528080,2.0377858);
out geom;

You can take a small radius (like 1) and increasing it if you dont have result. Depending on what you want to do with your data, but this should provide you the infos you want (if you dont need geometry you can use out; instead of out geom;). It might be useful to have some basics in a scripting language to make the queries (increasing the radius if no result, etc.) and to process the data retrieved (or/and you can use a library like overpy which provide python bindings for the overpass API).

2) If you have many points, maybe you can have a look on the photon project, it's a geocoder based on elasticsearch and nominatim. I think you can make a reverse geocoding request and get the road type (at least the value for the key "highway" and the corresping osm id) with a local instance of this geocoder. The reverse API is not really documented on the main page but here.

Hope that it can help you.

Best Answer

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