What should count as a severance?

[dabreegster]

Based just on OSM tags, currently a severance is when highway is motorway, trunk, primary, or those 3 with _link. I made this definition for Hong Kong. Do the results look correct everywhere? If it should be refined somewhere, please link to the OSM way that's either a false positive or negative (use debug mode and click).

[dabreegster]

Railways, bodies of water, and even parks with gates around them should also count

[democat3457]

This seems to be a false positive https://www.openstreetmap.org/way/1120402115#map=18/32.98030/-96.75926
while the neighboring secondary road is arguably dangerous to cross https://www.openstreetmap.org/way/419452359#map=19/32.98048/-96.75672 (or are severances supposed to be physically impossible to cross)

[dabreegster]

Thanks for reporting, I'm going to take another stab at this tomorrow and introduce "profiles." Originally I made this project to look at Hong Kong, then later on some places in the UK, and even between those two, the definition of severance is kind of different. Now looking at some places in the US (like this), it's wrong there too.

A severance should be anything that's physically impossible to cross (like a river or active rail line) or dangerous to cross for a pedestrian (many lanes, high speed, etc). That way, any crossings over the severances will be highlighted, and the lack of them studyable. I've been using highway classification as a proxy, which is OK in some places, but in many cases not.

[democat3457]

Also, ways with sidewalk=no should not be labeled "WithTraffic": https://www.openstreetmap.org/way/571968303

[dabreegster]

@democat3457, I started a (awfully named) "USA" profile: https://github.com/a-b-street/severance_snape/blob/main/backend/src/profiles.rs
Also added UT Dallas to the example list (for my own testing convenience mostly). Note it's using cached OSM data as of ~an hour ago, it's not updated unless I manually do it.

This looks much better to me, but there are still problems, like distinguishing https://www.openstreetmap.org/way/1120402115 and https://www.openstreetmap.org/way/571968303. If you have opinions about the classification in this area, please feel free to play with the code directly (if it's easy) or help me find more unit test cases

[dabreegster]

With these revisions, it picks up some pretty awful problems like

(Separately -- I need to find a basemap that's much better at showing lots of labels, because it's kind of impossible to know where this is. I have some ideas for rethinking the cartography totally, but it might take a while)