[Tagging] Feature Proposal - RFC - junction=intersection

Matthew Woehlke mwoehlke.floss at gmail.com
Fri Jul 10 14:15:33 UTC 2020


As some of you may recall, I'm working on a project to do traffic 
simulation with the help of OSM data and SUMO¹.

One of the issues that SUMO has is that the typical method of modeling 
intersections (which I don't propose to change, mostly) results in SUMO 
thinking there are multiple intersections where there should only be 
one. For example, intersections of two dual carriageways produces four 
intersections and makes the turns much sharper than in reality.

My use case isn't the only one that has issues with this sort of thing; 
routers can "see" more traffic lights than actually exist and can (so I 
hear, anyway) give directions that are potentially confusing. 
Intersection modeling is a long-standing issue that has had multiple 
previous proposals.

The major two prior proposals of which I'm aware are to map the 
'footprint' of the intersection as an area, or to create relations to 
map the intersection. Both are difficult, both to model, and for tools 
to parse. The area proposal has potential rendering issues.

I am proposing² a *much* simpler alternative, which is to simply tag the 
portions of a road that are "part of" an intersection (i.e. the 'm', 
'n', 'p', 'q' segments of 
https://wiki.openstreetmap.org/wiki/File:Doublejunction.svg) with 
junction=intersection. This is straight-forward to model, and I believe 
solves most of the issues for a majority of affected intersections. 
(Exceptions likely exist, but 'perfect' is the enemy of 'good', and 
right now we're at 'bad'.)

Comments would be appreciated!

Also, should I start just doing this for the areas I'm trying to use for 
my project, or is it better to wait for some degree of consensus?

(¹ https://www.eclipse.org/sumo/)

(² 
https://wiki.openstreetmap.org/wiki/Proposed_features/junction%3Dintersection)

-- 
Matthew



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