[Tagging] Often seen tagging problems regarding junctions

[Gerd Petermann]

Hi all,


while trying to clean up wrong highway=* tags in the OSM database

I noticed a few error patterns. Not sure if I can call it an error when

other people are using tags in a completely different way, but I think

I should report them:


1) the tag highway=crossing is/was used for ways, often instead of

bridge=yes, often at junctions instead of footway=crossing or cycleway=crossing

or in addition to them.

I think it happened in the past, so this seem no longer a problem.


2) Some mappers tag a footway that is crossing the road like this:

-  the way:

highway=footway

- the first and last node of the way (both on the sidewalk):

highway=crossing[,crossing=*][,crossing_ref=*]

The advantage of this tagging is that e.g. JOSM shows the

symbol for crossing=traffic_signals at the position where

one would expect the traffic_signal (and maybe the button)


3) nodes with tags like highway=traffic_signals;crossing or

highway=crossing;traffic_signals show that it is not very clear

how to use these tags, I am not even sure if some of the combinations

that Taginfo shows are valid, e.g. highway=motorway_junction;traffic_signals


The wiki http://wiki.openstreetmap.org/wiki/Tag:highway%3Dtraffic_signals

explains how to tag junctions with highway=traffic_signals,

the wiki http://wiki.openstreetmap.org/wiki/Key:crossing

explains the crossing=* tag. What I am missing is a combination of both.

Should I tag crossing=traffic_signals at a junction that has one or more nodes

with highway=traffic_signals? Or should I use crossing=controlled instead?

Is a crossing_ref=zebra correct when the junction is controlled by traffic_signals?

Should I map highway=stop at a junction with highway=traffic_signals?


My understanding is this:

- For the routers, we like to have the information that the junction is controlled by

traffic_signals, as this means a potential delay. For routing, we don't want to have

several different nodes with highway=crossing or highway=stop , highway=traffic_signals

etc. for a single junction, as it is difficult to sort out which one adds more delay.

- For renderers or "completeness" we like to have the position of each traffic_sign, each traffic_signal

and each crossing=zebra.


If I got that right, a few proposals were made to solve this conflict, e.g. relations

or closed ways to collect all elements of one junctions, but none seems to be

used often.


If anybody thinks that there is a good and correct solution for a complex junction in OSM, please

post a link.


ciao,

Gerd




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