Hey Chuck,
In the case of a Control Point, junctions, or Interlockings: 
Eample:  https://www.openstreetmap.org/relation/11204303 
Name=Colley Avenue 
railway=crossover
railway:position 1.9 (If the milepost markers have the prefix add LP) 
Here is an example of what the ref would be used for at the junction, crossover, or interlocking location. 
railway=ref1231.jpg




Nathan P


On Fri, Jun 19, 2020 at 7:14 AM Chuck Sanders <nathhad@gmail.com> wrote:
I'm trying to figure out another North American tag interpretation, to keep us consistent with everyone else.

For most North American railroads, operating sites like junctions, siding ends, and crossovers (really, all Control Points) are referred to by name and milepost (and milepost here is most often alphanumeric, example "LP 1.9" for a site named "Colley Avenue").  We've been discussing internally how to tag these this week, and realized we probably need a better international interpretation to help us stay consistent.

My initial thought a week ago was that this would probably be railway:position.  However, that tag isn't included by default in the tagging scheme for these types of operating sites, and based on how it's used, others have pointed out to me that this is probably a better fit for railway:ref for these sites.  I tend to agree.

For a good, quick typical view of how these are used, see here for a page out of an employee timetable (which is really the reference book for the subdivision), page 4 (PDF page 8) where the above example was taken: http://www.multimodalways.org/docs/railroads/companies/NS/NS%20ETTs/NS%20VA%20Div%20ETT%20%231%208-4-2008.pdf

So far in North America, railway:ref is only being used for the three-letter codes for passenger stations, which is a very clear correct use.  Using that tag for the many, many control point operating sites we have would very much be a different use to what's already done, so I'd want to verify that it's correct and intended before actually implementing it.  After all, if we stuck with railroad:position for this, it would leave railroad:ref an "uncluttered" tag for passenger stations, which do represent its most important use.

What is the sense of the wider community here on how this was meant to work?

A large part of the reason I've been bringing so many of these NA-specific questions to the list over the past week and a half is that we've been starting to work up a simplified NA-specific JOSM tagging preset.  Anything I include as an implicit tag interpretation is going to potentially get repeated over the map quite a bit, so I'm trying to be *really* careful about making sure my understanding of the tags built into the preset tools is correct, so they will be correctly applied.

Thanks for your help and input,
Chuck