Hi Charlotte (and talk-us, and apologies for the length of this):
Yes, any explanation of the difference between "main" and "branch" lines and "owner" is appreciated. I find myself rather confused at the moment.
It is complicated. The owner= tag is for the actual landowner of the railroad. This usually includes land (maybe twenty to a hundred or so feet on either side of the rails, sometimes -- but certainly not always -- a polygon tagged landuse=railway), tracks, ballast, ties and signalling equipment. Due to the real complexities of ownership (which may be private, like a railway corporation, e.g. Union Pacific, BNSF -- there are hundreds -- or public, like Port of Oakland, Santa Cruz County Regional Transportation Commission, hundreds of others), owner= can be hard to determine, but there is always only one owner. Adding to the complexity, there are also leasing agreements the owner may arrange with other entities (again, potentially both public and private) like railway companies, public agencies, and so on. These leasing / trackage rights arrangements are where it can make sense to add an operator= tag to a rail way with an owner= tag, if they are different.
The name= tag often includes the "subdivision" name of the "line" of the rail. There is a hierarchy, but it is loose: at the top is a rail company (again, like Union Pacific or BNSF). These "owners" (but could also be "operators") often are referred to as a "Primary Rail Organization" as a top-level entity. There are various abbreviations for these, like UP and BNSF, or even TTBART for Bay Area Rapid Transit, and I'm not sure what (federal?) standardization there is for all of these abbreviations, but they do seem to be largely consistent across much of the documentation I see. It seems like it might make sense to put these abbreviations into a ref= tag, but while I haven't seen that widely done, it is beginning to happen (perhaps for "shield tagging" like we see with MapQuest Open?)
OK, so below owner/operator/ref (the Primary Rail Org), there is what is known as "Division" or "Line" name. And below that, there is "Subdivision," especially among the very large/major railroads like UP and BNSF: these "majors" almost always have both Divisions and Subdivisions. However, medium-sized and smaller railroads might go straight to "Subdivision" as the next level down from their top-level ownership -- they might even go straight to something they call "Lead" or "Line." Below Subdivision is "Lead or Line Name." These are usually spurs and small industrial segments that branch off of usage=main or usage=branch segments. It is these names (except the Primary Rail Org, which goes into the owner= and/or operator= tag), especially Subdivision, is what should be put into the name= tag. This holds true for infrastructure (ways in OSM with a railway=rail tag) which is also tagged usage=main AND usage=branch, which I'll get to below. Now, it is also true that if an industrial lead (like "Spreckles Industrial Lead") is actually named that, EVEN IF it is a branch/spur off of a usage=main or usage=branch (its usage tag should be usage=industrial or service=spur) you should put the name of it into the name tag. So in the above example, the spur off of the Union Pacific's "main line" through Salinas (with tags name=Coast Subdivision and usage=main) has name=Spreckles Industrial Lead. I know, it is confusing, but I think you can get the hang of it.
Just enter owner= as the Primary Rail Org (unless there is a leasing agreement, in which case you might also use an operator= tag), and put into the name= tag the "name" of the "line" which is usually a Subdivision or Lead/Line name.
Now, adding a usage tag (usually usage=main, usage=branch or usage=industrial) is even more tricky: it isn't really clear what is usage=main or branch, especially in the USA. Often, usage=industrial is more straightforward, especially if it is clearly a small (often urban) spur off of a main or branch line that disappears into or along the edge of buildings in an industrial zone. So, a place to start thinking about where to add usage=main are the major "lines" of the major railroads which connect larger geographic areas: not county-to-county, but more like state-to-state or region-to-region. We (in the USA) are just going to have to "figure this out" as we go, as it is a bit of subjective interpretation where to best add the usage=main tag. At a hierarchical level distinctly below usage=main is usage=branch. Sometimes, it will be clear after sketching out a major line being usage=main that there is a "branching structure" that has rail connecting or radiating outward from the usage=main tracks, and it may very well be that adding usage=branch to these segments is correct. (Alexander Jones' work in the Central Valley illustrates this). But again, we are going to have to "feel this out" as we go along. This is where we need "rail fans" or "rail professionals" to correct us where we are wrong, as the structure of the network is what we are defining with these tags (main and branch), but people who really KNOW rail have a real sense of what "the" (or "a") more correct instance of this likely is. We just have to listen. Good stabs at usage=main and usage=branch can be carefully undertaken by us as an initial first step, and I think we should do this, but we must be willing to change the structure when told by those more knowledgeable that we got it wrong.
Finally (in this missive!) there are service= tags: service=spur is essentially equivalent to usage=industrial, service=siding is for a track (often in a rail yard or at a station) where "through traffic" can pass another "parked" train, service=crossover is for a short segment of track that "switches" from one rail to another parallel rail and service=yard is for tracks that make up a rail yard. The service= tags are "more rare" compared to usage= and name= tags (essentially, all rail ways should have usage= and name= tags), but when you need a service= tag, you need it, so tag it!
For instance, why does the BNSF line across Arizona and into New Mexico change to "Gallup Subdivision" at one point to the west of the city of Gallup? It seems to be still the BNSF main line. Further, other "subdivisions," such as the Springerville (Ariz.) Subdivision, clearly seem to be branches. So, when is a line a subdivision? If I get a handle on this and other distinctions, I can make corrections (or explanations) ... I think.
To be clear: something can be named "XYZ Subdivision" and STILL or ALSO be usage=main (or usage=branch, for that matter). The word "subdivision" is what a lot of people (I'm discovering) seem to prefer as the "name" of a segment of rail -- whether it is a "main line" (usage=main) or a "branch line" (usage=branch). In short: "subdivision" is a convenient name, without regard to where it might be in a usage= hierarchy. It is the usage= tag which defines hierarchy in OSM's rail network, not how it is named (even if that name has the word "division" or "subdivision" in it). Got it? Whew!
Just re-read this a couple times (if you must) and with these guidelines in mind, try a few fixes if you think the map needs them. ORM rendering only once a day is painfully slow from an interactivity perspective, but just have patience and you'll get the hang of it after a few edits / days of rendering.
If I had to answer Charlotte's specific question, I'd say that the Gallup Subdivision might have a usage=main tag, but Springerville Subdivision might have a usage=branch tag. Both are named "Subdivision" but that's just how the rail company (owner=, operator=) puts them into THEIR hierarchy. OSM's hierarchy that is expressed with a usage= tag is what we're doing our best to tune up here. We can get it a little wrong, and we should correct it when appropriate, but we can sketch in what we think are main lines and branch lines for now, if we keep all this in mind: add owner= (and operator=) tags and especially name= tags first, usage tags come after this and a bit of thought and/or "more network knowledge."
So, to Mike Henson about Oklahoma: one line might be named one, a few or even several "subdivisions," but it is the usage= tags we are concerned about which outline (in ORM) the "network structure" of rail in the USA. These might all be one single owner= (or they might not be), but if they are all a "logical main line" then they should all get "usage=main." Again, these are a bit subjective (right now), so let's just do our best to keep all this in mind. We can mid-course correct if/as necessary.
I'll try to help with the wiki, particularly from an English standpoint, my specialty.
Excellent! The USBRS WikiProject was my "first" and I had help from Minh, who created the pages out of nothingness (which you, Charlotte, might do for WikiProject USA Rail): Minh planted the seed, and I, he and others have grown it into a thriving and mighty tree. I do hope you can plant a similar seed and we can all grow a USA Rail wiki!
I'll also try to pick up more knowledge to contribute to the wiki, though I'm a bit busy with the HOT web pages at the moment. We don't have to hurry--there's no crisis--so probably it's better to take our time and get as much as possible from rail experts. I'm one of the "area" mappers, but I know little about railroads.
Correct: this isn't burning a hole in urgency (like some things, especially HOT, which IS truly hot!) I'm no rail expert, either, but it is becoming an interest of mine as we begin a potential passenger rail project locally here in my county of Santa Cruz. Good maps and map data can only help further, future endeavors. I often say that the USA has a 20th or even 19th century rail system, and the rest of the world is clearly in the 21st. We don't have to spend billions or even trillions "catching up" (well, yes, we do...) but we can certainly display "where we are now" with good geographic rail data and nice renderings like ORM show us -- without spending anything more than good volunteer effort!
Thank you for your enthusiasm! If my explanations aren't clear, or you have further questions, please ask and I'll do my best. But do take a look at that CPUC spreadsheet (it is HUGE!) as it really can be helpful (though tedious), and I can send you a very early version of some of the "branching spreadsheets" that Alexander and I are working on for California (as you are in LA). We know these probably are not 100% correct, but we'll both take 75% or 85% (where I think they are now) and start putting those into OSM and see how far that takes us. Actually, Alexander writes me he is becoming a full-time student again in about two weeks, so his work in Central Valley will rapidly fall off to zero very soon. As for me, I really do have other things to do, so while I might tap-tap-tap at California Rail in OSM a bit, I can't give it my full attention.
Cheers, SteveA California _______________________________________________ Talk-us mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk-us
