[Talk-us] Rail westerly
stevea
steveaOSM at softworkers.com
Mon Dec 29 22:27:29 UTC 2014
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
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