[Talk-us] Consensus on "SR" for state route versus state abbreviation?

David ``Smith'' vidthekid at gmail.com
Thu Sep 13 07:57:52 BST 2012

Concerning ref tags on ways, I don't think there's a need to impose
nationwide "consistency".  I also don't think it's worth even adhering to a
strict machine-parseable syntax (particularly dealing with overlaps) since
that kind of information is much better organized in relations.

That said, here are my "ideal" guidelines for formatting ref tags on single
state highways:

1) If there is one clearly-popular abbreviation, such as M-xx in Michigan
or possibly K-xx in Kansas, use it.

2) If a state has primary and secondary state routes, or numerous classes
of state routes like Texas, the prefix should indicate the route class.

3) If a state allows its state routes to have the same number as a US or
Interstate route in that state, a state-specific prefix (postal
abbreviation or other as described above) should be used.

4) If a state is large (such that most places aren't "near" the borders) a
generic prefix like SR or SH or STH (depending on preferred local
terminology) may be used, notwithstanding guideline 3.

5) If a state's state route markers are generic (circle/oval or box) and
don't specifically identify the state, a generic prefix or no prefix may be
used, notwithstanding guideline 3.

6) Consistency within a state, or within broad regions of larger states, is
probably still of value.  A format should be chosen by consensus of mappers
familiar with the state or region in question.
6a) As a mapper familiar with Ohio, I prefer SR xx, but would be amenable
to OH xx or OH-xx.

Slightly off-topic:

A) I strongly prefer I-xx and not I xx (and definitely not Ixx) for
Interstates.  The hyphen enhances readability and reduces the chance of the
I being mistaken for a 1.  The reasons I've heard in support of I xx are:
to match US and state routes (why does it have to?); to match European
route designations (making apples look like oranges); because "all" the
Interstates are already tagged as I xx (due to a few editors who value
consistency a little too highly, plus I see that as a circular argument);
changing it breaks renderers (nearly all renderers just pass a way's ref
tag directly to the output, and those that do try to parse it can and
should normalize tagging variations as a preprocessing step anyway).  On
the other hand, I would't argue against the format IH xx in Texas because
most Texans I've encountered write it that way.

B) When routes overlap, there is no "right" way to format the way's ref
tag.  I don't think any active renderers attempt to separate it into
multiple values; considering this information can be stored with much
better structure in relations, I don't think any programmer wants to bother
with trying to parse a ref string anyway.  That just leaves humans who will
ever read it, and we can optimize for that.  Brevity may be more important
than technical correctness when a human is reading.  Local understanding of
routes' relative importance may play a role.  The following "equations"
demonstrate options to represent overlapping routes in a way's ref tag that
seem perfectly sensible to me:
US 1 + US 9 = US 1-9
I-70 + I-71 = I-70/71
US 40 + US 62 + OH 16 = US 40-62
I-74 + I-465 + (?) = I-465
I-95 + MA 128 = I-95/128
US 68 + OH 15 = OH 15
These little white lies are close enough to match the line on the map to
the road on the planet.  (Every good map has to lie in some way to convey
information effectively.)  If someone really wants to know which routes
follow a particular way, they should examine the relation(s) that contain
it.  If a mapper really wants to make sure the correct, official truth is
represented in the database, they should make sure all relevant route
relations exist and are correct.  Trying to squeeze all that information
into a single string with a rigid syntax is optimizing for a use case that
essentially doesn't exist.
On Sep 12, 2012 8:59 PM, "Charlotte Wolter" <techlady at techlady.com> wrote:

>  Hello all,
> **        **Was there ever consensus on whether to use "SR" (or some
> variation on that) for state highways versus an abbreviation of the state
> name ("CA" or "NY"). I remember that there was discussion, but I don't
> remember if there was consensus.
> **        **Thanks.
> Charlotte
> **
> ** Charlotte Wolter
> 927 18th Street Suite A
> Santa Monica, California
> 90403
> +1-310-597-4040
> techlady at techlady.com
> Skype: thetechlady
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