[Talk-us] State highway refs (was Re: New I.D Feature)

[stevea]

Tod Fitch wrote:
>For what it is worth, California has a policy of avoiding duplicate 
>highway numbers between the state, US and Interstate highway 
>systems. As I understand it, that policy and the renumbering that 
>accompanied it occurred in the 1960s. So if highway 50 is specified 
>there is no ambiguity, it will be US 50 as there is no CA50. There 
>are some weird but understandable exceptions like the eastern most 
>section of "The 210" freeway in the greater LA metro area which 
>apparently has not been accepted into the Interstate system. So it 
>is labeled as CA210 but is otherwise indistinguishable from the much 
>longer western portion labeled as I-210. Near as I can tell, for the 
>locals and possibly for CalTrans too it is all simply "The 210".

This policy is reasonable, even smart, by California's DOT 
(Caltrans):  it avoids confusion by motorists who don't need to know 
there are "two numbered highway networks" of both State Routes and 
U.S. Interstates.  Actually, there are three networks, as County 
Routes (A#, D#, G#, J#, N#, S#...where # is a small integer), 
recently mentioned here by me, are another numbered highway network 
in California.  However, the preceding letter identifies a cluster of 
counties (a geographic area) and so easily avoids confusion with 
State Routes and Interstates whose designators (ref tags in 
OSM-speak) are "simply numbers."

"The 210" is a southern Californian colloquialism to refer to two 
different highways:  I-210 (a U.S. Interstate) and California State 
Route 210 (connected to I-210).  Indeed, SR 210 is not up to 
Interstate standards, but it might be someday, so this is why 
Caltrans named it this way, anticipating its eventual incorporation 
into the Interstate system.  I don't think this is weird:  it is 
explainable and again, reasonable and smart, balancing the need to 
avoid confusion (a larger than necessary set of routes) with minutiae 
of legal/technical details.

"The Great Renumbering" (of highways) took place in California in 
1964.  California also had "legislative route numbers," largely 
historical; the history and process of renumbering highways here is 
rich and colorful.  But in short, it has largely settled down since 
1964, and within the purview of Caltrans, there remain three 
networks:  Interstate, State Routes and County Routes.  The 50 states 
have two or more networks each -- "State Routes" and Interstates -- 
and some have more (California has three, Texas has seven? eight?). 
Each of the 50 states should and does have full purview over the 
naming and numbering conventions of its highway network(s), though 
Interstates do achieve their intention of being uniformly numbered 
into a cohesive network amongst the 50 states.

OSM seems to have the data elements to cope with all of this rather 
well:  ref tags (yes, on both ways and relations) which can capture 
multiple networks (concurrencies) with semicolon syntax.  But, 
standardization and consistency are still being hashed out and 
improved.  As each state decides (it does), let us endeavor for OSM 
to fully capture and correctly document these realities.

I agree with Minh that w.r.t. how OSM "numbers highways," in the USA, 
relations are an important component of "a best way forward."  We are 
getting there, but there yet remains discussion and full data harmony.

SteveA
California