[Talk-us] Highway Tagging Consensus to Improve OSM (and address some of 41 latitude's concerns)

Val Kartchner val42k at gmail.com
Sat Oct 23 19:31:23 BST 2010

On Sat, 2010-10-23 at 06:30 -0700, Craig Hinners wrote:
> [...] (Or, if you're of the brevity and ambiguity trumps verbosity and clarity
> camp, I give you "network:US:WI", "network:US:US", "network:US:I".)
> [...]
> No endless parsing of the tag value, looking for "I-" to determine
> whether that way is an interstate, oh, oops, this guy doesn't like
> hyphens, I need to look for "I*", oh, oops, that gets me everything for
> Iowa and Idaho, oops, now my function to determine whether a way is an
> interstate is 10000 lines long with 500 "if" statements and regular
> expressions that would make a CS major run for the hills.

No, it's very easy.  Colons separate fields, and non-alphanumerics
separate subfields.  Fields are arranged from highest level
administrative level, starting with ISO two-letter country codes.
Everything before the last subfield is used to determine the shield to

Look at these for example:

Ref:		Shield	Number
US:I-15		US:I	15
US:US-89	US:US	89
US:UT:67	US:UT	67
US:UT:CR-1983	US:UT:CR 1983

If people don't use the country reference, then it will be more
difficult to figure out which shield to use, but these could be tagged
and fixed manually.

The bigger problem is rendering the shield so that it is clearly
readable.  Another problem will be making state-specific shields that
can be clearly rendered.  Something that could be done is that the basic
shields will be made manually.  The numbers would also be done manually
or they become fuzzy at small sizes.  The shields and the digits would
be put together by a program, so the complete shield would be made by

The big map providers (Google, Yahoo, Bing, MapQuest, etc.) should be
considered a floor (minimum) for OSM rendering, not a ceiling.

- Val -

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