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

Shawn K. Quinn skquinn at rushpost.com
Sun Nov 30 06:45:29 UTC 2014

On Sat, 2014-11-29 at 22:21 -0800, Minh Nguyen wrote:
> Do any routing engines currently care about prefixes on way refs?
>  From what I've seen so far, most of the map styles that use the ref tag 
> to distinguish route networks will recognize either the state 
> abbreviation, "SR", or "SH". Some renderers use the prefix to choose a 
> state-specific shield, assuming any unrecognized prefix is for a county 
> route (white rectangle at higher zoom levels). MapQuest only recognizes 
> state/provincial abbreviations. Not that we should place too much stock 
> in individual renderer decisions. :-)

OSRM doesn't know that, for example, TX 6 and SH 6 are the same highway.
Once upon a time, I'd get directions that had things in them like:

Turn right on TX 6
Continue on SH 6
Continue on TX 6
Continue on SH 6
Continue on TX 6 ... etc

Granted, OSRM still doesn't handle it gracefully when another highway
multiplexes for a stretch, but at least one might be able to figure out
which highway one's supposed to stay on when it's ref'd the same across
the board. When it's not, it becomes much trickier.

Shawn K. Quinn <skquinn at rushpost.com>

More information about the Talk-us mailing list