[Talk-us] Freeway directions
Nathan Mills
nathan at nwacg.net
Fri Oct 18 01:11:10 UTC 2013
On 10/17/2013 1:03 PM, Richard Welty wrote:
> hmmm. we're using exit_to (i think) for off ramps, maybe we need
> entrance_to for on ramps
>
> the value would be more or less exactly the text visible on the
> signage.
>
This makes the most sense to me as the solution for the specific use
case Martijn is asking about, where the tag value will be used as the
basis for generating directions which the user will expect to be
consistent with signage. The directional tag on a wayfinding sign at the
motorway entrance may or may not correspond to the bannered direction of
the route or route segment.
If my GPS tells me to "turn right at the entrance to East Interstate
Whatever" and the sign says "North Interstate Whatever," I'm going to be
confused and wonder if I'm actually making the correct turn. Even more
so if it's a printed list of directions.
Being able to include control cities as well as cardinality is a nice
bonus, also.
FWIW, I have in the past typically done one relation for both directions
with the bannered cardinal direction in the segments' role tag, if it is
bannered, or forward/reverse otherwise. I settled on that for my own
work because it plays well with non-motorways that are sometimes divided
and sometimes not. There's not really any logical reason two relations
and a super relation couldn't be used in that scenario. It just seems
somehow less elegant to me to have the extra relations when most of the
route is undivided.
-Nathan
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