Re the comment by  Nathan: “I'm still confused as to why the consumers of a 
relation can't use the forward/backward roles…” The forward/backward roles only 
make sense on one-way roads. Other than that, which way is forward and which 
way is backward? Depends on which way you’re driving down the road. The same 
thing is true about the left/right thing used in some tags. When I created 
relations for the WA state routes, I put the cardinal directions in the role 
for each way. I only used forward in the role when there were separate 
relations for each direction of the way.

 

In general, I don’t agree with this proposal unless the highway is divided for 
its entire length. There are only three state highways in Washington that I can 
think of where this is true. I know for sure that one of them (WA 512) has a 
separate relation for each direction, but I don’t know about the other two.

 

-Compdude

 

From: Nathan Mills [mailto:[email protected]] 
Sent: Monday, November 18, 2013 12:28 PM
To: OpenStreetMap U.S.
Subject: Re: [Talk-us] Separate relations for each direction of US & State 
highways.

 

I'm still confused as to why the consumers of a relation can't use the 
forward/backward roles of the ways referenced therein rather than requiring 
completely separate relations. Why do we need two or more relations plus a 
super relation per road route even for undivided highways? Even for a somewhat 
experienced mapper like myself, it makes the editing process that much more 
error prone.

-Nathan

Chris Lawrence <[email protected]> wrote:

On Mon, Nov 18, 2013 at 10:52 AM, Paul Johnson <[email protected]> wrote:

Not a fan.  It greatly complicates things for information that can either be 
gleaned obviously or is a "nice to have."  Having 3+ relations for something 
that isn't fully divided just complicates things, with the exception edge case 
of a relation that starts or ends on a divided highway.

 

On Sun, Nov 17, 2013 at 9:30 AM, James Mast <[email protected]> wrote:

I'm just curious, but what's everybody's opinion on this?  I know it's 
acceptable for the Interstates (some are setup this way, some aren't) since 
they are all divided, but what about for US Highways and State Highways?  I 
know that we want to eventually have the cardinal directions in OSM for the 
routers so they can properly tell people which direction the of the highway 
they need to turn onto (like turn left onto Westbound US-30).
....
Also, on a side note, do you guys think we should remove the "symbol" tags in 
the relations from all the Interstates/US highways they show up in at the same 
time?

So, let's get this discussion going!

 

IMO direction-based relations, with correct forward/backward tagging, are 
borderline necessary for directions based on relations to work correctly in the 
US and Canada. That's something that's sorely lacking (along with exit numbers 
and usage of "destination" tags) in OSRM today.

 

All we should need is a single super relation for each route, along with 
reasonable numbers of directional relations with way members - since each 
directional relation will have 1/2ish the number of members, there's no reason 
to confine them to one per state unless we're doing that to match up with 
Wikipedia articles.

 

As for symbol tags, I'd vote to transition them to the wiki:symbol namespace if 
possible.

 

 

Chris

-- 
Chris Lawrence <[email protected]>

Website: http://www.cnlawrence.com/ 


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