[OSM-newbies] Speed Limits

[Alberto Nogaro]

>From: newbies-bounces at openstreetmap.org [mailto:newbies-bounces at openstreetmap.org] On Behalf Of John Wesley Simpson
>Sent: giovedì 11 dicembre 2008 15.24
>To: newbies at openstreetmap.org
>Subject: [OSM-newbies] Speed Limits

>For some reason, I never did see this post from you in my e-mail.
>I found it only because I went looking to review the thread in the archive.

I guess it's just because I made a late posting :-). I'm interested in keeping this discussion alive, as I've encountered myself ways with features (speed limit, number of lanes, even access restrictions) where a different tag value for each driving direction was required. 
 
>Unfortunately, the page looks rather cryptic to me, and I see no examples.

The page also states that it is currently only a proposed relation, the currently agreed on method for achieving its purposes being by splitting the way. 
I also read hostile comments to this proposal in the discussion page. So I guess we shouldn't use it yet. But splitting the way in shorter parts is no help when dealing with driving direction dependent tags, so we are in a tight corner :-(

>What I've done so far, is to duplicate the 50/55 road, reversing the direction of the new copy.

I've done the same so far: split the way into a dual carriageway highway. Not only it's a chore, but it's also incorrect, as in reality there is no physical barrier between the ways. I guess that shouldn't matter for any routing purposes, when an uncrossable line separates the two directions at any point. Otherwise it adds unnecessary restrictions (no U-turns, no turn left to access or leave side properties).

>I renamed the roads, putting N & S in front of the names.  (I'm betting that this will not be good when trying to find addresses on the street.)
>I then tagged each copy with the appropriate maxspeed.
>I then also tagged each copy with oneway set to true.

Maybe you could just drop the N & S prefix from the names, if it causes address searching issues. The oneway tag should be enough.



Perhaps the Segmented Tag is not the best approach to the problem, but we definitely need a proper way to handle the situations where a different tag value for each driving direction is required.

Alberto