[Talk-us] [Talk-ca] Telenav mapping turn restrictions

James Mast rickmastfan67 at hotmail.com
Tue Apr 4 03:31:02 UTC 2017

Martijn, that intersection for as long as I can remember, has allowed the right turn @ the intersection and also via the slip lane.  The slip lane being closed when StreetView drove by was indeed temporary.  They were using it as a temporary staging area for construction vehicles for the bridge they were replacing on Pine Creek Road (well since completed) that was on the other side of the intersection.


From: Martijn van Exel <m at rtijn.org>
Sent: Monday, April 3, 2017 1:18:38 PM
To: James Mast
Cc: talk-ca at openstreetmap.org; OSM US
Subject: Re: [Talk-ca] Telenav mapping turn restrictions

James -- I could not find any OSC / Mapillary imagery at the location of your example so I took a peek at <<AHEM>> google street view. What I see there is that the slip road / ramp was (as of Aug 2016 -- temporarily?) closed to traffic which may very well inform the allowed right turn at the intersection? Or do you know this to be permanent? In this particular case, based on the info I have, the _link way should have access=no and indeed no restriction would be necessary. (Obviously I can't make those edits because of <<ahem>> above.)

I'm not saying that there cannot be exceptions to the general rule that 'when there is a turn ramp one must use it', (and as I said before our team is not adding these 'implicit' restrictions until we clear this up). What I am looking for is more clarity (specifically in Canada but in the US also) as to traffic regulations that would make adding these restrictions not only valid but also a boost to the quality of OSM data. I would only want us to add these if there is no confusion regarding correctness and there is added value to adding them.

I'm cc-ing the US list as there are very similar traffic situations there and I'm interested in clarifying the situation there as well.


On Apr 3, 2017, at 6:47 AM, James Mast <rickmastfan67 at hotmail.com<mailto:rickmastfan67 at hotmail.com>> wrote:

Martijn, with your example you gave back 3/30 [1], are you 100% sure that it still might be legal to right turn at the main intersection?  It might be if you haven't been there, even with the slip lane being there.

Case in point, if you were to have one of your mappers modify this intersection [2] with a 'no right turn' relation, you would be adding false information to the OSM database.  While there is a 'slip' lane for right turns, there is overhead signage past that slip lane leaving US-19 saying that you are allowed to make a right hand turn at the intersection.  So, [3] would be completely legal and would be prevented if a false relation were to be added here.

This is just something you can't be 100% sure of without visiting it in person, or have imagery from something like Mapillary to see it.  So, I can see why Andrew was upset about this.


[1] https://www.openstreetmap.org/directions?engine=osrm_car&route=40.66610,-111.86760;40.66386,-111.86464#map=18/40.66520/-111.86552
[2] https://www.openstreetmap.org/directions?engine=osrm_car&route=40.58570%2C-80.04423%3B40.58680%2C-80.04410#map=19/40.58625/-80.04431
[3] https://www.openstreetmap.org/directions?engine=osrm_car&route=40.58614%2C-80.04461%3B40.58680%2C-80.04410#map=19/40.58648/-80.04457

From: Stewart C. Russell <scruss at gmail.com<mailto:scruss at gmail.com>>
Sent: Friday, March 31, 2017 7:26:12 PM
To: talk-ca at openstreetmap.org<mailto:talk-ca at openstreetmap.org>
Subject: Re: [Talk-ca] Telenav mapping turn restrictions

On 2017-03-31 04:29 PM, Martijn van Exel wrote:
> … the engine
> may decide, lacking an explicit restriction, to take the non _link turn
> because it's faster even if that is an illegal turn. That is why we need
> these restrictions to be explicit in the data.

but … but — that's Tagging For The Map, or worse, Tagging To Fix
Software Stupidity. It's explicitly mapping something that's *not*
there, and so is contrary to what we're supposed to map.

I don't have a problem with it being in Telenav's data, but it doesn't
belong in OSM.


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