[Talk-ca] Telenav mapping turn restrictions

Pierre Béland pierzenh at yahoo.fr
Thu Mar 30 18:24:33 UTC 2017

Bonjour Martijn
Le problème de navigation que tu mentionnes ne s'explique pas par les données OSM. Vous tentatives de régler ces problèmes des logiciels de navigation alourdissent inutilement la base OSM. Les cles turn peuvent souvent etre utilisées et sont moins complexes que les relations de restriction - voir exemples

The navigation problem you present is not due to OSM data. The fixes for software navigation problems make the database unecessary more complex, especially with restriction relations - See examples.

way=385943816, relation no left turn , junction to a oneway - Why ?
way=385943815, relation no left turn, turn=through key would be simpler

your routing example to turn right, the routing software skips the primary link. Why ?
way=172236000, primary link well connected -> routing software problem to fix first ?
More routing examples around:
routing software accepts the previous primary link to turn right

routing software accepts to turn left even if a restriction relation on turn leftway=385943814, relation 5743391, restriction no left turnhttps://www.openstreetmap.org/directions?engine=mapzen_car&route=40.66632%2C-111.86855%3B40.66641%2C-111.86492#map=18/40.66600/-111.86668

In the opposite direction, the software accepts to turn left on the primary linkhttps://www.openstreetmap.org/directions?engine=mapzen_car&route=40.66503%2C-111.86237%3B40.66532%2C-111.86682#map=17/40.66552/-111.86460
And worst, the software accepts to make a u-turn on the primary links - probably adding a simple key turn=through would fix this.

      De : Martijn van Exel <m at rtijn.org>
 À : Andrew Lester <a-lester at shaw.ca> 
Cc : talk-ca <talk-ca at openstreetmap.org>
 Envoyé le : jeudi 30 mars 2017 11h51
 Objet : Re: [Talk-ca] Telenav mapping turn restrictions
Hi Andrew (and let me reply to Pierre's comments too, sorry Pierre, I am a little slow parsing French).
First off thanks for your additional comments, they are really useful. I realize that I should have shared more detail about what we are planning to do and will do a better job in the future if new projects arise. We are actually working on a Github repository (similar to Mapbox's) where we will share more details about mapping projects and where everybody will be able to talk to the team about what we do. Of course we will continue to post here as well.
We do have a serious onboarding process for new mappers on our team where more experienced mappers guide the newcomers and introduce them to the OSM ecosystem. So they are not quite thrown in the deep end, but like everybody else they go through a learning process where they make simple edits first. We don't ever use live OSM data for pilot or test projects.
I don't feel there's a consensus about the turn restrictions in places where they are not marked. There are really good (routing / safety related) reasons for this as I pointed out before [1] and in my research I have found many of these in the U.S. as well, but until that is cleared up we will not add any more. This includes the left turn restrictions Pierre mentioned. To Pierre's comments, I don't think that there's really an easier way to map this, turn restrictions have been discussed in the community at length and other solutions not based on relations just don't scale well to complex situations.
The Bing imagery alignment issue is one that we have not given proper attention and I will impress upon the team that they should pay really close attention to this and be even more restrained in modifying local mappers' work. I seem to remember there is a site / place that lists offset issues with Bing imagery by region? Is there a good source to look at for this?
I'm thinking it would be good to hold an online town hall where some of our team members and myself can answer any questions and discuss the issues raised? If you're interested in this let me know off-list and we can set up a time.
Thanks again for your feedback and willingness to work on this with me and the team. We really do want to improve the map for everyone and we will be taking this as an opportunity to do significantly better.
[1] Look for example at this situation where there is no turn restriction on an intersection with a _link road and OSRM does not route over the _link road. https://www.openstreetmap.org/directions?engine=osrm_car&route=40.66610%2C-111.86760%3B40.66386%2C-111.86464#map=18/40.66520/-111.86552 It is these kinds of (potentially unsafe) situations that we are really looking to prevent, not only for Scout users but for all routing software using OSM. (This is in the US not in Canada but the situation could occur anywhere.) 

On Mar 29, 2017, at 11:14 PM, Andrew Lester <a-lester at shaw.ca> wrote:
Hi Martijn,

Thanks for your comments. Yes, I have commented on relevant changesets, though not every one I've come across. To be honest, there are far too many problematic changesets to start discussions on all of them.

In using some QA tools to fix other problems, I've come across further instances of what could best be described as "sloppy" edits. For example, adjustments to road alignments to align them with Bing, but obviously with no attempt to properly align the imagery first. Bing is off by 15-20 metres in much of southern Vancouver Island outside of downtown Victoria, and I've seen some roads being moved that much out of place. Here's an example changeset: https://www.openstreetmap.org/changeset/46740353 (viewed with Achavi: https://overpass-api.de/achavi/?changeset=46740353#map=16). I see the source "Geobase roads" has been listed as being used as part of the edits, which actually reflects the correct alignment, but this seems to have been ignored in favour of the poorly-aligned Bing imagery. In addition, I've found a number of edits by Telenav members creating or moving highways such that they cross footways without an intersecting node, which indicates that the JOSM validator isn't being used before uploading the changes.

In my opinion, based on what I'm seeing, the Telenav members don't have enough experience with the OSM ecosystem, tagging/mapping conventions, or editing tools to be making such widespread and prolific changes. I would strongly recommend that these members focus on mapping a local area that they can visit in person in order to gain experience with all aspects of actual on-the-ground mapping, and then later begin expanding to the rest of the country. Right now it seems like they're being thrown into the deep end with the hope that they'll just figure things out, and we're having to deal with the mess they're creating. I'm sure they mean well, but they just aren't qualified to be making the nationwide changes they are currently. I also strongly recommend that detailed proposals are brought to this community's attention before widespread tagging changes are made, such as the creation of tens of thousands of restrictions as detailed by Pierre. It would be good to confirm that the team is going to be making useful and correct changes before actually going ahead, just in case there's a better way of tagging/mapping things that the team wasn't aware of.

As for the right-turn restrictions that I brought up earlier, I've posed the question of the legality of these right turns to a couple of sources (one that's pretty official) and am just waiting on a response. I hope to have one soon. This will only apply to BC, but it might help indicate whether the laws need to be investigated for other provinces as well.


From: m at rtijn.org
To: "talk-ca" <talk-ca at openstreetmap.org>
Sent: Monday, March 27, 2017 9:08:26 AM
Subject: Re: [Talk-ca] Telenav mapping turn restrictions

Hi all, 

Thanks for your thoughtful commentary. 

First off, our mapping team’s only objective is to improve the map for us and for everyone. In doing this we always respect the work of local mappers, and follow community conventions. None of our edits are automated. There is a person using JOSM behind every changeset, so if you observe something untoward, please comment on the changeset so we can learn, discuss or undo if necessary.

Some of our mapping team members are on this list and they can (and will) explain a bit more about how (and why) we add turn restrictions.

I make a point to announce any new mapping projects we start to the local mailing lists (like I did when I started this thread). If there is anything we can do to be more open about our mapping projects I would be eager to discuss with you.

Again, if you have specific concerns about edits any of our team members make in your local area, please! raise them in the changeset comments. It’s the single most effective way for us to learn how to to do better. Members of our mapping team are always identifiable by their usernames ending in _telenav.


> On Mar 26, 2017, at 7:45 PM, Stewart C. Russell <scruss at gmail.com> wrote:
> Hi Andrew:
>> … I had already removed some of the
>> right turn restrictions, but I can add them back in
> Are the restrictions even necessary? If there are turn lanes present,
> one should use them. I can see, however, that routing software might
> send vehicles through the traffic lights if the turn lane were a longer
> route. I wonder if Telenav are tagging to work around their routing
> algorithms?
>> There's still the matter of armchair mapping wiping out on-the-ground
>> mapping.
> Yes, this is troubling to me too. Have you left comments on the
> changesets? Telenav's actions need to be brought out into the open.
> I'm really not looking forward to seeing what all this algorithmic
> mapping's going to do with Canada's logging roads ...
> Stewart
> _______________________________________________
> Talk-ca mailing list
> Talk-ca at openstreetmap.org
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