[Talk-ca] Telenav mapping turn restrictions

Andrew Lester a-lester at shaw.ca
Sun Mar 26 03:52:12 UTC 2017

I just discovered that user georges_telenav has been mapping turn restrictions in the Victoria, BC area. While some of them seem valid, there are hundreds of right-turn restrictions that can't possibly be based on either Mapillary or OpenStreetView as stated below, because these restrictions simply don't exist in reality. Here's an example: http://www.openstreetmap.org/relation/7014602 

I don't know about the rest of Canada, but at least in BC, this type of turn is perfectly legal unless otherwise indicated. Most drivers would use the link road and I'd expect routers should always prefer that, but there's nothing wrong if a driver gets past the link road and then changes their mind and wants to turn right. I can think of a handful of locations around town where there may be a sign explicitly forbidding this or at least implying it (e.g. "only left turn"), but the vast majority of the instances that this user has mapped do not have such signage. I'm in the process of cleaning all these up, but I'm worried there may be thousands more of these all over the place outside my immediate region. 

However, what I discovered while cleaning these up is even more disturbing. This is a region with significant growth, and there are frequent changes and additions to the road network. So far, I've discovered several cases where a reconfigured intersection or new road I had carefully mapped by GPS has been obliterated and replaced with an old configuration, apparently based on out-of-date aerial imagery. I take pride in mapping these changes as soon as possible after they're completed so end-users have the most reliable data (and I often mention this to people as one of the benefits of using OSM data in applications), so it's disappointing to see a distant armchair mapper destroy this careful on-the-ground work based on faulty assumptions and out-of-date imagery. I've also seen Telenav mappers adding residential roads that are clearly driveways and making edits without properly aligning aerial imagery, so I'm not exactly filled with confidence that they should be making widespread changes like they are. 

Martijn, I think Telenav needs to stop what they're doing and have a careful discussion with us about their plans and editing procedures before making any more edits. At least in my area, their edits have not only failed to improve the dataset, but in a number of cases has actually degraded it. Something needs to be done about this before things go too far. I already have a lot of cleanup work ahead of me, and I'd like to avoid this happening again in the future (at least by Telenav). 

Victoria, BC, Canada 

From: "James" <james2432 at gmail.com> 
To: "John Marshall" <rps333 at gmail.com> 
Cc: "talk-ca" <talk-ca at openstreetmap.org> 
Sent: Wednesday, October 19, 2016 11:44:53 AM 
Subject: Re: [Talk-ca] Telenav mapping turn restrictions 

Yeah no one really wants to do that, except maybe mapbox's india contractors 

On Oct 19, 2016 2:43 PM, "John Marshall" < rps333 at gmail.com > wrote: 

Make sense to me. A dding turn restrictions is something I don't want to add. 
Happy to see all my Mapillary and OpenStreetView imagery being used to help improve the map. 


On Tue, Oct 18, 2016 at 9:24 AM, Begin Daniel < jfd553 at hotmail.com > wrote: 


Go with the recommended scheme as described on the wiki. 


From: Martijn van Exel [mailto: m at rtijn.org ] 
Sent: Monday, 17 October, 2016 23:53 
To: Talk-CA OpenStreetMap 
Subject: [Talk-ca] Telenav mapping turn restrictions 

Hi all, 

I wanted to give you a heads up that my colleagues on the Telenav map team are starting work on adding turn restrictions in Toronto, Montréal, and later on also Vancouver, Ottawa and Calgary. We are using OpenStreetView and Mapillary as sources. If you have any questions or concerns, please reach out to me and we will address it right away. 

For conditional (time-restricted) turn restrictions, we intend to use the schema described in http://wiki.openstreetmap.org/wiki/Conditional_restrictions . We encounter a more complex mapping of conditional turn restrictions sometimes, where mappers have used day_on / day_off and hour_on / hour_off. This is uncommon and as far as I know not recommended for mapping time-restricted turn restrictions. If we encounter these, our proposal would be to remove these tags and if necessary replace them with the preferred scheme as described on the wiki. Opinions? 



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