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Turn restrictions, exit and destinations are important components of navigation system and enhance the routing and guidance accuracy of any routing engine. To improve OpenStreetMap, broaden its reach globally and make it more accurate for routing, we would like to join hands with the community to map missing turn restrictions, exit and destinations in Europe using Mapillary as the primary source.

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First stop is Germany, we want to concentrate on three major cities: Berlin, Stuttgart, Wolfsburg and map turn restrictions, exit and destinations, slowly branching out to other cities and countries in Europe.

Mapping workflow

Turn Restrictions

We have devised a simple way to add turn restrictions using the Mapillary and detected traffic signs using OSM navigation map that displays the detected turn restrictions from Mapillary, making it easy to know the position of the signage and to mark it as valid/invalid once it has been reviewed and mapped if required.

Marking a detected no left into a oneway as redundant restriction on the OSM navigation map

You can go through the detailed workflow: guide for mapping turn restrictions using Mapillary to know about the working procedure for mapping, tagging system and certain exceptional cases.

Motorway exit numbers & destinations:

Checkautopista2 by k1wi is a neat tool that highlights all the highways and their exits which makes it easier to add the missing exit and destination tags.

Here’s the detailed workflow for mapping exit & destinations using Tasking manager and Checkautopista2 with Mapillary as the primary source.

If you are a local mapper, please review the workflow and provide your suggestions on how it can be improved. When in doubt, notes will be added and local mappers contacted before updating an existing value.

Existing data

Current number of turn restrictions in 3 cities were extracted using overpass.

  • Berlin: 1057
  • Stuttgart: 828
  • Wolfsburg: 72

Current number of exit & destination tags in 3 cities extracted from overpass.

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Join in!

We have had tremendous support from the OpenStreetMap community so far, guiding us in every endeavor, suggesting us with new ideas and improvisations on how to make our workflows better, calling us out on occasional errors, answering our questions and clearing our doubts. We would love that collaboration and contribution to continue working together. Let’s all join in making OpenStreetMap the best!

From the data team at Mapbox


Comment from mvexel on 12 August 2016 at 13:47

Have you had any success with ImproveOSM data?

Comment from wambacher on 12 August 2016 at 14:18

There is a similar project from MapBox in canada. Do you work together? And do you share the tagging?

Comment from scai on 12 August 2016 at 15:47

Why does your blog post about “missing turn restrictions & exit numbers and destinations in Europe - Part 1 : Germany” show images that are clearly not Germany?

Comment from nammala on 12 August 2016 at 15:53

Hi Wambacher,

Yes, I am part of the data team at Mapbox and it is similar to what we have done in Canada. We follow the same tagging system for the mapping which we mentioned in our mapping guides.

Comment from nammala on 12 August 2016 at 15:53

Hi mvexel,

Thank you for the suggestion.

We have used improveOSM for missing one ways and roads in SF. Also, noticed that when we map turn restrictions or exit numbers & destinations, it still needs to be compared with mapillary for reference but we will try using it and keep you posted.

Comment from escada on 13 August 2016 at 06:32

It’s weird that you are in the same team as the one working in Canada. From I had the impression that they do not really know which tags to use, while you seem pretty confident that you know which tags one has to add.

Extra tips: in case you continue this work all over Europe, please localize your posts, i.e. replace all those US-signs with local signs (and yes they are different in the different countries), and try to post in the local mailing list/forum in the local language(s). Make sure that you really know the important towns in a country. This will probably give you more support.

Comment from Tirkon on 17 August 2016 at 01:20

Some Mapillary photos are quite old. They can give good hints that something is wrong in OSM. But they cannot tell you whether the situation has changed and whether OSM matches the more recent situation. There is only one truth which is the ground truth. Thus never change OSM without knowing the most recent truth you have seen with your own eyes.

Comment from nammala on 18 August 2016 at 16:44

Hello everyone!

We thank the community for getting back to us about mapping in Germany and also sharing your concerns. We appreciate your thoughts on this mapping project. Following the diary post and responses on the talk-de and #osm channels, we have looked into everyone’s suggestions and would like to respond to the various questions:

  • What is the objective of this project?
    • The high level objective is to build complete map data in OSM for routing and navigation
    • Understand how crowdsourced street view photographs can add missing data to the map
    • Evaluate the completeness and accuracy of data on OSM
  • Is there missing data in Germany?
    • The common understanding is that Germany has the best map data on OSM due to the very active field mapping community. This is a good place to test the accuracy of the data against other sources like street photographs to evaluate the data completeness and accuracy.
    • As per our initial analysis, these were the approximate number of turn restrictions & exit numbers and destinations present, as generated by an overpass query.

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TR number of Added + Modified

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  • Why use Mapillary?
    • Street view photographs are a great way to collect field observations using Mapillary. We have already updated and added over 1500 missing turn restrictions in North America in the last month using such images. Every photo has attributes like detected street signs, accuracy, time of capture which allows careful analysis to help improve OSM.
    • OSM Navigation map is a simple tool that detects turn restriction signages and their position. These are the few examples we came across during our initial research.
    • If the Mapillary image is more than 6 months old, we will not be mapping any restrictions/exit-destinations.

Remote mapping guidelines

To address the concerns of the local mappers, we have formulated a set of guidelines for remote mappers to follow to update the map: The conditions under which the remote mappers intend to add/modify data:

  1. External source(Mapillary or another verifible source) suggests missing data to add to the map
  2. External source suggests a change from the existing map data

Our Action:

  • We will add missing data with a documented comment and source, for later validation by local mappers if:
  • Source data is newer/recent than the last map edit to the object
  • There has been no edits in the last 6 months on the object or the neighbouring roads

  • We will add a note if:
  • Source data is newer/recent than the last map edit to the object
  • There have been recent edits in the last 1 month on the object or the neighbouring roads

  • We will comment on last object changeset if:
  • Source data is newer than the last map edit to the object
  • The last edit done to the object on the map is within 1 year

As the project progresses, we will document issues and localise the mapping workflow for Germany, as we did in our previous projects. Hope to hear feedback on these guidelines. It would be great to have you work alongside us in this endeavour, contributing to adding new restrictions, destinations and Mapillary, guiding us, keeping an eye on our edits and calling out on errors. Hope it makes the objective of the mapping clear - to make OSM the best in the world :)

Grüße, from the Mapbox data team

Comment from nammala on 19 August 2016 at 11:46

Hi Scai,

Thanks for your valuable suggestion, I have updated the images of Germany in the Diary post.

regards, nammala.

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