GRABOSM
commented
3 years ago @mishari @Paul012, do let us know how to approach these cases and what classification would be better for these roads. Thank you!
Open GRABOSM opened 3 years ago
GRABOSM
commented
3 years ago @mishari @Paul012, do let us know how to approach these cases and what classification would be better for these roads. Thank you!
cmoffroad
commented
3 years ago Residential tagged as tracks:
@GRABOSM The main reason many roads in rural and mountains are tagged as highway=track is simply that they are/were unpaved, hence are rendered automatically as off-road in all outdoor applications.
This is obviously not the right approach, hence the need to select the correct classifier AND specify a surface.
However, marking everything as residential as you often do (Chiang Mai), is also the wrong approach as most of these roads main purpose is traffic-through or agricultural/forestry.
A residential road should have no other function other than for residential purposes, it should have little to no traffic, and permanent residences should be present at least on one side. If it's not a major (tertiary+) or private (service), then it's unclassified or a track when the main purpose is agricultural/forestry.
As far as am I concerned, this should be the correct classification:
Note: OSM roads should be split when classification change (surface, highway) or when they don't follow the main way e.g. the main way of 105692248 is unclassified, but the branch going up could be residential.
As you can see only 1 track remains out of 14 roads, yet only 3 purely residential roads should be added.
In Chiang Mai, I see on a daily basis traffic-through, agricultural/forestry roads converted to residential. This is why we urgently need official country-specific guidelines for minor roads classifications.
I have raised the issue with the Thai community, and hope something comes out very quickly, so we can continue mapping together with the highest quality and the least distractions.
cmoffroad
commented
3 years ago Residential tagged as Service: We also observed some of the residential roads that were tagged as service alleys in many of the locations. These roads have a higher width that qualifies them for more than an alley and connects residential rooftops. We think these might be tagged as residential instead of a service.
These examples are clearly residential roads. Many of these have been wrongfully classified as service.
I am personally suspicious when I encounter roads tagged as service+alley, however, before changing them I would double-check whether the land surrounding the road is within a private estate and if these are really permanent residences. e.g.
stephankn
commented
3 years ago As a general note: When mapping from remote and your only source is aerial imagery, please be extra cautious and tend towards not mapping a feature is not certain. I understand that this might be a conflict with your business model, as you are selling "map something". But you are creating a lot of mess if you are wrongly tagging agricultural tracks as roads. In some areas this leads to the routing completely unusable, as routing engines try to be smart and "shortcut" via unsuitable roads. I had to skip OSM routing multiple times. This is causing extreme harm to the data usability.
The examples above are correctly explained by @cmoffroad , often existing data is not right. Especially if you are looking at border areas towards Myanmar or Cambodia. In these areas other "organized mapping" happened without quality control. So frequently the tagging there is not right. This does not mean that this is the "standard of local community". It is simply wrong.
Gold standard of mapping is a ground survey. There you see the current situation and can judge much better than just looking at potentially years old misaligned aerial imagery. As it was said before: Do add a surface tag, especially when dealing with roads having not paved surface. I do not mean agricultural tracks leading to a rice field. But for small rural roads connecting two settlements, which is not the "main" road, just some historically grown connection. Some small unpaved road used by locals to quickly travel between villages to reach a market or such. Here it is important to know it is unpaved, so rendering engines can take this into account when routing on OSM data.
Also for very narrow roads, please add a width tag/lanes. This again helps data consumers to judge about the road. If two cars can pass without much trouble (slowing down a little is OK), then it is two lanes. If one car would have to stop and drive to the shoulder, or even have to reverse back a bit, then it is one lane. Especially in city context, you will be surprised on what narrow lanes people still drive with their car. You can recognize this by seeing cars parked on property.
If it is even too narrow for this, then you can consider tagging as an alley. Here it helps again to map other physical properties like width.
And yes, it is quite common that agricultural tracks start at the end of other highways like residentials. So you have to split ways/start a new way where the residential ends and agricultural track start. Please make the geometry of ways follow the "natural" flow of a way. Do not create zig/zag residential ways in a village, just because it is so convenient to "draw" them like this. A soi starts off a main road, so it deserves its own OSM element. And as shown in the example above, way 105692248 should be split on the junction in the southern end and the way on south-west is a way on its own, potentially residential. The remaining way clearly interconnects, so at least unclassified.
Other mis-tagging in this area is for example the agricultural track 963637580 between fields, which here is wrongly tagged by you as residential.
cmoffroad
commented
3 years ago @GRABOSM
As promised, here is the set of guidelines that covers minor road classification: https://github.com/cmoffroad/osm-guidelines
It has been reviewed by members of the Thai OSM community. It may be subject to minor changes, however, it should cover most scenarios.
I will start reverting some of your changes that have been wrongly classified in areas I am familiar with.
Important: It came to my attention, that your mappers, assigned to an area, are watching for changesets and reverting any classification changes that were made after theirs (often within hours). Please refrain from doing this.
Please follow the guidelines accordingly. I will start reviewing some of your changes in areas I am familiar with (CM, CR, and MHS provinces) and inform mappers if the wrong classification may have been used.
To makes reviewing easier: could you kindly please reduce the number of changesets per user/day? Since your mappers are typically making changes within a small geographical area, and are using JOSM, it should be easy for them to save/combine them into a few changesets per day (instead of 10+)
As @stephankn said, I would honestly suggest you refrain from changing any road classification if you are not familiar with the area.
Not only your changes may conflict with local mappers (see above), but it also may not be possible to know, when only using satellite imagery, if a road:
Roads that have an obvious wrong classification and a clear replacement can be changed as long as guidelines are followed. e.g. a road between 2 settlements, a residential road tagged as service+alley
cmoffroad
commented
3 years ago @GRABOSM @poornibadrinath The minor road classification I have previously shared is now part of the official Thailand wiki:
Could you please kindly communicate these official guidelines to your mappers and ask them to correct their previous additions accordingly? As a general rule, if you are not sure of a road classification, do not add it or delete the old one.
I have seen some recent improvements in the usage of highway=residential roads, however, some have been simply replaced with highway=service which in most cases is also wrong. Additionally, I still find roads curved at visible junctions and long segments branching out of the main visible way without split.
I am currently manually fixing some of the wrongly added classifications and geometries, but this can be very time-consuming, I hope to see some improvements soon.
GRABOSM
commented
3 years ago @cmoffroad @stephankn, thank you for the suggestions above. We are working on including these in our written policies. Also, we will soon add our mapping docs to the Github Page. If there are any other documents or wikis the community uses as a verified source, please do let us know. Thank you!
GRABOSM
commented
3 years ago This is now resolved. We will soon be making our mapping docs available on our Github page and also update on the status on the same ticket. Marking this as complete.
cmoffroad
commented
3 years ago @GRABOSM for future mapping campaigns in Thailand, please kindly contact the community in the forum beforehand to discuss your mapping goals and things to take into consideration.
Forum: https://forum.openstreetmap.org/viewforum.php?id=46 Wiki with a note to company: https://wiki.openstreetmap.org/wiki/WikiProject_Thailand
With the unfortunately late inclusion of minor road classifications definitions in the country guidelines, there is a large number of minor roads that have been misclassified and require large efforts to correct manually. These will be resolved over time but we need to ensure that your future campaigns do not conflict with the recently updated local community guidelines.
Also since you are only mapping from satellite imagery, we will have to discuss what tags/values are acceptable to be added and changed.
Ref: #49
While reviewing and verifying map data in Bangkok we came across some edits and sharing the questions or doubts related to the same. We are forwarding the concerns here so we can discuss and reach a consensus on how to approach these cases and do we need editing here or not. Please do let us know what you think and how best we can improve the data around these data points. Below are some of the questions:
Case 31:
Residential tagged as tracks:
While mapping in Chiang Rai, we came across some of the roads which were mapped in 2011 or before that were tagged as tracks. Currently, it looks like the places have been developed with a good number of rooftops that can be upgraded to residential or up. We are attaching a few screenshots here for reference.
https://www.openstreetmap.org/way/963639445 https://www.openstreetmap.org/way/129315627
https://www.openstreetmap.org/way/488638460
https://www.openstreetmap.org/way/199259683
https://www.openstreetmap.org/way/111720314
A few other way ids: way 483289880, way 584176189, way 551981302, way 549442178, way 549442179, way 105692248, way 334808550, way 328078411, way 228088003, way 231530885
Residential tagged as Service:
We also observed some of the residential roads that were tagged as service alleys in many of the locations. These roads have a higher width that qualifies them for more than an alley and connects residential rooftops. We think these might be tagged as residential instead of a service.
Examples:
https://www.openstreetmap.org/way/527424480 https://www.openstreetmap.org/way/527424479 https://www.openstreetmap.org/way/527424473 https://www.openstreetmap.org/way/541260084
Other examples: way 541247343 way 539349018 way 548397539
@mishari, @paul012, We would like to know how to approach these cases. Would it be okay to change the classifications of these roads to the tags we suggested or should we retain these edits. Any suggestions, please do let us know and we will modify our mapping policies accordingly.
cc: @poornibadrinath @jinalfoflia