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#1 2021-07-27 16:56:02

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Proposal for highway classification revision

In WikiProject Thailand, the current highway classification has been using since 2014 with little change. Aside from something that is still unclear, the situation on the ground has changed, therefore the current guidelines may be troublesome and should be revised. For example, many highways have been upgraded to dual carriageways, the Grab team is mapping in many places, etc.

According to https://forum.openstreetmap.org/viewtopic.php?id=69749 , We have been unable to reach an agreement on a highway categorization for a long time. I'd like to do something to at least make things better than they are now, so I decided to write down a proposal about what I want to change on the wiki and let everyone comment on it until it is somehow pleased by the majority. Hope it covers issues raised in several previous threads.

My principle is:
- Performance and characteristics can be described by many tags such as lanes, shoulder, width, maxspeed, surface, smoothness, etc. but importance in the network cannot, so highway=* should be tagged based on how important that road be in the network, as stated in https://wiki.openstreetmap.org/wiki/Key:highway
- The low importance highway should be longer (in total) than the greater important highway.
- The Department of Highways (DOH) maintains a countrywide highway network, therefore national highway official classification that is defined by a number of digits is quite acceptable, though not all of it.
- For provincial network, there are several organizations that maintained the highway, so a 4-digit national highway, a rural road, and a local road can all be classified as the same thing. We should prioritize the importance of each route in the network over who owns it.
- The Department of Rural Roads (DRR) was originally established to administer a local road during the transition period. Many rural roads have been transferred to a local administrative organization, so the only distinction between a rural road and a local road is the entity that owns the route. By the way, time flies, and the DRR is now constructing higher and higher important roads, some of which are more important than 3-digit national highways.
- Current trunk description is unclear, as Paul mentioned at https://forum.openstreetmap.org/viewtopic.php?id=69749 .
- The low-importance road in the table has yet to be described. Clarify things by following the global wiki description should be done.
- The urban road has not yet been clarified.
- Due to an uncertain classification, numerous road classifications have been changed over time in Thailand's current OSM mapping, with some edit wars. We should explain things so that everything is on the same line, but keep in mind that not much needs to change.

So, here's what I'd like to edit in the wiki:

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1. Make the current table's heading as Intercity.

2. Change the current description of highway=trunk to

Trunk classification should be applied to region's top-level road network (apart from motorways), which connects numerous cities and is usually dual carriageway.
Most, but not all, of the 1-2-digit national highways are trunk.
Examples are
- National Highway 12 from Mae Sot to Mukdahan
- National Highway 314 then 304 from Bang Pakong to Nakhon Ratchasima

3. Change the current description of highway=primary to

Primary roads are built for long-distance travel, typically beyond province borders.
Most, but not all, of the 3-digit national highways are primary.
Examples are
- National Highway 113 from Phichit to Wang Chomphu
- National Highway 205 from Lopburi to Nakhon Ratchasima

(remove the typical features to avoid confusion)

4. Expand the Rural Road's table row to cover both secondary and tertiary.

5. Expand the Local Road's table row to cover both tertiary and unclassified.

6. Change the current example of highway=secondary to

- National Highway 3121 from Bang Khla to Plaeng Yao
- Rural Roads ฉช. 3001 from Lat Krabang to Ban Pho

7. Remove the typical features of highway=secondary to avoid confusion.

8. Change the note description of highway=secondary from

Note that new roads often receive a 4-digit reference number, regardless of their importance - they might also be primaries or tertiaries.

to

Most 4-digit national highways are secondary, however they can be primary or tertiary depending on their importance in the road network.
The high importance rural roads, which are on the same level as a 4-digit national highway in the road network, are also secondary.

9. Add to the tertiary description:

Some of the roads on this level are managed by a Local Administrative Organization. They are also tertiary regardless of an authority.
Note that the Rural Road classification is based on authority rather than importance. They might be classified as secondary or tertiary depending on their importance.

10. Remove from the tertiary description to avoid confusion:

most of them are paved, but unpaved roads are possible (adding a surface tag is appropriate)

11. Remove concession highway from the table, moving to the paragraph below the table.

12. Add to the unclassified description:

The lowest rank of a public road usable by motorcar.
Unclassified and residential road is similar. See the differences in highway=residential .

13. Moving the N/A type of road to the new Urban and Local Road table.

14. Move the paragraph above Intercity table to the table's bottom, and then add:

- A national highway or a rural road that passes through a city is frequently transferred to the Local Administrative Organization. These highways should still be tagged according to their previous administrative classification.
- Hanging ends should be avoid if possible. For example, if two primary roads from outside arrive at opposite points in the same city, both ends should be connected by upgrading the urban road between them to primary, even if it is not qualified in most cases.
- Frontage roads should be one rank lower than main roads and not higher than secondary.

15. Create new table:

Urban and Local Road wide enough for motorcars
highway=motorway Expressway (ทางพิเศษ) with full access control.
highway=trunk Not to use.
highway=primary Top-level urban road across the city connecting trunk to trunk, or road of equal or greater importance than the primary intercity highway that runs through that city.
highway=secondary Main urban road connecting primary to primary or higher, or road of equal or greater importance than the secondary intercity highway that runs through that city.
highway=tertiary Roads that are more important than regular unclassified or residential roads, or roads that connect several unclassified or residential roads.
highway=unclassified The lowest rank of public road accessible to motorcar for through traffic or outside of a residential area. Also used for the main throughfare in an industrial estate or a university campus.
highway=residential The lowest rank of public road accessible by motorcar in a residential area, often lined with a residential property, and rarely used for through traffic. At least a motorcar can easily pass. Also used for roads within a gated housing estate.
highway=service A road used to access to an estate, parking, or a specific part of large private area such as an industrial estate or university campus.
highway=service + service=driveway A service road leading to a specific building, residence, property or place of business. For example, each house's private road that branches off the residential road.
highway=service + service=alley Narrow service road usually located between properties to provide access things such as back gardens, rear entrances, fire exits, and storage areas. For example, a road built through the gap between the rowhouses.
highway=track Roads for mostly agricultural or forestry uses. This tag should not be used on unpaved roads that provide access to permanent human settlements or facilities.

16. Create new table:

Urban and Local Road that a motorcar cannot pass
highway=path + motorcycle=yes or highway=path + motorcycle=designated (if signposted) Narrow way which a motorcar can't pass. Motorcycles are permitted or commonly used by locals.
highway=footway Minor pathways which are used mainly or exclusively by pedestrians.

17. Add note below all table:

Highway tag values that are not mentioned here should adhere to OpenStreetMap's general guidelines.

------------------------------------------------------------------------------------------------------------

I wish we could have a discussion about this before making the change.
Regards

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#2 2021-07-31 14:25:48

Paul_012
Member
Registered: 2011-08-05
Posts: 211

Re: Proposal for highway classification revision

Ah, I had meant to create the Wiki page for the exceptions discussed in that thread, but kind of forgot. Apologies for that. It should still be compatible with the proposed changes, though?

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#3 2021-07-31 15:00:39

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

Paul_012 wrote:

Ah, I had meant to create the Wiki page for the exceptions discussed in that thread, but kind of forgot. Apologies for that. It should still be compatible with the proposed changes, though?

Of course, I tried to write this based on numerous concerns we'd talked for a long time. Please leave a comment on any text that you believe is a problem.

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#4 2021-07-31 19:38:57

Bernhard Hiller
Member
Registered: 2011-05-10
Posts: 1,069

Re: Proposal for highway classification revision

It is a good start. Let's use it.
While working with it, we will see where minor revisions might be needed.

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#5 2021-08-01 03:05:53

julotlafrite
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

Someone referred me to this topic while I was looking to collect feedback on different minor road classification scenarios:
https://help.openstreetmap.org/question … classified 

I would like to work together with you to come up with better guidelines including minor road classifications.
The proposal above is a good start but I believe still does not cover all cases. (If you think so, please kindly respond to link above)

Additionally, I see so many inconsistencies at least in Chiang Mai Province rural areas including:
- missing source tag
- lack of road segmentation (to support different tag classifications)
- wrong road name usage (when used for mtb/enduro route names)
- wrong path/track classification (added from satellite imagery, or not taking into account a 4-wheel car can go through regardless of vegetation)
- missing waterway crossing information (bridge vs fjord vs unknown)
- missing end of road survey (noexit=yes or fixme=continue)
- usage of footway vs path for hiking trails (ทางเดิน)
- lack of surface tag when it is already known or can be guessed through satellite imagery

Improved guidelines would help tremendously, as they could be referred in changeset comments, leading hopefully to higher quality contributions and reducing conflicting interpretations.

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#6 2021-08-02 18:04:39

Bernhard Hiller
Member
Registered: 2011-05-10
Posts: 1,069

Re: Proposal for highway classification revision

@julotlafrite I think this thread is more about the correct value for the highway tag, not so much about other features which could be added when mapping a road.
Please note that a lot of roads were mapped from imagery by people who never compared their tagging with the situation on ground...

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#7 2021-08-02 20:46:48

stephankn
Moderator
Registered: 2010-05-04
Posts: 625

Re: Proposal for highway classification revision

Thank you for starting to work on classification. This is a difficult topic. And the more and more  deviations from the tagging doesn't make it easier.

Do you think it is possible to split the task into smaller chunks when working on getting the definition aligned? Maybe start with motorway/trunk/primary?

That should then cover the roads visible at low-zoom.

The tagging scheme should be possible to be validated. So a 3rd party mapper should be able to come to the same tagging decision when looking at the road. Preferably also by looking at aerial imagery and road signs.

And maybe make it clear as you already suggested, that this tagging is about inter-city road network, not about road networks within a city or metropolitan area.


Starting with motorway, which is missing from your list below: Do we agree on the classification currently in the wiki, which is following the definition outlined here: https://en.wikipedia.org/wiki/Thai_motorway_network including the express ways?
Is the sign color blue/green a good enough indicator to classify as motorway?

Is the master plan being executed? These roads are overlapping with other major highways, which are often tagged as trunk.

Later you state that not all 1 or 2 digit roads are trunk. Can we list the 1-digit ones which are not trunk? Maybe something like "all of the 1-digit and most (but not all) of the 2-digit highways classify as trunk"

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#8 2021-08-03 13:58:21

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

stephankn wrote:

Starting with motorway, which is missing from your list below: Do we agree on the classification currently in the wiki, which is following the definition outlined here: https://en.wikipedia.org/wiki/Thai_motorway_network including the express ways?
Is the sign color blue/green a good enough indicator to classify as motorway?

In the current wiki, a blue sign denotes a motorway, while a green sign denotes a trunk, which I think is appropriate.

stephankn wrote:

Later you state that not all 1 or 2 digit roads are trunk. Can we list the 1-digit ones which are not trunk? Maybe something like "all of the 1-digit and most (but not all) of the 2-digit highways classify as trunk"

For current situation, 1 and 2-digit highways that are not trunk are as follows: 3 from Bang Na to Bang Pakong, 3 from Trat to Hat Lek, 4 from Cha-am to Pran Buri, 4 from Phang-nga to Thap Put, 4 from Huai Yot to Trang, 11 from In Buri to Wang Thong, 21 from Lom Sak to Loei, and 42 from Khlong Ngae to Pattani.

Last edited by nitinatsangsit (2021-08-03 14:10:40)

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#9 2021-08-04 18:52:08

cmoffroad
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

Regarding minor road classifications:

GrabOSM is currently updating massively the existing minor road network and is basically turning almost everything into residential roads, including agricultural/forest tracks, km long traffic through roads, links between settlements, and this looks and feels very wrong…

From my research based on the official wiki and best guidelines from UK, France, and Germany:
- 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.
- A service road should be used to access a building (parking, gas station, factory, driveway…) and access permissions should be often set
- A track should be used where the main purpose is agriculture or forestry, regardless of the presence of permanent housing. Is most of the time unpaved.
- A link between two settlements should be tertiary.
- Anything else should be tagged as unclassified.

@nitinatsangsit Your guidelines in table 15 match pretty well my findings, yet in my question on Help https://help.openstreetmap.org/question … classified, you answered everything should be tagged as residential.

Could you please clarify further?

Last edited by cmoffroad (2021-08-05 08:26:41)

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#10 2021-08-05 03:51:51

cmoffroad
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

In this answer https://github.com/GRABOSM/Grab-Data/is … -893114989,

I have documented perfect examples of different categories of minor roads,
and how I believe it should be normally classified based on official wiki interpretation and best practices.

Without guidelines available, GrabOSM has interpreted that any housing on any kind of road justifies a residential road.
I understand it benefits their own map rendering and business model, but to me, this violates OSM principles and will bring frustration to many mappers.

Hence the urgent need for updated and clear minor road classifications guidelines, so we can all map together happily and without further distraction wink

Update: Here is my decision-tree workflow proposal for minor road and paths classifications, which should be much easier to understand than separate definitions.
Please kindly let me know what you think:

https://github.com/cmoffroad/osm-guidelines/

Last edited by cmoffroad (2021-08-06 05:34:11)

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#11 2021-08-05 14:25:13

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

Your github method is nice, it should be put below the table on the wiki.

By the way, I think you should switch between the last track and residential; according to https://wiki.openstreetmap.org/wiki/Tag:highway%3Dtrack (footnote), a track is "roads are mostly not for general motor vehicle traffic, but are used by some subset. So these ways are seen as something a bit less than a road and not really part of this general-purpose road network.". See "How to decide" section for more information. A track criterion, in my opinion, is more strict than a residential one.
So, for the last 5 lines, it should be:

no: is the main purpose of the road for agriculture/forestry access?
- yes: highway=track
- no: is there a permanent residences along it?
    - yes: highway=residential
    - no: highway=unclassified

There may be more, such as adding a service=* and a pedestrian road to the chart; also, a service road is not always in a private estate. Anyway, this scheme is good enough for rough guidance.

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#12 2021-08-05 16:13:03

cmoffroad
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

Your github method is nice, it should be put below the table on the wiki. Anyway, this scheme is good enough for rough guidance.

Great to hear, it's definitely a work in progress and I am happy to improve it over time based on your input.

By the way, I think you should switch between the last track and residential;
There may be more, such as adding a service=*

I have updated the workflow accordingly and added a couple of important footnotes:

Note: A "traffic through road" means vehicles passing through an area whose destination is elsewhere.
The next destination could be a village, a temple, an estate, or joining a road of equal or greater importance.
Note: If a road qualifies for multiple tag classifications (e.g. different highway, surface...), it should be split 
into separate segments. e.g. The first 100 meters of an agricultural track may be paved and have permanent houses along. 
First part could be tagged as a paved residential, while the rest stay as an unpaved track.

is it the main link between 2 towns/villages/hamlets/settlements ?  `yes`: `highway=tertiary`

Is it ok to use tertiary for main links between villages including unpaved roads in mountainous areas?

a service road is not always in a private estate.

How would you describe where a service road can be found in a few words?

and a pedestrian road to the chart

Where would you classify such a road in the decision tree?

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#13 2021-08-05 16:53:00

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

cmoffroad wrote:

Is it ok to use tertiary for main links between villages including unpaved roads in mountainous areas?

The road surface should not have an impact on its importance in the road network, thus if it is qualified, it can be a tertiary.
The issue is that I'm not sure if all of the village links qualified for tertiary. Perhaps it must show that it is more significant than a general unclassified or residential road, such as connecting two villages, each with its own residential road grid, and some residential road branches off along the way.

cmoffroad wrote:

How would you describe where a service road can be found in a few words?

Maybe "A road that leads to a single building or property."

cmoffroad wrote:

Where would you classify such a road in the decision tree?

Perhaps above all of them, "is the road usually only for pedestrians?"

P.s. IMO "does the road have no other function other than for residential purposes?" is too strict, because many residential roads may also serve some little other purposes. If it is mainly for residential it should be qualified.

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#14 2021-08-06 04:24:30

cmoffroad
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

Maybe "A road that leads to a single building or property."

I don't think that's accurate or precise enough. Official wiki says "Generally for access to a building, service station, beach, campsite, industrial estate, business park, etc. This is also commonly used for access to parking, driveways, and alleys."

The road doesn't have to be leading to a building, it can be lanes inside some parking, campground, park, or factory.

I think it has really to do with the fact service roads are not part of the general public network and are maintained by owners. They (should) come with access restrictions. Renderers show services as thinner lines and routers usually avoid them even if you can go through.

The owner of the land could technically be the government so public/private distinction does not really work. Anyone has a suggestion?

Perhaps above all of them, "is the road usually only for pedestrians?”

Added on top:

- is the road mainly or exclusively for pedestrians ?
  - yes: highway=pedestrian

Perhaps it must show that it is more significant than a general unclassified or residential road

Added:

- yes: is it the main link between 2 towns/villages/hamlets/settlements ?
  - yes: is the surrounding network large enough (a few unclassified, residential) to justify a more significant road ?
    - yes: highway=tertiary
    - no: highway=unclassified

P.s. IMO "does the road have no other function other than for residential purposes?" is too strict, because many residential roads may also serve some little other purposes. If it is mainly for residential it should be qualified.

I agree it was too strict, but it should not be too loose either. Traffic-through or agricultural tracks should not be tagged residential even if some permanent houses can be found along. I have changed the condition to:

- `no`: is the main purpose of the road access to permanent residences?

btw, how should housing for workers within an estate/facility be tagged? e.g. factory, government facility, industrial estate...

Last edited by cmoffroad (2021-08-06 04:50:50)

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#15 2021-08-06 13:34:43

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

cmoffroad wrote:

The road doesn't have to be leading to a building, it can be lanes inside some parking, campground, park, or factory.

I think it has really to do with the fact service roads are not part of the general public network and are maintained by owners. They (should) come with access restrictions. Renderers show services as thinner lines and routers usually avoid them even if you can go through.

The owner of the land could technically be the government so public/private distinction does not really work. Anyone has a suggestion?

Ah.. I think your original criteria, which distinguishes it with public/private distinction, is good enough and cover most of them (some government-owned roads are also private if they are gated behind a state agency's fence). What I mean is for some of the public roads that should be service.

cmoffroad wrote:

btw, how should housing for workers within an estate/facility be tagged? e.g. factory, government facility, industrial estate...

IMO, this differs from residential housing, in which land ownership is divided among the owners of each house. Because the majority of these land are owned by a single owner, highway=service should be appropriate.

P.s. I see you added a service=alley. I think most cases in Thailand are not in a private area. Most of what comes to mind is a road running through the gap between the rowhouses, or a road for the rowhouse's rear access (not for main access). Also, I think that function is more important than width, because many residential roads in Thailand are narrower than an alleyway.

Last edited by nitinatsangsit (2021-08-06 13:47:52)

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#16 2021-08-06 15:57:06

cmoffroad
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

P.s. I see you added a service=alley. I think most cases in Thailand are not in a private area.

Ok. I removed it since it's a special case, and it's been used wrong in many places.

I think your original criteria, which distinguishes it with public/private distinction, is good enough and cover most of them

I improved the wording a little: "is the road inside a private property/estate/facility ?"

What I mean is for some of the public roads that should be service.

Ok. What would be the use-case for this?

Table 15. highway=unclassified Also used for the main throughfare in an industrial estate or a university campus.

Curious about this, can a road inside a large estate/facility really be something else than service?

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#17 2021-08-07 07:08:54

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

cmoffroad wrote:

Ok. What would be the use-case for this?

It could be something technical, a road leading to a private estate is sometimes not part of the estate and is a public road. There is also a service road in the highway area, such as at 15.147637, 100.254418 . Anyway, these might be the rare case and, for rough guidance, can be ignored.

cmoffroad wrote:

Curious about this, can a road inside a large estate/facility really be something else than service?

There is a discussion in https://forum.openstreetmap.org/viewtopic.php?id=68434 . A road within a large estate that is frequently used for through traffic could be unclassified.

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#18 2021-08-07 12:27:00

cmoffroad
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

There is a discussion in https://forum.openstreetmap.org/viewtopic.php?id=68434 . A road within a large estate that is frequently used for through traffic could be unclassified.

Makes sense. I see the need for it. I added it to the decision tree.

What about dirt tracks to access fields/gardens inside a research center/farm/property, can these also stay as track or should they be service?

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#19 2021-08-07 13:58:04

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

cmoffroad wrote:

What about dirt tracks to access fields/gardens inside a research center/farm/property, can these also stay as track or should they be service?

I think it is still track.

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#20 2021-08-13 14:34:58

nitinatsangsit
Member
From: Bangkok
Registered: 2020-04-03
Posts: 75

Re: Proposal for highway classification revision

I've already made changes to the wiki. cmoffroad's decision tree has also been added.

Regards

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#21 2021-09-27 07:35:01

cmoffroad
Member
Registered: 2021-07-15
Posts: 32

Re: Proposal for highway classification revision

FYI, I have improved further some of the minor road classifications wiki definitions to reflect the current general consensus:

https://wiki.openstreetmap.org/wiki/Wik … motor_cars

Please feel free to refine the wording, and refer to the topics below if you have any concerns or feedback.

highway=footway

Minor pathways that are used mainly or exclusively by pedestrians. For example, designated footpaths in urban and attraction areas, mountain trails that are only suitable for walking.

Topic: https://forum.openstreetmap.org/viewtopic.php?id=73864

highway=service + service=alley

A narrow service road usually located between the rear sides of buildings to provide access to utilities such as back gardens, rear entrances, fire exits, and storage areas. These tags should not be used for narrow residential roads that provide access to the front entrances of buildings.

Topic: https://forum.openstreetmap.org/viewtopic.php?id=73799,

highway=living_street

Not to use. There is currently no legislation in Thailand granting lower speed limit and pedestrians the right of way over other road users in residential areas.

Topic: https://forum.openstreetmap.org/viewtopic.php?id=73799, https://forum.openstreetmap.org/viewtopic.php?id=19316

Last edited by cmoffroad (2021-09-27 07:42:35)

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