Thailand Road Classification and Tagging

Sorry, I’m with Bernhard here. I have said it before and I’ll say it again: blindly adhering to the numbering scheme when classifying roads creates an “administrative” map, which is not very useful to anybody. The map should reflect the reality and not just some arbitrary numbering scheme.

As such, I have tagged sections of h’way 4 down South as primary, just like those kinks in the middle of h’way 1 should be (at most) primary, as these sections are of not a great significance in the network. H’way 32, on the other hand, is definitely a trunk road. It links (almost) Bkk to Chiang Mai.

In fact, the project page already states that roads should be ‘upgraded’ where appropriate and I suggest we also ‘downgrade’ roads in the same manner.

I have been mapping a lot of minor roads and tracks, mostly in the N. Some of these happen to have 4-digit ref numbers, but I doubt they are part of any classification scheme we know of. I was dismayed to find that people go and ‘upgrade’ these single lane dirt tracks to tertiary roads to “fill gaps in the road network”.

Regards,
Peter.

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Can you elaborate on this? Since I’ve started mapping in Thailand, I’ve been baffled as to why this highway type is considered inappropriate for any road in Thailand. Certainly from a routing perspective, it seems like a useful classification. In my opinion, there are many minor roads that are typically “less” residential, or typically used as “through-roads” more often than other more residential roads. According to the OSM wiki (http://wiki.openstreetmap.org/wiki/Routing#Highway-type) the default routing priority of unclassified is higher than residential. It seems to me we are leaving a valuable classification unutilized. I think its incorrect to assume that every road in every city (that is not considered at least a 4-digit highway) is of equal importance, and all considered residential (even if its not really residential).

Seems like there is some discussion on these matters, and I just wanted to add my opinion, thanks.

Also agree strongly with Beddhist. The reality of the road system is very different than the official classifications. I definately think that the “reality” of the individual road size, construction, traffic flow, and route should be the primary consideration of classification. The “official” designations often do not reflect the actual “priority of use” of the road. I certainly would trust the opinion of a local mapper over the goverments official designation.

And you are exactly correct about the bypasses, RocketMan. Absolutely daft of us to blindly follow the numbering system in situations like this! Often times, the bypass route around a city would be the preferred method of travel (due to traffic and traffic controls), and yet due to the guidlines in-place, you are invariably routed directly through the city. I think these situations could be handled similarly to the US “business route” system (where the old route through the city is downgraded in classification). Even though there is no official designation for business route here in Thailand, I don’t think we should wait around for the government to change its road classifications in order for us to have better maps - we’re not making maps for the government are we?

Anyway, just needed to vent and throw my 2 cents into the fray.

Please do not forget that almost all of the roads in Thailand with numbers are tagged according to their numbers now. Changes may cause inconsistencies.
I’d like to suggest to take a closer look at other usability criteria, e.g. width of the road (directly in meters, or indirectly by e.g. presence/absence of a central_line, existence of a shoulder), surface and smoothness, number of lanes, speed limits, …
Such criteria can be used for creating the maps instead of the “highway” tag.

Having the physical properties of every road surveyed and tagged would of course be the ideal solution. However, it is also unrealistic to expect this, at least in the short term. While it would be great to have renderers based on the roads’ actual characteristics, we should also be able to make the most of the default fallback when such information isn’t available, which is the highway tag. Having the highway tag reflect the number of digits in the ref 100% of the time would render it redundant. I agree that when local knowledge/experience is available, such information should be taken into consideration.

At any rate, we still need a good set of default classifications, for when detailed knowledge isn’t yet available. As noted above, the current scheme in the Wiki is inadequate as it leaves out / fails to distinguish many types of roads.

I see that my prevoius post could be mis-understood. I did not say: “do not chnage the highway tag”. Rather I’d like to say: “when you change the highway tag, do it with care”.

I’ve started updateing the highway tag of roads in South Thailand. Most changes were “upgrades”, only a few “downgrades”.

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Bernhard, I’m a bit unhappy about the tag changing.

What classifies a road for an “upgrade”. Just you thinking it is “more important” than others?
I kindly ask you to suspend tag changing until we have agreed and documented a set of objective criteria for road classification.

The old one was very objective. Simply count number of digits. Everyone could verify it on the ground.

How should other mappers now verify your tagging? Maybe they disagree with your feeling of “importance”.

The possibility to check OSM data by every other mapper willing to do so is the foundation of OSM. I not want to let it go that easy.

So before (!) re-tagging we need to have a common understanding of the tagging. At least inside Thailand this MUST be consistent. It’s certainly not desirable to have different criteria for tertiary/secondary in the South and in the North.

The wiki page the highway tag lists come criteria used for example in Germany where you should be familiar with the mapping:
http://wiki.openstreetmap.org/wiki/DE:Tag:highway%3Dsecondary

It lists criteria when a lower category can be upgraded. I’m not aware of examples when some road category gets downgraded. Do we really want this as well?

We should have such a definition for Thailand first.

It should also take into account intra town highways.

Stephan

Hi,

Mostly I agree with Stephan.

However,

I can give you some examples where this is appropriate.

1: ID 78388648 - last time I rode through here it was labelled ‘1’. It’s an average local road that happens to be a shortcut from h’way 1 to 105. I made it into a tertiary, but I see somebody has now changed that to trunk_link. I don’t think it fits that definition, either and the Thai authorities have since changed the number to 1351. Accordingly I am changing it back to tertiary.

2: Just a little N is Ban Tak. Passing through here a few years ago I saw to my great surprise a milestone ‘1’. (way 77572641) This is a dual carriageway that loops through the little town. It’s hardly a trunk road and one could argue for any classification up from tertiary, so I made it primary. Unfortunately, no Bing images here, so I could only map what I had tracks for, but you can see it clearly in GM and the junctions in Streetview.

3: Going down h’way 1 you come to Nakhon Sawan. The 1 goes through the middle of the town, traffic lights, chaos and all, while the newer 121 goes around the outside as a dual carriageway (and happily is marked as trunk). Since nobody passing through would consider going through the city I vote to downgrade this section to primary.

4: Continuing on S the road splits. AH1 and all traffic for Bkk continue straight on, while the 1 meanders like a river through Chainat and Takhli, where it turns into a little country road, eventually making it to Lopburi. Most of this should be no more than primary: nobody going from A to B will follow this road for any distance and there is little traffic. I would bet that anybody going through the history of these roads will find that the 1 was built first and there were reasons why it meanders. Modern day traffic bypasses this bit, so it’s less significant.

5: In the deep South near Chumphon h’way 4 loops West as a country road, while AH12 and all long-distance traffic follow the 41, which is DC right through to Malaysia. When I drew this a few years back it was primary, but I see most, but not all of it is now trunk, “because it has only 1 digit”. The 41 is a trunk on the map, as it should be.

6: Diagonally between the two runs the 44, which is in the process of being re-classified as we speak, judging from the colour changes when I zoom in and out. This is a big DC and I imagine it carries a lot of the traffic from Bkk to Phuket, Krabi, etc.

7: Hat Yai, same story as 4, it seems.

There are a couple of local roads that have 4-digit numbers right here where I’m staying now. They don’t, however, have any of the standard road signs. That didn’t stop somebody from changing them to tertiary.

I think nobody should re-classify roads s/he has not seen in person, just because of a number. (Unless it’s an obvious beginners error, like primary roads in the back blocks…) We should have some guidelines for classification (based on the numbering scheme, obviously), but allowing for deviations where it is appropriate. Size of the cities or areas connected, size of the road, traffic volume, etc. should all be regarded.

Otherwise (and I am repeating myself here) we will create an administrative map that will end up sending people down the wrong way.

Kind regards,
Peter.

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It still must be possible to spot tagging mistakes. I know the definition in the wiki was never great but does this justify not to write a better definition on what classifies a highway “upgradeable”?

@RocketMan: Does the affecting section of 3462 really has a sign giving the 4 digits? I’ve never been there but can’t believe people give 4-digits to ways which can’t be used by a vehicle. Or are you exaggerating? It might also be something planned for extensions which has not yet be done. There is tagging to describe this. And maybe this is the “one exception to the rule” which is always there.

Still I really want definitions which match in the vast majority of cases. If we do classification by “gut feeling” we’re steering right into edit wars and inconsistent tagging all over.

Let’s keep a minute with the city bypass roads: Do we want to upgrade the bypass? Or downgrade the major highway? If downgrade: How many levels? Only in towns? Only if the numbering does not change?
There are bypass roads which share the same highway number. In these situations we might want to downgrade the intra-town part.

But what about not so clear cases:
Sukhumvit 3 is going strait through Rayong. Using 364 and 36 it would be possible to bypass town. Would this justify to downgrade the Rayong section?
http://thaimap.osm-tools.org/?zoom=14&lat=12.6811&lon=101.26325&layers=B00T

Stephan

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Quite a few upgrade/downgrade cases appear to be that of a newer two-digit route overtaking an older one-digit route in importance. What do you think of my old suggestion of merging the two classes into the same tag? This would eliminate the problem of upgrading individual two-digit routes. (Most seem to deserve the upgrade, I think.) This could also open up a separate class for the rural highways.

If this is done, we could still make the case of downgrading certain portions of old one-digit routes which have been completely superseded, where appropriate.

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The road network of Thailand was projected several decades ago. The major roads went thru most of the villages along the road, of course (not different from Western countries). Later on, some bypass roads were built.
And that’s the point where the difference in the numbering system comes from: in Thailand, the old road keeps its (typically one-digit) number and the bypass road receives a new number (often 4 digits). In Western countries, the bypass road becomes part of the old road and receives its number. The old route thro town loses its former number, it may get a new (tertiary etc.) number or none at all.
When you stick to the number for classification, the bypass is then a tertiary, while the former road thru town a trunk.
By the way, Phetkasem road is just a minor road in Phattalung. I do not remember exactly which of the roads leading South showed a road sign with that name, I think it was http://www.openstreetmap.org/browse/way/151510987 - also take a look at Google Earth for that place, where you’ll find Phetkasem road to be just a road in town…

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