Having used maps from OSM in many countries, I can say that there are some international convention about the usage of the highway tag. The major determinant for the selectpion of the highway type is the importance of the highway. Next come usability features.
After travelling through Malaysia on bike with an OSM map, I am very disappointed by the strange usage of the tag. For example, the highway leading from Langkawi airport to Pantai Cengah was a “trunk” - even the taxi driver avoided it and took a detour on other roads (the taxi fares are fixed according to start point and destination - hence he can be expected to use the most “economic” route).
With Thailand, the classification was also far to strongly adhering to road numbers. Last year, we discussed how the international schemes can be best applied to the Thai road system (see http://forum.openstreetmap.org/viewtopic.php?id=22577 and http://forum.openstreetmap.org/viewtopic.php?id=22676), and changed the wiki several times, now reflecting international standards very well (see http://wiki.openstreetmap.org/wiki/WikiProject_Thailand).
I think we should try that also for Malaysia.
What’s your opinion?
[Edit: links should work now]
I agree. Although I myself found the OSM classification sometimes not clear enough, I believe following it as close as possible is a good practice.
Perhaps for the sake of newbies, quite a few of the highways are tagged according to numbering system. It is planned that some day, those tags will be revised. Trying to get highways traced is a higher priority than getting it tagged correct 100% the first time. Besides, in my observations, most highway tagging errors are not catastrophically wrong, for the time being.
Malaysia’s wiki page has been stagnant for a long long time. Probably need an easier english explanation regarding the differentiation between the highway classes.
Interesting.
Well, this is my take on road codes.
Usually I will refer every federal trunk road as highway=trunk. There is an official listing here (PDF). There’s supposed to have the English version as well, but probably missing somewhere in their server - getting 404’d. So probably would add an exception for not well-known federal roads i.e. there are two federal roads next to the Malaysia - Thailand borders; industrial federal roads; FELDA federal roads, etc.
In mainland Kedah (only, at this moment), roads with codes K-xx (below 99, but so far I haven’t seen yet K20 highway and above; e.g. K11 Jalan Langgar), I would tag them as highway=primary.
Also any roads with codes K-xxx (above 100; e.g. K135 Jalan Datuk Kumbar), then I will tag them as highway=secondary.
Any other roads that I have surveyed might fall in highway=tertiary if somehow an important (looks like it has a higher priority) highway but missing road codes, not a busy road, etc.
Only non-major roads will be treated according to their main function; they include highway=residential, highway=unclassified, highway=service. But this is quite subjective. Sometimes I found myself confused, not really knowing the appropriate tag.
By any other way, I think we should adopt a standardised highway tagging based on road codes, based on discussions.
“trunk” roads are normally understood to be similar to motorways - i.e. for fast, long-distance traffic, dual-carriage highways, with not many intersections / traffic lights. Hardly any of the roads currently tagged as trunk meets such an expectation.
There might be countries where official road numbering and importance of roads coincide quite well (e.g. Germany), but even there some deviations are sometimes necessary. Let’s face it: the tagging scheme cannot be fully “objective”, there will always be some “subjectivity”.
My suggestion (mainly for non-municipal areas):
- trunk: motorway-like roads. Typically federal roads (no privince code in road number).
- primary: roads which are important in the national road grid, but do not fall in trunk category. Road number without province code, plus many roads with province code (is there some suggestion possible based on the number of digits like with Kedah? - Ipoh-Cameron Highlands has 3 digits: A181).
- secondary: important roads on province level. Most roads with province code.
- tertiary: local roads. Some roads with province code, or no road number)
- unclassified: “jalan kampung”, road in scattered settlements. Often too narrow for car and motorbike to pass each other. With recent infrastructure projects, normally asphalted; typical speed limit 30 km/h, typical weight limit 5t.
Of course, that needs to be elaborated in more detail - see e.g. the Thai wiki mentioned above.
Over all, I think that currently most roads are tagged one level too high.
If that is the case, most of the Malaysian federal route will be tagged as primary routes. Hardly any motorways exist beyond urban areas outside Kuala Lumpur, Selangor, Johor Bahru, and Penang.
Malaysian roads might be special then :D. Federal routes 1 - 220-something, perhaps, is what Britain’s most A road and some B road perhaps (sorry, I am unable to give German analogues). Malaysia’s only counterpart to those motorways is just tolled highways (already being tagged as highway=motorway) and several federal routes. For example: the Kuala Perlis - Changlun highway (Federal Route 194) might resemble a typical British motorway (nearly full access control). That is the only example I know.
Even Federal Route 1 would only feature a dual-carriage highway near urban areas. Beyond urban areas, it exists as a single-carriage highway. There are hard shoulders on both sides of the road. Again, this is what I mostly observed in Kedah (and some northern part of mainland Penang), sadly. So it might not apply to every state in the Peninsular. This might be a good read. FYI, Federal Route 1 was upgraded to a dual-carriage highway from a single-carriage highway in the late 1990s to early 2000s from Alor Setar to Jitra.
OK. For this one, need everybody’s input. I can’t say the same thing would be implemented across every states’ Department of Roads and Public Roads. Probably different.
Thanks for your feedback! 
If we follow trunk to be motorway like with occasional crossing traffic lighted cross roads, and with controlled access, then there is basically none that exist in Malaysia.
If trunk to mean between cities divided motorway with cross road, then there are few candidates like Temerloh-Mentakab, Ajil-K.Terengganu, Johor Baharu highway 3 northwards (partially divided) etc etc.
If we include the original Brit built inter-state highways (not always divided), then we have old North south road federal route 1, route 5, route 3 n a few others.
From the three options above, if we follow strictly trunk highway description as controlled access, divided, inter-cities, with cross roads, then we should basically cross out this classification altogether for Malaysian, and change existing trunk highways to primary roads since controlled access is only implemented to motorways only.
The other 2, of course, already exists.
The listing of roads and the Wikipedia page are interesting sources. Looks like not all “Federal Roads” are “important” roads of the national road grid: FELDA or industrial roads may have local significance only.
Well, administration is concerned with:
- maintenance responsibility
- budget competence
In contrast, OpenStreetMap takes the point of view of a “common” man using the map. I.e. how can I get from A to B.
Though “controlled access” varies a lot between countries (in central European countries, trunk roads are for fast motorized verhicles only, while in Turkey or Thailand they can be used on bicycles, foot, etc. also), that is a useful suggestion:
I found a non-OSM Garmin map which does not distinguish between primary and trunk (and my suggestions above are based on my good experience with that map. By the way, they use “alley” for small rural roads instead of “unclassified”).
Since dual-carriage highways normally offer a faster speed for travelling than “normal” 2-lane-highways, I’d prefer the distinction between primary and trunk - and adjust the access to it as with Turkey or Thailand. But omitting “trunk” from the map of Malaysia is an alternative.
I have came across some forum (MalFreeMaps I think), so I believe the reason is to “hide” non-important, very minor routes on the GPS display.
By the way I have been comparing maps (e.g. Ireland, small towns in the UK, etc), I agree with Bernhard Hiller’s suggestion. Still, need more people to throw in their suggestions.
Somebody has been changing the highways in KL to trunk, despite being closer to motorway classification. Divided, controlled access and no crossing roads = motorway. Hmm… guess this highway classification flip-flop will never end. 
Need help on road classification, after reading wiki, I’m still somewhat confused. For example, I see Seremban as a small town but someone who’s born there might see it differently.
At most I’ll classify it as a tertiary road but someone else might see it as a secondary road.
The other problem is not using a line as a 2 way road but split into 2 one way road, should I merge them or not?
I reckon it is one of the things that have been not fully decided yet. Perhaps it is time (for us) to make it official and update the OSM Wiki?
If it is not really clear, then I usually refer to the [http://wiki.openstreetmap.org/wiki/Highway](more general wiki pages).
I’m sorry but probably some links, screenshots maybe, please? We possibly could throw in some suggestions.
Oops, replied to wrong post. 