[OSM-talk] UK: Trunk-Primary

Ben Robbins ben_robbins_ at hotmail.com
Mon Aug 13 13:49:19 BST 2007


>that is, to be completely frank, a ludicrous proposal. Tagging something
>explicitly based on the colour of the signs is just ridiculous.

Thats how we currently do it.

>What is important is not whether the sign is green or white, but the
>categorisation of the road

as I said.

>(which happens to be
>implied by the colour of the signs).

not always, hence examples.

>So the highway tag is the right place to record this information, not
>some new tag that records the colour of the road signs.

I wasn't suggesting not using the highway tag, I was just suggesting making 
it clear where there are roads that are green signed but not trunk.

>The reason is that there are very few HA managed A roads left, and they
>are getting fewer all the time as the HA palms them off to the local
>highway authorities. As a results the traditional trunk road concept is
>now more or less meaningless.

Its irrelevent to me really how much you or I value something, somepeople 
somewhere may wish to no what roads are part of the HA managed road network, 
and that is currently not possible with OSM.

>That's just nonsense though.

Maybe.  I don't think it is though I'm affraid.

>I'm sorry, but exceptions are important.

It would be if there were many, but if the majority of something is all 
similar then its not, because a tag can state the common, and be corrected 
with specific tagging.  Hence there is no need to list them.  Unless of 
corse they are the majority, which there not.

So to round up your reply.   To know weather or not a road is a HA managed 
trunk road has no interest from your perspective, thus nobody needs to know 
it.  Cheers for that reply.

>David Earl

>I'm don't understand what advantage is to be gained by recording who runs 
>what roads as the main means of recording them.It isn't obvious on the 
>ground, which is where we're getting our information from, and it isn't 
>obvious to an end user, who we're trying to communicate with.

well, its not unclear on the ground usually, as the HA maintained roads are 
usually faster to travel on.  Again I imagin there are many exceptions, but 
for by far the majorty of roads I've ever been on, the mass of trunk roads 
are faster than none trunk.  Although, It's not really justification; If 
somebody wished to make a map of HA roads in the UK from OSM's data they 

>This seems sensible to me because to do navigation of some kind you want to 
>see on the map a representation of what you see on the ground.

I agree, and I'm not suggesting stopping this, I just want someway of 
recording what roads are not actually part of the HA managed network.

Nick >

>Because it's the most useful and the most easily surveyed

As we have a list on the wiki of trunk roads, how easy it is to survey them 
doens't matter too much. We have the data, why not record the data.

"corresponds to commercial maps" Acturally I was going to list OS as an 
example as up till a few years ago they had the trunk roads green.  e.g. A5. 
  That wasn't trunk but its had green signs for as long as I rememeber, and 
it was red on OS maps. It is now trunk apparently, so the example is 
nolonger valid.  Again though, as I said a sec ago, what one map does or 
another shouldn't really matter.  If I wanted to render off a map of HA 
managed roads (motorway/trunk roads) from OSM I couldn't.

>'signage' seems an unnecessary tag. A 'green' road is not just an arbitrary 
>form of signage - it is an indication that the road is suitable for long 
>distance travel, and thus the 'highway=trunk' seems very sensible.

I'm not suggesting its critical, but rather additional detail that would 
allow people to filter HA trunk roads from all green signed roads.   Just as 
a hospital and library can be split even though there both just 
buildings/amenities.  More data as people may wish to find it.

>If you really want to note who runs UK roads, I suggest you use something 

 >management=Highways Agency
 >management=Scottish Executive
 >management=Midlands Expressway Ltd
 >management=UK Roads Ltd
 >management=Leicestershire County Council

Thats fine, I did say in the original email that adding additional 
information for management or signage would do it, so thats just the other 
option.  The reason I suggested signage is becuase it would help for a few 
other things.  e.g. if it said signage=yellow on a road, and I was setting 
up a renderer, I may choose to use the signage value to base how something 
renders.  from managment==highways agency that can't be worked out, it would 
need to be checked somewhere else.

>But bear in  mind that _no_ UK maps now differentiate trunk/HA-managed 
>roads in  that way. Even the OS has abandoned the A34(T) notation for trunk 
>  roads on its maps, and just shows them the same as other primary A  

Yes, I have noticed, but thats no reason not to have the data available so 
that a person can render a map as they choose, not as OSM has chosen for 

>Certainly, navigable waterways could do with a management tag:

That is a valid point for management over signage.  Noted.

>>3) Primary Roads, roads which aren’t HA, and don't have green signs.

>No. That's wrong. All primary A roads have green signs _except_ where  the 
>authority has made a mistake. Local authorities are very bad at  signage. 

hmm, thats way too common then. On the wiki it reads "while 
black-and-white-signed A-roads (ie non-primary routes) are tagged 
highway=primary."   I was refering to primary for these "non-primary 
routes"..!, (based on the OSM tag rather than just the desire to use 
contracting termonology)


I dislike the way the most common arguement around here is if people 
themselves have an erge to know something.  If there is data and its about 
things being added, and its relevent to a map then don't restrict people 
adding it.   I never said I have any intention of printing off maps of the 
UK HA managed Trunk road system, but someone may, and there are the list of 
green signed roads is difffernt to the governments list of HA roads, and we 
should allow people to be able to render off maps in either of these ways, 
not just a way that we have chosen. The data is avaiable from the HA and its 
on the wiki, so we may as well use it.

In conclusion to my reply's to the points above:

management= would be fine rather than signage, doesn't really bother me 
which is used.  Then on the wiki, I'd alter the bit that says "Many UK OSM 
users follow the practice that all green-signed A routes " to say something 
more definate then, so that the tag has a understood value.

Bicker on that...


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