[OSM-newbies] Question about how to connection correctly highway links

[Philip Barnes]

Hi Sebastian
The road classification is something that can only really be gleaned from a survey, as you travel around. There is no other source that I know of that can be used legally.
 Cheers Phil
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On 17/12/2012 8:12 Sebastian Arcus wrote:

Thanks Phil. I have to say although I live in UK, I've never noticed 
until now that some A roads are green and others are black. 
Incidentally, would this information be gleaned just by driving around 
on the ground and looking at road signs, or is there another source of 
classification?


Sebastian



On 16/12/12 23:58, Philip Barnes wrote:
> Hi Sebastian
>
>> Thanks for the extra info. I will download a fresh copy of maps for
>> Navit with the restrictions in place to make sure that junction works as
>> expected. I kind of figured out Navit's navigation must have thought
>> that route would have been shorter or better somehow - but in real life
>> it wouldn't have been a viable one.
> Routers do seem to overuse road classification, it works with motorways
> but in built up areas classification is largely irrelevant. In the
> example you gave Navit is assuming that the trunk road is faster, even
> if its just by a second or two. In this case it wont be faster. Even if
> it was legal, there is a 90 degree turn.
>
>>
>> I must admit I haven't figured out yet the business with trunk roads - I
>> always sort of assumed based on OSM's wiki that "A" roads in UK are
>> primary highways - clearly I must go back and read the OSM highway
>> classification again.
> You do need to read the OSM wiki page, WikiProject United Kingdom A and
> B Roads at
> http://wiki.openstreetmap.org/wiki/WikiProject_United_Kingdom_A_and_B_Roads
>
> Quote from the page:
> In the UK, the OSM rule goes like this:
>
> green signed A roads: highway=trunk
> black-and-white signed A roads: highway=primary
> B roads: highway=secondary
>
> (It might sound confusing if you're used to hearing A roads described
> differently. Sorry, it's just how we do things round here.)
> /end quote
>
>
>> It doesn't quite help the fact that tertiary
>> highways correspond to "C" roads, and secondary highways correspond to
>> "B" roads - thus living primary highways without a direct correspondent
>> in UK.
> Tertiary roads are a bit of a black art, there are very few C roads
> numbered on the ground and unless you have access to council info you
> will not easily get hold of the numbers.
>
> I tend to tag the main unclassified roads through an area as tertiary,
> the ones that are used by through traffic, but I may be wrong.
>
> Regards Phil
>
>
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> http://wiki.openstreetmap.org/wiki/WikiProject_United_Kingdom_A_and_B_Roads
>


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