[OSM-talk] Highway=trunk : harmonization between countries ?

Marc Gemis marc.gemis at gmail.com
Sat Aug 19 19:29:27 UTC 2017

As you can see from
trunk roads are defined differently in many countries. If you look at
e.g. Denmark, a trunk road needs a special sign. Those signs typically
come with some rules and permissions (e.g. higher speed allowed, no
pedestrians). In many cases there will be "end-of-trunk-roads" signs
at town boundaries. This means that the trunk road effectively ends

So trunk roads are more about physical characteristics and traffic
signs and less about their importance in the road network. The same is
more or less true for motorways.

I see no reason why a trunk road has to continue inside village
boundaries, where the maxspeed is e.g. limited to 50.



On Sat, Aug 19, 2017 at 5:30 PM, djakk djakk <djakk.djakk at gmail.com> wrote:
> "strategic" may not be the right word (my english is rusty :) )
> The thing is, I want to avoid those dotted highway=trunk like this :
> https://www.openstreetmap.org/#map=13/48.5884/-1.4035 (trunk then primary in
> the town then trunk again), I'd prefer trunk - still trunk in the town -
> trunk, like in England :
> https://www.openstreetmap.org/#map=14/51.1057/-2.1245
> 2017-08-19 14:00 GMT+02:00 Greg Troxel <gdt at lexort.com>:
>> Colin Smale <colin.smale at xs4all.nl> writes:
>> > Interesting approach, which might work for Europe, but at the moment I
>> > am not entirely convinced. What is strategic at a European level might
>> > not be so strategic locally, and vice versa. The European numbers are
>> > also not signposted everywhere, so there may be a challenge of
>> > verifiability. I believe the European definition basically defines the
>> > endpoints and a few waypoints, and it is left to national authorities to
>> > join the dots as they wish. So it may or may not achieve your goal of
>> > having a harmonised definition between countries.
>> I agree with caution in trying to change anything.
>> "Strategic" is an imprecise term.   In the US, different people have
>> different opinions about which roads are important, depending on where
>> they live and where they want to drive.
>> The tagging scheme is very much the UK system, and has adapations in
>> other countries.  In the US, motorway/interstate is easy, and we more or
>> less have primary for US highways, secondary for state highways, and
>> tertiary for the next level of importance (reaching adjacent population
>> centers).
>> In the US, "trunk" is fairly well defined.  It's a road that is
>> substantially more than a regular highway in that it has some aspects of
>> a motorway.  To be "motorway" (interstate class), the road needs to be
>> divided, multiple lanes, no stoplights, no at-grade intersections, with
>> controlled access.  To be trunk, the road has to be part way to that
>> standard.  So that means that almost all trunks are divided with
>> multiple lanes in each direction, but they typically have some
>> intersections (every few miles to maybe every mile), and may have some
>> but not a lot of non-ramp access.  They often have narrower lanes than
>> Interstate specifications allow.
>> Around me, the poster child for trunk is Route 2.  It's the second most
>> important east-west road in Massachusetts,, and in many places has two
>> lanes each way, is divided, and has occasional farmstands and roads on
>> the edge, but fairly few.  Lights (and one rotary) are at least a mile
>> apart, and sometimes 5ish miles apart.  But, way out west, it is no
>> longer trunk - it's just ~Main street, undivided, one lane each way,
>> lights, houses.  There it's highway=primary, because it's still a key
>> route, as important as a US highway.  In some places it meets motorway
>> specs and is tagged as such.
>> Calling a regular highway trunk, when it should be secondary or primary
>> would defeat the purpose of trunk, which is to identify roads that feel
>> intermediate between regular US highway and Interstate.   We don't have
>> any formal designation between US highway and Interstate.
>> In addition, there's history of people wanting to retag highways to
>> match their own view of these tags, and many others being unhappy about
>> this.  This is hugely important in OSM, which is about a group of people
>> cooperating to improve the map.
>> > Are you actually sure there is a problem to be solved? Do you have
>> > examples of inappropriate or inconsistent use of highway=trunk?
>> That's a very good question.   Certainly I find cases where roads are
>> over or under tagged, and as long as it's occasional, I just fix them to
>> match the norms of the larger surrounding area.   This is very different
>> from trying to make large-scale changes in what the tags mean.
>> Perhaps the OPs could rephrase the discussion in terms of what seems
>> wrong with actual tagging and how that impacts users of the database
>> (not any particular render :-).
>> All that said, a problem in OSM is the blurring of road classification
>> and road characteristics.  But that partially reflects a larger societal
>> blurring in terms of how people identify and use roads.   It partially
>> reflects a choice made by renderers to emphasize classification.
>> Imagine a map where colors depend on whether the road is divided, how
>> many lanes it has, and intersection frequency, and aren't affected by
>> government labels!
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