[Tagging] Superroutes - good, bad or ugly?

Jo winfixit at gmail.com
Fri Mar 15 18:30:14 UTC 2019


When I start mapping a bus line, I have several route relations which
contain all the stops for each variation in itinerary.

When I add the ways, it would be nice to reuse subroute relations for the
parts where ways are shared between lines.

When I come back later and I want to compare whether the number of
variations for a line is still the same, I want to compare against
sequences of stops in the route relations, hence the reason why I would not
add the stops to the subroute segments. (Compare against data from the
operator or GTFS)

We also have 'express' lines that skip stops. if the stops are put in the
subroute relations, then they can not be reused for those lines.

As far as I'm concerned, the sequence of stops is the 'signature' defining
each variation in itinerary.

Polyglot

On Fri, Mar 15, 2019 at 6:55 PM seirra blake <sophietheopossum at yandex.com>
wrote:

> key: almost tagging should occur here | data may be reused in parent |
> data may be reused in parent and any 'adjacent' (with the same letter)
> parent
>
> *public transport network* [A]
>
> *route_master=public transport *[B]
>
> *route variant* [C]
>
> *combined stop/way relation suitable for public transport v2* [E]
>
> *shared way relation* [G]
>
>
> *road network* [A]
>
> *road *[C]
>
> *shared way relation* [G]
>
>
> *cycle network* [A]
>
> *cycle route *[C]
>
> *shared way relation* [G]
>
>
> _____________________________________________________________________________
>
> potential new tags that may be required:
>
> [C]: shared=yes (to tell the software there is use of shared ways, but the
> software probably should be able to work that out)
>
> [E/F/G]: route=shared (this is considered in case type=route explicitly
> requires a route=* key)
>
>
> _____________________________________________________________________________
>
> notes:
>
>    - [G] may be infinitely nested as required to prevent duplicate sets
>    of ways (although this should rarely be required)
>    - [G] may require names in some cases and should always require
>    type=route, but should include no other tags unless it very specifically
>    relates to only the members of the relation and can't be included in any
>    parent relation (unicorns are probably more common)
>    - [G] should almost always not be used for a single way unless it will
>    assist in maintainability. if a
>    - I don't believe route_master=public transport actually exists, but
>    the same concept should work for any public transport
>    - the route=* tag should not be required until you move up to [C],
>    shared way relations and bus stop relations should be open to any route
>    type to increase re-usability
>    - as they are just a connected line of ways, shared way relations
>    should be usable in either direction, the direction to use could be
>    specified via a role. although reusable for routes going in the same
>    direction, [E] will rarely be reusable for both directions of a route
>    because it contains both platforms and stops, and platforms usually differ
>    depending on direction.
>    - if this becomes accepted it may become a good idea to specify a
>    members limit for relations (at which point it should be split up). such
>    ways should probably
>    - I may consider adding a rough idea on perceived pros/cons, depending
>    on demand
>    - I may add a more visual version, depending on demand
>    - I may add an actual example, depending on demand (if you wish to add
>    your own as well, or an inspired version please base it heavily on reality
>    if it is on main OSM. do not make any existing route relations unusable)
>
>
> _____________________________________________________________________________
>
> changelog:
>
> #0
>
>    - initial concept
>
> #1
>
>    - removed [D] and [F]. [D] was meant to be removed prior to sending,
>    [F] is not required.
>    - added a few more notes so it may be referred to on its own
>    - the bus example applies to any public transport really, adjust
>    language accordingly
>    - warned against damaging existing relations' usability/the creation
>    of fictional data
>    - added extra details on a request if needed basis
>    - added this changelog and relevant versioning to help people keep
>    track. this should be traceable to the (unlabelled) version 0
>
> special thanks:
>
>    - you may request your name here and optionally credits for ideas you
>    contributed (being kept in an opt in basis in case people don't want their
>    names shown)
>
> On 3/15/19 2:37 PM, seirra blake wrote:
>
> I can see *a lot* of shared routes in my area because most of the buses
> heavily use a star topography (everything must take you to a central
> station) as opposed to a hybrid mesh/star topography (everywhere has access
> to a service to a central station, but there are circular routes to allow
> quicker travel in some circumstances). for example my local service has one
> incredibly early train station detour (presumably for long distance
> commuters), the two main routes (incoming/outgoing) and a route that stops
> at the bus depot. all 4 of these routes share a large part of it and that's
> just one route number! such route segments could help shrink and simplify
> maintaining the relations a lot. for example if there's a detour due to
> roadworks, you don't have to edit the very large number of relations
> individually, (our bus station has around 20 bays, each taking multiple
> services...) just the shared child relations. I don't think we need a
> specially labelled super route relation, but perhaps we do need a way to
> tell the data user that a segment is shared. these are the problems I see:
>
>    1. where do the tags go?
>    2. do you need a separate one for each direction?
>    3. is type=super_route or similar the best idea?
>    4. how far can they nest?
>    5. a shared route is being used for public transport, should the stop
>    positions and bus stops be included with all the ways?
>
> so... what do we do? this is what I see as a solution:
>
>    1. if a route is shared, tags should be minimal and only related to
>    the physical route itself perhaps not even including the usual route tag
>    (AFAIK wouldn't just about any route relation in existence define the route
>    tag? so this would just be another pointer to the software that this isn't
>    your regular route. but maybe it still is best to tag it, in which case....
>    maybe route=shared?), rather than things such as what bus routes it is part
>    or anything, this can easily be seen simply by looking at parent relations
>    2. maybe use the roles forward/backward? I don't think these are used
>    for much any more
>    3. what do we gain? I think this can more easily be solved by simply
>    adding another tag such as shared=yes which can tell the software that
>    there are route relations that are intended to be treated as just one big
>    way. see below for a more detailed explanation.
>    4. I don't see a reason to limit the nesting, I imagine in most use
>    cases, the benefit of sharing duplicate relation data probably outweighs
>    any impact from processing nesting
>    5. if a shared route is used for both a numbered road route and public
>    transport it's probably unfair on the road user that doesn't need them if
>    they are included. also this would make it difficult to work out where to
>    place it in a public transport V2 relation.. as they have stops at the top,
>    ways at the bottom but this has both!
>
> so here's an indented, somewhat simplified example of how it roughly would
> nest based on the idea of a public transport route, a cycle route and a
> road relation that share the same set of ways (*underlined*=can be shared
> in parent nesting level, *bold*=can be shared in nesting levels outside
> of the parent one, italic=the level at which main tagging should occur. for
> easier referencing each equivalent level of nesting has been assigned a
> letter):
>
>
> _______________________________________________________________________________
>
> *bus network* [A]
>
> *route_master=bus *[B]
>
> *route variant* [C]
>
> *route segments* [D]
>
> *combined bus stop/way relation suitable for public transport v2* [E]
>
> *shared bus stop relation* [F]
>
> *shared way relation* [G]
>
> *road network* [A]
>
> *road *[C]
>
> *shared way relation* [G]
>
>
> *cycle network* [A]
>
> *cycle route *[C]
>
> *shared way relation* [G]
>
>
> _____________________________________________________________________________
>
> potential new tags that may be required:
>
> [C]: shared=yes (defaults to no)
>
> [E/F/G]: route=shared (this is questionable in terms of benefits though)
>
>
> _____________________________________________________________________________
>
> notes:
>
> [G] may be infinitely nested as required to prevent duplicate sets of ways
> (although this should rarely be required)
>
> as you can see, this allows a lot of the data to be shared between the
> various types of relations, whilst also allowing current relation structure
> to remain the same, this is just an extra higher level of detail, where
> required. due to the way public transport relations are handled it may be
> required to even have every segment in [D] contained in a relation, however
> as cycle and road relations are purely made up of ways they may not need
> the same kind of treatment and be able to mix items from [G] with directly
> referenced ways. the separation of bus stop and way data allows public
> transport relations to still correctly identify the different bus stops in
> each direction but not have to duplicate the way data. the naming of parts
> is solved, as this can be applied to [G] level relations. the use of [G]
> and [C] would help solve where routes need to be split up to keep
> maintenance possible. [E], [F] and [G] theoretically shouldn't need to be
> tagged as the fact they include any child relations at all should be enough
> to indicate what they are, however if not route=shared would certainly make
> it obvious. I hope this theory on how we could solve it was helpful, if any
> further clarification is required or there's a notable mistake/error please
> let me know and I'll try to respond as best as I can to that. I have
> thought about perhaps making an example of this, if it would help please
> let me know.
>
> On 3/15/19 12:07 PM, marc marc wrote:
>
> Le 15.03.19 à 12:27, Hufkratzer a écrit :
>
> is that a good/sufficient reason to define a new relation type?
>
> imho nearly no routing tools (nor foot nor bus) is currently able
> to use a relation type=route with relations as child.
> so that's a good reason to create/improve a doc if superrelation is
> needed for ex for routing (of course maybe some mapper need superroute
> only for the fun of having a relation that collect all other).
>
> for ex how a "data user" can detect "it 's a superroute" <> "it's 2
> route with a shared segment" ?
> for the moment, the trick is to notice that the name of the main
> relationship is close to the name of the children's relationships
> and to know that the names of all these children's relationships
> are fake names (which should therefore be removed/corrected).
> there is for ex nothing called "European long distance path E4 - part
> France". it's an artificial name to descript how the relation is splited
>
> maybe the tag network should be the same and/or the name (the country
> XYZ may move the a scope tag)
> the main relation must/should/mustn't/shouldn't have all/some same tag
> as the child ?
> all/a lot of child tag must move to the main relation only ? (that's
> what we do with MP : we don't duplicate alls tags to way + relation)
> etc...
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