[Tagging] Route sorting

Volker Schmidt voschix at gmail.com
Thu Aug 15 21:55:17 UTC 2019

Sorting is not the same thing as connection checking.
RA does not sort anything. It is able to find for *route* relations the
minimum number of unconnected pieces that are required to cover the entire
Sorting can only be defined on some special routes. Routes can be connected
in a single set of connected ways, but may not be sortable.
Lets take to simple examples of perfectly correct route relations that
cannot be sorted.
A) A star shaped arrangement of three ways.
B) A single way from A to B that is interrupted by a loop
All this assumes that all ways that are part of the route relation only
appear only once as a member in the relation. Obviously if you have a way
appear several times in a route yo can use this trick to be able to reach
every part of the route graph.

On Thu, 15 Aug 2019 at 20:43, Paul Allen <pla16021 at gmail.com> wrote:

> On Thu, 15 Aug 2019 at 18:41, Martin Koppenhoefer <dieterdreist at gmail.com>
> wrote:
>> I’m usually splitting roundabouts to contain only the part that is in the
>> route. We’re splitting all roads for routes (or other properties or
>> relations, e.g. turn restrictions), why would you not do it for roundabouts?
> I assumed, from the last time I read the documentation, that splitting
> roundabouts was the
> correct thing to do (although it was a bit ambiguous, if I recall
> correctly).  Also, it seemed to
> me that it would mean a simple router would get it right whereas not
> splitting the roundabout
> might cause a simple router problems.
> --
> Paul
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