[Tagging] Superroutes - good, bad or ugly?

Paul Allen pla16021 at gmail.com
Wed Mar 13 14:02:26 UTC 2019


On Wed, 13 Mar 2019 at 13:29, Andy Townsend <ajt1047 at gmail.com> wrote:

> On 13/03/2019 13:18, Paul Allen wrote:
> > I've hesitated to ask this question for months now: what's the
> > consensus on superroutes?
>
> In what context are you asking the question?  I can think of examples
> where the answer would be "a really bad idea" and others where the
> answer would be "essential; there's really no other sensible way to have
> that data in OSM".
>

That's more positive than I expected: they're not always on a par with
eating babies but the use
has to be justifiable.

Can I get the data into OSM without a superroute?  Sure.  Is that data
useful without a superroute?
Not so much.  It is this bus route:
https://www.openstreetmap.org/relation/8592409#map=14/52.0860/-4.6644
That is incomplete and has some omissions and errors.  I really ought to
fix it, but I had
this thought about superroutes and realized if I fixed and then found out I
could use a
superroute I'd later have to rework a few things.

It's a circular.  It starts at what can loosely be called the bus station.
It does what can loosely
be called a hairy circular route to return to the bus station.  The route
then continues on a side
trip and eventually returns to the bus station, completing the "circle."

There are places where the bus goes into a dead-end and gets out by
reversing into a side
junction.  This differs from similar manoeuvres at a terminus of a
non-circular route because
passengers are on board.  It does a loop-the-loop.  It appears to do a
figure-8 but actually
there are other side-trips that mean it really isn't.

One problem that I don't see a solution for in PTV1, PTV2 or "we don't tag
it PTV3" is a stop
that is ignored on the first pass but comes into play on the second pass.
The bus starts at
the bus station A, passes through nodes B, C and D and turns right at D to
E.  On this pass
through C it ignores the bus stop there.  After it's gone through the
alphabet back to A, it
again goes through B, C and D but this time turns left to alpha, beta,
etc.  On this pass it
does stop at C.  Piling all the stops into the relation may lead the
routers to conclude that
you can wait at the stop C to get directly to E when you can't (but you can
get on at C to take
a detour through the greek alphabet and eventually get to E because it's a
circular).

Splitting it into route segments would fix the problem with the stop at C.
On one segment it isn't
a listed stop.  On another segment it is.

Splitting it into route segments would also make it clearer what happens in
the loop-the-loop
and the figure-of-8 in the town centre, if the splits are chosen
judiciously.  If I'm really clever
I can find splits that make the variant routes fit in nicely, too.  You
think that route is insane?
Wait until I add the variants.

Best of all, I could pull these into umap.  It would then be possible to
display route segments
in turn to see where the bus goes rather than trying to puzzle it out from
the overall route.  Yes,
if you're very familiar with OSM you can puzzle it out from the relation,
but most people can't do
that (and I find it difficult, even with knowledge of how the route runs).

So, good idea, bad idea, or should I stick to eating babies as that would
be more socially
acceptable?

-- 
Paul
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