[OSM-talk-be] Complex kruispunt / Complex crossing

Tue May 13 15:58:04 UTC 2014

Jo,

a can of worms ? I hope it , this mailing list is too quiet :-)

Wouter,

While I understand that for routing one does not need the separate
cycleways, I don't see much difference in a router that sends me over the
N47 with separate cycleways (illegal in your eyes) or without separate
cycleways (ok for you).

The possible problem with a badly connected separate cycleway, is that a
GPS with very high precision, won't let me make the second left turn into
Baan nr. 90

So as long as the N47 is not tagged with bicycle = no, there won't be any
problem IMHO
But as you wrote, you get the same result with less work by putting tags on
the main road.

regards

m

On Tue, May 13, 2014 at 10:34 AM, Wouter Hamelinck <
wouter.hamelinck at gmail.com> wrote:

> OK, I'll bite about the cycleway.
>
> Go a bit south and you will see something called Macharisdreef and
> something called Baan nr. 90. Imagine you want to cycle from
> Macharisdreef to Baan nr. 90 along that N47 and use only the map data
> as a routing algorithm would do.
> * First attempt: well it is obvious, you just take the cycleway at the
> east of the N47 to cycle from the one to the other. Shortest, lots of
> cycleway, it looks perfect. Reality: this is illegal, you only can
> follow that cycleway north, otherwise you cycle on the wrong side of
> the road. So we have to correct the data. Let's say we put a
> oneway=yes on the eastern cycleway.
> * Second attempt: well obvious again, you simply take the N47 instead
> of that cycleway. Only slightly longer, a bit less attractive, but not
> too bad. Reality: this is illegal. There are cycleways, you have to
> follow those. So we have to correct the data. Somehow we have to make
> explicit that you are not supposed to cycle on the N47 but have to
> follow the parallel cycleways. So let's put some tag explaining that
> on the N47. I don't really care which one. It could be boldly
> bicycle=no or the proposed bicycle=use_sidepath or whatever. I'm just
> not supposed to cycle over the highway=primary.
> * Third attempt: let's see. When leaving Macharisdreef, I have only
> two options. Either I take the N47, but that is illegal, or I take the
> cycleway east of N47. Nothing else connects to Marcharisdreef. So my
> only option is to follow the eastern cycleway to the north. Hmm, I
> then can cross the N47 right before that terribly complicated junction
> and start following the western cycleway. Until I find a place to
> cross the N47 again. The first one that I find is right at the
> roundabout about 500m to the south. There, I can traverse to the
> eastern cycleway and follow that north to Baan nr. 90. OK, I have a
> solution. Not exactly short (about 1km instead of the 50m in my
> previous attempts), but at least it is legal. Reality: not entirely
> legal (at least at the roundabout you should go around it instead of
> traversing before the roundabout), but close enough for me. With the
> slightest bit of common sense I wouldn't follow that anyhow. What I
> would do is traverse N47, follow the western cycleway and traverse
> again when I am at Baan nr. 90. Why didn't the algorithm propose that?
> Simple: the road to the east of N47 are not connected to the western
> cycleway and vice verse. So we have to modify the data again. At every
> point where there is a sideroad from only one side we need to add a
> short cycleway to connect the cycleway on the other side with the
> junction.
>
> Once those junctions are made, I will get the obvious, correct route.
>
> Conclusion: lots of work and near impossible to maintain.
>
> Now, let's see what happens if I tag the cycle paths on the
> highway=primary in stead of drawing them separately. It is in any case
> a lot less work. No need to draw the separate cycleways and no need to
> add all the technical tags on both highway=primary and
> highway=cycleway that I described previously to get correct results. I
> just add cycleway=lane or something similar to the highway=primary.
> What does the algorithm say? I will just say: "At the end of
> Macharisdreef turn left on N47. I know there are are cycle lanes so
> you should follow those instead of cycling in the middle of the road.
> And after 50m you turn left in Baan nr. 90.".
> Simple, clear, robust.
>
> That is why I only will draw separate cycleways if there really is no
> other option. Even if it is not wrong to draw to the cycleway
> separately, it is just a lot of work, impossible to maintain and a
> huge source of errors waiting to happen.
>
> Bonus question 1: what happens with routing for pedestrians in both
> situations?
> Bonus question 2: in how many ways is it possible to make mistakes
> when mapping cycling routes? Especially the case of a route that can
> be followed in both directions is enlightening.
> Bonus question 3: which situation has the least tags (=lowest database
> size) and the least junctions and ways (=greater efficiency for
> routing algorithms like Dijkstra)?
>
> wouter
>
> On Tue, May 13, 2014 at 9:16 AM, Jo <winfixit at gmail.com> wrote:
> > We have more recent AGIV imagery now. All I see wrong is that the
> cycleway
> > is connected to the underground waterway. But the main road is too.
> Probably
> > to silence validator warnings in a totally inappropriate way...
> >
> > I still think it's correct to draw the cycleways separate cases like
> this.
> >
> > Marc, you opened a can of worms there :-) But it's good that the subject
> of
> > using separate ways to represent lanes is brought up on the list.
> >
> > Jo
> >
> >
> > 2014-05-13 8:15 GMT+02:00 Wouter Hamelinck <wouter.hamelinck at gmail.com>:
> >
> >> Wow, based on the Bing images a simple T-crossing and a bypass is all
> >> there is in reality.
> >> Also, note the nice examples of about everything that can go wrong
> >> when drawing parallel cycleways along the N47.
> >>
> >> wouter
> >>
> >> 2014-05-13 6:35 GMT+02:00 Jo <winfixit at gmail.com>:
> >> > Zeker wel, het klopt niet om een aparte weg te tekenen voor elk
> rijvak.
> >> >
> >> > Absolutely, using a separate way to represent traffic lanes is not how
> >> > it's
> >> > supposed to be done.
> >> >
> >> > Jo
> >> >
> >> >
> >> > 2014-05-13 5:48 GMT+02:00 Marc Gemis <marc.gemis at gmail.com>:
> >> >>
> >> >> Hallo,
> >> >>
> >> >> Ik vraag me af of het OK is het volgende kruispunt te vereenvoudigen
> >> >> via
> >> >> turn:lanes : http://osm.org/go/0Ejo5_fqb--?way=51738440
> >> >>
> >> >> I wonder whether it's ok to simplify the following crossing with
> >> >> turn:lanes tagging: http://osm.org/go/0Ejo5_fqb--?way=51738440
> >> >>
> >> >> met vriendelijke groeten
> >> >> regards
> >> >>
> >> >> m
> >> >>
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> >>
> >> --
> >> "Den som ikke tror på seg selv kommer ingen vei."
> >>                                        - Thor Heyerdahl
> >
> >
>
>
>
> --
> "Den som ikke tror på seg selv kommer ingen vei."
>                                        - Thor Heyerdahl
>
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