I just noticed the version I uploaded from 4709 was not identical to the one I once created with I think 4709. However I do not know what I had done for that time. I cannot identify which mkgmap version I used for creating the smaller and better routing version - or what changes I had done (the style was definitely identical except for the addition on the set mkgmap:has-direction=yes tag for some lines).

I tried going back a couple of versions but none produced a that much smaller (over 1%) download file (and while compressing differs each time, that is a tiny bit within 0.2% or so). That one routed better but I think it reversed some oneways it was not supposed to reverse. The routing from 4709 to 4715 on the lower resolution branch is absolutely identical. Scratching my head how I produced this version on the 12. May...

https://openmtbmap.org/mtbaustria_merge.exe

On Fri, 14 May 2021 at 22:51, Andrzej Popowski <popej@poczta.onet.pl> wrote:

Hi all,

reading the discussion, I think it would be good to separate 2 cases:
- routable roads with one-way attribute,
- all lines which have direction.

As for routing, I would assume, that all problems are resolved
automatically and correctly by mkgmap. Routing is only valid at level 0.
On lower resolution one-way attribute can be ignored by default. I don't
see any problems here and I hope we could drop this case.

Second case is more general an it include roads too. It is about
preserving direction of a line to get a correct drawing on a map. This
is dependent on a style and TYP. Basically style defines, which objects
should preserve direction because graphics defined in TYP is not
symmetrical. It seems obvious, that direction should be preserved at all
levels.

Now, if we get one-way road, we have 2 option. Leave it at default and
allow for reverse merging at lower resolution. Or we can add
"preserve-direction" attribute, and make it behave like any other line,
that has direction. Which means no revers merging at lower resolution.

I don't get the idea of a list of types with preserved direction. For me
this attribute is defined in style and separate list, or even list as a
part of style doesn't make sens. I would prefer to have all attributes
directly in style at place, where I define object. It seems tedious to
sync list, whenever I do a change to object in style.

@Ticker
My nuvi 3540 shows direction arrows on roads, when TYP doesn't override
graphics. Older nuvis don't and I got no newer one to check.
I have looked more carefully and I found that arrows are present on
railroads too. This is probably due to mkgmap processing oneway=yes for
railroad (actually tramway). I can't see anything on rivers, but river
is a thin line and it is difficult to tell if anything is drawn over it.

--
Best regards,
Andrzej
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