[mkgmap-dev] Bicycle routing improvements (reverting breakage from r1431)

Tue Aug 10 16:27:34 BST 2010

  On 10.08.2010 15:12, Marko Mäkelä wrote:
> On Tue, Aug 10, 2010 at 02:37:42PM +0200, Valentijn Sessink wrote:
>> Marko Mäkelä schreef:
>>> I am planning to remove the { add bicycle=no; add foot=no } from
>>> highway=trunk and to restore non-bicycle paths to road_speed=0.
>> I'd suggest you don't. I do not know why bicycle routing differs.
>> Adding random patches to my random reports won't help.
> It is not totally random. Someone just yelled that defaulting bicycle=no
> on highway=trunk is not right, and I cannot disagree with that. If there
> is no traffic sign that prohibits bicycles and pedestrians, then they
> are allowed. And I haven't seen such traffic signs in Finland, except in
> some places when there is a cycleway next to the highway=trunk.
>
>> Please note that r1431 was quite carefully engineered by Felix Hartmann
>> (at least, that is what I understood from it), and you shouldn't change
>> these back just because I'm yelling something ;-)
> The road_speed=1 for a non-bicycle highway=path does not seem to make
> too much sense. It may be possible to ride some bicycles on a 20cm wide
> unofficial forest path, but not with a bicycle trailer or a
> tandem/triplet/quad or at the same speed as on a purpose-built cycleway.
> Maybe Felix had too much emphasis on mountain bikers?
>
>>> Do you have test cases in mind? Can you try the attached patch?
>> I will. But not now.
> No hurry, this has (or may have) been broken such a long time :-)
>
> 	Marko
>
I designed the routing in such a way, that it works much better for 
motorcars/motorcycles (bare the Mapsource intertileroutingproblems). As 
you cannot have different road_speed for cyclists vs cars, one should 
better compromise on the bicycle side, as proper bicycle routing will 
anyhow not work on a map that is rather made for motorcars.

highway=trunk and bicycle=no --- well that is based on the crap 
introduced by having country defaults. Were an international map, but we 
fuck it up by introducing different rules by country (and those not 
clear either). Usually trunk roads suck outright for cyclists, if you 
don't add bicycle=no, bicycles will primarily be routed on primaries and 
trunk roads. That's good for people that take a pleasure in being able 
to calculate a route for 200 or 300km distance, but bullshit if you want 
to be routed on roads without much traffic. As long as there is no 
consensus worldwide whether or not cyclists by default are allowed on 
trunk roads, I wouldn't add them (and even then it probably makes not 
much sense, you would have to enter them as road_class=0, road_speed=0 
--> but that clashes with motorcar usage).

highway=path has usually tags like sac_scale, mtb:scale, tracktype and 
similar attached, if not than it should be added, therefore roadspeed=1 
is IMHO correct. Else pathes won't be chosen at all (except for tiny 
distances).

Only road_speed=0 and road_speed=1 are taken for route priority, however 
TTP is still valid for bicycles as for motorcars, which of course is 
clearly a default in the Garmin GPS Software, because even on a 
trunk_road you will never need say 2 minutes to turn as a cyclist, but 
this TTP is calculated.

As I wrote back then, routing for cars would still work much better, if 
indicated max_speed can only decrease road_speed, not increase it. Loads 
of problems related to this fact here.