[mkgmap-dev] Garmin Edge 705 bug in bicycle routing

Tue Aug 25 21:29:31 BST 2009

Hi Mark, Chris, all,

Sorry, I was wrong about the bicycle=no.  I removed the bicycle=no, foot=no
in a local copy of the tile, and it did not affect the suggested routes.

This is within a single map tile.  mkgmap spits out some "zero length arc"
warnings, but none should be on this route.  java -ea -jar mkgmap.jar does
not fail.

On Tue, Aug 25, 2009 at 01:20:15PM +0100, Mark Burton wrote:
> Just a thought, is it related to the zoom level of the cycleway as set
> in the style file? What happens if you make the cycleway have the same
> zoom level as the road next to it?

I tried raising the resolution from the default 23 to 19, but it only
affected the map display (I'm able to see cycleways above 130m zoom levels).

On Tue, Aug 25, 2009 at 03:01:08PM +0200, Chris-Hein Lunkhusen wrote:
> Did you check, if the online routing services are able to route
> bicyclers correct on this location? Maybe some missing link
> from the main road to the cycleway?

I validated the whole route based on track logs I recorded last week on
a bicycle ride (2*160 km).  I did fix some errors and omissions, and the
map extract should include all my fixes.  Besides, the routes from A to B
and B to C are just fine, just ignoring some cycleways that ran in parallel
to the highway 140.  It is the route from A to C that is nonsense, making a
detour off highway 140.  (A=Jokivarsi, B=Heinola, C=Kuortti.)

I updated
http://wiki.openstreetmap.org/wiki/Mkgmap/routing/issues#Bad_bicycle_routing
with this info.

> But indeed: the garmin bicyle routing is a little bit mystic.
> That's the reason for me using "taxi" in my style for bicyle routing.

I prefer to stick to the standard types.  Besides, the Edge 705 only offers
three major routing modes: car/motorcycle, bicycle, and pedestrian.  Minor
modes include "avoid unpaved roads", "avoid toll roads", "avoid highways".

To summarize, this just a demonstrates a deficiency in the routing algorithm
of the Edge 705.  It is probably impossible to get bicycle routing work right
by tweaking the maps alone.  Generally, I have found the route suggestions
useful for bicycle rides up to 30 km in urban areas.

Best regards,

	Marko