Hi Alain

On 2017-09-12 07:22, Alain Berguerand wrote:

Hello all,

I recently noticed unexpected results when using the routing interface at routing.osm.ch. When planning a bike or foot hike, the algorithm uses ferry routes over lakes if this makes the route shorter.

For instance, this bike course between Brienz and Bönigen mostly uses ferry routes : https://routing.osm.ch/?z=13%C2%A2er=46.715386%2C7.975903&loc=46.755034%...

Thanks for this example. Indeed that should not route on the ferry routes. Probably the weights need some adjustment. Ferry routes are already heavily penalized (less than 1/3 the speed of a normal road. See https://routing.osm.ch/debug/bike-touring.html#13/46.7150/7.9758). But they still are too fast. Maybe because there are no turns along a ferry route, while there will be a bunch of turn penalties along the roads.

To me, routing over ferries is conceptually wrong, because the user is not actually biking or hiking on the ferry route. To stretch this to the extreme, the foot/bike routes should also include motorways and railways because a pedestrian/cyclist can mount a car/bus/train.

When cycling longer distances, it is often difficult to avoid ferries (and sometimes trains). For example if you want to cycle from Hirzel to Uster, you probably want to take a ferry, because otherwise you have to make a detour to Zurich or Rapperswil. It would be trivial to exclude ferries, but I think it is a nice feature to show that we can include ferries where needed.

Regarding making a "no ferries allowed" mode: We currently run a very optimized router, with lightning fast responses (making this live dragging of routes possible). The draw back is that we can not customize routing preferences. So individually prohibiting something is not possible.

Michael