Long distance ferry routes
  • There were several bug reports related to long distance routing using ferry (in particular UK/Ireland). The routing algorithm often failed even if the roads and ferries were correctly connected in the OpenStreetMap data. The most common reason was usage of "service roads" (i.e. road with very low category) in the ferry terminal area. The Navigator routing refuses to leave motorways to use such small roads ...

    ... this changed (now), October 2013 data. At the moment you can download Ireland OSM (131009 - this is 2nd update original was yesterday), where the network near ferry is modified. I do not know at the moment which ferry is important for long distance routing and which is not, so heuristics is used. Ferry is considered important if it has a name and it is at least 10km long. In this data batch there will be mix of "patched" and "not patched" data (if the date is bigger than 131010 they should be already patched).

    Please let us know if you discover any problem caused by this "fix_ferry_patch".
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  • Reading this I understand now, why this problem exists:
    So we got a conflict. But you can solve it that way: Allow routing through "highway=service" only if there are no other possibilities to reach the target.
  • I don't know if it's the described problem but I have a similiar behaviour when trying to find a route from Town Center Helsingborg (Sweden) to Town Center Helsingør (Denmark). In my road restrictions I have everything allowed but "Small Local Road" and "Other Road" (there is no entry for "service road"): Routing doesn't use ferry. Only if I allow "Small Local Road", ferry is used. But allowing this kind of road causes a lot of other problems so I don't want to allow it generally.
  • Thanks, that's a good example, which should work and which is not working at the moment (way 4066778). One reason is that Denmark was computed sooner before the routing script was integrated, but ... still the "hint" that it is important ferry would fail. It was set for 10km and this ferry is approx 4.9km long.
    There are two ferries - are both important/often used? The second is way 150208446. The first one is part of other relations and has reference E47 and E55, while the other does not ... but is there any difference in reality?
  • Another example: http://www.openstreetmap.org/browse/way/23567561
    This ferry-route is about 400 m long but you need about 15 km or so more to come from Knightstown to Caherciveen without it. And so for me "important ferry" is pretty relative.
  • Yes, it is relative. There are two levels (for Navigator). One is that it is used (sometimes it is the only way) for really long distance routing. This is for trips where you travel most of the time on motorways, and then you switch to ferry. Quite useful is the tag "duration" which would give us an idea if to use 15km bypass or ferry (it is not integrated at the moment).
    The second is that the ferry is usable for cars in general. For that probably access tag is sufficient.

    What I am trying to find out now, if there is a way how to distinguish these two categories from the OSM data (other providers have transit network, for example, so important ferries are on the transit network).
  • Hi Martin!

    The ferry I used this year was what you call "way 4066778", I landed there following the "Helsingör" and "Helsingör Sandlines"-signs. Google Maps and TomTom also show this way. When watching the start of the other way (150208446) in Helsingborg on Google Street View it doesn't look like a ferry would start here but that's my personal opinion.

  • Hi,

    I just tried to set a route from a road just outside Fishguard Harbour in Wales (The Parrog) to a bit of the N25 just outside Rosslare Harbour in southeast Ireland; the route was not found.

    Are you still working on the ferry problem?


  • mdx is on holiday, please be patient
  • Sure, no problem - just thought I'd mention it.
  • Hi Jochen,
    I just tried "The Prrog"/town centre -> "Rosslare Habour"/town centre ... and it worked (with blocked roads)
    united_kingdom_osm              : data version=44, data creation=201406200
    ireland_osm                     : data version=44, data creation=201407240
    but ...

    If you look at "Rosslare Habour" you will see many crossed/blocked roads. Here is example:
    it has tag access=destination ... which should be probably cleared during conversion to MCA, as it can be used in the middle of some long route.
    thanks for comment

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