There appears to be an error causing a routing glitch when using this ferry. OSRM refuses to route eastwards with a vehicle. Westward is fine, and navigating as a pedestrian is also fine.
I’ve narrowed it down to this specific location - past this point, the route works; prior to it, it sends the navigator all the around the other side of the bay by road.
The most recent changes on the ways here were 3 years ago, and mention the removal of access=destination. It sounds like this could be related to the problem but thought I’d seek advice first.
Passing the first point, there is no way out except along the queuing lane which is highway=service and access=customers. I suspect it is the access=customers that is the stumbling block. (given that the land route also traverses a highway=service)
I see that OSRM and Valhalla go around, while GraphHopper does what you expected.
That’s right, if you check the car profile at osrm-backend/profiles/car.lua at master · Project-OSRM/osrm-backend · GitHub you can see that access=customers is a restricted, so once the router has no other options it will route over access=customers but since it has a large penalty, if it can find an alternative route it will use it.
The intention is likely to allow routing over access=customers at the start/end of the journey, but it doesn’t work in the middle.
It’s a tricky one since access=customers is used to say only customers of the ferry can drive there. It’s an inherit problem with customers as a tag value since it doesn’t say customer of what.
Thankyou! Yes the customers thing seems the most likely explanation. I’m not sure why it works one way and not the other though. Possibly to do with the specific geography of each terminal meaning the lane arrangements are slightly different?
Others (e.g.) the Spirit of Tasmania routing from Geelong-Devonport work fine, but that could be explained by the fact there is no alternative?
It sounds like it’s a glitch with OSRM and not OSM, but it also sounds like access=customers isn’t the best tag to use - sounds a bit ambiguous. Others such as Google Maps treat ferry routes as a “toll road” which I guess is kind of what they are. I don’t know if there is an equivalent tag for OSM (apart from the ferry route tag itself).
Because westwards it never passes a way with access=customers that’s only on the ways leading onto the ferry when travelling eastwards.
Yes the OSRM profile here doesn’t forbid routing over access=customers it just increases the penalty so it will only do it if practically no other option exists.
Yes, it’s fair to question the tag. I get it being access=customers to mean only customers of the ferry can go there, ie. you can’t or at least not meant to start queuing there but then not take the ferry.
Yes there is toll=yes which the ferry itself is already tagged as, but it’s still orthogonal to tagging the access.
Apparently it’s common in OSM to have access=customers in the roads leading to a ferry, Handle destonly ways/edges around ferry terminals · Issue #3942 · valhalla/valhalla · GitHub talks about the issue with Valhalla, based on the discussion it appears they “fixed” it within Valhalla by de-restricting access=customers ways adjoining the ferry, however in this case there is a short road section without the access restriction so that’s likely not triggering this fix in Valhalla
This is putting aside the question if the ways should be access=customers at all, but at least this change should make it consistent and should fix it in Valhalla.
The other thing, of course, is that while a router may say you can’t drive through there, I don’t think anybody is then actually going to give up & drive all the way round to Sorrento!
