[OSM-talk] TAG-Suggestion: highway:trailer_shipment

Carsten Moeller cmindividual at gmx.de
Sun Jan 17 11:14:11 GMT 2010


Felix Hartmann schrieb:
> I think the main part that has to be done here is that ferries, or 
> motorails however as well aerialways get connected to the main road 
> network using lines (routing over polygons is so complicated that no 
> router will soon master it in a useful way).
> 
> How they are connected should be dependant on the transport mode to use. 
> Image huge ferries with different, but consistent places to enter.
> 
> We could have
> highway=footway & pier=yes (or similar)for pedestrians entering the 
> ferry (this is actually one of the rare cases I like to see footway and 
> not path),
> highway=service &  motorcycle=yes & foot=no & bicycle=yes
> highway=service & access=no & motorcar=yes & hgv=yes
> 
> And the ferry route should connect all three.
> 
> Another example would be a cable_car.
> We should have highway=footway (or another key) to connect the street 
> network to the cable_car. If there are steps inside the building, well 
> then lets add a section highway=steps......
> 
> 
> The principle should be no matter what kind of line there is that can be 
> used somehow, it should be interconnected with all other transport 
> usable lines. This means that we should also connect railways to roads, 
> because otherwise no autorouter can calculate routes using busses and 
> trains (with walking from one to another) for example. Only airports I 
> would rather just connect by having a relation list to which other 
> airports you can get from airport XY.

I get to the conclusion that we exactly have two perspectives. First 
there is the question of how to get from A to B including public means 
of transport. The other one guides me to the closest parking lot. A 
cable car for instance has the same quality as an aerialway. But not as 
highway=footway. The latter is rather like a highway=service. You can 
use a car. Ok. it might be forbidden but you can. Offering mountain tops 
and similar things as addresses on your routing topology will blow up 
the data dramatically.
The key to a fast routing is the reduction of data. "Make things as 
simple as possible, but not simpler" (Einstein). There are some grey 
zones. I am living in a "highway=pedestrian" connected to a 
"highway=service", so I decided to take these tags into account but gave 
them a low priority so the router selects them only if there is no other 
way.
I do agree. Railways, aerialway etc. should be connected to highways. 
But this should not be expressed by connecting same nodes. Here ramps or 
links come into play. If you have a closer look at todays OSM-Data 
railways are in fact connected to streets. But I wonder if you'd like to 
stop a train by parking your car on a railroad crossing ;-) What about 
aerialways? Are they connected, too? In the air?
A highway=steps would imply you can use your car here. I think we should 
strictly distinguish between highway and other tags. If I understood the 
intention correctly then highway is something you can drive on. Even on 
highway=pedestrian but not on steps.

I hope OSM will take these two perspectives into accoung one day. So we 
can have routable highway tags like highway=railway, highway=ferry, etc. 
These are much easier to handle (and to tag) than railway=rail + 
motorcar=yes + amenity= ... and so on.
On the other hand we should consider the real world. This of course 
means we'll need to build topologies on relations or tags like 
motorcar=yes, railway=rail.

Regards

Carsten (alias PiMapper)


















More information about the talk mailing list