> Why would it matter to someone that there is another highway going into the > opposite direction of where they want to go, that someone considers to be > part of the "same road"?
Besides statistical purposes, it could be used for rendering at mid zoom levels. Many highway maps in the United States have a different rendering for "divided highways" aka "dual carriageway" roads. Often it looks similar to the current highway=trunk rendering at in the German map style used at openstreetmap.de - and I believe "highway=trunk" is always for dual-carriageway "expressways" there. Also, a dual carriageway road might be preferred in routing when all else is equal. > limited_access I should explain this further. In American traffic literature at least, we talk about whether a road has frequent access to adjacent properties and parking lots. Sometime this is called "controlled access". If there are lots of service roads entering, that will increase the risk of collisions and slow down traffic. Roads called "expressways" usually have no or very few service roads entering, so they have "partial access control" and most motorways have "full access control" - you can only merge on to the motorway from a link (on-ramp). Motorways are almos always fully "grade separated". My understanding is that not all highway=trunk roads have full or even partial access control in most countries. Certainly in the United States this varies greatly. > replacing "expressway" with "trunk" Do you mean retagging all ways with key:expressway as highway=trunk? That would be treating highway=trunk in the German way, as a property which combines a number of characteristics. But in Alaska, Oregon, California etc, many mappers prefer to use highway=trunk for the top level of intercity roads which are not motorways, without considering number of lanes, access control, etc - in remote forest areas even the busiest road does not need grade separations. And also, expressway=* is used differently in some States, as mentioned on the wiki page: sometimes it is about limited access, other times it's about grade separation. - Joseph Eisenberg On 2/20/20, Martin Koppenhoefer <dieterdre...@gmail.com> wrote: > Am Do., 20. Feb. 2020 um 13:07 Uhr schrieb Joseph Eisenberg < > joseph.eisenb...@gmail.com>: > >> >> If people are interested in using it, I might make a proposal. But >> perhaps we will decided that database users should interpret the >> geometry and name=/ref= tags of parallel highway ways to add this >> information in post-processing. Does anyone know if that is feasible? > > > > I guess it is possible to do it, but I cannot imagine a usecase for this > kind of information, besides statistics maybe. Why would it matter to > someone that there is another highway going into the opposite direction of > where they want to go, that someone considers to be part of the "same > road"? Isn't it sufficient to know the amount of lanes, oneway property, > highway class, etc. for most practical usecases? > > As to the "limited_access" key in the thread title: it doesn't appear to be > in use, likely it would express the same concept as "motorroad"? > > What about replacing "expressway" with "trunk", is there any information > loss or is this only about which term is better understood in a certain > context? > > > Cheers, > Martin > _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
