Yesterday the local newspaper did report on a car getting stuck in snow on a closed road due to following routing advice from a device. I looked at what the openstreetmap main page routers would suggest. GraphHopper did fine. The other two not so great. I know for a certain that at least Valhalla knows about conditional restrictions. But not on the openstreetmap main page?
Shouldn’t the openstreetmap main page showcase the consumers of openstreetmap data at their best?
Is this a question about carto?
I do not think Carto will ever show seasonal restrictions. As somebody grown up with paper maps, I honestly would not expect a raster (a.k.a printed) map to show such. No idea what to expect from a vector (a.k.a live) map, such perhaps could do that; I hold my breath. Said that, it is about routing, Linked samples not tellingly enough?
PS: s/show/showcase/ in top-post.
PPS: Indeed, pondering the question a bit, I’d expect a vector map to honour seasonal restrictions, as time of display for them is a known fact, unlike with raster maps.
Maybe it’s because the months in access:conditional are lowercase (e.g. here)? (no @ (nov-may) instead of no @ (Nov-May))
In Conditional restrictions - OpenStreetMap Wiki, I only see uppercase months.
Please note that for foot & bike profiles we also ignore seasonal access restrictions as otherwise it is tricky to plan in winter for summer routes and vice versa.
(We are unsure if we should do the same for car as the same problem exists.)
However, on GraphHopper Maps we show potential obstacles like conditional access restrictions and if you click on the icon multiple times you can iterate through them:
IMO I think for openstreetmap.org this would be the best solution too as the details could be shown (in this case they have different start months), but likely only GraphHopper supports this, I don’t know.
answer to that rhetorical question is yes, have you expected other answer?
are you asking for advise how to fix that or are you implying that others should drop what they do and should fix it?
in either case, have you checked is it already reported at relevant issue tracker(s)?
If I remember correctly, Valhalla on the fossgis instance allows to specify a date for the journey. Such will allow for planning. This is even more intricate, as they have to actually parse the opening hours string instead of just echoing it. The default result though for “today” (after having parsed the string.) Me thinks, that what ordinary users expect.
I wouldn’t call “today“ the default and also not what the user expects as there are different use cases.
But having the conditionals displayed is a good first step (and algorithmically easy) and then, as second step, allowing the user to specify a departure day would be IMO the best solution, but algorithmically much more complex, especially as you still want to get fast responses.
For me it was a pleasant find that GraphHopper chose the detour when asked for the itinerary. The Elephant in the Room selected same route. Regarding linked post above, I still consider those arches over unknown terrain a mistake however much the Elephant makes use of those. Obviously, nobody here ever noticed that part of the linked journey is not only blocked seasonally, but for the time being, not even our most prolific Vorarlebergian mappers. The incident with the driver though happened on thy Tyrolean side. The car broken beyond repair, fortunately no personal harm.
Auf dem Bildschirmfoto fällt mir auf, dass das gar nicht über die gesperrte (nicht nur im Winter, aber mehr als einen Hinweis auf OSM plazieren kann ich auch nicht, da keine Ortskenntnis) Silvretta Hochalpenstraße leitet sondern eine Abkürzung nimmt, die aber auch im Winter gesperrt.
Zum Glück drehn die Meisten beim Schild um und ärgern sich nur übers Navi. Die Wenigsten fahren ihr Auto zu Schrott.
Das Bildschirmfoto (und GH Maps Link) ist wie geschrieben bzgl. bike nicht car.
Silvretta Hochalpenstraße leitet sondern eine Abkürzung nimmt, die aber auch im Winter gesperrt.
Welcher OSM way ist das genau? Wenn das übers ganze Jahr gesperrt wäre, dann kann man das ja übers access tag machen und muss keine conditional tags nutzen.
While I don’t expect every paper map to show every seasonal restriction in great detail, many of the maps in my collection note winter road closures for through routes. This is important information in a mountainous region where the next through route can be a long distance out of the way. Some examples:
There is no reason an OSM based map couldn’t also choose show this sort of information based on motor_vehicle:conditional=* and winter_service=no.
Nice cartography, we call it Guglhupf mountains, first picture above, last seen in maps from 1786 
The shortcut obviously all year round unconditional for cars (motor_vehicle). The main route as well conditionally/seasonally open, regardless the mode. It is 25 (shortcut) vs. 35 (main) vs. 105 (detour) km of travel.
