[Tagging] Spatial triggers/conditions changing/affecting tags elsewhere

[Ilpo Järvinen]

Hi,

We've have *:conditional=* which is useful to describe complex tagging 
cases, however, it is not able to cover one particular case with spatially 
distinct trigger. Lets look to this issue through two examples:

A) There's Vantaanjoki river that goes under a motorway. Alongside the 
   river there's highway=unclassified road Laamannintie, which is the 
   normal access route to Haltiala mansion that resides NNE of the linked 
   area. In case the river is flooding and Laamaanintie is submerged, 
   there's alternative route for motor_vehicles to access Haltiala 
   mansion which is highlighted here (Torpparinmäenpolku):
     http://www.openstreetmap.org/way/158753778#map=16/60.2650/24.9643
   Under normal circumstances, the alternative route does not allow 
   ordinary motor_vehicles but only some special conditions such as tall 
   vehicles that wouldn't fit under the bridge (supposedly to reduce the 
   negative effects on the residential area there).

   We can see that the access tags for Torpparinmäenpolku depend on the 
   conditions that are determined by a spatially distinct trigger on
   Laamannintie (in contrast to typical environment effects such as wet,
   icy, windy, etc. that are/can to be decided/determined locally).


B) I was recently told that there are crosscountry ski tracks where 
   lighting is activated by the skiers using some button/switch nearby 
   (and then remains on until 22:00 or so, assuming that the info is 
   correct).

   Again, the trigger is elsewhere than the way itself that is lit.


In both of the above examples, *:conditional=* isn't enough because
it would only allow very non-sensical tagging on the way itself such as 
motor_vehicle:conditional=yes @ flooding :-). More importantly, there 
isn't clear way to tag the object way at all(!) with yes nor no because 
neither is accurate without those additional conditions.


I wonder if some other mappers have encountered similar situations 
(beyond obvious cases where one needs to get a ticket from somewhere to 
access a particular area/spot)?

Would it make sense to define some kind of relation to handle
these case so that a proper *:conditional=* could be applied on
the relation so that the tag transformations would be in a 
machine-readable form?


-- 
 i.