I have a question which is both simple and rather complex. In my country, when a highway is restricted for some vehicles (for instance with maxweight=3.5 or hazmat=no), it may happen that a nearby highway, not subject to these restrictions, is signed to advise, say, vehicles over 3.5 or hazmat vehicles to use it instead of the restricted highway.
How could I tag the advised highway for these 2 examples?
Thanks in advance for your answers, and a happy new year if you are already in 2026!
No, absolutely not: in my case, the advised highway is only advised: one can also u-turn, or drive along another road… as long at it is not the forbidden one.
I’d think something like hgv:conditional=designated @ (maxweight > 3.5) could work. Of course, evaluation of conditionals is quite tricky, so probably not much in terms of software support, though it is mapped in some recognisable way.
Similarly: hazmat=designated.
The problem is, that is is not a route: it’s limited to a junction, often not necessarily signed at later junctions, not named nor with a ref… A relation for that sounds overkill to me.
I also thought about that, but it’s in fact not an obligation for these vehicles to use the signed highway, merely an advise as If you want to go in this direction, but are forbidden to do so, you are encouraged to use this other highway..
