Add Vietnam expressway shields

[1ec5]

Added a shield for expressways in Vietnam. The tagging scheme for Vietnamese route relations coalesced around the network=vn:* prefix too recently to be picked up by the tile server, but here’s how it’ll look:

As in #141 (comment), I’m not sure putting CT. in the ref is quite correct, since no one would ever say or write “expressway CT.01”. But it does match what’s on the shield, so this is expedient for now. Even if there’s consensus to drop the CT. from ref, it might be desirable to drop the “CT.” from the map as a simplification anyways.

[ZeLonewolf]

Looks good!

[ZeLonewolf]

It appears that the standard we chose, network=vn:expressway, is no longer the one most commonly in use:
https://taginfo.openstreetmap.org/search?q=network%3Dvn%3Aexpressway#tags

[1ec5]

I discussed this back in February 2022 with ZioDragon, who at the time was the only mapper working on Vietnam’s national route and expressway relations. The network tags were all over the place, but I recall that they decided on vn:national and vn:expressway. To my surprise, last December, they unilaterally changed vn:expressway to VN:CT and then VN:Expressway, but now it’s inconsistent with national routes. I reached out to the OSM Vietnam Facebook group again for opinions. 🤞

[ZeLonewolf]

Thanks for reaching out. If there is a change in local consensus on how to map Vietnam route relations, of course we should change our scheme to match whatever consensus emerges.