User:Minh Nguyen/Commonwealth highway numbering
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It is commonly accepted that route relations are a Public Good that represents the future of mapping. Data consumers such as OsmAnd and OpenStreetMap Americana showcase this powerful, extensible corner of the OSM data model, helping travelers find their way amid a cacophony of inconsistent, sometimes incoherent wayfinding signage. Concern about non-relation-savvy data consumers is holding back OSM, and mappers should adopt route relations everywhere posthaste.
Enter Britain.
In the UK, there is such a thing as a road and there is such a thing as a route. But contrary to the Global Consensus, only roads are known by numbers. "Routes" meanwhile are identified only by colour but, topologically, are nothing more than three colours of rubber bands in a tightly bound rubber band ball. The closest American analogue would be the concept of a "truck route", or a "bike route" in cities that don't name or number them.
The A723 road is a non-primary road – that is, a road that carries the non-primary route network – where all the signs along the road are in white. But at this approach to the road on a motorway, the number is rendered in plain text against the same blue background as all the signs along the motorway.
Newer signs in the UK can contain "patches", sort of a little preview of the sign background colour you'll see once you get to the road being mentioned, but this is actually just a box containing all the information about the road, including but not limited to the road number.
Regrettably, the British concept of numbering roads has spread to other countries that prefer chips with their fish. In this Irish sign, the patch is very large, containing also destinations and height restrictions, but the road number is still just in plain text.
Patches within patches!
Compare to France, which also assigns a different sign background to each road classification. The route number is always isolated in a shield coloured by route network.
Germany colour-codes its sign backgrounds too, but a single colour always corresponds to a single route network.
Any "patch" is limited to the shield (an actual graphical shield) and optionally a motorway symbol, but nothing else.
South Africa and its neighbours have also adopted the British system of road classification–based colour coding on directional signs.
In this system, the numbers are always yellow. Yellow just means it's a road number.
However, South Africa continues to use shields as trailblazers for some kinds of routes, and shields conventionally appear on maps for all kinds of routes.
Australia historically had a proliferation of shields just like in the US and Canada. However, in recent years, the eastern states have adopted some elements of British route signing.
It's inconsistent because the concept of a numbered route never went away.
Going back to the British Isles, there's nothing really stopping someone from mapping a route relation for the A723 road, but it wouldn't be any more useful for rendering a route shield on the map than a plain ref=* on the way – the only thing that really differentiates a route relation from a street relation, practically speaking.
For those of us in the US, the possibility of a route concurrency and the presence of many shield designs strongly contribute to a desire for route relations. However, these are just consequences of how roads are designated and branded – the fundamental distinction between a signposted route and a road that it traverses. Many other countries lack concurrencies too, but they make this distinction, so there is a difference between a route relation and a street relation.
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