2009/7/31 Greg Troxel <g...@ir.bbn.com>: > But, as I understand trunk, it's meant to be a physical upgrade from > primary, which is a national-level highway.
Well, you could argue that it would be valid to adopt this standard in a country where it was deemed useful. But that's not how it is here. Ireland has two grades of National road, primary and secondary (corresponding fairly well to how the UK has two types of A road). Like the UK, we use trunk and primary to differentiate between the two (trunk for primary, primary for secondary, and yes, I know this isn't how you'd ideally design the terminology...). But primary and secondary are measures of the route's significance, not of the actual build standard, which can vary widely. > I've driven in .ie, and > don't remember the numbering scheme, but the non-motorway main roads > between towns that are not divided and have at-grade junctions and have > national-type numbering seem like they ought to be 'primary'. Again, it's an argument that could be had, but that's not how we do it and not how most other cartographers do either. Not even Michelin, which in other respects does heed a road's quality and certainly its significance over actual classification. Cartographic norms here tend to favour blue (motorway), green (national primary) green-striped or red (national secondary), orange (regional), which, usefully, with our tagging scheme is what OSM renderers give us. This is not really a co-incidence if we consider the UK bias of the renderers and the closeness of our hierarchy of road types to theirs. And going with your suggestion would leave us without a useful differentiation between the primary and secondary national roads. What we have works, and build quality can be inferred by other means. > And it > seems that's how it is - the N62 from Thurles to the M8 (amusingly, > someplace I've been to - the horse and jockey pub shows up at z12) is > tagged as primary. That's because N-roads of 51 and above are national secondary routes. So far, none of these have had motorway upgrades and I'm not holding my breath. > The N8 is trunk when it isn't M8, and I'm guessing N/M is a hint that it > doesn't quite meet motorway standards, but I don't remember this well > enough. Well, we've had N roads since before we had motorways, and for a long time we had very few motorways. So it's more a case of a motorway being a part of a national route that _is_ at motorway standard _and_ has been so classified (since we also have a now-dying[1] tradition of building motorway-standard roads and leaving them classified as N roads). In fact, on this last point, it's a good reason _not_ to tag for road quality. If you did, Ireland would have plenty of roads appearing on the map as motorway but not identifiable as such on the ground. Confused yet? Dermot [1] The majority of motorway-grade road not previously classified as motorway is being redesignated as motorway on 28th August, and most already appear as such on the ground. OSM is once again the first map to reflect this reality. -- -------------------------------------- Iren sind menschlich _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
