Proposal talk:Bridge Number

Archived Discussion

• What about when a railway bridge crosses over a canal? You have a canal bridge number and a railway bridge number. How would that be tagged? Perhaps there should be two tags, one for the "span" way and one for the way passing under the span. I guess there could even be multiple ways under the span that all use a different reference. --Thewinch 17:19, 3 February 2008 (UTC)

I considered this, but I thought it was so unlikely as to not be worth bothering with. To be honest, I doubt anyone is ever going to tag the railway bridge numbers. Canals are by far the major use for this. I guess we could have two tags like you suggest, or perhaps canal_bridge_ref and railway_bridge_ref, etc. But it seems like overkill. Gerv 22:53, 4 February 2008 (UTC)

Well,... You are passionate about canal boating. Other people are passionate about trains. There are currently tags under voting that enable people to map all the individual tracks in a railway yard, including their index number. It is not unlikely that people who want to tag that, also want to tag the bridge numbers of the railway. When I look at Wikipedia, the train and canal routing diagrams have about the same level of completeness, so it is not the lack of volunteers interested in such things. --Cartinus 17:28, 7 February 2008 (UTC)

When deciding what to map I generally evaluate how useful it will be and the time cost of collecting the info. Railway bridge refs would score pretty low on my useful scale but they might score high on the time cost scale. I'm stopping at the bridge anyway to record the canal ref, why not also record the railway ref if it only takes a couple of seconds longer? I just can't think up any good way of tagging both. Perhaps operator_ref for the railway and waterway_ref for the canal? --Thewinch 17:17, 15 February 2008 (UTC)

someone will want to do it. it's really not a huge change to allow both, and it allows us to tag more things. there may not be a railways nut on osm at the moment, but i guarantee some of them will get into just this, and far more (individual signals, junction numbers, overhead electric power lines,...), just as the canal buffs get into adding this sort of info. one of the key points of osm, is to make it as easy/flexible as possible for mappers. no-one is more important Myfanwy 09:31, 16 February 2008 (UTC)

• Is the tag on a node at the point of intersection, and is the node on the canal or on the railway(etc) or on both? The last is misleading since the railway does not intersect with the canal. The first two are considered poor mapping practice because they look like an intersection, but aren't. There could be a real difference, for instance if the towpath was included as a tag on the canal, a crossing footway may or may not connect with it. I think the least bad option, but still not nice, is to put the bridge_ref tag on a canal node slightly displaced from the crossing point. Chrismorl 15:03, 15 February 2008 (UTC)

• I presume the tag would be on the bridge way. --Thewinch 17:17, 15 February 2008 (UTC)

Or we could solve that problem by putting the railway_ref and the canal_ref in a bridge relation. --Cartinus 20:11, 15 February 2008 (UTC)

• I anticipated the tag being on the bridge way. I agree that an intersection node is bad practice; I don't want to encourage that. If people really think we need _ref tags for both, I suggest over_ref and under_ref. That's probably the easiest terminology to understand. Gerv 09:42, 16 February 2008 (UTC)