Talk:Proposed features/Level crossing

From OpenStreetMap Wiki
Jump to: navigation, search

It could be used for map rendering, and giving additional information to spoken or routing instructions, but for actual route planning, there should be no need for it, since unless your vehicle is defined as allowing to travel along both highways and railways (and there are some such vehicles, mostly used for railway maintenance), then it will not attempt to take that route.

Welshie 09:41, 18 September 2006 (BST)

railway=level_crossing, is good. junction=level_crossing might work also (but probably implies that you might turn from rail to road or vice versa). I would see level crossing as a warning to users of both the railway and the road. Some consideration of the beacons and barriers at the crossing is worth considering. (and an example is offered below) Rw 17:34, 11 November 2006 (UTC)

Levelcrossing.png

Lots of examples at wikipedia:Level crossing. Ojw 18:31, 11 November 2006 (UTC)

If the tag is just railway=level_crossing, then this would have to asume that it was a certain railway type. Narrowgage, monorail and all other sorts may render differnt on the map, and then not each have there own type of railcrossing. Therefore would it not work better if the levelcrossing was added as a 'feature=' or 'structure=' (additional proposed feature). So the railway can be speicifed and the highway, and then the levelcrossing added to each. Ben. 19:03, 11/11/2006 (UTC)

The wikipedia link above includes an example of a level crossing of a road + tramway and a rail line. A level_crossing, like a road junction need not define the connecting way types explicitly; they are defined by the connected ways.
So is this tag being proposed to be added to the road that is crossing? (e.g. highway=secondary railway=levelcrossing). Just tagging a node would seem incorrect, as its a phisical feature. I think it needs to be attached to the road, so a route planner notes it in the route. This could just be one of the many many things that is just a feature along the way, and features as a key has been proposed. Ben. 03:57, 18/12/2006 (UTC)
But a level crossing is just a "junction" between a road and railway that is at-grade. Surely the level crossing should therefore be just a node - or pair of nodes for a dual-carriageway road - which lies both on the road and rail lines. The node should be tagged railway=level_crossing, it doesn't matter then what is connected to those nodes - one obviously is going to be a railway, the other a road or perhaps a footpath. Most maps, a level crossing is shown by appending an "LC" written on the map adjacent to the actual level crossing - with the rail usually rendered above the road on the final map. E.g. see this one on the A27 in South East England Richard B 13:03, 19 December 2006 (UTC)


finalized Discussion

Can someone explain why we need this? If you have road and railroad segments/way connected to the same node, thats a level crossing. What else can it be? If there is a bridge, you would not connect the road and railroad segments to each other. Do we really need to tag this specifically? Joto 21:56, 19 December 2006 (UTC)

Take a look at any map showing a level crossing; you usually see something like "LC" appended in letters on the map next to the crossing so that you can instantly see at a glance which road crossings are level crossings, and which just simply have the rails going over the road. Remember that nodes do not appear on the final rendered map.Richard B 01:31, 20 December 2006 (UTC)
I have never seen the LC label, maybe its an UK thing. But that really doesn't matter. What my argument ist: The fact that it is a level crossing can be inferred from the way the segments/ways attached to the node are labelled. Introducing another label on the node doesn't add any information, in fact it makes it more difficult, because what do you now do with such crossings which are not labelled? How would you render those? Joto 13:53, 20 December 2006 (UTC)
At the data level is possible to differentiate a level crossing from a bridge because in the former the ways intersect at a node and in the latter they don't, however with the current renderings from Osmarender and Mapnik it is impossible to tell whether the junction of a highway and a railway is a bridge (two ways crossing) or a level crossing (two ways intersecting at a node), see the maps of Baldock and Foxton. In the Baldock map these are all bridges (both over and under), in the Foxton map this is a level crossing, I know this because I know the area but I cannot differentiate it on the rendering. Tagging the junction node so that the level crossings can be rendered with a distinct symbol resolves this ambiguity, and it is substantially easier to render a tagged node rather than render a node based on the ways that connect to or pass through it. Whilst a level crossing can be inferred from the existence of a junction node, having the node tagged also allows further properties to be added at a later date such as whether the crossing is manned or unmanned, has gates, barriers, half barriers or neither, lights or no indicators whatsoever or in the case of crossings on tracks whether the gates are locked. --Batchoy 14:44, 20 December 2006 (UTC) (Updated 22:56, 26 December 2006 (UTC))
Tagging level crossings would be useful to indicate the presence of safety equipment like warning lights and barriers, the train traffic density, and other related metadata. --Tml 01:22, 7 October 2007 (BST)
As a first priority, we are building a street_map, and the railroads+stations data are only entered into the database as destinations and as point of attention/danger. In Belgian signalling regulations, *any* same-level crossing between rail and road is considered one of 5 level crossing categories. It would be possible to add this detail, but I believe only the rail-road infrastructure company has that data and it would be impossible to enter it all. In conclusion, I would also be against the "level_crossing" element on itself for now. The rail track being locally on a bridge or in a tunnel should definitely be solved using the layer=1 or layer=-1 key and the tunnel or bridge constructs? Secondly, I agree on Tml's remark where the potential of this openmap is considered (also for rail traffic planning, travel times between stations, densities, etc.), yet I think first things first. -- Orwall 22:17, 13 January 2008 (BST)
I disagree that railways should be de-emphasized. There are plenty of OSM users and surveyors who are rail passengers, and the inclusion of comprehensive rail information adds only a small proportion to the total database. The rail network in certain areas (e.g. UK) is nearly complete, and may soon be sufficient for routing purposes. --alastairj 22:00, 13 March 2008 (UTC)

Please note that there is no explicit osmarender rule for this tag and it is currently rendered automatically based on a railway (except a tram) sharing a node with a highway. To disable this, I believe you need to add osmarender:render=no tag. --Dean Earley 13:06, 4 December 2007 (UTC)

Shouldn't this be moved to Deprecated Features? It's not useful neither for routing nor rendering. And in current state it can't be used for railway metadata, as Tml suggested. --Jttt 06:43, 29 April 2008 (UTC)

Disagree with what you say here. Mapnik gives the tag a specific symbol, so it is currently useful and used for rendering. In the UK at least the concept is well-understood by the general public and there are typically specific pieces of safety equipment, signage and signal lighting associated with them (not to mention specific legal restrictions). They make good landmarks, and being able to instruct a driver to "turn left after the level crossing" would be helpful for routing apps. Finally, I fail to see how this piece of railway metadata can't be used for railway metadata.
You're right about rendering. I thought mapnik renders level crossing icon at every node shared by road and railway like osmarender does.
The problem with level_crossing is that it's redundant. When you have two roads sharing one node then you don't have to say it's junction, it's implied. You only add some tags when you have additional information about junction - like traffic lights or roundabout. It should the same with road and railway crossing. level_crossing tag would make sense if it had additional information about crossing - like no safety device/lights/barriers. --Jttt 08:23, 2 May 2008 (UTC)
You could of course argue that this could just as easily be done with derived data rather than explicit tagging provided that mappers always place a Node at the 'junction' of the railway and the other Way to distinguish it from the (non-joining) bridge or tunnel conventions currently in use. I kinda like distinguishing the unfinished case from the finished, tagged case though: it's useful to be able to go out and correct/verify the map in a targeted way. The Wiki way as applied to models of the real world, as it were. --achadwick 10:58, 29 April 2008 (UTC)