One of the best data sources for mapping in the U.S. has been the Federal Railroad Administration's GIS Data http://fragis.fra.dot.gov/GISFRASafety/; and the most expansive data is the level crossing inventory. There's a few things in there that are documented that don't have tags yet, and I think they are useful. They are:
- key=crossing:cantilever - Values: yes/no - Description: Metal cantilever that extends over the road, and usually has a crossbuck/saltire and/or flashing lights mounted to it. - key=crossing:contact:emergency - Values: <string> - Description: A designated contact number for contacting emergency operators. - key=crossing:contact:railroad - Values: <string> - Description: A designated contact number for contacting the railroad. - key=crossing:contact:state - Values: <string> - Description: A designated contact number for contacting state government. - key=crossing:quiet_zone - Values: yes/no - Description: Locomotive engineers/operators are not to sound the horn at these crossings. There is often some sort of additional sound-producing device at these crossings. - Federal Railroad Administration page http://www.fra.dot.gov/Page/P0689 - key=crossing:traffic_signal - Values: control/interconnected/no - Description: In Urban environments, highway intersections and level crossings are often adjacent to each other and therefore the level crossing is integrated into the traffic signal controller. "control" is to indicate a crossing where traffic signals replace the typical alternating crossing lights and other standard protections. "interconnected" is when the traffic controller program will alter from typical operation when a train is approaching. It could be a red light for traffic in that direction, a temporary no right/left turn restriction, or a number of other scenarios. - key=crossing:wigwag - Values: yes/no - Description: Old type of crossing protection consisting of a pendulum swinging back and forth. There's approximately 100 left in service in the U.S. - Wikipedia page https://en.wikipedia.org/wiki/Wigwag_%28railroad%29
The inventory reports also list the count of crossing lights, crossbucks/saltires, and other such warning devices. I am unsure if these would be useful enough to tag, however.
In addition, the integration of traffic signals at highway intersections with level crossings leads to a problem of grouping together elements of the entire junction, or even just the level crossing with itself. This is a problem with highway junctions in general. I think it could be a good idea to co-opt the complex junction relation from Proposed_features/Junction https://wiki.openstreetmap.org/wiki/Proposed_features/Junction. This would also allow level crossings of multiple tracks to be grouped together. They way I would structure it is:
- Relation tagging: - key=type=junction - key=junction=level_crossing - key=ref:fra_crossing - Value: <string> - Note: While not an approved value, this is the value I have been using for marking the ID used in the FRA's Crossing Inventory. - Any of the tags used for the level_crossing node, as many of them are better applied to the relation than the node. - Relation roles: - (blank) - Used on: Anything else - Description: Used to include anything else that isn't listed below. The only thing I can think of that could be is the segment of track that is embedded in the roadway. I have tagged this in the past as key=embedded=yes/pavement/metal/wood/plastic (plastic includes rubber). The highway section between stop lines/traffic signals could be added as well, as I suppose those are part of the junction as well. - level_crossing - Occurance: 1 or more. - Used on: key=railway=level_crossing or key=railway=crossing - Description: This is where the railway track intersects a highway or pedestrian path. - traffic_signal - Occurance: 0 or more - Used on: highway=traffic_signals - Description: Any traffic signals that are part of this junction. This assumes that the traffic_signal is not mapped at the intersection of roadways. - stop_line - Occurance: 0 or More, mutually exclusive with traffic_signal - Used on: Nodes tagged with key=highway=stop_line - Description: This is where vehicles are to come to a stop, in cases where a traffic signal would not otherwise be tagged at this position. - location_hint - Occurance: Optionally one. Mutually exclusive with. - Used on: Any node. - Description: A hint to a renderer as to where a good place to put the the junction number or name on the map.
Anyways, just seeing what other thoughts you have. I cannot say that all of the terminology used in tags or roles are optimal.