[openrailwaymap] Level Crossing suggestions

[Erich Pfistner]

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.
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