       for m in o.members
         if m.type == 'way'
           segmentIds.add(m.ref)
+
+    if o.type == 'node' and o.tags? and o.tags.natural?
+      naturalIds.add(o.id)
 
 
   pos = (id) -> node = obj[id]; return [node.lon, node.lat]

    geometry:
      type: 'LineString'
      coordinates: pos(n) for n in way.nodes
  }

  layer = (features) -> {type: 'FeatureCollection', features: features}

  obj = {}
  routeIds = d3.set()
  segmentIds = d3.set()
  naturalIds = d3.set()

  for o in osm.elements
    obj[o.id] = o

