Add usage_count to map layer obs_roads

tile-generator/layers/obs_roads/layer.sql

@@ -8,6 +8,7 @@ RETURNS TABLE(
   distance_overtaker_median float,
   distance_overtaker_array float[],
   overtaking_event_count int,
+  usage_count bigint,
   direction int,
   offset_direction int
 ) AS $$
@@ -21,6 +22,7 @@ RETURNS TABLE(
       PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY distance_overtaker) as distance_overtaker_median,
       array_agg(distance_overtaker) as distance_overtaker_array,
       count(overtaking_event.id)::int as distance_overtaker_count,
+      (select count(id) from road_usage where road_usage.way_id = road.way_id) as usage_count,
       r.dir as direction,
       case when road.directionality = 0 then r.dir else 0 end as offset_direction
     FROM road

tile-generator/layers/obs_roads/obs_roads.yaml

@@ -16,6 +16,8 @@ layer:
       All overtaker distance values in meters.
     overtaking_event_count: |
       Number of overtaking events.
+    usage_count: |
+      Number of times the road was traveled on.
     direction: |
       Contains -1 for events while going along the way backwards, 1 for
       forwards. Each road is emitted twice, if it has data for both directions,
@@ -40,6 +42,7 @@ layer:
           distance_overtaker_median,
           distance_overtaker_array,
           overtaking_event_count,
+          usage_count,
           direction,
           offset_direction
         FROM layer_obs_roads(!bbox!, z(!scale_denominator!))