---
style:
  layers:
    - id: bbg-boundary
      type: line
      filter:
        - all
        - - any
          - [==, [get, "admin_level"], "4"]
      line-cap: round
      line-color: "#f63c"
      line-width: 4
    - id: gravel
      type: line
      filter:
        - all
        - [==, [get, highway], track]
      line-cap: round
      line-width:
        - case
        - - all
          - [==, [get, tracktype], grade3]
          - [==, [get, surface], compacted]
          - [==, [get, smoothness], bad]
        - 3
        - - match
          - [get, tracktype]
          - grade2
          - 3
          - grade3
          - 2
          - 1
        
      line-color:
        - case
        - - all
          - [==, [get, tracktype], grade3]
          - [==, [get, surface], compacted]
          - [==, [get, smoothness], bad]
        - "#448"
        - - match
          - [get, tracktype]
          - grade2
          - "#448"
          - grade3
          - "#66a"
          - black
---

rel(62504) -> .bbg;

(.bbg;);

out geom;

.bbg map_to_area -> .boundary;

way(area.boundary)
  ["highway"="track"]
  ["tracktype"~"(grade2|grade3)"]
  ["surface"~"(compacted|gravel|fine_gravel)"] 
  -> .filtered_tracks;

(
  way.filtered_tracks["smoothness"~"^(intermediate|bad)"];
  way.filtered_tracks[!smoothness];
);

out geom;