{
  "params": {
    "piece": {
      "type": "choice",
      "options": [
        "straight",
        "corner",
        "t-junction",
        "crossroads",
        "crosswalk",
        "dead-end"
      ],
      "default": "crossroads",
      "label": "Piece",
      "describe": "straight (runs N-S), corner (bend joining S and E), t-junction (E-W through road with a side road to S), crossroads (all four edges), crosswalk (straight with a zebra crossing and tactile paving), dead-end (road from S ending in a round turning bulb)."
    },
    "lanes": {
      "type": "choice",
      "options": [
        2,
        4
      ],
      "default": 2,
      "label": "Lanes",
      "describe": "2 lanes of 3.5 m on a 10 m tile, or 4 lanes of 3.5 m on a 20 m tile (a 2 x 2 block of grid cells). Do not mix them on one edge."
    },
    "sidewalk": {
      "type": "toggle",
      "default": true,
      "label": "Sidewalk",
      "describe": "Raised paved sidewalks with a 15 cm concrete curb. Off gives low grass verges at road level (suburban or rural edge) and white edge lines."
    },
    "lines": {
      "type": "choice",
      "options": [
        "dashed",
        "double yellow",
        "none"
      ],
      "default": "dashed",
      "label": "Lines",
      "describe": "Road markings: dashed (white dashed centre line, European style), double yellow (solid double yellow centre, American style), none (unmarked lane). Lane dividers on 4 lanes are dashed white; junction arms get stop lines."
    }
  },
  "presets": {
    "downtown crossing": {
      "piece": "crosswalk",
      "lanes": 4,
      "lines": "double yellow"
    },
    "country bend": {
      "piece": "corner",
      "sidewalk": false,
      "lines": "dashed"
    },
    "cul-de-sac": {
      "piece": "dead-end",
      "lines": "none"
    }
  },
  "night": null
}