[
  {
    "vehicle_type": "Single-unit truck (box / dump)",
    "count": 339
  },
  {
    "vehicle_type": "Tractor + semi-trailer (big rig)",
    "count": 155
  },
  {
    "vehicle_type": "Single-unit truck w/ trailer",
    "count": 42
  },
  {
    "vehicle_type": "Tractor (bobtail)",
    "count": 34
  }
]