"shell road" meaning in English

{
  "forms": [
    {
      "form": "shell roads",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "shell road (plural shell roads)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2005, Chris Rose, 1 Dead in Attic, Simon & Schuster, published 2015, page 22",
          "text": "You know, the kind of New Orleans rain that […] tamps down the dust of the old shell roads and washes down the oyster stink in the French Quarter gutters and slicks up all the playground equipment and makes New Orleans smell—is it possible?—so fresh.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A road with a bed or other layer made from shells."
      ],
      "id": "en-shell_road-en-noun-6NT~o~Ze",
      "links": [
        [
          "road",
          "road"
        ],
        [
          "bed",
          "bed"
        ],
        [
          "shell",
          "shell"
        ]
      ],
      "raw_glosses": [
        "(US) A road with a bed or other layer made from shells."
      ],
      "tags": [
        "US"
      ]
    }
  ],
  "word": "shell road"
}

{
  "forms": [
    {
      "form": "shell roads",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "shell road (plural shell roads)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "American English",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "Quotation templates to be cleaned"
      ],
      "examples": [
        {
          "ref": "2005, Chris Rose, 1 Dead in Attic, Simon & Schuster, published 2015, page 22",
          "text": "You know, the kind of New Orleans rain that […] tamps down the dust of the old shell roads and washes down the oyster stink in the French Quarter gutters and slicks up all the playground equipment and makes New Orleans smell—is it possible?—so fresh.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A road with a bed or other layer made from shells."
      ],
      "links": [
        [
          "road",
          "road"
        ],
        [
          "bed",
          "bed"
        ],
        [
          "shell",
          "shell"
        ]
      ],
      "raw_glosses": [
        "(US) A road with a bed or other layer made from shells."
      ],
      "tags": [
        "US"
      ]
    }
  ],
  "word": "shell road"
}