"track bed" meaning in English

{
  "forms": [
    {
      "form": "track beds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "track bed (plural track beds)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "trackbed"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2022 September 7, “East–West track laying heads westwards”, in Rail, number 965, Peterborough, Cambridgeshire: Bauer Media, →ISSN, →OCLC, page 36:",
          "text": "The Bicester–Bletchley section is being rebuilt on the alignment of the line that closed to passengers in 1968. Since 2019, the track bed and bridges have been rebuilt, and this work is mostly complete.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Alternative form of trackbed"
      ],
      "id": "en-track_bed-en-noun-b976nv2A",
      "links": [
        [
          "trackbed",
          "trackbed#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "track bed"
}

{
  "forms": [
    {
      "form": "track beds",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "track bed (plural track beds)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "trackbed"
        }
      ],
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "examples": [
        {
          "ref": "2022 September 7, “East–West track laying heads westwards”, in Rail, number 965, Peterborough, Cambridgeshire: Bauer Media, →ISSN, →OCLC, page 36:",
          "text": "The Bicester–Bletchley section is being rebuilt on the alignment of the line that closed to passengers in 1968. Since 2019, the track bed and bridges have been rebuilt, and this work is mostly complete.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Alternative form of trackbed"
      ],
      "links": [
        [
          "trackbed",
          "trackbed#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "track bed"
}