"flat crossing" meaning in English

{
  "forms": [
    {
      "form": "flat crossings",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "flat crossing (plural flat crossings)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "British English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Rail transportation",
          "orig": "en:Rail transportation",
          "parents": [
            "Transport",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A crossing where two railway lines cross each other on the same level."
      ],
      "id": "en-flat_crossing-en-noun-DZ01VCIF",
      "links": [
        [
          "rail transport",
          "rail transport"
        ]
      ],
      "raw_glosses": [
        "(rail transport, UK) A crossing where two railway lines cross each other on the same level."
      ],
      "synonyms": [
        {
          "word": "diamond crossing"
        },
        {
          "word": "diamond junction"
        },
        {
          "word": "flat junction"
        },
        {
          "word": "level junction"
        }
      ],
      "tags": [
        "UK"
      ],
      "topics": [
        "rail-transport",
        "railways",
        "transport"
      ],
      "wikipedia": [
        "Newark flat crossing",
        "flat crossing"
      ]
    }
  ],
  "word": "flat crossing"
}

{
  "forms": [
    {
      "form": "flat crossings",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "flat crossing (plural flat crossings)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "British English",
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "en:Rail transportation"
      ],
      "glosses": [
        "A crossing where two railway lines cross each other on the same level."
      ],
      "links": [
        [
          "rail transport",
          "rail transport"
        ]
      ],
      "raw_glosses": [
        "(rail transport, UK) A crossing where two railway lines cross each other on the same level."
      ],
      "tags": [
        "UK"
      ],
      "topics": [
        "rail-transport",
        "railways",
        "transport"
      ],
      "wikipedia": [
        "Newark flat crossing",
        "flat crossing"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "diamond crossing"
    },
    {
      "word": "diamond junction"
    },
    {
      "word": "flat junction"
    },
    {
      "word": "level junction"
    }
  ],
  "word": "flat crossing"
}