{
  "edition": "2026-11-07",
  "id": "jre-e721",
  "locale": "ja",
  "url": "https://senroam.com/ja/trains/jre-e721/",
  "name": "E721 · Sendai · 仙台",
  "summary": "E721 · Sendai · 仙台 · 地方線区のホームに合わせて床面を低くした。仙台空港アクセス用の500番代は車内の荷物置場にも注目。",
  "type": "train",
  "questions": [],
  "sources": [
    {
      "url": "https://www.jreast.co.jp/train/local/e721.html",
      "checked": "2026-11-07",
      "lang": "ja"
    }
  ],
  "detail": "地方線区のホームに合わせて床面を低くした。仙台空港アクセス用の500番代は車内の荷物置場にも注目。",
  "technical": {
    "record": [
      [
        "E721",
        9,
        "120 km/h",
        "e721"
      ],
      [
        "E721 · 0 / 500 / 1000",
        13,
        [
          "Lowered passenger floor",
          "低床化した客室床面"
        ],
        "e721"
      ]
    ],
    "sources": [
      {
        "id": "813",
        "title": "813系電車ロングシート化します",
        "publisher": "JR九州",
        "url": "https://www.jrkyushu.co.jp/news/__icsFiles/afieldfile/2023/11/30/231130_813_long-seat.pdf",
        "source_language": "ja",
        "effective_date": "2023-11-30",
        "locator": "§1",
        "supports": "Converted three-car set; 120 longitudinal and 28 box seats.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "815",
        "title": "社会・産業・家庭",
        "publisher": "日立評論",
        "url": "https://www.hitachihyoron.com/jp/pdf/2000/01/2000_01_06.pdf",
        "source_language": "ja",
        "effective_date": "2000-01",
        "locator": "九州旅客鉄道株式会社納め815系電車",
        "supports": "A-train, FSW aluminium double-skin body, IGBT equipment; delivered June–September 1999.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "817",
        "title": "最近の鉄道車両 A-train",
        "publisher": "日立評論",
        "url": "https://www.hitachihyoron.com/jp/pdf/2003/08/2003_08_02.pdf",
        "source_language": "ja",
        "effective_date": "2003-08",
        "locator": "Opening figure, 817系電車",
        "supports": "817 belongs to the A-train aluminium vehicle system.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "821",
        "title": "第8回グリーンボンド レポーティング",
        "publisher": "JR九州",
        "url": "https://www.jrkyushu.co.jp/company/ir/library/greenbond/pdf/241218_8th_greenbond_reporting_jp.pdf",
        "source_language": "ja",
        "effective_date": "2024-03-31",
        "locator": "821系車両新製",
        "supports": "SiC main circuit; March 2019 service entry Kokura–Arao.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "701",
        "title": "701系",
        "publisher": "JR東日本",
        "url": "https://www.jreast.co.jp/train/local/701.html",
        "source_language": "ja",
        "effective_date": null,
        "locator": "車両紹介",
        "supports": "AC train; standard-gauge variants for mini-Shinkansen corridors.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "e127",
        "title": "E127系",
        "publisher": "JR東日本",
        "url": "https://www.jreast.co.jp/train/local/e127.html",
        "source_language": "ja",
        "effective_date": null,
        "locator": "車両紹介",
        "supports": "Two-car minimum; three doors per side; semi-automatic door operation.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "e129",
        "title": "E129系",
        "publisher": "JR東日本",
        "url": "https://www.jreast.co.jp/train/local/e129.html",
        "source_language": "ja",
        "effective_date": null,
        "locator": "基本情報・車両紹介",
        "supports": "DC; 110 km/h; E233 technology.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "e131",
        "title": "相模線E131系車両の概要",
        "publisher": "JR東日本",
        "url": "https://www.jreast.co.jp/press/2021/yokohama/20210917_y1.pdf",
        "source_language": "ja",
        "effective_date": "2021-09-17",
        "locator": "別紙2 comparison table",
        "supports": "Sagami 4 cars 2M2T; Boso/Kashima 2 cars 1M1T; 2950 mm; stainless steel; 110 km/h; SiC VVVF, enclosed induction motors.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "e721",
        "title": "E721系",
        "publisher": "JR東日本",
        "url": "https://www.jreast.co.jp/train/local/e721.html",
        "source_language": "ja",
        "effective_date": null,
        "locator": "基本情報・車両紹介",
        "supports": "120 km/h; 0,500,1000 subseries, lower passenger floor.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "ginza",
        "title": "東京メトロ 銀座線1000系 主要諸元",
        "publisher": "東京メトロ",
        "url": "https://www.tokyometro.jp/corporate/enterprise/passenger_rail/cars/working/ginza_1000/pdf/specifications.pdf",
        "source_language": "ja",
        "effective_date": "2023-03-31",
        "locator": "p.1, specification table",
        "supports": "Six cars; 16000 ×2598 ×3465 mm; PMSM, VVVF; 80 km/h design speed; 3.3 km/h/s acceleration.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      },
      {
        "id": "tram",
        "title": "フォトギャラリー",
        "publisher": "鹿児島市交通局",
        "url": "https://www.kotsu-city-kagoshima.jp/cust-photo/",
        "source_language": "ja",
        "effective_date": null,
        "locator": "1000形・7500形 vehicle specification tables",
        "supports": "7501–7504 dimensions and motor rating; 1011 dimensions.",
        "checked": "2026-11-07",
        "rights": "Consulted for facts. No source text or artwork redistributed."
      }
    ]
  },
  "engineering": {
    "record": {
      "scope": {
        "en": "E721 low-floor design; monitoring adaptation is a specific development project.",
        "ja": "E721系の低床設計。監視装置の改良は個別の開発案件として記載。"
      },
      "facts": [
        {
          "label": {
            "en": "Platform interface",
            "ja": "ホームとの関係"
          },
          "value": {
            "en": "The low floor removes the internal entrance step at lower regional platforms.",
            "ja": "地方線区の低いホームに合わせて低床化し、出入口の車内段差を解消。"
          },
          "sources": [
            "regional:reg-e721-profile"
          ]
        },
        {
          "label": {
            "en": "Door technology",
            "ja": "戸閉方式"
          },
          "value": {
            "en": "JR East identifies pneumatic doors in its cold/snow-door development comparison.",
            "ja": "JR東日本の耐寒・耐雪ドア開発比較では空気式ドアの採用車として記載。"
          },
          "sources": [
            "regional:reg-cold-doors"
          ]
        },
        {
          "label": {
            "en": "Monitoring clearance",
            "ja": "監視装置の搭載余裕"
          },
          "value": {
            "en": "Existing optical track monitors exceeded the low-floor vehicle installation envelope; layout and optical geometry were redesigned.",
            "ja": "従来の光学式線路監視装置は低床車の艤装限界に支障し、機器配置と光学寸法を見直した。"
          },
          "sources": [
            "regional:reg-e721-monitor"
          ]
        }
      ],
      "insights": [
        {
          "title": {
            "en": "Accessibility changes underfloor engineering",
            "ja": "低床化が床下設計にも及ぼす影響"
          },
          "text": {
            "en": "The monitoring study shows why a lower passenger floor also changes sensor packaging. The paper reports a planned installation, not fleet-wide fitment.",
            "ja": "監視装置研究は、客室の低床化がセンサ配置にも影響することを示す。論文は搭載計画の報告で、全車装備を意味しない。"
          },
          "sources": [
            "regional:reg-e721-monitor"
          ]
        }
      ],
      "gaps": [
        "Exact motor and auxiliary-converter models remain unverified from accessible original sources.",
        "Monitoring paper describes planned 2018 installation; present deployment is not established by that paper."
      ]
    },
    "sources": {
      "regional:reg-e721-profile": {
        "title": "JR東日本会社要覧2017–2018：車両",
        "publisher": "JR東日本",
        "url": "https://www.jreast.co.jp/youran/pdf/2017-2018/jre_youran_group_p21-26.pdf",
        "date": "2017",
        "language": "ja",
        "locator": "E721系",
        "checked": "2026-11-07"
      },
      "regional:reg-cold-doors": {
        "title": "耐寒・耐雪電気式ドアの開発",
        "publisher": "JR東日本",
        "url": "https://www.jreast.co.jp/development/theme/safety/pdf/safety15.pdf",
        "date": "2022",
        "language": "ja",
        "locator": "空気式・電気式ドア比較表",
        "checked": "2026-11-07"
      },
      "regional:reg-e721-monitor": {
        "title": "線路設備モニタリング装置の改良に関する研究開発",
        "publisher": "JR東日本・JR EAST Technical Review 62",
        "url": "https://www.jreast.co.jp/development/tech/pdf_62/tech-62-27-32.pdf",
        "date": "2019",
        "language": "ja",
        "locator": "§2.2、図3、pp.27–32",
        "checked": "2026-11-07"
      }
    },
    "checked": "2026-11-07"
  },
  "literature": []
}