{
  "slug": "tt001.us-gateways.arrivals",
  "name": "Berthings per day at US gateways",
  "unit": "berthings/day",
  "horizon": "short",
  "grade": "observed",
  "grade_means": "We watched it happen: our own AIS receivers (via the aisstream.io terrestrial network), our timestamps, our archive.",
  "description": "Count of merchant vessels observed coming alongside per day at the monitored US container gateways. Merchant vessel = AIS ship-type 70-79 (cargo) and 150 m or longer. Without that filter this count is dominated by tugs.",
  "instrument": {
    "id": "TT-001",
    "name": "Gateway watch",
    "clock": "fast",
    "role": "reporter",
    "source": "AISstream.io → own recorder",
    "source_url": "https://ais.trimtabist.com"
  },
  "coverage": {
    "from": "2026-07-26",
    "to": null
  },
  "publishable_ranges": [],
  "status": "suspended",
  "withdrawn": {
    "since": "1970-01-01",
    "until": null,
    "reason": "SUPERSEDED. Computed from the crew-set NavigationalStatus field and the old event state machine, both disproven 2026-07-30: the status field recorded 153 anchor events against 3,273 berth events because crews rarely set it, and the state machine split single calls into fragments on speed noise. Replaced by position-based detection in berthing.db — see tt001.gateway.* and berthing/METHOD.md.",
    "finding": null
  },
  "citation": "Trimtab TT-001 Gateway watch, own-recorded AIS.",
  "citationShort": "Trimtab TT-001 Gateway watch, \"Berthings per day at US gateways\" (retrieved 2026-08-06).",
  "licence": "CC BY 4.0",
  "retrieved_at": "2026-08-06T13:50:50.967Z",
  "urls": {
    "page": "https://trimtabist.com/series/tt001.us-gateways.arrivals",
    "csv": "https://trimtabist.com/series/tt001.us-gateways.arrivals.csv",
    "metadata": "https://trimtabist.com/series/tt001.us-gateways.arrivals.metadata.json"
  }
}