> ## Documentation Index > Fetch the complete documentation index at: https://www.worldmonitor.app/docs/llms.txt > Use this file to discover all available pages before exploring further. # China Logistics Corridors > Four reviewed China logistics corridors, six source families, composition rules, provenance, freshness, and API behavior. The [China logistics control towers](/docs/api-reference/supplychainservice/getchinacorridorcontroltowers) are transparent source compositions over reviewed geographic corridors. They report evidence availability and freshness by family. They do not generate an opaque logistics-risk score, forecast disruption, or infer activity from source presence alone. ## Reviewed corridors | Corridor ID | Name | Reviewed scope | | - | - | - | | `china-yangtze-river-delta` | Yangtze River Delta | Shanghai, Jiangsu, and Zhejiang ports, aviation, and advanced-manufacturing nodes | | `china-greater-bay-area` | Greater Bay Area | Guangdong, Hong Kong, and Macao-facing ports, airports, hazards, and industrial gateways | | `china-bohai-rim` | Bohai Rim | Beijing-Tianjin, Hebei, Shandong, and Liaoning maritime-industrial gateways | | `china-western-land-sea-corridor` | Western Land-Sea Corridor | Inland manufacturing hubs, Xinjiang land crossings, and Guangxi maritime gateways | Each corridor has a reviewed polygon, node registry, node owner, and source selector. A source record contributes only when its selector or reviewed geography maps it to that corridor. National inputs are clearly marked as national and can apply to all four corridors. ## Six signal families | Family ID | Source contract | Scope and observation | | - | - | - | | `port` | IMF PortWatch | Reviewed China/Hong Kong port IDs; calls, DWT measures, trend deltas, and anomaly flag when published | | `aviation` | AviationStack | Reviewed PEK, PVG, CAN, SZX, CTU, KMG, URC, and HKG provider coverage | | `hazard` | Western Pacific cyclone sources and Hong Kong Observatory | Events inside a corridor boundary plus explicit HKO warning coverage for the Greater Bay Area | | `power_energy` | WorldMonitor energy spine | National China energy dependency coverage, latest source observation time, and the observed year-over-year oil-product demand change with its own period end when published | | `strategic_industry` | UN Comtrade | Annual strategic-product observations for reporter 156 | | `trade` | UN Comtrade and Shanghai Shipping Exchange CCFI | Annual reporter-156 trade observations, the current China Containerized Freight Index, and its period-over-period change — the exchange's own percentage, or the change between two period levels it published — with the prior period it was measured against | IMF PortWatch and AviationStack are node-scoped. Hazard observations are regional. WorldMonitor energy spine, UN Comtrade, and Shanghai Shipping Exchange inputs are national. The output keeps those scopes visible rather than presenting national evidence as a measured node value. ## Availability composition Every source signal carries: * publisher identity and class; * source URL when applicable; * node, regional, or national scope; * observation, release, and retrieval time with precision; * revision metadata when available; * transport and content freshness; * an inspectable summary and source metrics. Each family condition is `available`, `partial`, `stale`, or `unavailable`. A corridor is: * `available` only when all six conditions are available; * `stale` when every condition is available or stale and at least one is stale; * `unavailable` when all six are unavailable; or * `partial` for every mixed or provenance-invalid state. An absent configured port or airport becomes an explicit unavailable signal. A healthy feed with zero hazards can establish feed coverage, but it does not create a hazard event. Energy-spine coverage flags do not establish an activity direction; only an explicitly published demand change does, and it is dated by its own period end rather than by the family's latest source timestamp. A current CCFI level without a prior comparison does not become a freight change. ### China energy-demand change contract The published JODI demand change is a same-month year-over-year percentage. Its basket sums `TOTDEMO` for the available `GASOLINE`, `GASDIES`, `JETKERO`, `RESFUEL`, and `LPG` secondary products. At least three products must be available in both comparison months with the identical basket; a change beyond ±50% is refused as an implausible reporting or unit error. The source signal keeps the product list and current/prior `kbd` totals in provenance, while the directional value is labeled `% change`. ## Freshness budgets The composer evaluates source timestamps at request time: | Input | Transport budget | Content handling | | - | - | - | | PortWatch | 36 hours | Individual observations stale after 72 hours | | AviationStack | 90 minutes | Individual observations stale after 180 minutes | | Western Pacific hazards / HKO | 9 hours | Observations stale after 9 hours | | Energy spine | 48 hours | Year/month/day precision gets a corresponding periodic budget | | UN Comtrade | 48 hours | Annual observations use a 550-day budget | | CCFI | 7 hours | Index content stale after 28 days | Transport freshness proves that collection ran. Content freshness proves that the observation itself is timely. Neither substitutes for the other. ## API and caching `GET /api/supply-chain/v1/get-china-corridor-control-towers` reads the canonical Redis source seeds in one batch and isolates missing dependencies. It validates every composed provenance envelope before returning the wire payload. Healthy aggregates use a five-minute server cache. An all-unavailable result is not positively cached, so a recovery can appear immediately. The client circuit breaker deliberately retains no last-good aggregate that could hide a current fail-closed response. The panel refresh interval is 15 minutes. The response exposes `upstreamUnavailable: true` only when every corridor is unavailable. Partial corridor evidence remains inspectable rather than being collapsed into total outage or false health. This detailed control-tower response is a REST/UI surface. MCP has no dedicated corridor-control-tower tool; Pro MCP receives only its bounded contribution to `get_china_decision_signals`. ## Relationship to the nowcast The [China Activity Nowcast](/docs/methodology/china-activity-nowcast) can use a corridor-family breadth change only when a comparable prior corridor snapshot exists. The control-tower response itself remains a source composition and does not publish a directional economic conclusion.