The figures on this page are presentation values: a transparent proxy calculated from public IMF PortWatch traffic data, using the method shown below. They are not SCFL operator-derived measurements. UCMS readings appear only where marked, each with its own date.
Global Shipping Flow Observatory
Network
Chokepoint flow against the 2025 reference year
Six chokepoints that carry a large share of seaborne trade. Traffic is compared with each chokepoint's own typical level in 2025.
Tonnage-weighted average of each chokepoint's current traffic as a share of its 2025 typical level.
Readings are posted by UCMS on their own schedule and dated. They are separate from the presentation values on this page.
Chokepoints
Current flow by chokepoint
Flow is the latest 7-day average of daily transits as a share of the 2025 typical level. Mix shift shows how far the ship-type mix has moved from 2025 (0 = same mix, 1 = entirely different).
| Chokepoint | Flow state | Transits / day (7-day avg) | 2025 typical | Flow vs 2025 | Mix shift | Last 180 days | UCMS reading |
|---|---|---|---|---|---|---|---|
| Loading live traffic from IMF PortWatch… | |||||||
Linked routes
Red Sea and Cape of Good Hope
Suez and the Cape of Good Hope are alternative routes between Asia and Europe. When one falls while the other rises, ships are rerouting and the network is reorganizing.
of 2025 typical flow
of 2025 typical flow
Shown when one route is below 90% of typical while the other is above 110%.
Method
How the presentation values are calculated
Every value above follows this recipe, using public data only. It is a proxy for traffic conditions and contains no SCFL operators.
FOR each chokepoint c:
daily = PortWatch transits per day (all ship types)
current = average of daily over the latest 7 days
reference = median of 7-day averages, 1 Jan – 31 Dec 2025
flow = current / reference # 1.00 = typical
mix_now = share of each ship type, latest 28 days
mix_ref = share of each ship type, 2025
mix_shift = ½ × Σ |mix_now − mix_ref|
state = Normal flow if flow ≥ 0.90
Reduced flow if 0.60 ≤ flow < 0.90
Constrained flow if 0.20 ≤ flow < 0.60
Near-closed if flow < 0.20
NETWORK FLOW INDEX
weight(c) = average daily tonnage of c in 2025
index = 100 × Σ weight(c) × flow(c)
/ Σ weight(c)
REROUTING SIGNAL (Suez ↔ Cape of Good Hope)
shown if one flow < 0.90
and the other flow > 1.10
Data: IMF PortWatch Daily Chokepoints Data
(UN Global Platform; IMF PortWatch)
Refresh: on every page load
Notes
Not a forecast or an alarm. Flow states describe current traffic only. They say nothing about what happens next.
Note on terminology. Earlier UCMS maritime work, including the HCDI 1.2 paper, used the phrase "public early-warning layer." That wording was not intended to describe an early-warning system (EWS). It referred to a structural layer reading only.
Data limits. PortWatch figures come from vessel AIS signals and are published with a delay of several days. Ships that switch off transponders may be undercounted.