IN BRIEF
AIS tracking measures potential and effective route capacity.
Utilization losses appear months before visible port congestion.
Macroeconomic costs are model estimates, not directly observed losses.
WHY IT MATTERS
Supply chains can deteriorate before conventional indicators show it.
Physical vessel measures may give companies and governments an earlier warning signal.
WHAT IS NOW POSSIBLE
Before: shipping shocks were largely inferred from prices and congestion. Now: vessel movements provide an earlier physical measure of capacity loss and reallocation, revealing costs before ports visibly clog.
WHAT MADE IT POSSIBLE
Satellite AIS data for U.S.-bound container ships from 2016–2025.
A model that explicitly represents fleet reallocation and congestion.
THE STORY
A maritime logistics crisis can already be under way while ports still look normal. A new study reconstructs route-level capacity for U.S.-bound container shipping and finds utilization losses of 20–40 percentage points beginning months before visible congestion.
The authors use ship AIS signals to separate potential capacity from capacity actually deployed. That reveals how carriers reallocate a common fleet when one route is disrupted.
Putting these measurements into a general-equilibrium model, they estimate that the 2021 West Coast crisis cost 0.69% of output and the 2023–2024 Red Sea attacks 0.35%.
The model also values naval protection of Red Sea shipping at 0.04–0.08% of output against a fiscal cost of 0.02%.
Those macroeconomic numbers are not direct observations; they depend on the model. The strongest observable result is the early physical signal in shipping routes, which can reveal disruption before port bottlenecks become obvious.
WHAT WE KNOW
Real vessel movements show large utilization losses during recent disruptions. [1][2]
The decline can begin months before port congestion.
Fleet reallocation is a material part of the response to disruption.
WHAT WE DON'T KNOW
How precise the aggregate welfare and output estimates are.
How well the model generalizes beyond U.S.-bound routes.
Whether AIS indicators can become reliable operational early-warning systems.
WHAT HAPPENS NEXT
Test the method on other maritime networks.
Compare AIS signals with prices, inventories and delivery times.
Validate structural estimates against future logistics shocks.
SOURCE TRACE
The authors estimate utilization losses of 20–40 percentage points in recent U.S.-bound shipping disruptions, beginning months before port congestion became visible.
The structural model estimates output costs of 0.69% for the 2021 West Coast crisis and 0.35% for the 2023–2024 Red Sea attacks.
SOURCES
- Shipping to AmericaOpen source
- Shipping to AmericaOpen source
CURRENT EVIDENCE
EARLY EVIDENCE
REAL-WORLD MEASUREMENT / MODEL-BASED CONSEQUENCE ESTIMATE
WHAT WOULD CHANGE THIS?
- Reanalysis of AIS data that removes the early signal.
- Alternative models that materially shrink the estimated macroeconomic costs.
- Failure to generalize across other maritime routes.