Panama
Binding·Constraint: Fresh water — Gatun Lake levels set draft and slot count·Alternative: Land bridge
The passage does not close; it becomes a price.
Alternatives fanVoyage days, indexed to a secured slot · placeholder scale
Canal slot secured34%
Canal auctioned slot38%
US land bridge56%
Suez routing78%
Cape of Good Hope100%
What constrains it
Panama’s constraint is fresh water, not steel or transit rights. Gatun Lake’s level sets the maximum draft the canal can carry, and a lower lake means fewer vessels at a shallower draft — the canal authority converts a hydrological constraint into a schedule.
Rationing mechanism
The rationing mechanism is a slot auction: transit capacity is fixed by the draft restriction, and the canal authority allocates the scarce slots by price rather than by queue order. A shipper who needs certainty of transit date pays for it; a shipper who can wait does not.
Incidence
ShippersPay the auction premium directly, or absorb the delay of an unauctioned transit.
Agricultural exportersCarry the least ability to reroute around a seasonal draft restriction.
Shelf pricesAbsorb the auction premium last, and only after it has moved through freight.
The canal authoritySets the draft restriction and the auction mechanism, and answers for both.
Comparable passagesWho decides is the most useful column: a rationing mechanism run by the asset’s own authority behaves differently from one run by a third party with no stake in the transit.