Quay cranes are shared resources. Splitting them evenly between two ships may seem fair, yet keeping both ships in service longer can delay a third vessel that needs a berth. The time at which a ship leaves can matter more than how busy every crane appears at each instant.
The first scenes compare crane assignments across ships and show how those choices change service completion. Giving one ship enough cranes to finish sooner releases its berth for the next arrival; a simultaneous split may postpone that release. The final port-wide comparison adds the waiting imposed on other ships, not just the work done on the first pair. This is the scheduling insight behind the example: local utilization is not the same as system-wide efficiency. A crane plan should be judged by the chain of berth occupancy and ship delays it creates. The animation illustrates that mechanism with a specific small fleet.
A port has a limited length of quay, and a ship must occupy one continuous stretch of it for the duration of service. Assigning an arriving vessel to the first apparently open place can block another vessel that needs a different length or arrival window.
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An electric train can return energy to the traction system while braking. Another train can use some of it if that train is accelerating at the same time and the electrical connection can carry the power. Without such a match, the opportunity may be lost even though the braking train still produces energy.
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An inbound flight is late, and some passengers are trying to board a departing connection. Holding that outbound aircraft could save their trip, but it also delays the people already aboard and may cause new missed connections farther down the route.
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