Container port: how many berths and quay cranes are needed?
Enter annual TEU throughput and vessel size — the calculator gives the number of berths, quay length, quay cranes, quay-to-yard trucks and vessel waiting time. Below is a second-by-second simulation of quay crane, truck and yard dispatching.
What the model calculates, and what it doesn't
Simulated second by second over the selected time window. A quay crane discharges one container every 3600/speed seconds if an AGV is waiting at the berth; the AGV travels to the yard (distance ÷ speed, plus handling time), queues for a yard crane (each crane serves one box every 3600/speed seconds), then returns to the berth.
The three dispatching rules are three different ways of handling the same input: quay crane priority the crane works whenever a vehicle is available; throttling makes the quay crane wait when the number of vehicles heading to the yard or waiting for a crane reaches twice the number of yard cranes; shortest queue sends the vehicle to the yard crane with the least work. The "order surge" scenario speeds up the quay crane by 30%; "one slow block" slows one yard crane by half.
Stage 5 — knowing the vessel schedule in advance: 20 containers for 3 arriving vessels come in mixed; a container for a later-departing vessel sitting on top of one for an earlier-departing vessel counts as a block. Machine rule when stacking in the yard: place a container on a stack where it does not block an earlier-departing vessel, choosing the tightest fit. Tested on 200 random truck sequences: random stacking averages 6.8 rehandles, rule-based stacking 0.1.
Stage 4 — stacking yard: a block of 6 stacks, up to 4 tiers, 21 containers with a random pick-up order. Each time a container sitting on top of the one to be picked has to be moved counts as one rehandle. The baseline uses the min-max rule (place the relocated container on a stack where it does not sit on top of one needed earlier, choosing the tightest fit), a classic rule in research on the container relocation problem. The trade-off chart runs 120 random yards for each stack height of 2–7 tiers.
Not calculated: external trucks, intersecting internal routes, AGV battery charging, stowage-based order sequencing, and interleaved import and export (dual cycling). Use it to see which layer the bottleneck sits in, not to choose how much equipment to buy.
Frequently asked questions
Why doesn't throughput rise when you add AGVs?
When the yard crane is the bottleneck, extra vehicles just form longer queues at the yard crane. The simulation shows this: the number of vehicles waiting for the yard crane rises while throughput stays flat.
What is the point of the throttling rule if throughput doesn't change?
It trades a few percent of quay crane idle time for a yard that doesn't clog — fewer vehicles queuing, fewer accidents and easier incident handling. Whether it is worth it depends on the port; the simulation only shows the cost of each choice.
Have real project parameters? Send them to CGD and get feedback on the design scope
This simulation stops at the principle. For a specific project, CGD builds the model on real operating data and floor plan drawings.
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