A quay crane unloads containers from the ship onto a grid of yard stacks. Because a crane can only reach the top of a stack, any container buried underneath others must wait — and when a truck asks for a buried one, the crane first has to relocate everything sitting on top of it to other stacks before it can lift the target out. Those extra lifts are called re-handles, and minimising them is the core planning problem every real container terminal solves every day.
re-handle moves for a target = number of containers stacked above it
lower stacks + planned placement → fewer re-handles → faster truck turnaround
- Routing incoming containers — click a yard column before the crane picks up the next ship container to send it there instead of the automatic least-full column. Spreading containers thin (or grouping ones likely to leave together) keeps future targets near the top.
- Truck requests — each truck asks for one specific container already in the yard. A green-outlined target sits on top and comes out in one lift; an orange-outlined target is buried and costs one re-handle per container above it.
- Prioritising a truck — click a row in the truck queue to serve it next, useful when a truck with an easy (top-of-stack) target is waiting behind one that needs several re-handles.
- Crane speed / arrival rate — a faster crane clears re-handles quicker; a higher truck arrival rate raises pressure on the yard layout, exactly like peak-hours gate traffic at a real terminal.