Cargo terminals with ULD automation

How does Cargo terminals with ULD automation work, step by step?

1. 1

   Step 1: Design the handling system before the building

   The operator states throughput, the mix of ULD types, storage capacity and how the flows should work, and the handling supplier designs a system to deliver it. That design produces the aisle and rack layout, the number of storage levels, the transfer and work positions, and the loads and tolerances the structure must meet. Only then does building design start in earnest. Reversing this order is the classic failure on these projects: a building designed first will almost always have a column, a level or a tolerance in the wrong place, and moving the machine is not an option.

2. 2

   Step 2: Set the grid, the levels and the tolerances in writing

   The supplier issues the interface information the contractor builds to: column positions and permissible deviations, floor level and flatness tolerances, rack base fixing details, concentrated loads, pit and trench positions, and clearances that must be kept free. These are recorded formally and change-controlled. On most projects a single agreed interface document governs, and every later change to it is a controlled change, because an undocumented tweak to a column position discovered at installation is very expensive.

3. 3

   Step 3: Build the structure to machine tolerances

   The frame is conventional high-bay steel, but the setting out is not conventional. Column positions are surveyed to the supplier's deviations rather than to ordinary building tolerances, and verticality matters where racking will be fixed. The roof height is fixed by the topmost storage level plus the clearances the system needs, so it cannot be trimmed for cost without going back to the handling design. Bracing and any high-level walkways are coordinated with the machine envelope so they do not intrude into an aisle.

4. 4

   Step 4: Cast the floor to the flatness the machine needs

   The slab is the most unforgiving element on the project. It is designed for concentrated rack, vehicle and loaded-ULD loads, and it is finished to the flatness and level tolerances the supplier states, which are tighter than general warehouse practice. Joint layout is planned so that joints do not fall where a vehicle transfers or a rack base sits. Surveys are taken as the floor is laid rather than only at the end, so that a drifting level is caught while it can still be corrected. Pits, trenches and fixing points are set out and proved before the pour.

5. 5

   Step 5: Install the racking, the vehicles and the roller beds

   The handling supplier installs their equipment against the as-built survey. Racking is set out, plumbed and fixed, aisle rails are aligned, transfer vehicles are installed and roller beds and work positions are built up. This is when any structural or floor tolerance failure becomes visible, which is why the surveys during construction matter so much. Access, craneage and power for the installation are planned into the construction programme rather than bolted on, because the installation team needs the building weathertight and clear while other trades still want to be in it.

6. 6

   Step 6: Complete the envelope, the services and the docks

   Cladding, roofing, doors and the landside dock arrangements are completed around the installed machine. Power, data and control cabling are run to the supplier's requirements, with the electrical capacity and resilience the system needs. Lighting is designed around the aisles and work positions. Fire protection is designed by the fire engineer for a building with high-bay storage and moving equipment in it, and the authority accepts that design; the layout has to leave room for whatever it requires.

7. 7

   Step 7: Commission the automation in stages

   Commissioning runs from powered-up checks of individual devices, through sub-system tests, to integrated running of the whole machine with the control software. Empty running comes first, then running with test loads, then running with real ULDs. Faults found early are cheap; faults found during a throughput trial are not. On most projects this phase takes considerably longer than people expect and is the single most common cause of late handover, so it is programmed realistically and the operator's staff are involved throughout.

8. 8

   Step 8: Prove throughput and hand over into live operation

   The final proof is not that the equipment moves but that the terminal handles the volume it was bought to handle, within the times stated, with the failure and recovery behaviour agreed. That is demonstrated under something close to operating conditions. Staff training, maintenance regimes, spares holdings and the fallback manual procedures for when the automation is down are all in place before go-live. Where the terminal replaces or extends a working facility, the switchover is phased and rehearsed, because cargo does not stop arriving while the changeover happens.