TZ Decker is the decking component of Transfer Zone Management. TZ Decker is entirely different and separate from Expert Decking. Expert Decking decks containers in large inventory blocks that have low slot turnover and multiple tiers for stacking. However, TZ Decker decks containers in a transfer zone where TP resources are scarce and stacking may not be allowed, depending on the type of AHT that is used. In addition, in a transfer zone, TPs can incur a very fast turnover.
TZ Decker takes into account the following:
The number of available TPs in a transfer zone and the TP turnover, which are both very important.
Timing and duration of the TP reservation, which are much more crucial than the spatial assignment.
Long occupancy in a TP, which creates congestion and denies access even if the TP is not actually used but simply reserved.
When a TP is not available, in which case a carry CHE can be queued up in a pending dispatch state. For queued-up pending dispatches, TZ Decker can later refine, re-schedule, or pre-position these, as needed, to relieve TZ congestion.
If the TP is for AGVs, containers cannot be stacked; however, for autoshuttles the TP supports two tiers.
The TZ Decker strategy uses temporal rules for major queuing policies. Temporal logic is a system of rules for representing and reasoning about propositions qualified in terms of time.
Each time TZ Decker is called, TZ Decker evaluates the degree of TZ congestion, referred to as the traffic regime. All TZ Decker rules and penalties are contingent on the estimated traffic regime.
For more information, see Traffic regimes (on page 1) and High-level design of temporal rules.