SlipBots mostly decouple trailer loading from trailer dwell time. To fully realize this benefit, trailer operations must support continuous flow. A trailer should either be loading, unloading, or in transit — not staged or idle.
The 9-Bot Baseline Model
The baseline model is one trailer for every nine SlipBots. Three bots are loaded at Shipping, three are unloading at Receiving, and three are either in transit or dock swapping. This structure allows for constant motion without creating excess inventory or dock congestion.
Adding trailers beyond this typically reduces efficiency. More trailers introduce additional handling, more dock doors in use, and longer trailer dwell times. The goal is often to move the same or fewer trailers faster.
The number of trailers allocated (trailer fleet) will always be a direct function of SlipBot fleet size and allotted staging across sites. We use only enough trailers to hold the excess SlipBots, subtracting the quantity planned to be "staged" across all sites.
Avoiding Drop & Hook
Drop & Hook refers to the practice of truck drivers detaching from trailers after docking and reattaching to a different trailer to move while the first is reloaded/unloaded. This is an attempt to solve one of the same problems as SlipBots, which often makes them incompatible in terms of realizing labor savings.
Drop & Hook increases the value-added labor of a driver, but slows the material flow process and does not impact dock labor (at best). Furthermore, it requires additional trailers, increasing costs and complicating scheduling. Dock teams can still load faster, but if the trailer does not complete the full cycle faster, trailer fleets cannot be reduced, and empty SlipBots often cannot return in time for the process to be sustained.
The antonym to Drop & Hook in this context is "Dedicated" drivers — truck drivers assigned to a truck + trailer without a plan to detach within the duration of their shift.
Fleet Planning Examples
SlipBot efficiency is not only a product of robot performance but of trailer discipline. Trailers must keep moving. Delays at any point — trailer swaps, driver unavailability, excess trailers — erode the gains SlipBots provide. Maintaining the prescribed trailer-to-bot ratio, avoiding Drop & Hook practices, and keeping trailer moves as the top operational priority are critical to sustaining high utilization and maximizing ROI.
Understanding more complex fleet allocations will still follow the principles of the standard route.
Standard 9-SlipBot Fleet (1 Trailer)
Total (9) − Site 1 allocated (3) − Site 2 allocated (3) = 1 trailer (3 bots)
Expanded Route: 12-SlipBot Fleet
Total (12) − Site 1 allocated (3) − Site 2 allocated (0) = 3 trailers (9 bots)