Layout Planning of Sortation Conveyors in Parcel Distribution Centers

Abstract

Fully automated sortation processes play a crucial role in modern distribution networks of the parcel service industry. In this context, the paper on hand systematically investigates dierent design alternatives of closed-loop tilt tray sortation conveyors. Especially, the number of loading stations for feeding parcels into a conveyor system and the relation to the subordinate decision problem of assigning inbound and outbound destinations to dock doors are shown to considerably inuence the throughput of a hub terminal.A novel destination assignment problem is formalized, suited solution procedures are presented and, by means of simulation, the resulting throughput is quantied, so that an experienced terminal manager can weigh the operational gains against the investment cost of dierent conveyor layouts.

Truck Scheduling in the Postal Service Industry

“…From a network perspective, the structure of the huband-spoke network and the specific terminal locations have to be determined. At a specific postal distribution center, the following main decision problemsordered according to decreasing time frame-can be differentiated (Fedtke and Boysen 2014):…”

“…• Layout planning mainly decides on the shape of the terminal (e.g., I-, L-, T-, or X-shaped, see Bartholdi and Gue 2004), the number of inbound and outbound docking doors, their arrangement around the perimeter of the terminal (see Stephan and Boysen 2011b), and the layout of the sortation conveyor (see Fedtke and Boysen 2014). Sortation conveyors necessitate a high investment, so that they often constitute the bottleneck of a terminal.…”

“…1-14, © 2017 INFORMS 3 is executed by forklifts, are, e.g., provided by Chang (1990, 1992), Gue (1999), Bartholdi and Gue (2000), and Bozer and Carlo (2008). Postal distribution centers, in particular, are addressed by McAree, Bodin, and Ball (2002) and Fedtke and Boysen (2014). Obviously, more flexibility is added if the assignment of trucks is not fixed, but can be adapted according to the current workload.…”

“…The resulting (leveled) sequence is, then, appended to the current queue at a loading station. At the head of the queue, the next shipment is loaded whenever a free tray passes by (first-empty-tray rule, see Fedtke and Boysen 2014).…”

“…In modern postal distribution centers, closed-loop tilt tray conveyors are applied to ensure a fast and reliable sortation of parcels. For instance, Hermes Logistik-Germany's second largest postal service provider-erected its central hub terminal in Friedewald in 2009 for e45 million (Fedtke and Boysen 2014). The largest part of this investment, i.e., e25 million, was consumed by the central sortation system, which consists of two closed-loop tilt-tray conveyors (on top of each other) each having a length of 700 meters (m) and 766 trays.…”