Truck Scheduling in the Postal Service Industry

Abstract

The distribution networks of the postal service industry are organized according to the hub-and-spoke paradigm, so that parcel distribution centers play a crucial role to consolidate the parcel flows to full truckloads. In these terminals, inbound trucks are unloaded at gates, shipments are identified, sorted by the central sortation conveyor system, and loaded into outbound trailers, in which they are moved toward their next destination. In this context, the scheduling of inbound trucks, which assigns a gate and a processing interval to each truck, is an essential operational decision problem. We formalize the resulting optimization problem and provide suited solution procedures. Furthermore, we test the impact of truck scheduling on the sortation performance of the central conveyor system with the help of a comprehensive terminal simulation.

The parcel hub scheduling problem with limited conveyor capacity and controllable unloading speeds

“…Another frequently used type of parcel hub is terminals with closed loop sortation systems where parcels are transported on cyclic conveyor belts. Truck scheduling in these systems is investigated by Boysen et al (2017) and Molavi et al (2018).…”

“…To investigate the performance of the mathematical model and the genetic algorithm, we use three distinct data sets of different sizes. An overview over the different instance sets is shown in Table 3 and For the large class of instances we do not have any direct data to use as a reference from practice but hubs of similar size are described in Boysen et al (2017). Generally, we mainly seek to investigate the computational performance of our solution methods with this more synthetic instance set.…”

Robust spotter scheduling in trailer yards

“…RSSP is an operational planning problem, which has to be solved once truck schedules (i.e., the where and when of trailer processing at the dock doors) are known. The typical planning horizon for the truck scheduling problem is one day (Boysen et al 2017). Thus, it is typically pointless to plan spotter schedules more than one day in advance.…”

“…Increasing freight traffic in many regions of the world (e.g., in Europe Statista 2018) does not only burden the edges (streets) of road networks but also many nodes. Examples of huge terminals where up to several hundred trucks are to be loaded and unloaded each day are cross docks (Ladier and Alpan 2016), automobile plants (Battini et al 2013), distribution centers of food retailers (Bodnar et al 2015), freight airports (Ou et al 2010), and hub terminals in the postal service industry (Boysen et al 2017). In many of these nodes, especially during peak hours, considerable waiting times for an (un-)loading of trucks occur.…”