A Singapore online grocery retail chain (GreenMart) operates its own distribution facility at Jurong and hire truck services from contractors directly. After a period of rapid growth at the retailer, its inhouse logistics solution team is reviewing the potential for a new freight distribution solution and a move to a larger facility. GreenMart is also investigating alternative models to the truck-hire model adopted by GreenMart. A bottleneck process at GreenMart's current facility is the small number of inbound docks, which has often led to congestion among tractor trucks waiting to unload containers delivered from the port at Pasir Panjang. Moreover, GreenMart engages trucking services for inbound transportation on an ad-hoc basis, which leads to difficulties in finding drivers, trucks and trailers (chassis) at short notice, as well as a lack of visibility of the amount of resources required at any one time. Therefore, the Logistics Director at GreenMart has decided to explore whether there is any scope to optimise the transport process. She also wants to conduct an analysis to determine the number of inbound unloading docks, drivers, trucks and trailers required on a typical busy day. Each trip to/from the port requires about one hour (including driving time and waiting time at the port). At the GreenMart's distribution facility, it takes between 1 and 4 hours to unload a container. A container is always returned to the port on the same day to avoid detention charges and free up space at the unloading docks. To eliminate the need for a driver to wait for unloading, drivers can detach the trailers from their tractors and move on to other delivery jobs. The inbound receiving department at GreenMart operates from 8am to 8pm. Besides incentives for on-time deliveries, drivers are paid for by the day (7 working hours and up to 5 hours of overtime). When drivers are not occupied, they can be assigned to performing cargo staging activities at the docks. Table 3.1 shows the schedule for one of the busiest days. The round-trip delivery schedule for a typical workday is shown as follows where "D" stands for an inbound delivery, "U" for unload and "R" for return to port.