II. A CASE STUDY: TRANSPORT AND LOGISTICS PROCESSES
A. Process outline
This section gives a general overview of a transport and
logistics process. Obviously, these processes differ dependent
on the type of product, its physical shape, climate
requirements, etc. But basically it involves the transportation
of goods from a factory or supplier to the end customer.
In many cases, the actual products are placed on or inside
Returnable Transport Items (RTIs), such as pallets, carts,
containers, or trailers. After delivery of the products, the RTIs
will be returned to the supplier and reused in a future delivery.
In our case study, the RTIs in question are rolling
containers. These rolling containers are mostly used in retail
distribution and have the characteristic that they can be
dismantled when they are not transporting goods and in that
way take up less space. The rolling containers are a valuable
asset. Keeping track of where they are and that – in the end –
they are returned to the distribution center is an important
issue.
Currently, the distribution process of our case study is
partly automated by an Optical Barcode System (OBS).
Tracking is achieved by attaching order-associated barcodes
to RTIs, but position and state of an RTI is only monitored
when an employee actually scans the code and submits it to
the system; a time-consuming and error-prone activity that
only allows for discrete-time tracking. Years of deployment
have proven the value of the OBS, but the yield in
functionality has reached its maximum.
The distribution process of our case study starts at a
warehouse where an order picker will get an order list,
construct an RTI, pick the requested products from the
warehouse shelves, and put them in the RTI. Once the RTI is
full or the order is complete, the order picker will put a sticker
with a barcode on the RTI, which henceforth uniquely
identifies that particular RTI. Then, the RTI is moved to the
expedition floor. A large grid is painted on the expedition
floor and each cell of the grid is associated with a certain
distribution route. The RTIs belonging to a single order and/or