What happens on a lower level of detail?

At each of the servers (entrance, substations and exit) there are processes going on at a lower level that are important to clarify in order to model them correctly. These are so-called logic flows. To start, an overview is given of the process at the entrance of the waste disposal station. Figure 25 gives a clear overview of the actions performed sequentially before the visitor actually enters the waste disposal station and moves on including the data registration moments needed to calculate the performance measures later on.

Upon arrival at the entrance, the arrival time at the site is registered and if the visitor is next in line for processing then he proceeds to the front desk. Otherwise he will have to join the queue at the entrance. At the entrance the arrival time at the front desk is recorded. Afterwards the visitor’s waste content is determined and in our programmed model this is also a convenient moment to assign

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processing times (these are drawn from the determined distribution functions) for each waste stream the visitor brought. After this process is finished the visitor prepares to leave the front desk. At that moment his next destination on the waste disposal station is determined. Simultaneously his departure time at the front desk is recorded to calculate the sojourn time and waiting time at the front desk and the waste content of the visitor is updated. Depending on whether there is space on the waste disposal station (no blocked entrance) and the substation that is the visitor’s next destination, the visitor will have to wait at the front desk or is allowed to move on to the next destination.

Visitor reaches Entrance Is visitor next in line? Register Arrival Time Go to Front Desk Queue up no Yes Determine visitor waste content

Assign processing times for waste streams

brought Register arrival at Front Desk Determine Next Location to visit

Register departure and Sojourn time; waiting time at Front Desk & update

visitor waste content

Capacity terrain

filled? Capacity Substation of

next destination filled? no no yes yes Wait at Front Desk Direct Visitor to Next Destination

progress without time delay progress with time delay

Figure 25 Logic flow of the process a visitor upon arrival at the entrance

What happens at these substations is described below. At every waste disposal station there can be two types of substations. The first is like the free area at the waste disposal station we collected our data at. There is a central parking area from where the visitors can dump waste in all the containers dedicated to the waste streams located there. This may happen in any random order. This substation is usually located at the location of the small chemical depot of the waste disposal station. That is why we have called this flow process as that of the small chemical depot. This process can be observed in

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Figure 26. Upon arrival, the arrival time is registered and the availability of the small chemical depot is updated. If there is a free parking spot the visitor can park there, if not the visitor will have to wait in a buffer space (usually the driveway). Upon arrival at a parking spot the staying (processing) time in that spot is calculated by adding the processing times of all the waste streams he brought that are located at the small chemical depot area. Once this time is known, the departure is scheduled. When the visitor prepares to leave the small chemical depot area, the next destination to visit is determined. Just like at the departure at the front desk the departure time is registered, the sojourn time and waiting time are calculated and the waste content is updated. If there is space available at the next destination the visitor is allowed to move on, if not he will have to wait at his current location.

Visitor reaches Small Chemical

Depot Is there a _parking

spot?

No

Yes Register arrival and update availability status

Small Chemical Depot

Calculate staying time Schedule departure Visitor prepares to leave SCD Is there available capacity at next desination? yes _no Determine Next Location to visit

Register departure and Sojourn time; waiting time & update visitor waste

content Move to parking spot Wait in buffer Arrival at parking spot Direct Visitor to his next location Wait at Current Location Stop

progress without time delay progress with time delay

Figure 26 Logic flow of process upon visitor arrival at Small chemical depot, a parking spot there and upon departure

The other substations are of a different type. They are more like the classical platform design of the Modulo Bèton system. There is a fixed number of containers and at each of these containers there is parking space for two cars or for one big vehicle (a truck or a car with a trailer). The process at these type of substations is different (see Figure 27). Upon arrival the visitor checks whether there is a free parking spot close enough to the container of the waste stream he has to dump waste at. If there is

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no space available the visitor waits at the buffer. If there is space available the visitor moves to that spot and the arrival time is registered. The staying (processing) time is calculated and the departure time is determined. When the visitor prepares to leave the parking spot the same processes take place as at the small chemical depot and the front desk. However, one process is added. Upon the departure of a visitor from a parking spot at one of these substations capacity is freed for other visitors that had been waiting for processing and as the visitors are handled on a first come first served basis this departure event triggers a backward search. The other containers and the buffer of the respective substation are checked first. Then previous substations are checked and finally the front desk is checked. From these visitors the first one whose arrival at the front desk was registered is sent through. Other visitors that are blocked but who arrived later at the waste disposal station are moved on to the buffer space of the respective substation if there is space available. In other words the blocked visitors are sent through according to the “First Come First Served” principle.

65 Visitor reaches SS other than

one containing Small Chemical Depot

Determine nearest available parking spot for

waste stream visitor will dump next Is there a spot available? Visitor waits at entrance to Substation Move to the nearest available spot Register arrival time Calculate staying time for visitor at that spot Determine departure time Visitor prepares to leave

parking spot once all containers accessible from the parking

spot have been visited

Is there available capacity at next desination? yes no Determine Next Location to visit

Register departure and Sojourn time; waiting time at that parking spot & update visitor

waste content No

Yes Parking spot becomes

available due to departure other visitor

Is there a visitor at a previous substation that has to dump a waste stream accessible from that parking spot?

Is there a visitor at the Front Desk that has to dump a waste

stream accessible from that parking spot?

no yes

yes Is there a visitor in the Substation at

another container or the buffer that has to dump waste accesible from that spot?

yes No Nothing happens no Stop Direct Visitor to his next location Wait at Current Location

Figure 27 Logic flow of process upon visitor arrival at a substation other than the SCD, upon departure and when a parking spot becomes available

Once a visitor has dumped all the waste he brought to the waste disposal station he leaves the waste disposal station and upon departure the performance measurement statistics are recorded.

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