Destination accounts

Destination accounts are defined in the destination.csv file created by the Build Road Segments tool (see the section called “Generating a Road Model”). One account name is defined for each destination in the mill location shapefile. These accounts are created when the route model data files are read into Patchworks during the initial data loading phase. At the time that they are created these accounts are end points waiting for a decision to be made as to what products should be sent to them.

The next step in the setup of the route model is the definition of the products that are to be delivered to each destination. Products are usually defined using product attributes, or accounts that sum product attributes. It is possible to set up the accounts so that specific products are used to meet mill requirements (for example, only aspen to an OSB mill or only sawlogs to a sawmill). Group accounts can be used to limit wood supply to geographically defined woodsheds. As the model runs and begins to send products to destinations, the destination account will keep track of the total amount of product that each mill is receiving.

In some cases a single processing facility will be the destination for all of a given type of product (e.g. a sole sawmill receives all sawlogs from the forest). In other cases, multiple processing facilities may require the same product, and the model will have to choose where to ship the product harvested from each stand. We will go over a simple example of products going to a single destination first, and then look at a more complicated multiple destination situation.

Models with products going to a single destination account usually have products assigned to them using a duplicate account (see Figure 39, “Product accounts for single destination account”. Harvested products are directly assigned since there is no choice the model needs to make about where the product should go. When you assign a product to the destination, the product volume is added directly into the destintion account when the block is harvested.

[Important]Important

Summary accounts must already exist that identify the product attributes of interest. Summary accounts are usually defined in the accounts.csv (see the section called “Summary Accounts”).

Figure 39. Product accounts for single destination account

(a) Single product to one destination

(b) Multiple products to one destination

/*
 * PIN FILE
 */

control.duplicateAccount(
	"product.Yield.Managed.Conif"
	"destination.MILL1",1);


		
/*
 * PIN FILE
 */

control.duplicateAccount(
	"product.Yield.Managed.Conif",
	"destination.MILL1",1);
control.duplicateAccount(
	"product.Yield.Managed.Decid",
	"destination.MILL1",1);


		  

Although there is more than one way to set up single destination accounts, one of the easiest ways is to define a product account in the accounts.csv file, and then add a statement to the PIN file to duplicate the value into the destination account. In example (a) only a single account value is being forwarded to the MILL1 destination. In example (b) two product accounts are being forwarded. Example (b) could have been further simplified if a single product account summed up both attributes.


When the product is added to the destination, the model will follow the segments that connect the stand to the destination. Construction and maintenance costs are tallied, and haul costs are multiplied by the amount of product. These cost are added in to the appropriate cost account.

The model starts with an initial least-cost path from the block to the destination. As the scheduler runs it will begin to alter the route, changing the direction of flow, in order to find ways to reduce the objective function. This may involve strategies such as increasing construction spending to build more direct road segments and thus reducing distanced travelled, hauling costs and the overall cost of operations. The strategies that are followed will depend on the forest, the model setup and the objectives.