Only parent nodes have parameters. These parameters determine which path through the decision tree is followed depending on the conditions encountered in the performance model. In other words, these parameters distinguish one child node from another.
To set the parameters for a parent node, follow the steps below:
- Right-click the parent node that will have its parameters set and select Edit Decision Var Limits.
- The system displays the dialog box for setting the node's parameters. The Variables pane on the left side of the dialog box shows the decision variables that can be used for this node. In any branch of the decision tree, a decision variable can only be used once. If no decision variables are shown in the left pane, this means all decision variables have been used in this branch. To add decision variables, navigate to the Setup PMS Analysis Columns window (Pavement Analyst > Planning > Setup > Network Analysis Setup > Setup PMS Analysis Columns) and check the desired variables in the Perf. Class Variable column.
- The Limits pane on the right side of the dialog box shows the value assigned to each child node for the variable selected in the left pane. (Child nodes are identified by a number, with node number 1 at the top of the window.) Variables can be configured to have either numeric or character values. If the variable is configured to have numeric values, then the right pane shows a record for each child node. Each record shows the upper threshold at which the next child node will be activated. The upper threshold of the first child node then becomes the lower threshold of the next child node, and the process repeats for any additional child nodes. If the variable is configured to have character values, then the right pane shows all character values that can be assigned to the variable. You assign a node to each character value, with that node being activated when the variable equals the assigned character value. Note that not all values need to be assigned; use Node 0 for any character values you do not wish to assign. In other words, with numeric values you assign threshold values to the child nodes, while with character values you assign child nodes to the values.
- In the left pane of the dialog box, click the decision variable that you want to use.
- If the selected variable is configured to have numeric values, in the first row of the right pane, click in the High Limit column of the first row. Type the value for the threshold when the next child node will be activated. If necessary, repeat this action for any additional rows in the table (other than the last row, which is not assigned an upper threshold). For example:
- If the selected variable is configured to have character values, for the first character value listed in the right pane, click the down arrow to display the list of nodes and select the node to which this value will be assigned. (If the value is not to be assigned, select Node 0.) Repeat this action for each character value in the right pane.
- When all values are assigned, click OK to close the dialog box and save the new values.
