HERS-ST Highway Economic Requirements System - State Version: User's Guide
Chapter 8 Running HERS-ST Analysis
This chapter addresses the how to run the HERS-ST analysis.
Running the Analysis
After you have defined the Workset, specified your data sources, and set the control parameter and output settings, you are ready to run the analysis. To start the analysis, select the File/Run HERS-ST menu option or click the run button on the tool bar. The HERS-ST software will then present you with the run wizard.
Run Items
The HERS-ST Run wizard allows you to select various run options and start the analysis. In the dialog window (Figure 8-1), HERS-ST displays a list of the items that are selected in the Workset tree. These are the items that will be used to run the HERS-ST analysis.
The Scenario name and description are prefilled with values taken from the selected Control settings displayed in the list. These are default values and you may change them if you wish. Changing these values does not affect the original values in the Control settings.
At a minimum, the HERS-ST software requires a highway data item and control and parameter items. If any one of these three items are not included, then the Run button will be disabled.
Figure 8-1. HERS-ST Run Wizard (Items).
Run Objectives
The Objective page (Figure 8-2) allows you select the analysis type objective that the HERS-ST analysis will use. Depending on the objective and options selected here, other wizard pages may appear as needed. There are four types of analysis.
This page is pre-loaded with the values from the selected Control settings. You may change them here if you wish. Any changes you make to these setting will be applied to this run only; the original values in the Control settings are not affected.
Chapter 3 describes each of the four types of analysis objectives in more detail.
Figure 8-2. HERS-ST Run Wizard (Objective).
Minimum BCR Run. When performing a single minimum BCR analysis, you must specify the minimum BCR that an improvement must meet before HERSST will implement it.
Multiple Minimum BCR Runs. When performing a multiple minimum BCR analysis, HERS-ST will automatically change the minimum BCR value between each run. When selecting multiple runs, you must specify the starting, ending, and increment value to be assigned to the minimum BCR for each run. The number of runs conducted by the HERS-ST analyzer will depend upon the size of the minimum BCR range and the value of the increment.
Funding Constrained Run. When performing a funding constrained run, you must specify the amount of funding available for each funding period. You will be given an opportunity to enter funding levels later.
Performance Constrained Run. When performing a performance constrained run, you must either use the current conditions as your performance goal or specify the goals yourself. If you choose to specify the goals, you will be given an opportunity to enter those goals later.
Full Needs Run. When performing a full engineering needs run, you must specify the deficiency levels. You will be given an opportunity to enter the deficiency level thresholds later.
Analysis Options
The Analysis Options page allows you to select options that affect the HERS-ST analysis.
- Perform Sensitivity Analysis. This type of analysis will perform multiple analysis runs using different settings for the control, parameters, or both. You must specify the control and parameter settings to be used with each analysis iteration.
- Perform Continuation Analysis. This type of analysis is similar to the sensitivity analysis except where the sensitivity analysis resets the highway conditions before each run, each iteration of the continuation analysis starts with the highway conditions as determined at the end of the previous run.
- Override HERS using State-Specified Improvements. This option will conduct the analysis in override mode. You must provide the Improvements data for HERS-ST to use in place of its own improvement recommendations.
- Override Pavement Roughness (IRI) with Pavement Conditions (PSR). This option will cause the analysis to use the PSR information for each highway section during its analysis instead of its IRI information.
- Borrow from the next funding period when the last improvement exceeds budget. When implementing improvements in a funds-constrained analysis, ultimately HERS-ST will reach a point where some funds remain, but they are insufficient to implement next improvement. This option will cause HERS-ST to implement the last improvement by borrowing the required funds from the next funding period, thus exceeding the funding constraint level originally specified. If this option is not selected, the last improvement will not be implemented and the remaining funds will be transferred to the next funding period.
- User Intermediate-Year File. This option will cause HERS-ST to use the specified intermediate-year file. This option is useful to specify changes in the highway system that occurs at an intermediate point during the analysis period.
The Intermediate Year data file is discussed in more detail in Chapter 6.
Figure 8-3. HERS-ST Run Wizard (Options).
Sensitivity / Continuation Analysis
This page (Figure 8-4 ) allows you to design a multiple run analysis. When performing a Sensitivity or Continuation Analysis you must specify which Control and Parameter settings are to be used for the iterations of the analysis. You can also enter a run name for each iteration. This page will appear only if you have chosen to perform a Sensitivity or Continuation run on the Analysis Options page.
This page will appear only if you have chosen to perform a Sensitivity or Continuation run.
Figure 8-4. HERS-ST Run Wizard (Multiple Runs).
Funds / Goals
The Available Funds or Performance Goals page (Figure 8-5) allows you to specify the constraint criteria used when performing one of the constrained analysis types. This page is pre-loaded with the values from the selected Control settings. You may change them here if you wish. Any changes you make to these settings will be applied to this run only; the original values in the Control settings are not affected.
This page will appear only if you have selected a funds constrained analysis or a performance constrained analysis.
Figure 8-5. HERS-ST Run Wizard (Funds / Goals).
Deficiency Levels
The Deficiency Levels page (Figure 8-6) allows you to specify the engineering design criteria used as the deficiency level thresholds that determine if an improvement is required.
This page is pre-loaded with the values from the selected Parameter settings. You may change them here if you wish. Any changes you make to these settings will be applied to this run only; the original values in the Parameter settings are not affected.
This page will appear only if you have selected a full needs analysis.
Figure 8-6. HERS-ST Run Wizard (Deficiency Levels).
Executing HERS-ST
The HERS-ST analysis consists of two parts, the pre-processor and the HERSST analyzer. Both parts execute in a DOS window and will scroll status information about the execution (Figure 8-7). During the time while the DOS window is displayed, the rest of the HERS-ST application is locked.
Figure 8-7. HERS-ST DOS Window.
The pre-processor is executed prior to the analyzer. If the pre-processor generates any error or warning messages, the analysis execution is halted and you are given a choice to either review the messages or ignore them and continue with the HERS-ST analysis (Figure 8-8).
Refer to the HERS-ST technical information for further information on the error and warning messages encountered here.
Figure 8-8. Warning Message Dialog.
If you chose to halt the analysis execution to review the error or warning messages, you can then determine if they are of any consequence. The messages are displayed in your system text editor. After reviewing them you are given a choice to either terminate the analysis or ignore the messages and continue (Figure 8-9).
Figure 8-9. Warning Message Dialog.
TRY IT ON YOUR OWN!
Run the HERS-ST Analysis
- Click the Run button in the tool bar.
- Enter a name and description for the new run Scenario.
- Enable the HERS-ST override mode if you have included any State-specified improvements.
- If you are doing a multiple minimum Benefit to Cost Ratio run, ensure that you have entered the Beginning, Ending, and Increment values for the BCR.
- If you are doing a sensitivity or continuation analysis, select the Control and Parameter settings for each iteration.
- Click the Run button. After HERS-ST runs the analysis, the Workset tree displays a Scenario branch containing the results of the analysis.