RealCost User Manual
The RealCost software was created with two distinct purposes. The first is to provide an instructional tool for pavement design decisionmakers who want to learn about LCCA. The software allows the student of LCCA to investigate the effects of cost, service life, and economic inputs on life-cycle cost. For this purpose, a graphical user interface (GUI) was designed to make the software easy to use. The second purpose is to provide an actual tool for pavement designers, which they can use to incorporate life-cycle costs into their pavement investment decisions.
RealCost automates FHWA's LCCA methodology as it applies to pavements. The software calculates life-cycle values for both agency and user costs associated with construction and rehabilitation. The software can perform both deterministic and probabilistic modeling of pavement LCCA problems. Outputs are provided in tabular and graphic format. Additionally, RealCost supports deterministic sensitivity analyses and probabilistic risk analyses.
While RealCost compares two alternatives at a time, it has been designed to give the pavement engineer the ability to compare an unlimited number of alternatives. By saving the input files of all alternatives being considered, the analyst can compare any number of alternatives. Furthermore, the software has been designed so that a basic understanding of the LCCA process is sufficient to operate the software.
The software automates FHWA's work zone user cost calculation method. This method for calculating user costs compares traffic demand to roadway capacity on an hour-by-hour basis, revealing the resulting traffic conditions. The method is computation intensive and ideally suited to a spreadsheet application.
The software does not calculate agency costs or service lives for individual construction or rehabilitation activities. These values must be input by the analyst and should reflect the construction and rehabilitation practices of the agency.
While RealCost compares the agency and user life-cycle costs of alternatives, its analysis outputs alone do not identify which alternative is the best choice for implementing a project. The lowest life-cycle cost option may not be implemented when other considerations such as risk, available budgets, and political and environmental concerns are taken into account. As with any economic tool, LCCA provides critical information to the overall decision-making process, but not the answer itself.
How RealCost Works
RealCost consists of a Microsoft Excel 2000 worksheet with additional Visual Basic for Applications (VBA) code. The VBA code provides the ability to perform Monte Carlo simulation in the analysis, and it is used to construct the GUI. The software has two interface mechanisms, the form and the worksheet.
The form GUI is the primary means to work with the software. Each form has four components, and some data entry forms have a fifth function that supports probability analysis.
- Form Name: Name used in RealCost to refer to the form.
- Data Entry Field: Area for data input.
- Data Field Description: Phrase used to identify the data entry field.
- Command Button: GUI device that triggers a command or series of commands to the software.
- Probability Button: Specific type of command button that opens a form where probabilistic inputs can be assigned.
The components of a form are identified in Figure 1.
Figure 1. An example data entry form, Value of User Time.
The worksheet interface is available when the form interface is closed. Data may be entered in the appropriate worksheet cells, which carry the same labels as the corresponding fields on the form interface. While the form GUI is the primary means of interacting with the software, all of the entered data is stored in Excel 2000 worksheet cells. Data entered into a form's data entry field are automatically transferred to corresponding cells in the appropriate underlying worksheet. For example, the worksheet extract in Figure 2 contains the data entered in the Value of User Time form shown in Figure 1. Data can be entered directly in the worksheets as well, but the form interface is required for some functions.
All outputs (e.g., calculation results, analysis results) are also written to worksheets. These outputs are accessed just as data inputs are.
Note: Excel 2000 files are composed of one or more worksheets. The collection of worksheets in a file is termed a workbook.
Figure 2. An example worksheet extract, Value of User Time.
RealCost follows FHWA's best practice LCCA methodology, which is fully documented in FHWA's Technical Bulletin, Life-Cycle Cost Analysis in Pavement Design (FHWA SA-98-079). The Technical Bulletin presents a formal treatment of LCCA methodology, the economic basis of discounting future expenditures, and probability, and it recommends input values. The Bulletin is also the source of RealCost's default values. LCCA best practices are outlined in FHWA's Life-Cycle Cost Analysis Primer (FHWA IF-02-047).
Although this User Manual provides a working knowledge of RealCost, these related documents, particularly the Technical Bulletin, can provide a more in-depth understanding of the process that is helpful for including LCCA in the pavement decisionmaking process. The Primer and the Technical Bulletin are available in electronic format on FHWA's LCCA Web page (www.fhwa.dot.gov/infrastructure/asstmgmt/lcca.htm) or by request from FHWA's Office of Asset Management. Additional references and contact information are listed at the end of this manual.