RealCost User Manual

Using RealCost in Life-Cycle Cost Analysis

Entering, Saving, and Loading Data

RealCost data needs are identical to the data needs of the FHWA's best practice LCCA process. When the data have been entered, the software performs the required calculations to produce life-cycle costs. Furthermore, the software permits the analyst to quickly consider natural modifications to the data that result from analysis of earlier LCCA iterations. The LCCA steps and their corresponding data entry and output forms are listed in Table 2.

Project-Level Versus Alternative-Level Data

The LCCA process requires two levels of information: 1) data pertaining to the proposed pavement project and 2) data defining the pavement design alternatives that are being compared for accomplishing the project.

Project-level data apply to all alternatives being considered for the project at hand. FHWA's best practice LCCA methodology requires that the analysis period, discount rate, normal operations traffic data, and normal operations roadway geometry be the same for all alternatives. Alternative-level data define the differences between project alternatives (e.g., agency costs and work zone specifics for each alternative's component activities).

In comparisons of alternative designs intended to similarly fulfill the performance requirements of a project, LCCA requires that each alternative carry the same amount of traffic during normal operations throughout the life of the project. In this way, the benefits to road users provided by all alternatives are the same. The exception to this rule is during periods of work zone operations, when traffic flow may be restricted in some fashion. Work zone traffic flow restrictions are modeled by RealCost with the user cost methodology described in the FHWA technical bulletin Life-Cycle Cost Analysis in Pavement Design.

To emphasize the difference between the two types of inputs, RealCost requires that project-level data be entered separately from alternative-level data. Figure 10 illustrates the division between project-level and alternative-level data.

Figure 10. The hierarchy of project-level and alternative-level data.

Project-Level Data Input Forms

The options selected and data entered in the project-level data input forms apply to all alternatives being considered to fulfill the performance requirements of the single project. If the project-level data or options are changed, all alternatives must be reconsidered with the new data and options in order to be properly compared. Alternatives analyzed using different project-level options cannot be directly compared in LCCA.

Project Details

The Project Details form (Figure 11) is used to identify and document the project. Data entered into this form are not used in the analysis. The analyst may enter data according to the field names on the form or may use the fields to include other project documentation details.

Figure 11. Project Details form.

Analysis Options

Generally, analysis options are decided by agency policy rather than the pavement design decisionmaker. Options defined in the Analysis Options form include the analysis period, discount rate, beginning year, inclusion of residual service life, and the treatment of user costs in the LCCA (see Figure 12). A checked box equals "yes," an unchecked box equals "no." The data inputs and analysis options available on this form are discussed in Table 3, with FHWA's recommendations.

Figure 12. Analysis Options form.

Traffic Data

Pavement engineers use traffic data to determine their design parameters. In RealCost, traffic data (Figure 13) are used exclusively to calculate work zone user costs in accordance with the method outlined in FHWA's LCCA Technical Bulletin. The traffic data inputs are described in Table 4.

Figure 13. Traffic Data form.

Value of User Time

The Value of User Time form, shown in Figure 14, allows editing of the values applied to an hour of user time. The dollar value of user time is different for each vehicle type and is used to calculate user costs associated with delay during work zone operations.

Figure 14. Value of User Time form.

Traffic Hourly Distribution

To transform annual average daily traffic (AADT) to an hourly traffic distribution, default Rural and Urban Traffic hourly distributions from MicroBENCOST are provided with RealCost. The Traffic Hourly Distribution form (Figure 15 and Table 5) is used to adjust (or restore) these settings. Distributions are required to sum to 100 percent. (Note: The rural/urban option is entered on the Traffic Data form, shown in Figure 13.)

Figure 15. Traffic Hourly Distribution form.

Added Time and Vehicle Stopping Costs

"Added Time per 1,000 Stops (Hours)" and "Added Cost per 1,000 Stops ($)" values are used to calculate user delay and vehicle costs due to speed changes that occur during work zone operations. This form (Figure 16) is used to adjust the default values for added time and added cost per 1,000 stops. The "Idling Cost per Veh-Hr ($)" is used to calculate the additional vehicle operating costs that result from traversing a traffic queue under stop and go conditions. The costs and times are different for each vehicle type.

The Restore Defaults button functions much the same as it does on the Traffic Hourly Distribution form. The default values are drawn from NCHRP Study 133, Procedures for Estimating Highway User Costs, Air Pollution, and Noise Effects.

Figure 16. Added Time and Vehicle Stopping Costs form.