The SelecTie™ II economic benefit analysis model was developed by ZETA-TECH Associates, Inc. for the Railway Tie Association. The model is an interactive user-friendly Windows application that allows the user to determine the economic benefits for various cross-tie configurations based on defined track, traffic conditions and overall life cycle costs. The system was developed for Windows 3.1 or higher, and is a multiple document interface program that allows the user to edit/view multiple sessions at one time.

The primary interface screen is shown below along with the system menu, tool bar, and child analysis form.

• Basic Force
• Undercutting
• Rail Replacement
• Rail Grinding
• Rail Transposing
• Gaging
• Tie Replacement
• Anchor Adjustment
• Alternate Tie Repair
• Fuel Usage
• Surfacing
• Derailment
• Conversion to Alternate Tie

The cost associated with each category is determined based on individual labor, equipment, and material costs. Each of these cost components are determined based on the number of units required (i.e., hours of labor by type, pieces of equipment, amount of material) and the cost for each unit. An example of the material costs for Tie Replacement is shown below.

Based on the maintenance/life cycles associated with each category and the overall costs associated with each category (labor equipment, and material), a present value cost for that particular category (for each cross-tie configuration) can be determined. Based on the total costs, a Net Cost Benefit and Return On Investment (ROI) can be calculated to provide the user with a measurement of economic performance of one cross-tie configuration as compared to another.

The maintenance/life cycle for each cost category is determined based on the track and operating characteristics of the analysis segment as entered by the user. These maintenance/life cycles are calculated using engineering equations developed and calibrated by ZETA-TECH Associates for both general freight and transit traffic types. However, should a specific life cycle be known, the user has the ability to override any calculated life cycle. The input parameters for the analysis segment that affect the maintenance/life cycle calculations are shown in the next figure.

The SelecTie™ II model offers the user several options for viewing and understanding the results of the economic benefit analysis. The first is a constant view of the net cost benefit and ROI along with a summary of all the cost categories as part of the child analysis window. This is the primary window from which the user can view the analysis results and launch all other edit capabilities for that session. These values are automatically updated each time a change is made.

In addition to the child analysis form, a graphical summary of costs (as shown below) can be obtained with the click of a button. The cost for each maintenance category (for each cross-tie configuration) is plotted to easily relate the various costs.

A sensitivity analysis can be performed on several key variables to show the effects of changing that variable while keeping all other variables constant. An example of a sensitivity analysis for degree of curvature is shown in the next figure.

Several software interface features are available to the user that make the SelecTie™ II model intuitive and easy to use. All inputs are via easy to understand forms. Whenever possible the input choices are limited through the use of drop down list boxes and/or radio buttons. All numeric inputs are verified by the model and input ranges for these values are applied.

A user’s favorite form is available that allows the user to add a specific input (up to six favorites) to that form such that the input variable is always immediately available to the user.

A standard Windows format toolbar allows the user to access input screens immediately and easily. Those options, available through the menu system, are also available through the toolbar.

A standard Windows help file is also available. This allows the user to access information pertaining to any form, input screen, output screen, etc.

The results of a SelecTie™ II session are stored in a file for later retrieval. Multiple files (sessions) may be opened at one time so that comparisons of different analyses can be performed.

A SelecTie™ II session can be printed to obtain a hard copy output of the data comprised in that session. All of the input data and associated cost calculations are printed in a logical format, so that the user has a document that can be referred to for any given analysis as necessary.