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ABSTRACT Effective planning of dozer operations plays a very important role in determining their productivity. Since these units have a wide application in surface mining and civil engineering operations, there is a need for the tool for obtaining precise estimates of dozer production and costs. A research project was undertaken at The Pennsylvania State University to develop a software package to assist a wide range of professionals in quick and consistent evaluation of either new equipment purchasing options or the production and costs related to operating the owned equipment. This paper presents an overview of the structure and code capabilities of the software for dozer production and costs estimation.

1. INTRODUCTION Calculating dozer production rates and costs associated with dozer operation seems to represent a relatively simple task. In most cases, it is based on available literature and manufacturer-published equipment specifications. Evaluations of the performance of the dozer in use and planning new activities often rely on past experience, best estimate or other factors whose objectiveness is difficult to assess. The unique equipment features provided by each manufacturer are usually targeted to emphasize usefulness and technical performance of their equipment under particular field conditions. The technical and cost data summarized in the project bids or other submittals contain generally the aggregate numbers, within which the results of various calculations are embedded. The verification of background calculations in such submittals is not always either available or possible. While each sales representative handles his own company’s equipment data, it is not common to have sales people providing information comparing the performance of their own equipment in contrast to other manufacturers. This situation represents a common
   V.J. KECOJEVIC AND M.J. MRUGALA
   practice and is understandable, as each sale contributes to the equipment manufacturing company’s bottom line.
   While several civil engineering and mine design software packages are available and are being used, a smaller program designed to perform specialized tasks does not exist. One of the reasons is the fact that the potential market for such programs is relatively small. Left somewhat behind in this setting is the customer, who often has no other means but collect the data from several sources for comparison and optimization purposes. It is also likely that these comparisons may be incomplete or inconsistent as the data provided by each manufacturer vary. In addition, these comparisons may contain terminology, which is either imprecise or ambiguous. Within an operational environment there are no conditions for maintaining catalogues and up-to-date information on equipment at the site. It is clear that under these circumstances a tool serving the both manufacturer sales representatives and the users/operators would be useful.
   To facilitate addressing these issues, a research project was undertaken to develop a tool that can be used for a quick and accurate estimation in planning of equipment purchase and evaluations of costs and performance of the equipment currently in operation. As a result, a Dozer Productivity and Cost (DPC) software package was developed.


2. SOFTWARE CAPABILITIES
   The DPC is a Windows-based software package that is used for determining the productivity and economics of dozer units, using the logic that models simulate real mine situations. DPC can be applied to analyze and optimize the performance of the existing dozers or to plan the selection and acquisition of the new equipment. In either case, the performance of a single unit can be examined, or a comparison be made between two or more different machines. Using the interaction between the DPC and other commercial mine design software, the process of scheduling earthmoving operations can be combined with calculations of the dozer productivity, calculating operating costs and forecasting budgets.
   The DPC program includes the following features:
   – Calculation of dozer drawbar pull, haul, return and cycle time.
   – Calculation of dozer production.
   – Estimation and comparison of dozer’s ownership costs including: residual value at replacement, value to be recovered through the work, cost per hour through the work, interest, insurance and taxes costs; and operating costs (fuel, lubricants, undercarriage, repair reserve, special wear items, labor).
   – Compilation of results from calculations to examine the relationship between variables in the calculation, e.g., dozer type versus costs, operating hours versus costs.
   V.J. KECOJEVIC AND M.J. MRUGALA
   The DPC program was designed utilizing the current version 6.0 of MS Visual Basic. As any modern software package, DPC includes a dropdown hierarchical menu system that permits access to all software features. To assure program usability under any circumstances, the program can be accessed using both a mouse and a combination of the designated keys on the keyboard. A toolbar is provided to pursue specific applications, which are activated by clicking the specific function button. Program functions are associated with specific icons that provide a clue regarding the purpose of the given function. It was also assumed that buttons with a particular image (function buttons) alone are not sufficient. As an enhancement to the program functionality, each function button was supplemented by an appropriate tool tips. These tool tips can be used as a quick learning tool for the new program operator and as a reminder for those using the program sporadically.


3. STRUCTURE AND PROGRAM FEATURES
   3.1. Program Structure
   As shown in Figure 1, the DPC software is designed using a four-level structure. Level I includes the following five input elements: (1) equipment database, (2) equipment cycle elements, (3) material properties, (4) roster data, and (5) cost-related data. The execution of program function occurs at Level II. Level III is included to facilitate technical and economic evaluations. By returning to Level I and selecting new input parameters the results can be modified. Upon completion of technical and economic evaluations, Level IV provides a number of options, where the results of analyses can be displayed.
   3.2. Equipment Database In simple terms, a database is a collection of information. The DPC database was developed using MS Access and applies the Open Database Connectivity (ODBC) standard. It is organized using the relational database model, which produces the database structure with minimum data redundancy, while maintaining relationships between all data. A relation database stores information in a number of tables related by a common field known as the primary key. The record is a single entry in a table, consisting of a number of data fields, where each field is a specific piece of data contained in a record. These tables and queries consist of data records, each record containing the same type of information. A typical display of a dozer database, derived from the data published by various manufacturers [1–3], is shown in Figure 2.
   3.3. Rimpull Diagram Drawbar pull is the horizontal force that dozer can produce at the track-ground contact. Dozer performance is characterized by the performance curve of the drawbar pull versus dozer speed. The display used to calculate the drawbar pull is shown in Figure 3.
   3.4. Dozer Cycle Time and Production
   The dozer cycle time is defined as the time required for the dozer to complete a full pass including the required time components. Calculation of the dozer production is performed by selecting a dozer from the existing database and specifying the cycle elements. As indicated earlier, the dozer production calculations can be combined with other commercial mine design software, where the process of scheduling earthmoving operations can be merged with calculations of the dozer productivity, calculating operating costs and forecasting budgets. In this context, the dozer productivity can be integrated easily into any design providing a valuable source of information needed for accurate estimation of time, which is needed to complete specific earthmoving tasks. A typical display showing the results of dozer cycle time and production is shown in Figure 4.
   3.5. Ownership Costs
   A write-off straight line based on the number of years and hours the owner expects to use the machine gainfully represents an estimate of ownership costs. The ownership cost per hour is calculated based on input of the following parameters: (1) machine
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   delivered price, (2) ownership time period, (3) operating hours per year, (4) percent of value at trade-in time, (5) interest rate, (6) insurance rate, and (7) respective taxes. A typical template summarizing the result of ownership costs calculations is shown in Figure 5. This option is supplemented by a series of charts illustrating the distribution of ownership costs expressed in percent over the period of a designated number of years. A distinction has been made between the various components of the overall ownership cost to account for the following: (1) cost per hour through work, (2) cost of insurance, (3) cost of interest, and (4) applicable taxes.
   3.6. Operating Costs
   Operating costs include the following seven components: (1) fuel cost, (2) lubricants, (3) undercarriage, (4) repair reserve, (5) special wear items, and (6) labor. The total operating cost represents the final aggregate number component (7) summarizing all .
   ESTIMATION OF DOZER PRODUCTION AND COSTS
   other components. This operating cost section is also supplemented by a series of charts designed to display in a combined fashion all components contributing to the overall operating cost. Figure 6 shows an example of the display used for calculating the operating costs, while Figure 7 shows a typical chart displaying the distribution of ownership costs.
   3.7. Help Menu
   The help section provides the user several pieces of information. It was designed to provide the definition of all terms used in the program such that ambiguity in terminology can be avoided. As would be expected, the help section contains information needed to understand and operate the program.


4. BENEFITS OF USING DPC SOFTWARE
   One of the benefits of computer technology is the availability of large amounts of information, which can be accessed easily. The planning of any successful technical activity requires that the algorithm used in calculations is correct and the access to and the availability of the accurate information are assured. As users of this information, we would like to be reassured in our decisions often asking others to verify our findings. The DPC software was designed to fulfill this very need by providing the theoretically-based procedure, which can be applied consistently and in a correct manner any time it is employed by a wide range of potential users. Availability of the database including data on equipment produced by a number of manufacturers allows the potential customer to perform his own analyses before seeking information from the specific producer. This ‘‘do-it-yourself’’ aspect was considered important, as some operators would prefer to perform their own analysis of equipment performance before entering the negotiation stage. It should also help the user and the salesperson as both can negotiate more productively, keeping in focus a number of interrelated factors including not only technical performance data but all the other costs and equipment productivity as well.
   One of the basic tenets of effective communication is the use of proper terminology. As an example, the term ‘‘cost,’’ which by definition includes a number of components, can have many applications that make its use ranging from potentially imprecise to misleading. The DPC software contains the help sections, where in clear terms each calculated quantity is defined. Its use is envisioned as a facilitator during discussions, negotiations and as an educational aide.
   Mine-operating personnel is often reminded to keep the cost of operation under tight control. The issue of cost control due to its multi-faceted nature is sometimes.
   V.J. KECOJEVIC AND M.J. MRUGALA
   misunderstood as to what is it that we are trying to control. The set of graphs included in the DPC software allows for conveying two important messages. First, the graphs in a combined fashion allow the operator to see the relative contribution of each cost element to the overall cost. Secondly, they permit the user to concentrate on improving performance in these areas that have the largest weight in the overall cost, thus making their efforts more effective.
   The DPC program can be applied to evaluate the predicted versus real equipment performance more readily. The purchase of equipment is based on manufacturersupplied technical parameters and projected performance both in the area of work accomplished as well as costs associated with operation. While larger operations can afford sophisticated equipment performance tracking systems, smaller operations must rely on less precise measurements of such performance. The DPC software provides the small-scale operators with a tool in precise and standardized form, that can be used for the short- and long-term evaluations of equipment performance. Such a tracking effort is perceived to offer benefits not only to the field operators but also to accounting personnel, who can, with limited training, maintain an accurate history of equipment performance. The personnel can also alert the field operators to potential discrepancies encountered between the predicted versus real equipment performance. If encountered, potential surprises can be dealt with more effectively. Software can be used to develop real history of equipment use and point to areas that need focus.
   The DPC software is also designed to fulfill the needs of the equipment manufacturer sales representatives. At the click of a button an entire line of equipment produced by their employer can be retrieved from the database helping to address needs of different potential clients. It should be recognized that each leading manufacturer makes their recommendations of a particular piece of equipment using not only numbers calculated according to the standard practice but often applying procedures or coefficients, which are part of the intellectual property of the given company. These hidden procedures and/or numbers are often the result of many years of experimentation with equipment and information, which need to be protected. The program developers recognize this aspect of software ownership and any software user can choose to display or to protect portions or types of information that are made available to others.
   The time required to learn software is becoming an important issue as software packages grow in functionality and sophistication and the need to follow changes made in subsequent updates becomes a full-time occupation. The expense involved with hiring personnel designated to learn and operate these complex programs can be costly. In this process smaller operators are at a disadvantage. Obtaining answers even to simple questions requires involvement of experts, who are both expensive and seldom readily available. The DPC software is designed to fulfill such needs by being applicable in any type of operation, especially those smaller in size.
   ESTIMATION OF DOZER PRODUCTION AND COSTS
   self-contained package is designed to address a specific need, and it can be used quickly and effectively with modest training.


5. CONCLUSIONS
   Trends observed in mining and construction industries favor the use of complex software packages. These multi-faceted programs are capable of fulfilling a wide range of uses related mainly to mine design and are designed for routine daily use by trained personnel. Accounting departments perform operational cost analysis of equipment. These calculations remain a part of the operation accessible to those responsible for the daily task of keeping the company running financially, however, somewhat distant for those responsible for the day-to-day operations. As the economy goes through its cycles, companies emphasize the need for every employee to contribute to the company’s bottom line. A large portion of the company profit is related to the proper use of the available equipment. Requirements for the efficient equipment use can be fulfilled better if the factors contributing to the operating cost are accessible easily and listed in an orderly fashion and calculations can be performed instantly. The sales personnel also could take advantage of such a standardized process whenever comparisons are to be made between various new machines.
   The Dozer Productivity and Cost software was developed by faculty in the Mining Program at Penn State. At the core of the DPC software development was an assumption that both dozer operators and manufacturers’ sales personnel will benefit from the product that addresses a specific type of equipment. This specialized software could be developed keeping in mind concerns of cost and a format that can be used easily by a wide range of potential customers. It was designed as a flexible package, of which size and complexity can grow to fit the needs related to individual applications. Its main characteristics can be summarized as follows:
   – Availability of small, specialized programs can make them available at all levels of business involved in dozer applications.
   – Programs can be used effectively with little training.
   – Tangible benefits in terms of cost-based evaluations/decisions provide rational basis for decision makers at all levels.
   – Communication among business managers, operations and equipment sales can be improved due to standardization of language and terminology used in exchange of information.
   – Improvements in equipment use and maintenance based on real ‘‘Case Histories’’ can be postulated promoting better understanding of business goals and using more precise method of performance assessment.