PERFORMANCE ASSESSMENT OF CONSTRUCTION OPERATIONS USING EXPERT SYSTEM

INTRODUCTION

A construction project is characterized by its diverse operations and a multitude of participants who are often working together for the first time. The many problems involved in construction operations must be solved while meeting a rigid time schedule, an investment budget, and safety requirements. From the beginning, the project management must reconcile the conflicting interests of the following: directly related parties (owner, architect, contractors, supplier and consultants); Indirectly related parties (financial agencies, Insurance companies, and stock-holders); and initially unidentified evaluating groups representing users, tenants, and the public. These groups must have their needs considered throughout the construction process and the aftercare stage. A construction company must meet, If possible, the needs of all parties while simultaneously making a profit.

To do so, the construction company must operate the project within the limitations of its contract. Consequently, the company will encounter short run pressures to minimize costs, to complete the job, and to move forward with other projects. However, there will be long run pressures to build a high quality project, to finish according to schedule, and to perform all works safely. In addition, governments have added many restrictions to certain construction methods. Therefore, it is only natural that construction firms have begun to investigate managerial techniques to handle problems related to the efficient management of large and sophisticated projects.

In this paper, we introduce the development of knowledge bases to provide on-site projects with a system to identify construction problems and methods that can be used by upper management as decision-making tools to establish strategic schemes for construction projects. Management can also employ this system to evaluate the performance of current operations and to determine the efficiency of completed projects.

This paper is a part of the more extensive study conducted at The Ohio State University concerning the development of an Integrated management Information System (IMIS) for international construction projects [1]. However, emphasis of this paper is placed on the determination of the factors affecting on-site construction practices and on the development and application of the knowledge bases using an expert system shell.

FACTORS AFFECTING CONSTRUCTION SITE ACTIVITIES

Factors concerning the performance of construction site operations are: cost achievement, performance degree, project manager, administrative efficiency, labor control, material control, equipment control, and site contingency management.

Cost Achievement (CA).

In this study, the construction costs are categorized as either Contract Cost (CC), Target Cost (TC), or Actual Cost (AC).

CC is the formal documented construction costs that owner and construction firm have agreed to. TC is the tentative construction cost guidelines for the site office which the home office has approved. AC is the real costs of the construction on site which is an accumulation of all expenditures as required by the contract. The interrelationships of CC, TC, and AC are demonstrated as follows: If CC is larger than TC, and TC is larger than AC, then CA is very good.

Performance Degree (PD).

The general evaluation of the performance degree of a construction project can be determined by the number of dispute occurrences and incentives/penalties occurrences.

Every agreement must provide a mechanism for handling disputes. Prompt attention to any dispute facilitates the timely completion and improves the profitability potential of the project. If there is no agreed upon method for handling disputes, disputes will thwart the timely completion of a project. Damage caused by disputes during the life of the project should be minimized so that all parties concerned may benefit.

Arrangements are made in the terms and conditions of the contract whereby incentives or penalties are applied to a contractor based on demonstrated performance in meeting agreed upon schedule dates. This function applies special emphasis to the timely completion of tasks critical to the overall timing of the project. For example, if the construction project is begun with built-in financial incentives and no dispute arises, then the PD may be considered excellent.

Project Manager (PM).

The project manager must performed competently in the areas of legal, business, and engineering judgments, balancing between his/her authority and responsibility. The project manager must exhibit knowledge in all areas related to the complete nature of construction operations. His/her competence is required for problem-solving and decision-making needed on the construction site.

A true professional project manager will also have the ability to balance authority and responsibility in relation to project operations. A competent project manager, for instance, whose authority equals his/her responsibility may be rated as very good, while an incompetent project manager whose reponsibility is greater than his/her authority can be rated as extremely poor.

Administrative Efficiency (AE).

Efforts made toward site performance are factored into the overall efficiency rating of the site office. Site office administrative efficiency is determined by the strength of the organization and the interrelationship among parties involved.

Since project vary widely, standard organization of a site office is difficult to define. However, each site office must be organized to operate at maximum efficiency and optimum cost. Consideration must be given on site to facilitate and support the total operation of the project to protect the contractual position of the construction firm. For example, if the site office is staffed with effective and efficient personnel, it should operate at a high level of administrative effectiveness.

The efficiency of the site office also depends on a high level of communication among all parties. Moreover, the well organized site office should harmonize the relationships among parties involved. For example, a strong organization with compatible participants Is usually a factor in excellent administrative efficiency.

Labor, Material, and Equipment Control (LC, M C_

Broadly defined, a construction project is the result of resources and resource-related activities including labor, material, and equipment needed to complete the project efficiently.

In international construction management, labor control is one of the most difficult aspects. The basic approach is to divide labor concerns into three categories: productivity, wage, and working condition. Productivity or the amount of work a worker or crew accomplishes in a defined period of time is determined by a highly qualitative judgment. The amount of money allocated for wages includes hourly rates, fringe benefits, insurance, taxes, and premiums. In considering working conditions, one includes such items as weather, terrain, topography, and environmental factors, such as heat, noise, light, dust, etc. The evaluation of the ability of the site office to effectively cope with labor control must be made within the context of the wage structure of the project, and the working environment at the site of the project.

Methods and practices in material control may differ with each individual project and company. Two factors of particular concern are cost and handling of material. Normally, the site office would prefer focus on the economic use of materials, whereas the home office usually handle major procurement of all necessary materials. The site office is also responsible for material handling so that it can be used efficiently. Handling of material includes functions such as the ordering schedules and quantities, adequate inventory, storage space, maintenance of access roads, quality inspections and function tests, pollution control, etc. If the site office properly manages all of these, materials will move through the project efficiently and at a low cost.

One of the largest single factors of construction costs is the leasing of or the investment in, and the operation and maintenance of equipment. The success of any project depends on proper control of this asset. Here, equipment productivity and cost are the affecting factors. The question of whether to lease or buy equipment is constantly being reviewed by the construction industry. Once the equipment has been acquired, it must be utilized to its maximum productivity and at the lowest possible cost. The site office is responsible for ascertaining that all equipment used in the project is operated to Its greatest potential.

Site

Adequate analysis based on recognition of potential contingencies as a base for the working agreement will help to Increase significantly the chances for successful completion of the project. Consequently, these potential contingencies should be Identified and then measured with the lowest possible cost.

For example, a highway was built on a government land in the middle of a farm country. It required the erection of a high livestock type fence along the project. However, soon after the fence was erected, the local farmers whose life line was affected, began to protest and eventually vandalized the fence. Pedestrian overcrossing bridges were then erected In the affected area. Should such a contingency be identified earlier, adequate measures can be planned at a more adequate time at a more reasonable cost.

DEVELOPMENT AND APPLICATION OF THE KNOWLEDGE BASES

The factors and subfactors affecting the construction site operations were compiled and listed in Table 1. These factors are used for developing the knowledge base (KB) throw h the use of an expert system shell: 1ST-CLASS [2] which Is designed for the IBM PC/XT/AT and other compatible systems. 1ST-CLASS allows the user to create an expert system without previous knowledge of programming or artificial intelligence. For illustration purposes, the development of one of the KB is presented here.

When the user enters the main system, Figure 1 will be displayed. This figure is the first of the six steps in creating the KB. These steps are: FILES, DEFINITIONS, EXAMPLES, METHODS, RULE, and ADVISOR. The first column in the figure shows the KB or files created earlier for IMIS [1]. However, when a user wish to create a new KB, user should press N for the function NEW. Then the user should define the new KB. Suppose that, as an example, the user wish to create the KB of factor Site Management Contingency (SC). The user should then go to the second step by selecting DEFINITIONS to define the KB of SC (see Figure 2). Figure 2 shows the affecting factors: IDENTFIABLE, MEASURE, and COST and their values described In the previous section (Table 1). The last column in this figure shows the RESULT and its values which represents the outcome or conclusion of the rules in the KB.

The third step in creating the KB for SC is by choosing EXAMPLES. The screen EXAMPLES will display Figure 3. In this step, the user can input the information required for the affecting factors and their values. This step Is essentially the KB. The fourth step is the METHODS in which the user selects one of the four inferencing methods: optimize, left-to-right, match, and customize. Here, the left-to-right method was chosen as shown in Figure 4. This method is particularly useful when the user wants the most important factor to be asked first. The fifth step is to display the RULE such as shown in Figure 5. There are essentially 18 IF-THEN rules in this figure. For example, the first four lines of the rules can be represented by:

IF IDENTIFICATION of SC Is obvious and MEASURE is adequate and COST is low THEN SC is rated excellent

The remaining knowledge bases for CA, PD, PM, AE, LC, MC, and EC are shown in Figures 6 through 12. Before the user runs the system, he/she must be certain that each KB in the system is created logically. The last step, ADVISOR, is used for assuring that the rules are logical, and the factors, values, and results are compatible with the logic used by the user. ADVISOR is also the step in which the KB is used by the user for entering his/her information needed to generate a result. A step-by-step example is shown in Figure 13 for SC. Note that since emphasis of this study is in the area of site operations, selection of this area is shown in Screen 1 (underlined). Screen 2 will then follow, showing the affecting factors In this area. Selection on Site Management Contingency (SC) will lead the user to the remaining screens with questions concerning the values of the factors.

Note that linguistic values are employed to describe the consequent in the THEN statements (or the result) of all the rules. For example, the value of SC in the above THEN statement is "Excellent." Ten values are consistently used for the result of the rules, and they are: Excellent, Very Good, Good, Fairly Good, Fair, Fairly Poor, Poor, Very Poor, Extremely Poor, Undecided/Unknown. The first four values have positive characteristics, the value "Fair" Indicate neutrality, and the remainders have negative characteristics.

The above KBs can tie used for integrating information gathered from all affecting factors. This Integrated Information can be used to assess the performance of a construction project, to compare the performance of several projects, and to make decisions for improving the performance or progress of a project.

The procedure described above can be used by the Quality Control Manager or Vice President of Operation or other officers of a construction company whose opinion may affect the decision of handling a construction project in an efficient manner. Therefore, it is essential for the user to first collect information concerning all affecting factors, and then, to get the results through the use of the rules. For example, the Cost Achievement (CA) in Figure 6 can be rated as "Very Good" if information concerning CC, TC, and AC shows that CC is larger than TC and TC is larger than AC. In another example, if the Site Organization (ORGNIZATION) in Figure 9 Is judged as "Strong" and the Interrelationship among the involved parties (INTER-REL) is "Undecided/Unknown," then the Site Administrative Efficiency (AE) is considered as "Fairly Good."

The values of the results of the production rules can be plotted for each factors as illustrated in Figure 14 for a hypothetical construction project. Three curves are shown indicating the variability of the project performance at certain periods of time. For example, the first curve representing the performance of the project in 1986 has negative characteristics, way below the neutral performance value. Improvements in 1987 in all affecting factors have gradually moved the curve upwards, towards the neutral area. The solid curve represents the predicted project performance in 1988 if further efforts in improving all factors are performed.

SUMMARY AND CONCLUSIONS

This paper presents the development and application of knowledge bases for factors affecting construction site operations. The process for identifying and categorizing construction operational factors is demonstrated from a practical standpoint. The knowledge bases, are constructed in the 1ST CLASS expert system shell. They are used to integrate the information obtained from the site office and to assess construction performance of a project. In addition, the knowledge bases In the study can be used as a decision support system to increase the efficiency of management In planning operational tasks.

We can graphically represent the values of the affecting factors, depicting the entire picture of the project performance, status, and characteristics. The performance curves are especially useful for a decision maker In a construction enterprise to identify the etiology of the problems and to determine measures to be taken to improve the project performance. Furthermore, the variability of the project performance can be clearly seen as time progresses.

ACKNOWLEDGMENT

The writers wish to thank DAE WOO Corporation for their support of this study. Ms. Nancy Grace provided excellent editorial assistance.

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