Journal of Construction Engineering and Management

The accuracy of an estimate is measured by how well the estimated cost compares to the actual total installed cost. The accuracy of an early estimate depends on four determinants: (1) who was involved in preparing the estimate; (2) how the estimate was prepared; (3) what was known about the project; and (4) other factors considered while preparing the estimate. This paper presents results of a research effort that developed an estimate scoring system to measure the impact of these four determinants on estimate accuracy. The estimate scoring system consists of 45 elements and is organized into 4 divisions. Data were collected from 67 projects, representing $5.6 billion in total installed costs, and used to correlate the estimate scores with estimated versus actual costs. Statistical analyses determined the relative influence of the 45 elements, based on collected project data. The results showed a significant correlation between the estimate score and the accuracy of the estimate. Computer software, the Estimate Score Program (ESP), was developed to automate the scoring procedure, assess estimate accuracy, and predict contingency, based on historical cost data. The estimator can enter the base estimate into ESP and then rate the estimate, relative to each of the 45 elements. ESP automatically calculates the estimate score, as the user rates each element. The user can query the ESP historical database to view the estimate scores and estimate accuracy of similar projects. A cumulative probability S-curve, generated by ESP, is based on projects selected in the query and the estimate score of interest. The user can also predict the cost range—upper and lower limits—of a desired confidence level. ESP can be used to “check” the amount of contingency determined by other methods, as well as a method of predicting its own contingency.

A practical model for scheduling and cost optimization of repetitive projects is proposed in this paper. The model objective is to minimize total construction cost comprising direct cost, indirect cost, interruption cost, as well as incentives and liquidated damages. The novelty of this model stems from four main aspects: (1) it is based on full integration of the critical path and the line of balance methodologies, thus considering crew synchronization and work continuity among nonserial activities; (2) it performs time-cost trade-off analysis considering a specified deadline and alternative construction methods with associated time, cost, and crew options; (3) it is developed as a spreadsheet template that is transparent and easy to use; and (4) it utilizes a nontraditional optimization technique, genetic algorithms, to determine the optimum combination of construction methods, number of crews, and interruptions for each repetitive activity. To automate the model, macroprograms were developed to integrate it with commercial scheduling software. Details of the model are presented, and an example project is used to demonstrate its benefits.

The purpose of this paper is to extend the modification of the minimum moment approach applied to networks with single resource leveling to networks with multiple resources. Specifically, the contribution of this paper is to outline a procedure to level multiple resources using the modified minimum moment approach. The heuristic procedure is applied to both methods of leveling multiple resources: leveling multiple resources in series and combined resource leveling. For comparison purposes, the proposed procedure is demonstrated through the same examples that were used to illustrate the use of the traditional minimum moment to both methods of multiple resource leveling. The application of the modified minimum moment approach showed the same results of the traditional minimum moment method. In some cases, the obtained results were even better than those of the traditional method.

This paper presents the development of an object-oriented model for scheduling of repetitive construction projects such as high-rise buildings, housing projects, highways, pipeline networks, bridges, tunnels, railways, airport runways, and water and sewer mains. The paper provides an overview of the analysis, design, and implementation stages of the developed object-oriented model. These stages are designed to provide an effective model for scheduling repetitive construction projects and to satisfy practical scheduling requirements. The model incorporates newly developed procedures for resource-driven scheduling of repetitive activities, optimization of repetitive construction scheduling, and integration of repetitive and nonrepetitive scheduling techniques. The model is named LSCHEDULER and is implemented as a windows application that supports user-friendly interface including menus, dialogue boxes, and windows. LSCHEDULER can be applied to perform regular scheduling as well as optimized scheduling. In optimized scheduling, the model can assist in identifying an optimum crew utilization option for each repetitive activity in the project that provides a minimum duration or cost for the scheduled repetitive construction project.

Many construction systems have been used to build several highway bridges and elevated roads in Egypt. Recently, the stepping shuttering system has been used in Egypt for cast-in-place concrete bridge. This system is most appropriate for concrete bridges of moderate spans ranging from 40 to 70 m. The stepping shuttering system provides appropriate means to satisfy local needs for concrete bridge construction in an urban environment, practically without infringing on traffic or property below. This paper presents an innovative method of construction that has been used in Egypt for the first time to build the 6th October Bridge extension. Issues regarding the constructability and innovation are highlighted, and the significant aspects during the bridge construction are documented. Also, the difficulties encountered and the lessons learned are thoroughly investigated. In addition, evaluation of the system is discussed in terms of construction cost, schedule, and flexibility. Finally, this paper presents an innovative method that offers substantial opportunity for enhancing constructability of concrete bridges using the stepping shuttering system.

Owing to the high cost of large construction projects in recent years, build-operate-transfer (BOT) contracts are getting popular in the global construction market, especially in infrastructure construction. With BOT, the government is able to put projects on track without concerning itself too much about raising funds. On the other hand, due to the fact that the concessionaire who is awarded the project is responsible for the operation of the end facility for a certain period of time, reliable quality of the facility and effective operation could be expected. This paper introduces the financial model used by the Bureau of Taiwan High Speed Rail for its BOT projects. The parameters and variables of the model are presented. Its basic assumptions, input data, cost requirement, self-financing ability analysis, financial statements, and indices are discussed. The scenario analysis is used to highlight the application of the model.

Based on the comparative analysis of 24 construction disputes, this paper presents a process model that explains the development of disputes. The model examines the combined effect of project uncertainty, contract, working relations, and problem solving effectiveness on the development of disputes. The model develops a classification of problem situations, and identifies the problem-solving requirements and the potential for dispute in each situation. The model indicates that the prevention of complex, high cost disputes depends more on the planning and problem solving ability of the project organization, and less on the contractual terms. The paper identifies the following actions that can reduce the number and severity of claims: reduction of project uncertainty, reduction of contractual problems, reduction of opportunistic behavior, increased the project organization's problem-solving ability, and use of alternative dispute resolution methods to reduce resolution costs.

The qualification process in the construction bond business is very complicated, labor-intensive, and time-consuming. The construction bond underwriting processes contain subjective judgments that require human involvement to reach decisions. Thus, underwriting evaluations are bound to be very difficult, ambiguous, and have potentially great losses. This paper identifies and classifies quantitative and qualitative risk factors impacting construction bond underwriting, to improve the quality of the evaluation analysis and to reduce the highly unstructured environment and the subjectivity of the bond evaluation in underwriting. The methodology provides a systematic information analysis for the heuristic knowledge of the construction surety bonds underwriting process, provides better control over the risk assessment process by providing independent judgments for the major decision factors and an overall judgment for the final contractor's risk assessment decision, and reduces the time and effort required of the current evaluation process to reach a certain decision and to simplify the complicated nature of this process.

Research by the Construction Industry Institute Maintainability Research Team investigated how maintainability is being incorporated into the project delivery process. This paper presents a comparative analysis of two formal maintainability programs drawn from that research. The programs differ in terms of application and project type and size, in addition to the organization leading the implementation (owner-led versus contractor-led). This paper identifies program attributes contributing to effective maintainability programs. These have been grouped into five categories: (1) corporate commitment; (2) program resources; (3) maintainability planning; (4) maintainability implementation; and (5) program updating. Additionally, the comparative analysis provides readers with insights into different applications used to implement maintainability.

“Ergonomics” is derived from the Greek words “ergon,” meaning work, and “nomos,” meaning natural laws. Thus, one can interpret ergonomics as the “natural laws of work.” As documented in the literature, ergonomics has long been ignored by management and workers in construction alike. Unfortunately, a sore back in the evening is not always the effect of healthy hard work at the jobsite made apparent by the staggering cost of workers' compensation. Occupational back injuries result in more lost workdays than any other illness, secondly only to the common cold. In addition, manufacturers of construction tools have started to redesign their products because of liability concerns. This paper describes an effort that considers the health epidemic of back injuries as an opportunity. The basic premise is to apply the “natural laws of work” in a scientific manner to reach and treat the root of the problem and not its symptoms. Pneumatic nailing of subfloors is used to explain that back pain and the risk of back injuries for the average construction worker can be decreased, while at the same time maintaining short-term productivity and increasing long-term productivity.