Journal of Construction Engineering and Management

Integration of cost and schedule control systems has been an issue of great concern for researchers and practitioners in the construction industry. Nevertheless, the real-world implementation of this promising concept has not been popular enough to maximize the benefits that this integration has to offer. One of the major barriers is the overhead effort to collect and maintain detailed data. The purpose of this paper is to propose a flexible work breakdown structure (WBS) that optimizes the overhead effort by means of reducing the amount of data to be controlled. In order to have a flexible structure, the WBS numbering system needs to utilize standard classification codes and should not have a common strict hierarchy for all components. A case study is analyzed in this paper in order to examine the proposed concept. Practical implications are outlined as well.

Buffering is a common practice in project planning. Project managers or schedulers have used a time contingency to guarantee the completion time of either an activity or a project. This traditional buffering, however, often fails to protect the project schedule performance, resulting in an unnecessary resource idle time. To deal with this problem, reliability buffering, a simulation-based buffering strategy, is presented. Reliability buffering aims to generate a robust construction plan that protects against uncertainties by reducing the potential impact of construction changes. The effectiveness of reliability buffering is examined by simulating a dynamic project model that integrates the simulation approach with the network scheduling approach. The research results indicate that reliability buffering can help achieve a shorter project duration without driving up costs by pooling, resizing, relocating, and recharacterizing contingency buffers. A case study of bridge construction projects also demonstrates how construction projects can benefit from reliability buffering in real world settings. Although further validation is needed, reliability buffering can potentially impact the planning and control of construction projects by improving the consideration of construction feedbacks and characteristics in buffering, and serving as an input to a dynamic project model.

This paper presents a model designed to integrate the planning and scheduling phases of highway construction projects, focusing primarily on the planning aspects. The model automatically generates the work breakdown structure (WBS) and precedence network respecting job logic and stores a list of construction operations typically encountered in highway projects. The generated network can subsequently be modified to suit the unique requirements of the project being considered. An object-oriented model is developed for planning highway construction operations. The model employs resource-driven scheduling in order to suit the repetitive nature of this class of projects. It accounts for (1) resource availability; (2) multiple preceding and succeeding activities; (3) transverse obstructions; (4) activities with varying quantities of work along the highway length; (5) the impact of inclement weather on crew productivity; and (6) the beneficial effect of the learning curve. At the core of the model is a relational database designed to store available resources and their respective unavailability periods. The model enables both: (1) activities executed by own force; and (2) activities subcontracted out. The model is incorporated in a prototype software that operates in the Microsoft Windows environment and generates schedules in both graphical and tabular formats. An example project is analyzed to demonstrate the features of the developed model.

Contractors are required by the Michigan Department of Transportation (MDOT) to submit a progress schedule identifying the controlling path of activities for a construction project. During the 2000 construction season, MDOT allowed contractors to submit a progress schedule with overlapping or concurrent controlling operations. Prior to this, only one activity at a time could be controlling on the progress schedule. This paper reports on the results of a research project where the focus was to examine the accuracy of the progress schedules, which only list controlling items. Eight construction projects were studied and a determination of progress schedule accuracy was made. This was done to determine if there was an increase in accuracy of the schedules when concurrent controlling operations were used. Included in the eight projects were four without concurrent controlling activities and four with concurrent controlling activities. A comparison based upon similar projects with and without concurrent activities was made. Additionally, 22 projects were analyzed, all without concurrent controlling activities, to determine the accuracy of progress schedules for two types of projects. The comparison revealed that, in three of the four cases, the accuracy of progress schedules increased with the allowance of concurrent controlling activities. The 22 projects revealed that the accuracy of progress schedules varied considerably. It was also determined that contractors overestimated the duration of activities included in progress schedules.

The concept of constructability in the United States or buildability in the United Kingdom emerged in the late 1970s, which evolved from studies into how improvement can be achieved to increase cost efficiency and quality in the construction industry. It is an approach that links the design and construction processes. The studies in the Unites States, United Kingdom, and Australia have demonstrated that improved constructability has lead to significant savings in both cost and time required for completing construction projects. However, in implementing constructability improvement, it is important to consider the uniqueness of the construction industry in a specific country. This paper presents the study performed on the construction contractors in Indonesia with regard to their current constructability practices and its impact on the project performance. The study shows that many contractors in Indonesia have been implementing part of the constructability concept in their projects. The concepts that usually applied during the construction stage as part of the overall construction plan were planning the sequence of field tasks and analyzing layout, access, and temporary facilities

A critical contributor to the success of a public/private partnered (PPP) infrastructure project is the selection of the right private-sector partner, the concessionaire, who would provide the best overall deal throughout the build-operate-transfer (BOT)[build/operate/transfer] development process. This paper proposes a core concessionaire selection protocol that incorporates public procurement principles, best-value selection approach, competitive selection process, and multicriteria tender evaluation. Key pointers for an improved concessionaire selection protocol are discussed and analyzed by drawing experience and learning lessons from worldwide PPP practices. These include improved project brief and tender documents, formulation of a best-value selection methodology, determination of suitable criteria and methods for prequalification and tender evaluation, capital structure (equity-to-debt ratio), financial models, and potential improvements in different stages of the concessionaire selection process. Relevant results of a questionnaire survey of international PPP expert opinions on an enhanced concessionaire selection protocol are also presented.

This paper describes a process to assist project managers, within owner companies, define work relationships between owners and their contractors for capital project development, and execution. The owner–contractor work structure process was developed by the Construction Industry Institute as a step-by-step process for making rational decisions about the most appropriate owner–contractor work structure for capital projects. A work structure is described by a set of project competencies and the extent of involvement of the owner and contractor in performing, leading, and/or providing input with respect to those project competencies. The process is described using a formal process modeling technique. Three case studies, conducted to validate the owner–contractor work structure process, are discussed. The results from these case studies suggested some basic changes to the process that would enhance its use in practice. A modified owner–contractor work structure process is then presented.

An accurate prediction of contractor potential is of vital importance during contractor selection and evaluation process. Such prediction enables identification and classification of contractor performance to ease the selection process. This paper outlines the use of clients' tender evaluation preferences for predicting a contractor performance via a logistic regression (LR) approach. A total of 31 clients’ tender evaluation criteria were selected to develop a LR model for predicting contractor performance. The proposed model was developed based on 48 of United Kingdom public and private construction projects and validated in 20 independent cases. It was found that 75% of the cases correctly and the model statistically accurate for contractor performance prediction, where the input variables consist of nominal and interval data. The paper summarized techniques and advantages of LR analysis and discussed literature findings of contractor selection and evaluation methodologies undertaken by construction researchers and commentators from the United Kingdom and Northern America.

According to the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) report in 1982, radiation from radon contributes about 50% of all natural radiation sources to the public. The situation is worse in Hong Kong where large area is granitic containing larger amount of uranium when compared to the global mean. Radon level can therefore be on the high side during tunneling especially where poor ventilation is envisaged. This article includes realistic field study of radon in tunnel under construction. A maximum concentration of over $30\text{,}000\mathrm{Bq}/m^3$ was recorded (1 Becquerels per cubic meter is equivalent to $0.027\mathrm{pico}\mathrm{Curies}/L$). Radon concentration in tunnel environment is found to be related to groundwater ingress, ventilation provision and geology. A review of the current statutory control in Hong Kong is done as well as its comparison with other countries’ practices. In fact, the situation can be improved through education, adopting control legislation and more specifically, having a suggested radon management plan in every tunnel drilling project.

A manufactured home is completely built in a controlled factory environment. Despite a large share of the market, the manufactured housing industry has a long way to go towards streamlining its production process. The objective of this paper is to map the production process of a manufactured housing factory and to demonstrate via simulation how the process can be improved. The production process including assembly, feeder, and storage stations were mapped using data from several manufactured housing plants and in-depth case studies at two plants in northern Indiana. The case study plants were also used for collecting cycle-time data for developing the simulation model for the roofing process. Subsequently, four “what if” scenarios were conducted to illustrate potential improvements to the production process. The efforts presented in this paper are part of on-going research sponsored by the National Science Foundation under the Partnership for Advancement of Technology in Housing (PATH) initiative.

In recent past the United States Department of Transportation has implemented a number of changes in regulations regarding federal-aid transportation projects. Some of these regulations are designed to help the disadvantaged business enterprise (DBE) firms and subcontractors in general, by requiring the general contractors to pay their subcontractors in a timely manner. Further, these regulations require that general contractors pay their subcontractors’ retainage after the subcontracts are completed, even if they have not received their own retainage from the owner. This paper reviews these new regulations and introduces a financial model for quantifying the effect of these new regulations on the contractors’ profit and the cost of transportation projects. The analysis is done using a spreadsheet-based cash flow model that takes into consideration the expenditure curve, the owner and general contractor’s payment and retainage policies, front money, finance charge on negative cash flow, and interest income on positive cash flow, and final payment and return of retainage policies. A survey was conducted among contractors in Massachusetts and their input was used to run the cash flow model. The results of the analysis for eight different projects are presented and it is shown that the new regulations, on average, reduced the contractor’s profit by 4.35%. It is also shown that the average potential cost increase for transportation projects is 0.14%.

In today’s construction, small projects can be just as important if not more important than the larger projects. However, small projects are usually fast track projects, which often involve overlapping design and construction time. Subsequent modifications may be required for the sections that are already under construction. These disruptions to the ongoing project are labeled as change orders. The impact due to changes has been described as the adverse effect upon the unchanged work due to changes in the contract. For this study, 34 projects were selected to develop a statistical model that estimates the amount of labor efficiency lost due to change orders for small projects. The variables in the final model are percent design related changes, percent owner initiated changes, the ratio of actual peak labor to estimated peak labor, the ratio of actual project duration to estimated project duration, and project manager’s percent time on the project. The results of this paper are of value to owners, electrical and mechanical contractors, and construction managers. The model quantifies the impact of change orders by introducing the most important variables that bring the largest disruptions.

A novel approach has been used to attempt to understand how contractors justify their claims on construction contracts and how contract administrators are likely to assess them. This is done by encapsulating particular claim types into scenarios and interviewing not only contractors and contract administrators, but also claims consultants, to hear their views on how the situations represented by the scenarios should be resolved. In this paper, four areas of general uncertainty surrounding claims in the United Kingdom are described and the results of the survey on these four areas are reported. The concerns addressed are: the treatment of exceptionally adverse weather; dealing with early completion schedules; quantification of the prolongation costs associated with an approved extension of time; and concurrent delays. The results show some good agreement, particularly on the problems of dealing with exceptionally adverse weather and with some aspects of concurrent delay assessment. Although the consensus was not so clear on the other two issues, there was a majority view that should give professionals working in this area greater confidence when dealing with these problems.

System simulation has proved to be an effective tool for planning and improving the performance of a construction process in many successful case studies. However, with the aid of a three dimensional $\left(3D\right)$ visualization system, simulation technology will be engaged to its farthest-reaching potential. This paper presents a geographic information system (GIS)-based visual simulation method, in which system simulation techniques are integrated with visualization techniques. The GIS-based visual simulation system (GVSS) was developed by the authors. The GVSS is a simulation tool offering powerful planning, visualizing, and querying capabilities that facilitate the detection of logic errors in simulation models. The software also helps to understand the comprehensively complex modeled construction process, and is capable of organizing vast amounts of spatial and nonspatial data involved in simulation. A hydroelectric project, which will take place on the Yellow River in the northwest of China, is used as an example. An optimum equipment set scheme is determined by simulating a variety of scenarios taking place under different construction conditions. Likewise, other parameters, such as the construction sequence of dam blocks, the monthly intensity of the concrete process, and the construction appearance at the middle and end of each year, are obtained. Meanwhile, the complex processes of dam construction are demonstrated dynamically using $3D$ animation, which provides a powerful tool for quickly and comprehensively understanding the whole construction process. The GVSS has proven to be a helpful and useful tool for the design and management of concrete dams.

The history of construction engineering and management education closely follows the emergence of the construction industry as an economic force in the United States. The initial introduction of programs in the post-World War II era was followed by specialization and the introduction of graduate construction specialties in the early 1960s. However, the lack of qualified individuals was recognized as a factor in successfully developing the construction engineering management (CEM) focus as an academic discipline. Today, that concern continues as CEM programs in the United States find themselves under attack by academic colleagues for issues such as lack of qualified faculty candidates and lack of funding opportunities. This paper addresses the status of the construction academic community by examining the common history of the CEM faculty through a genealogical approach, the historical research record through an examination of the publication record, and the questions that face a community that has appeared to slip from its intellectual peak.