Journal of Construction Engineering and Management

This paper concludes that 4D models are a useful alternative to project scheduling tools like CPM networks and bar charts. They enable more people to understand a schedule quickly and identify potential problems. By developing a 4D model for a commercial construction project, we were able to detect the incompleteness of the original schedule, find inconsistencies in the level of detail among the schedule activities, and discover an impossible schedule sequence. We were also able to anticipate potential time-space conflicts and accessibility problems. The results of the case study show that 4D models are effective in evaluating the executability of a construction schedule. The case study also highlighted the need for improvements to 4D tools. 4D tools should include bar charts, component lists, and annotation tools in their graphical user interface. Automating schedule data preparation and 4D model generation in the design stages of a project can expedite 4D model development and use. Users need to be able to generate 4D models at multiple levels of detail and generate and evaluate alternative scenarios rapidly.

This paper details how construction labor efficiency is affected by deviations from the normal flow of work. A methodology is presented to estimate the loss of labor efficiency, based on variations in the percentage of labor hours used each week. The procedure can be used without the need for contractor production records. The theoretical basis for the method rests on the assumption that the rate of manpower utilization is consistent with the amount of work available for the contractor to perform. Using productivity data from three electrical projects that were accelerated, the labor efficiency is shown to be correlated to changes in the percentages of weekly work hours. Loss of efficiency curves are developed for various project phases. A case study is presented of an actual electrical construction project. Losses of efficiency are calculated for each phase, and it is shown that the contractor incurred an estimated loss of productivity of 25%. The analysis is validated by comparing a weekly inefficient work-hour profile to the chronology of events that occurred on the project.

This paper presents the results of a structural equation model (SEM) for describing and quantifying the fundamental factors that affect contract disputes between owners and contractors in the construction industry. Through this example, the potential impact of SEM analysis in construction engineering and management research is illustrated. The purpose of the specific model developed in this research is to explain how and why contract related construction problems occur. This study builds upon earlier work, which developed a disputes potential index, and the likelihood of construction disputes was modeled using logistic regression. In this earlier study, questionnaires were completed on 159 construction projects, which measured both qualitative and quantitative aspects of contract disputes, management ability, financial planning, risk allocation, and project scope definition for both owners and contractors. The SEM approach offers several advantages over the previously employed logistic regression methodology. The final set of structural equations provides insight into the interaction of the variables that was not apparent in the original logistic regression modeling methodology.

This paper proposes a modification to the minimum moment approach that is used for resource leveling as presented by Harris and based upon the critical path method. The proposed and the traditional methods were developed with the assumption of no activity splitting and a fixed project duration with unlimited availability of resources. The difference between these methods is in the criteria of selecting the activity that has to be shifted from its original position to a better position. This is judged by the change in the statical moment of the resource histogram before and after such movement. In the proposed method, and for the activities that lie at the same sequence step, the activity that is to be shifted first is selected based upon both the value of its free float (S) and the value of its resource rate (R). In this way, the calculation of the improvement factor is needed only to determine the extent to which an activity is to be shifted. On the other hand, using the traditional method, the activity with the maximum improvement factor found for each possible day of shifting is selected first. The process is then repeated for all remaining activities using the updated histogram resulting from the shifted activity. The proposed method significantly reduces the calculations so that the number of iterations in each sequence step is equal to the number of its noncritical activities (n) as compared to (n!) in the traditional method. In addition, the calculation process using the proposed method is easier—especially for manual computations—than the traditional one. The results were insignificantly different, and in many cases they were identical. In this paper, the traditional and the proposed methods will be presented along with an example problem that was solved using the two methods. It should be noted that neither of the two methods provides the true minimum moment.

The need for reliable simulation systems has been discussed and recognized by many researchers. At the same time researchers have recognized that the quality of a simulation model's results are strictly related to the quality of the input probability distribution functions. The data used in this research were acquired from the Atkinson-Washington-Zachry joint venture on the Eastside Reservoir Project in California. The data were analyzed using BestFit software to obtain the parameters of the theoretical distribution functions that best described the field data set. The research validated previous warnings about the influence of the class interval decision on the selection of a distribution function when the chi-square fitting test is utilized. A second issue of importance that was encountered was the reliability of goodness-of-fit tests when dealing with large data sets.

Over the last decade, research in the construction industry has explored the owner-contractor relationship in project management resulting in a different paradigm called partnering. Partnering is a relationship characterized by cooperation and collaboration in contrast to the adversarial relationship more commonly experienced between owners and contractors. This study utilized data collected from 276 construction projects to examine the stability in the owner-contractor relationship. Owner-contractor relationships were classified as being adversarial, guarded adversarial, informal partners, or project partners. Fifty-eight percent of the projects experienced some fundamental change in working relationship—either positive or negative. Projects that began as formal partnerships were the most stable with over two thirds ending as they began. Guarded adversarial was the least stable with fewer than 30% maintaining this kind of relationship at the end of the project. Content analysis of the reasons stated for the change revealed factors that contribute to an improvement or deterioration in working relationships. The writers use this analysis to make recommendations for sustaining and improving partnerships between owner and contractors.

Although parking revenue is a principal source of income, supply of parking infrastructure at airports is based largely on expected needs. Although that is a rational basis, high investment costs and management fees are requiring developers and financiers to carefully analyze investment risks. This paper focuses on sources of investment risk in airport parking infrastructure development and discusses the application of Monte Carlo simulation to estimate and understand the impacts of cash flow uncertainties on project feasibility. It is shown that cost overruns, which are common in construction project development, have the most significant impact on return risk.

A lack of consensus surrounds probability estimates provided by the two leading bid models, one by Friedman and the other by Gates. Each model relies on essentially the same information but arrives at different probabilities of submitting the winning bid. A synopsis of both Friedman's and Gates's models is provided, followed by a descriptive chronology of literature dealing with this controversy. To date, attempts to resolve this debate have been unsuccessful in formulating a consensus view of which model supplies the correct probability. Using a third bid model proposed by Carr as a base, sensitivity curves visually demonstrate both similarities and differences in the models resulting from hypothetical shifts in the underlying location and scale parameters of the bid problem. It is clear from these curves that both models are simultaneously correct and incorrect. Friedman's model is theoretically correct, yet the bid problem is incorrectly specified. Gates's model is practically correct, yet the formula is incorrectly specified.

Construction of asphalt overlays for urban highways is generally restricted to off-peak hours, often exclusively nighttime hours, and to partial closures to minimize public inconvenience. Such constraints are thought to adversely affect production and quality. In August 1997, the Washington State Department of Transportation implemented a pilot project to evaluate the option of a full weekend closure—closure of all lanes in a single direction throughout designated weekend hours—as an alternative to nighttime closures. Two concerns were consistent construction quality between nighttime and daytime paving and general comparison of the full weekend closure with other closure strategies. Surface smoothness (rideability) and in-place density were compared between nighttime and daytime mainline paving for this project, and gradation and asphalt cement content variabilities were compared with published average values. Production rates were compared to those from a comparably sized nighttime project. The investigation revealed that consistent quality, exceeding reported average values, may be achieved. High paving production rates resulted from close proximity of the hot mix plant to the work zone.

This paper presents a systematic approach to environmental management of pollution and/or hazards caused by urban construction projects in China. It proposes a qualitative approach to assess and control the problem and a method to calculate the construction pollution index (CPI), which provides a quantitative measurement of pollution and/or hazards caused by the urban construction projects. Based on the analysis and discussions, the paper further proposes that major construction companies in China should obtain ISO 14001 Environmental Management System (EMS) certifications. By doing so, the construction companies can integrate the concept of environmental management into their construction management practice.