Journal of Construction Engineering and Management

During the planning and execution of construction projects, it often becomes necessary to shorten the duration of the project. A widely used technique for reducing the duration of a project is commonly referred to as least-cost scheduling. This procedure is based on deterministically arriving at the shortest project duration for the minimum cost possible. There is, however, one major problem with the typical application of this technique. It does not address the variability inherent in the duration and cost of the project activities. Thus, the resulting compressed schedule value cannot be applied with any stated level of statistical confidence. This paper presents a new procedure that addresses some of the major shortcomings of least-cost scheduling. It does so by accounting for the variability inherent in the duration and cost of the scheduled activities by simultaneously applying range estimating and probabilistic scheduling to the historical data. The resulting data set is then analyzed to provide a compressed schedule duration and cost estimate that have a higher overall confidence of being achieved.

During the past two decades, drug testing in the workplace has gone from virtual nonexistence to widespread employer acceptance. This growth is particularly critical for the construction industry. High rates of alcohol and other drug use, coupled with the high-risk, safety-sensitive nature of the industry, have prompted the implementation of a variety of drug surveillance and prevention strategies. Despite this growing vigilance, however, no scholarly works have examined the impact of drug-related policies in the construction industry. The present study investigates the efficacy of workplace drug-testing programs in reducing injury incident rates and workers' compensation experience-rating modification factors within the construction industry. Analyses indicate that companies with drug-testing programs experienced a 51% reduction in incident rates within 2 years of implementation. Furthermore, companies that drug test their employees experienced a significant reduction in their workers' compensation experience-rating modified factors. Policy implications are discussed in light of the current findings.

The fast-tracking delivery method has received considerable attention over the last decade, and its time saving feature has placed it as a possible alternative to the traditional more sequential method. Along with its benefits, however, fast-tracking also has greater potential to impact the project development process than the traditional method. In the literature, this is usually attributed to the increased level of uncertainty and research on fast-tracking has mainly focused on uncertainty reduction but without explicit study of the feedback processes involved in fast-tracking. However, closer observations of the project development process suggest that to effectively handle uncertainty and minimize the negative impact of fast-tracking, the feedback processes involved in fast-tracking need to be identified, and the dynamic behavior of construction resulting from those feedback processes needs to be dealt with in a systematic manner. As an effort to meet these needs, this paper presents the Dynamic Planning Methodology, a planning methodology based on system dynamics. Focusing on the dynamic behavior of fast-tracking construction, the Dynamic Planning Methodology aims to improve the planning and management of fast-tracking building construction projects by providing overlapping strategies, workforce control policies, and schedule adjustments that will minimize the negative impact of fast-tracking.

Malaysia's privatization program, which began in 1983, has been praised by some, while others have been less impressed. This paper describes the return of a privatized infrastructure after seven years to government hands after it had been relinquished to the private sector. Right from the beginning the privatized national sewerage scheme was plagued with controversy—from selection of a concession company, charge structure, and performance to ownership changes. The award of the infrastructure facility was made in the absence of competition. The charge structure accepted by the government was never revealed completely to the public. Inefficiencies and management blunders aggravated public sentiment. The change of ownership three times in as many years gave the impression of industrialists out to make quick money at the expense of public welfare. Despite copious government assistance, Indah Water Konsortium, the concession holder, became infeasible as an independent operating company. This case study provides salutary lessons of what to avoid when structuring a privatization arrangement.

This paper presents a subcontractor information system (SIS) to support the estimating and project control functions of subcontractors and small/medium-size contractors. For the proposed SIS to be simple and practical, it was developed in a spreadsheet program designed to maintain information related to resources and projects and to generate important business reports. Resource data are stored in six worksheets for labor, equipment, crews, material, subcontractors, and alternative methods of construction for various tasks. In addition, a separate worksheet is designed for each project to be used for estimating and control purposes. The latter worksheet allows the user to specify the work breakdown structure and optional methods for construction. As such, it represents a transparent estimating model that allows for quick what-if analysis regarding time and cost. In addition, the reporting worksheet provides information related to time, cost, and resource use at the individual and the multiproject levels. In a companion paper, the use of the SIS as basis for overall schedule optimization is described.

Overall schedule optimization, considering time, cost, and resource constraints is a difficult task due to the inherent complexity of projects, the difficulties associated with modeling all aspects combined, and the inability of traditional optimization tools to solve this large-size problem. In this paper, a practical approach is presented for the modeling and optimization of overall construction schedules. To simplify modeling, a spreadsheet-based model is developed to be easily usable by practitioners. The spreadsheet model integrates critical-path network scheduling with time-cost trade-off analysis, resource allocation, resource leveling, and cash flow management. The model uses the total project cost as the objective function to be minimized. To facilitate this large-size optimization, a nontraditional optimization technique, genetic algorithms, is used to locate the globally optimal solution, considering all aspects simultaneously. Details of the proposed model are described, and a hypothetical case study was used to experiment with it. Integration of the model with a simple information system is described to automate the development of optimal construction schedules.

Horizontal site characterization technologies present a rapidly evolving alternative to traditional vertical site investigation methods for subsurface investigations of large diameter trenchless construction projects. A state-of-the-art review of horizontal site characterization tools, both currently available and under development, is presented. Additionally, a rational methodology for the selection and deployment of horizontal site investigation techniques in trenchless construction projects is also presented. The methodology enables the user to define and quantify the risks involved in a particular project, as well as to evaluate the degree to which these risks can be mitigated using various site characterization techniques. The proposed model is demonstrated using a working example. The paper concludes with a discussion of future trends in this exciting new field. The main conclusions drawn from this work are (1) adequate subsurface information is invaluable for underground construction; (2) site investigation programs of linear construction projects can be enhanced by horizontal characterization techniques; and (3) the availability of continuous and near-continuous subsurface information enables the utilization of new approaches for the analysis and representation of subsurface data.

This paper reports on a fully structured interview survey, using a multisectional questionnaire, of experienced construction contract price forecasters. The aim of the research was to investigate the relationship between the accuracy of “early-stage” forecasts and experience (defined in terms of the forecasters' length of service as a forecaster and the number of forecasts prepared), learning styles, and approaches to learning. The results show that, although the forecasters rated experience very highly, the relationships between their ability to learn from experience, measured in terms of individual learning styles and approaches to learning, and the quality of their forecasts were found to be very different from those anticipated. No significant correlations were found between forecasting accuracy and the experience measures used, except for the approaches-to-learning dimensions labeled Risk taking, Insecurity, and Self-confidence. The results for the Insecurity and Self-confidence dimensions suggest that balanced forecasters (i.e., those who were neither insecure nor overconfident) produce more consistent forecasts. Similarly, the results for the Risk-taking dimension indicate that high-risk takers tend to underestimate whereas those who are more conservative tend to overestimate contract prices.

The just-in-time (JIT) philosophy has tremendous potential for managing the movement of precast concrete components from the prefabrication yard to, and within, the construction site. The space constraints for storage and the traffic congestion at the worksite can then be alleviated. By means of a survey and interviews, this paper helps a precast concrete supplier examine if contractors are ready to adopt the JIT philosophy for receiving and installing precast concrete components on-site. Lessons are drawn from the empirical findings to determine how contractors can prepare for JIT management of precast concrete components. The findings suggest that the contractors are, by and large, obscured by price and have generally overlooked the bigger picture of total costs. Only a minority of the respondents show an interest in JIT deliveries as a cost-saving management system. Conversely, the precasters are better prepared to provide logistical support for JIT deliveries. In this context, reimbursement of costs or sharing of the savings can help to motivate the precasters to commit to JIT deliveries.

This paper discusses an approach based on artificial neural networks that enables an estimator to produce accurate labor production rates (labor/unit) for industrial construction tasks such as welding and pipe installation. The paper first reviews factors that were found to affect labor production rates on industrial construction tasks, current estimating practices and their limitations, and the process followed in collecting historical production rates. An artificial neural network model is then described. The model is composed of a two-stage artificial neural network, which is used to predict an efficiency multiplier (an index) based on input factors identified by the user. The multiplier is then used to adjust an average production rate given in man-hours/unit for use on a specific project. Estimates of production rates from the new approach are compared to the existing estimating practices and conclusions are presented.