Editor's Note

“Bid Compensation Decision Model for Projects with Costly Bid Preparation”: Ho addresses the issue of bid compensation, used to stimulate extra effort or input in bid preparation. The writer studies the impacts of bid compensation and develops appropriate bid compensation strategies, including developing a model that provides equilibrium solutions under bid compensation, a quantitative formula, and qualitative implications for the formation of bid compensation strategies.

“International Comparison of Cost for the Construction Sector: Purchasing Power Parity”: Walsh, Sawhney, and Brown examine the comparison of different countries' construction sector output as performed by The World Bank. The trio critically reviews the construction cost comparison approach used by The World Bank, the Casselian Purchasing Power Parity Doctrine, as opposed to other traditional methods such as basing comparisons off exchange rates.

“Graphical Approach for Manpower Planning in Infrastructure Networks”: Due to their large size and their repetitive/distributed nature, construction and/or maintenance operations for infrastructure networks become complex tasks that require huge resources, particularly manpower. Elhakeem and Hegazy provide a transparent tool for quick manpower planning and sensitivity analysis using a graphical approach. The nomographs encode the mathematical formulation and the results of many optimization experiments of a distributed model for scheduling large projects with multiple sites.

“Stochastic Time-Cost Optimization Model Incorporating Fuzzy Sets Theory and Non-Replaceable Front”: Managers and planners must take uncertainties such as weather, resource availability, and productivity into account to provide an optimal balance of time and cost based on their own experience and knowledge. Zheng and Ng use fuzzy set theory to model managers’ behavior in predicting time and cost, as well as proposing the application of the nonreplaceable front concept to assist managers in recognizing promising solutions from numerous candidates on the Pareto front.

“Time-Cost Relationships in Australian Building Construction Projects”: Love, Tse, and Edwards, having examined 161 construction projects across Australia, analyzed the relationships between time and cost using the method of weighted least squares. The analysis was performed between six different variables. An alternative model for forecasting time and cost performance is proposed, in contrast to the model proposed by Bromilow more than $30\text{years}$ ago, after which results are then drawn based upon the relationships.

“Determination of Quality Level in Mass Housing Projects in Turkey”: Addressing the issue of extremely low quality construction in Turkey, Kazaz, and Birgonul identify the type of deviations resulting in rework in mass housing projects. The writers point out that firms can only increase their profit margins by paying more attention to the deviation types, as well as improving their image in the sector and thus being able to take on new projects.

“Multilevel Formwork Load Distribution with Posttensioned Slabs.” When a slab is posttensioned using draped tendons, slab lift occurs as a portion of the slab self-weight is balanced, causing the formwork and shores supporting that slab to be unloaded by an amount equal to that from posttensioning. Kajewski presents two design methods suitable for modeling the multilevel formwork process for posttensioned slabs, which will both be of immediate use by industry practitioners and of interest to researchers examining the load distribution phenomenon.

“Risk Concession Model for Build Operate Transfer Contract Projects”: Shen and Wu expand on the build operate transfer concession model by establishing a risk concession model for build/operate transfer projects. Due to a major limitation in the former model regarding its lack of consideration to the impacts of risks on the estimation of various economic variables, the latter was developed to address such issues. The model provides an approach for formulating a concession period to consider the impacts of risks and at the same time protect the basic interests of both the investor and the government concerned.

“Describing a Beta Probability Distribution Function for Construction Simulation”: Schexnayder, Knutson, and Fente present a formulation for developing a beta probability distribution function for use in construction simulation modeling. The writers hypothesize that there is a ratio that relates the 75th percentile to the mode of the activity duration. The research demonstrates that using such ratios along with the minimum, mode, and maximum activity durations result in estimates of a beta PDF that accurately describes the underlying duration distribution of construction activities.

“Lognormal Distribution Provides an Optimum Representation of the Concrete Delivery and Placement Process”: Due to the random nature of the process of concrete supply and delivery, Graham, Smith, and Dunlop aim to identify a sufficiently flexible representative of the concrete placement process. A computer package, PDFit, is presented in order to identify a suitable distribution in this context. The package is founded upon the production of probability density functions of select theoretical probability distributions plotted against the histogram of the input data.

“Optimizing Implementation of Value Management Processes for Capital Projects”: Cha and O’Connor detail a new, systematic approach to determining the best process from among the many value management processes that are being introduced into capital facility projects. The writers identify and quantify the selection principles, as well as detailing research methodology and the findings from industry surveys. A computerized tool is described that is designed to facilitate the implementation of VMPs in the construction industry and to maximize the potential benefits to a particular project.

“Prediction of Organizational Effectiveness in Construction Companies”: Many researchers agree that the task of defining, modeling, and measuring organizational effectiveness has historically been quite difficult. Dikmen, Birgonul, and Kiziltas attempt to construct a conceptual framework to model organizational effectiveness (OE), to derive major determinants of OE from this framework, and to measure OE by constructing prediction models based on artificial neural network and multiple regression techniques. Using information associated with 116 Turkish contractors, the most significant variables that determine OE are identified to create the model.

“Nature of Struck-By Accidents”: Struck-by accidents accounted for 22% of all construction-related fatalities recorded by OSHA between 1985 and 1989. More recently, this number has increased. Hinze, Huang, and Terry employ results from a study to gain insights about struck-by injuries. While determination of possible causation factors is often difficult, the study attempts to indicate the root causes of the accidents, upon which effective methods for accident prevention can be developed.