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The use of modular construction has gained wide acceptance in the industry. For a specific construction facility layout problem such as site precast standardized modular units, it requires the establishment of an on-site precast yard. Arranging the precast facilities within a construction site presents real challenge to site management. This complex task is further augmented with the involvement of several resources and different transport costs. A genetic algorithm (GA) model was developed for the search of a near- optimal layout solution. Another approach using mixed-integer programming (MIP) has been developed to generate optimal facility layout. These two approaches are applied to solve with an example in this paper to demonstrate that the solution quality of MIP outperforms that of GA. Further, another scenario with additional location constraints can also be solved readily by MIP, which, however, if modeled by GA, the solution process would be complicated. The study has highlighted that MIP can perform better than GA in site facility layout problems in which the site facilities and locations can be represented by a set of integer variables. DOI: 10.1061/(ASCE)CO.1943-7862.0000214 CE Database subject headings: Algorithms; Computer programming; Construction sites; Planning. Author keywords: Genetic algorithms; Mixed-integer programming; Facility layout.

A case study describing the application of conflict analysis to a public engagement program of urban planning in Hong Kong is presented in this paper. The technique of conflict analysis is used to investigate the possible conflicts and alliance between interest groups in order to avoid opinion domination by those groups that generate the loudest noise in the process of urban planning. The case study shows that this application helps collect public opinions more accurately that can represent the public interest in the selection of the best development and design scheme for the territory, which would not be corrupted by the 'dominating opinions.' CE Database subject headings: Urban development; Public participation; Public opinion; Conflict; Case reports; Hong Kong.

This study proposes an integration of particle swarm optimization (PSO) and a construction simulation so as to determine efficiently the optimal resource combination for a construction operation. The particle-flying mechanism is utilized to guide the search process for the PSO-supported simulation optimization. A statistics method, i.e., multiple-comparison procedure, is adopted to compare the random output performances resulting from the stochastic simulation model so as to rank the alternatives (i.e., particle-represented resource combinations) during the search process. The indifference zone and confidence interval facilitate consideration of the secondary performance measure (e.g., productivity) when the main performance measures (e.g., cost) of the competing alternatives are close. The experimental analyses demonstrate the effectiveness and efficiency of the proposed simulation optimization. The study aims to providing an alternative combination of optimization methodology and general construction simulation by utilizing PSO and a statistics method so as to improve the efficiency of simulation in planning construction operations. CE Database subject headings: Optimization; Simulation; Construction management; Particles.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ejor.2005.03.013 Byline: C.M. Tam, Thomas K.L. Tong, Gerald W.C. Chiu Keywords: Decision support systems; Multi-criteria construction problems; Non-structural fuzzy decision support system Abstract: Analytical Hierarchy Process (AHP) is a commonly used decision-aiding tool for resolving multi-criteria decision problems. However, users sometimes find it difficult to ensure a consistent pairwise comparison between voluminous decisions. The cause of which is that the Consistency Ratio (CR) is produced after the evaluation process and its global acceptance criteria is limited. When the derived ratio reports some inconsistency, it requires a long process to locate and rectify the problem. The major aim of this study is to look for an alternative decision-aiding tool to AHP, helping to avoid the above problem. The alternative approach proposed in this study is the Non-Structural Fuzzy Decision Support System (NSFDSS). The application of the system is illustrated with a worked example. The results generated by NSFDSS are compared against those generated by the conventional AHP that shows the effectiveness and some unique advantages of the proposed tool over AHP. Author Affiliation: Department of Building and Construction, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong Article History: Received 18 March 2003; Accepted 14 March 2005

This paper introduces a particle swarm optimization (PSO)-based methodology to implement preemptive scheduling under break and resource-constraints (PSBRC) for construction projects. The PSBRC under study allows the preemptive activities to be interrupted in off-working time and not to resume immediately in the next working period because all the limited resources are to be reallocated during a break. The potential solution to the PSBRC, i.e., a set of priorities deciding the order to start the activities or restart the interrupted activities, is represented by the multidimensional particle position. Hence PSO is applied to search for the optimal schedule for the PSBRC, in which a parallel scheme is adopted to transform the particle-represented priorities to a schedule. Computational analyses are presented to verify the effectiveness of the proposed methodology. This paper provides an attempt to make use of preemption and break for the resource-constrained construction project with the objective of minimizing project duration. DOI: 10.1061/(ASCE)0733-9364(2006)132:3(259) CE Database subject headings: Optimization; Scheduling; Construction management.

The Chinese construction market is, and will continue to be, attractive to construction firms of the world. When China joins the World Trade Organization, many foreign contractors can enter the [...]

The usage of fuzzy set theory and a fuzzy ranking measure with discrete-event simulation for modeling uncertain activity duration is discussed.

The application of an object-oriented (OO) approach including the OO modeling concept and the OO programming mechanisms to develop an activity object-oriented (AOO) simulation strategy for modeling construction operations is introduced. After discussing simulation strategies generally used for construction simulation and analyzing the problems related to the simulation strategies, the AOO simulation strategy that guides modeling or controls simulation experiments for construction simulation is introduced. The AOO simulation strategy considers activities to be objects and is able to overcome some pitfalls that result from other general simulation strategies. In addition, the AOO graphical modeling interface associated with the AOO simulation strategy is described. Finally, comparisons of the graphical model or the simulation results of the AOO simulation system with other simulation tools are illustrated. CE Database subject headings: Simulation; Models; Object-oriented languages; Construction management; Control systems.

In December 2000, the new series of ISO 9000 standard was issued. This new quality management series carries some significant changes and modifications, bringing some impact and requiring adaptation for [...]

The Superiority and Inferiority Ranking (SIR) method, a multicriteria decision-making technique, is proposed for facilitating the process of construction plant selection. The SIR method draws together the strengths of most multicriteria decision-making models in handling nonquantifiable, cardinal, and/or ordinal data and allows imprecise information by introducing concepts like indifference and preference thresholds for each criterion. In addition, the technique is capable of dealing with data in different units. The application of the SIR method is illustrated with a case study in the evaluation of l0 alternative concrete pumps based upon nine decision criteria. From the case study, the benefits and strengths of the SIR method in the selection process are unveiled. DOI: 10.1061/(ASCE)0733-9364(2004)130:6(827) CE Database subject headings: Decision making; Construction industry; Hong Kong; Pumps.

The increasing awareness of environmental impacts from construction wastes has led to the development of waste management as an important function of construction project management. Various approaches for managing construction wastes have been developed in the existing research works and practices, and these works can be grouped largely into three areas: waste classification, waste management strategies (avoiding waste, reducing waste, reusing waste, and recycling waste), and waste disposal technologies. Nevertheless, these approaches give less attention to the management of the waste handling process on construction sites. In fact, construction wastes pass through a number of processes from generation to final disposal, and proper flow of these processes can improve waste management effectiveness. This paper examines the waste handling process during construction through mapping six cases selected in Hong Kong construction, with the assistance of the free-flow mapping presentation technique. The examination leads to developing a waste management mapping model (WMMM), which incorporates the good operations embodied in the existing practices. The WMMM provides an alterative tool assisting in planning waste management procedures on construction sites. It can serve as a vehicle for comparing the waste management practices between construction sites, thus both good practices and weak areas can be identified. CE Database subject headings: Construction industry; Construction sites; Waste management; Hong Kong; Mapping.