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Forecasting the supply of labor in the construction industry is pivotal to long-term economic growth. A labor supply model using a stock-flow approach was developed in this research for use in the construction industry. The model was tested using Hong Kong census statistics and data derived from interviews with 3,000 randomly selected construction workers. The findings were determined using a stock-flow model, which enabled the determination of future aging distribution trends and workforce supply for specific trade types. The developed stock-flow model can be effectively used in countries in which registration schemes for construction workers are in use. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

With the scarcity of land supply, complex high-rise buildings of more than 50 storeys are not uncommon in property developments in Hong Kong in the last ten years. Large and deluxe commercial complex, shopping malls or resident clubhouses are usually built below the tower blocks aiming at maximizing the investment returns and maintaining the cutting edge in the competitive property market from the mindset of developers. Consequently, different structural layouts have to be devised for the upper and lower structures in order to meet the functional requirements. Transfer plates are often employed to separate and transfer the loadings of the tower blocks to the podium structures. Building developments are becoming more complex in terms of technology applied, scale of investment and tight construction schedule. This induces new challenges for construction management and there are needs to refine the complexity of building projects to facilitate construction planning. In this study, the characteristics of building projects are reviewed and studied by using factor analysis. The analysis attempts to re-group the project data into meaningful factors. These variables have been used in previous relevant researches and are analyzed with subjective measurements. On the contrary, an objective approach is used in this research. This study aims at exploring their contributions and interrelationship, and hence classifying and defining the project natures by using the factors devised. The proposed approach in defining building projects enables construction planners to distinguish the differences between building projects from the view of production processes and to improve resources allocation. [ABSTRACT FROM AUTHOR]

There is a growing concern about environmental impacts resulting from construction activities. Accordingly, there is a pressing need for the adoption of recycled aggregate in Hong Kong. One of the key quality yardsticks in assessing the performance of recycled aggregate is the quantity of cement mortar that remains on the surface of the aggregate. There have been a number of methods designed to assess the mortar remains indirectly such as densities, water absorption rates, 10% fine values, etc. The present paper proposes a new method to assess the cement mortar remains and categorise the recycled aggregate using a classification system called CSAggregate with a CSAggregate index ranging from 0 to 100. A total of 10 samples of recycled aggregate collected from ten demolition sites and one ordinary aggregate were examined and compared. The reliability of the classification system was verified by correlating the index to water absorption rates and densities of aggregate. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

With the rise in the public concern on environmental protection, more construction firms start to apply environmental management for their construction activities. As a result, environmental management systems (EMS) have been implemented in construction. However, to improve the construction environment in Hong Kong, environmental performance assessment (EPA) has been designed for reviewing, monitoring, checking and evaluating environmental performance. A list of evaluation factors for EPA are identified and grouped into seven major factors: management and training; air and noise; auditing; waste and water; cost saving on resources; energy; and regulation. The results from a survey highlight that the most important evaluation factor is management and training and the least significant result is regulation. A voluntary approach has been promoted instead of the traditional mandatory system. Furthermore, three case studies are used to test the reliability with seven groups of evaluation factors in measuring the environmental performance for construction. The results from the case study analysis proved the effectiveness of the developed environmental performance assessment. Therefore, the developed environmental performance assessment can benefit the construction industry and help to achieve continuous improvement on environmental performance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

There is a growing concern about environmental impacts resulting from construction activities. To help minimize the environmental impacts from construction, Environmental Management Systems (EMSs) have been advocated and in some cases, implemented. Within the construction industry, Environmental Performance Assessment (EPA) forms one of the most important tools in monitoring and evaluating environmental performance. However, the relations between Environmental Operational Indicators (EOIs) (inputs) used in EPA and Environmental Performance Indicators (EPIs) (outputs) have not been tested and correlated, casting doubt on the reliability of these inputs. This paper attempts to develop a series of input (EOI) and output (EPI) indicators for EPA and measure their relations based on the perceptions of project managers. The results show that EOIs defined correlate strongly with EPIs. Therefore, EPA can help to identify areas for continuous improvement, and also provide an early indication of the environmental performance for an organization. [ABSTRACT FROM AUTHOR]

The whole construction industry (contractors, consultants and suppliers) is suffering from business shrinking under the prevailing deflationary economy in Hong Kong. Local contractors are facing tremendous financial problems. The financial situation of a typical local contractor has been analysed for the years since 1997 – the Asian Economic Crisis. By using the financial ratios together with one of Altman's distress models, it is possible to monitor and assess the financial health of contractors. Based on the results of the case study, the financial health of the contractor under study is found satisfactory. In addition to this quantitative analysis, it is advisable for local contractors to conduct a strategic review for their construction industry and their business environment so as to improve their financial performance in both the near future and longer term. [ABSTRACT FROM AUTHOR]

Purpose - To assist contractors in Hong Kong to review their past financial performance and to formulate new strategies for their business survival in the coming years. Design/methodology/approach - The financial accounting ratios and distress scoring are very useful tools to measure the financial performance. These tools are also useful to compare the performance among themselves and over the years. The mathematical analysis together with a review of the current business environment and the characteristics of construction industry will assist contractors in Hong Kong to formulate new strategies for their own business survival in the coming years. Findings - The results have shown that the financial performance of most contractors in Hong Kong have been deteriorating very fast in the past few years. The results of all financial ratios, together with the prevailing situation of over competition, inelasticity of construction costs and reduced aggregate demand in Hong Kong, has revealed the extreme difficulty of reversing the financial performance in the coming years. Originality/value - Contractors in Hong Kong now understand that theft own financial performance have been deteriorating to an alarming limit. There is an urgent need to review their business environment and to formulate new corporate strategies. [ABSTRACT FROM AUTHOR]

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 10 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. [ABSTRACT FROM AUTHOR]

Construction-oriented discrete-event simulation often faces the problem of defining uncertain information input, such as subjectivity in selecting probability distributions that result from insufficient or lack of site productivity data. This paper proposes incorporation of fuzzy set theory with discrete-event simulation to handle the vagueness, imprecision and subjectivity in the estimation of activity duration, especially when insufficient or no sample data are available. Based upon an improved activity scanning simulation algorithm, a fuzzy distance ranking measure is adopted in fuzzy simulation time advancement and event selection for simulation experimentation. The uses of the fuzzy activity duration and the probability distribution-modeled duration are compared through a series of simulation experiments. It is observed that the fuzzy simulation outputs are arrived at through only one cycle of fuzzy discrete-event simulation, still they contain all the statistical information that are produced through multiple cycles of simulation experiments when the probability distribution approach is adopted. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between the characteristics of construction personnel and their degree of recognition of safety signs and symbols. The safety signs and symbols are split into categories of mandatory action signs, prohibition signs and warning symbols. Thirty safety signs and symbols printed in colour and in Chinese were distributed to 560 construction personnel working in eight different construction sites in Hong Kong. The results drawn from 388 respondents indicate that substantial problems exist in comprehending the signs and symbols that are posted in construction sites. The percentages of construction personnel who correctly identified mandatory action signs, prohibition signs and warning symbols are 90%, 61% and 55% respectively. Drinking habits, involvement in on-site safety promotion activities and their job positions play a determinant role in their ability of comprehending these construction safety symbols. These findings provide meaningful implications to the industry in the design, selection and positioning of safety symbols on site. [ABSTRACT FROM AUTHOR]

The rapid growth of the Chinese economy sparked off a great volume of construction activities, but the damage caused by construction activities to the environment is indisputable and has alerted some large Chinese construction firms to seek effective environmental management. The ISO 14000 series offers a framework for managing construction operations to improve environmental performance. To discover the conditions of implementation of ISO 14000 in the construction industry, a structured questionnaire survey was conducted whose results show that the major motivation for implementing the system was to seek entry to the international construction market. Other motivations include standardization of the environmental management procedures for internal operations, obtaining social recognition, gaining confidence from clients and a better corporate image, enhancing the environmental awareness of subcontractors, and cleaner sites as a result of better housekeeping. However, some obstacles remain along the path, such as the financial burden, poor rates of return for most firms, low environmental awareness, and inadequate legal enforcement. Based on the analysis and discussion, the paper concludes that the government should take the lead in encouraging training, providing financial support, and improving the legal framework to promote ISO 14000 for the Chinese construction industry. [ABSTRACT FROM AUTHOR]

In this paper, we discuss how a multi-criteria decision-making technique (ELECTRE III) facilitates construction practitioners in decision making for selecting an appropriate construction plant. We first introduce the theoretical background of the technique. Then a case study on how to apply the technique to select concrete vibrators is presented. The findings demonstrate the effectiveness of the model in outranking various options in the process of concrete vibrator selection. The use of ELECTRE III can systematically analyse expert judgments on the decision factors and alternatives that can rationalize the selection process. [ABSTRACT FROM AUTHOR]

This paper describes the application of fuzzy logic to discrete event simulation in dealing with uncertainties of construction operations. The uncertainties in the quantity of resources required to activate an activity are modeled with fuzzy sets in linguistic terms. The fuzzy logic if-then rule is built to control the activation of activities. The duration of the activity that varies with the quantities of resources involved is determined through the fuzzy logic rule-based model. The fuzzy logic control of activities is incorporated with the activity scanning simulation strategy to implement the fuzzy simulation system for construction operations. In addition, the fuzzy activity element is adopted in the graphical modeling process. Examples are given that illustrate uses of the fuzzy simulation system and the impact of flexible demand of resources on productivity. [ABSTRACT FROM AUTHOR]

For construction activities, timely resource allocation is crucial to avoid unnecessary waiting time of resources and delay of activities, especially under the condition of limited supply of resources. Timely resource allocation, i.e. determination of an activity that has the highest priority to obtain resources at that instant, is a dynamic decision-making process dependent on real-time information during a construction process. With the consideration of operational and stochastic characteristics of construction operations and the fuzziness of multiple-decision objectives for an appropriate allocation policy (due to imprecision or subjectivity in decision criteria), a fuzzy dynamic resource allocation (FDRA) based on the fuzzy decision-making approach is developed. In order to model the timely resource allocation decisions, the FDRA is built into a discrete-event simulation system with an activity scanning strategy. The benefit of FDRA on construction productivity is analysed through simulation experimentation by which comparisons among different allocation policies are made. [ABSTRACT FROM AUTHOR]

This paper describes a discrete-event simulation that incorporates the critical path method (CPM) in generating comprehensive information for construction project scheduling or planning. An activity-based graphical model able to consider complexities in construction, for example, unbalanced logical dependencies, unbalanced resource involvements and repetitive activity operation is proposed. An activity scanning (AS)-based forward pass algorithm for early-time information and a backward search algorithm for late-time information are developed. The simulation results that include both resource utilization statistics and late-time information (i.e. latest start or finish time and total float (TF)) of every activity for each cycle of operation cannot be easily achieved through traditional simulation or CPM. Illustrations demonstrate the advantages of the activity-based graphical model and the impacts of resource allocation policies on the schedule. The proposed methodology aims at widening the application of construction simulation by providing float time information and enhanced modelling capability. [ABSTRACT FROM AUTHOR]

Site layout planning can affect productivity and is crucial to project success. However, as construction is heterogeneous in the nature of its organizations, project designs, time constraints, environmental effects, etc., site layout planning for each project becomes unique. Affected by many uncertainties (variables) and variations, site layout planning is a typical multiobjective problem. To facilitate the decision-making process for these problems, a nonstructural fuzzy decision support system (NSFDSS) is proposed. NSFDSS integrates both experts' judgment and computer decision modeling, making it suitable for the appraisal of complicated construction problems. The system allows assessments based on pairwise comparisons of alternatives using semantic operators that can provide a reliable assessment result even under the condition of insufficient precise information. [ABSTRACT FROM AUTHOR]

A number of procurement selection systems have been developed over the last decade. The use of multi-attribute decision analysis has been considered the foremost technique for examining client needs and the weightings of preferences from experts for each procurement system in the most objective way available. However, the major difficulty of these selection models lies in the lack of consensus among the experts on the utility factor of the selection criteria. To overcome these deficiencies, a Delphi technique was adopted to develop a multi-attribute model. Four rounds of Delphi surveys were conducted. A statistically significant consensus on the weighting of the utility factors for each procurement system was obtained from eight experts. The results vividly reveal that the Delphi method is a powerful and appropriate technique for deriving objective opinions in a rather subjective area such as the multi-attribute model for the selection of procurement system. [ABSTRACT FROM AUTHOR]

The quantity of some resources is limited because of project cost constraints. These resources may be required by multiple activities simultaneously during a construction process. In a discrete simulation that models the construction process, tracing and controlling such entities, e.g. resources, is crucial to simulation. This paper presents a resource allocation point (RAP) heuristic that takes into account the dynamic and stochastic characteristics of simulation to enable the activity-based construction simulation system to process a decision-making ability, i.e. allocating the limited resources to the multiple computing activities during simulation. In addition, this paper introduces an activity object-orientated approach that implements the RAP heuristic and speeds up the simulation experimentation through initiating and checking only related activity objects instead of scanning all activities as in a pure activity scanning (AS) simulation strategy. [ABSTRACT FROM AUTHOR]

The construction industry of Hong Kong has a very poor site safety record. The overall accident rate has gone down a little during the last few years, but the number of fatalities has risen dramatically. In the past, the Hong Kong Government adopted a laissez-faire approach in managing construction safety, hoping that market forces would regulate the safety performance. However, the approach has proved to be ineffective. Since 1986, the Government has taken a proactive approach in combating construction site safety, and has introduced a series of safety programmes, which consist of encouraged and mandatory schemes aiming at nourishing a proper safety culture in the construction industry. Recently, the Government decided to criminalize site accident cases by introducing a so-called 'Supervision Plan', aiming at changing the safety attitude and culture of construction practitioners. This paper applies an attitude-changing model, 'reinforcement theory', to predict the changing attitude of people in the construction industry. The results show that the attitude of construction practitioners in Hong Kong will change to be more positive when they receive more messages to confirm that people really are put into jail for negligence under the Supervision Plan. [ABSTRACT FROM AUTHOR]

With mandatory implementation of the Iso 9000 quality system by the Housing Authority in Hong Kong, most construction firms there now claim to have initiated quality systems in their processes as defined in their quality manuals. In addition, an objective quality measuring yardstick, the Performance Assessment Scoring Scheme (PASS), has been administered by the Housing Authority of Hong Kong to monitor the performance quality of contractors. These two measures, coupled with the two other contractual requirements stipulating the use of mechanized formwork and precast facade units, are directed towards achievement of a desired quality standard. However, the PASS analysis has revealed that the general level of quality has not improved significantly and the expected continuous improvement in construction quality has not been realized over a specific time period. Quality appears far better on paper than does the actual work on site. This suggests that quality management in the construction setting is far more difficult to achieve than it is in other industries. This paper explores possible reasons for failure in the quest for quality in public housing construction, and proposes changes needed before the vision of continuous quality improvement can be realized. [ABSTRACT FROM AUTHOR]

Comments on the article "Closure to ISO 14000 and the Construction Industry: Survey in China," by S. X. Zeng et al. Percentage of Chinese construction enterprises that obtained ISO 1400 Environmental Management System certificates; Distribution of the ISO 14001-Certified Construction Enterprises in China by December 2001; Conflict in the issue of Financial Aid.