Construction is a major contributor to pollution in the natural environment. Among all construction pollutants, construction dust is the most significant pollutant that endangers human health. To ...expand the limited scope of studies on construction dust exposure, this study investigates current dust control practices in the construction industry in Hong Kong through dust monitoring data compilation. The database constructed and compiled by this study is larger than any other previous dust-related datasets in the construction industry in Hong Kong. A total of 837 samples are collected from 33 construction sites and 16 contractors, among which 783 valid samples are analyzed. Descriptive statistics are reported in terms of “construction process”, “trade”, “tools”, “data source type”, and “dust control measure”. Overall geometric mean for personal exposures are 0.314 (geometric standard deviations: 3.929) mg/m3 for respirable dust and 0.003 (geometric standard deviations: 5.105) mg/m3 for quartz concentration. It is found that the top three dust respirable exposures are from cement mixing, concrete breaking, and manual demolition, whereas grinding and rock breaking are recorded the two highest processes in terms of quartz exposure. Analytical results indicate that respiratory protection commonly used on construction sites is often inadequate for exposures encountered. Data variability within task and tool is large, with high exposures reported for a broad spectrum of tools. This study attains a large dataset to represent as many dust production construction activities as possible, determining the most influential factors for predicting dust exposure and evaluating the effectiveness of current dust control practices. This knowledge should, in turn, lead to enhanced practices of dust control in Hong Kong and highlight areas that need improvements.
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Various schedule risks beset prefabrication housing production (PHP) in Hong Kong throughout the prefabrication supply chain, from design, manufacturing, logistics, to on-site assembly. Previous ...research on the risks in prefabrication construction projects has mainly focused on the construction stage and has been confined to issues of completeness and accuracy without consideration of stakeholder-related risks and their cause-and-effect relationships. However, in reality, the supply chain is inseparable as precast components should be manufactured and transported to sites to fit in with the schedule of on-site assembly in seamless connection manner, and most risks are interrelated and associated with various stakeholders. This study applies social network analysis (SNA) to recognize and investigate the underlying network of stakeholder-associated risk factors in prefabrication housing construction projects. Critical risks and relationships that have important roles in structuring the entire network of PHP are identified and analyzed. BIM (Building Information Modeling)-centered strategies are proposed to facilitate stakeholder communication and mitigate critical schedule risks and interactions underlying the risk network. This study not only provides an effective method to analyze stakeholder-associated risk factors and to evaluate the effect of these risk factors from a network perspective, but also offers a new visual perspective in the promotion of the use of the Internet of things (IoT) and helps identify housing construction problems in Hong Kong.
The construction industry in Hong Kong has been exposed to serious housing production issues such as insufficient manpower, safety, environmental concerns and inefficient housing supply. ...Prefabrication housing production has shown as efficient construction model which enables to overcome these issues and it is applied in construction industry in Hong Kong. In this paper, hybrid modeling techniques that combine system dynamics and discrete event simulation are used to analyze the interrelationships of schedule risks within the six-day cycle assembly of prefabrication housing production. Moreover, a hybrid dynamic model is developed to simulate and evaluate the impact of schedule risks on the schedule performance of the six-day cycle assembly of PHP via the Anylogic software package. The resulting model is validated by data which is collected from a PHP project in Hong Kong. Based on the simulation results, the first most influential level contains five schedule risks, namely, inefficient verification of precast components because of ambiguous labels, misplacement on the storage site because of carelessness, owner crane breakdown and maintenance, slow quality inspection procedures, and inefficient design data transition that cause average schedule delays of more than 300 min. The second most influential level includes delay of the delivery of precast element to site, design information gap between designer and manufacturer, installation error of precast elements, and logistics information inconsistency because of human errors, with average schedule delays less than 300 min and greater than 200 min. Design change, low information interoperability between different enterprise resource planning systems, and inefficiency of design approval belong to the third level that imposes the least influence on the schedule delay of the assembly. This research contributes to the current knowledge of the management of prefabrication construction by developing an effective model that offers an in-depth understanding of how schedule performance of PHP is dynamically influenced by interrelationships of various risk variables. Also, it provides an experimental platform for simulating and analyzing schedule risks that significantly affect the schedule performance of the six-day cycle assembly of prefabrication housing production. Such critical schedule risks could be identified and managed prior to the implement of prefabrication housing production projects. Compared with traditional techniques, the hybrid dynamic model simultaneously considers macro and micro levels, thereby enabling project managers to gain a deeper insight into schedule management and acquire a multidimensional understanding of schedule delay.
The rapid urbanization in China has produced a large demand for energy in the past decades. It is therefore urgent to have an understanding of the driving forces behind the energy increase in the ...construction industry. This study applies structural decomposition analysis (SDA) to quantify the effects of driving factors from insight into consumption and production. The results show that the energy consumption trajectory of China's construction industry is the result of competition between the effect of increasing final demand and improvement in energy efficiency. Although the effect of consistent efforts in structure optimization by the central government was significant from 2007 to 2012, the potential to save much energy still lies in structure optimization in energy, production, and final demand. According to the projection, structural upgrades in economy would be the most important factor for energy reduction in 2020. Scenario analysis further indicated that the percentage change of energy increments in 2020 can be reduced at 22% of 2010 level under the optimistic scenario. Sector aggregation analysis revealed that more aggregates would increase uncertainty to some extent and result in a misinterpretation of the importance of the underlying factors. According to the quantitative analysis in this study, the percentage change of total embodied energy consumption in the construction industry should be limited below 25% of 2010 level at the end of the 13th Five-Year Plan.
With its generally recognized benefits of clean and safe working environment and good quality, prefabricated house construction (PHC) as a solution is gaining momentum in the face of various housing ...challenges in Hong Kong's construction industry. Although prefabrication has its own benefits, its fundamental disadvantages of fragmentation, discontinuity, poor interoperability, and scarce real-time information availability have imposed significant adverse influence on the schedule performance of prefabricated house construction. As a result, despite the promise of the government to provide sufficient houses and harmonious housing, schedule delay problems still frequently beset the industry of PHC. To help address schedule delay problems encountered in the construction of prefabrication housing, this research first identified and analysed critical schedule risk factors that may have significant influence on the schedule performance of PHC. Based on the identified schedule risks, the challenges and corresponding required functions for enhancing schedule performance are determined. Then, a radio frequency identification device (RFID)-enabled BIM platform that integrates various involved stakeholders, information/data flow, offshore prefabrication procedures, and state-of-the-art construction technologies, is developed to handle the critical schedule factors. Smart construction objects and RFID-enabled smart gateway work collaboratively to ease operations within the three echelons of prefabrication manufacturing, logistics and on-site assembly construction, while real-time captured data are used to form a closed-loop visibility and traceability mode in which different end users can supervise the construction statuses, progresses in real time. The developed platform can provide various services, tools and mechanisms to different stakeholders, improve the success of daily operations and decision makings throughout PHC management, such that critical schedule risks can be mitigated and the schedule performance of PHC can be enhanced to ensure timely project delivery.
Improvement of building energy performance is crucial in achieving energy conservation goals. Previous studies have indicated that effective collaboration among stakeholders can help to address the ...building energy performance gap. However, only a few studies have examined the effects of underlying collaboration between designers and contractors. To fill this research gap, this study proposes an evolutionary game model to investigate the underlying logic of the collaboration by analyzing the dynamic behaviors of designers and contractors. First, the main possible drivers and barriers of the collaboration between designers and contractors were identified through a literature review and an expert interview. Second, a Nash equilibrium model was utilized to analyze the decision of designers and contractors under different scenarios. The results show that the best means to promote the collaboration is “reducing collaboration costs”, followed by “increasing the collaboration benefits” and “decreasing the loss caused by a lack of collaboration”. Based on the parameter discussion of the evolutionary game model, five solutions were proposed for the effective collaboration between designers and contractors. This study helps to clarify the dynamic collaboration decision process of designers and contractors, who are considered players with bounded rationality. The proposed evolutionary game model provides a theoretical basis for quantitative research on the collaboration between designers and contractors. This study could help researchers to consider the dynamics of collaboration among stakeholders in building projects, and it could also help practitioners to select proper strategies for improved collaboration.
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Every country is dealing with its own housing problems; however, none compares with Hong Kong where housing has always been a major concern as a result of low supply over the past decades. Against ...the constraints in delivering sufficient houses, prefabrication as a sustainable solution for housing has been increasingly advocated for its potential merits of better quality, construction safety and cleaner built environment. However, schedule delay caused by various risks affected the prefabrication housing production (PHP) in Hong Kong. This problem can be further worsened when the manufacturing sector of PHP has entirely moved to offshore areas in the Pearl River Delta region. This study applies system dynamics to recognize and investigate the potential effect of various risks on the scheduling of prefabrication housing construction projects through the employment of Vensim software package. The simulation results show that schedule risks, namely low information interoperability between different enterprise resource planning systems (LIIBDERPS), logistics information inconsistency due to human errors probability (LIIHEP), Delay of delivery of precast element to site (DDPES), and Design information gap between designer and manufacturer (DIGDM) significantly contribute to the schedule delay in PHP. However, schedule is more sensitive toward LIIBDERPS than for the other three risks, indicating that LIIBDERPS should be monitored and given priority. The system dynamic model serves as an effective tool for quantitatively evaluating the effect of various risks on the schedule of PHP, offering valuable references for managers though comparing simulation results under different risk scenarios, so that potential risks that might lead to schedule delay could be identified and handled in advance.
Design, manufacturing, storage, transportation, and on-site assembly are fundamental processes in prefabricated housing production (PHP) in Hong Kong. However, these processes are fragmented and ...entail various risks that adversely affect the schedule performance of PHP, thereby causing frequent delay problems in PHP projects and hindering the government from satisfying the high housing demands. Accordingly, many researchers have examined these schedule risks to resolve these delay problems. However, none of these studies developed an effective tool for managing schedule risks of PHP by envisaging the key characteristics of schedule risks and PHP. Most of previous research regarding to the management of prefabrication construction tends to consider risks from static and isolated perspectives, despite that these risks are coherently interrelated with each other and their influence varies throughout the whole PHP process. To fill the research gaps, a hybrid dynamic model is developed in this research to evaluate and simulate the impact of identified schedule risks on the schedule performance of PHP in view of underlying interrelationships and interactions, employing the hybrid system dynamics (SD) and discrete event simulation (DES) method. The resulting hybrid model is validated through a serial of model structure tests and model behavior tests, with the use of data collected from a PHP project in Hong Kong. This study offers an in-depth understanding of how schedule performance of PHP are dynamically influenced by interrelationships and interactions underlying various schedule risk variables. The developed model not only has the benefits of ease of modifying model structure to reflect real schedule situation of PHP project, performing various risk analyses and communicating with simulation results, but also is of value of providing an experiment platform for identifying and determining managerial and technical solutions proposed to minimize and mitigate the influence of corresponding schedule risks prior to implementation.
Prefabrication housing production (PHP) processes are fragmented and full of variability. Their schedule reliability is particularly disturbed by the constraints deriving from task executions in the ...on-site assembly process. Proactive constraints modeling, including identifying constraints and understanding their interrelationships, is crucial to ensure successful task executions and enhance sociability in collaborative working. However, current methods for constraints modeling are often sluggish and heavily rely on human's commitments because there is no real-time and value-added information for decision-making. To address this issue, this study proposes an approach of smart work packaging (SWP)-enabled constraints modeling service, which consists of three dynamic sub-services: social network analysis (SNA) service, hybrid system dynamics (SD)-discrete event simulation (DES) model service, and constraints scenario analysis service. It can equip the workers with the ability to (1) automatically identify the critical constraints, (2) dynamically explore interactional and interdependent relationships of these constraints, and (3) simulate and analyze the impact on schedule performance under different constraints scenarios. Five critical constraints are identified, including adverse weather conditions, lack of collision-free path planning, lack of visible and audible communication mechanism, lack of optimal buffer layout, and lack of optimal installation sequence. Most interrelationships are depicted in the four modules of the hybrid SD-DES model, including the assembly process, resource availability, operation efficiency, and schedule performance. Finally, the most influential constraint “lack of collision-free path planning” to schedule performance is identified in the constraints scenario analysis process.
•Constraints modelling can improve task execution, which includes constraints identification and relationships mapping.•The smart work packaging (SWP) approach is proposed to improve constraints modelling for prefabrication housing projects.•Social network analysis, hybrid simulation model, and constraints scenario analysis are encapsulated into the SWP modelling.•Critical constraints and interrelationships are explored and the effect of constraints to schedule performance is analysed.
Constraints management is the process of satisfying bottlenecks to facilitate tasks assigned to crews being successfully executed. However, managing constraints is inherently challenging in ...prefabrication housing production (PHP), due to the fragmentation of processes and information during project delivery. Enlightened by the broadly accepted work packaging method and the smart construction objects (SCOs) model, this study aims to define and implement smart work packaging (SWP) for constraints management in PHP. Firstly, the framework of SWP-enabled constraints management (SWP-CM) with three primary functions, including constraints modeling, constraints optimization, and constraints monitoring, is established. In addition, this study develops a layered abstract model as a prototype representation to elaborate on the implementation of SWP for practitioners. Finally, a laboratory-based test is applied to validate the framework. It can prove that SWP indeed opens new avenues for smart constraints management for PHP.
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