Sangwon Han

A system dynamics model for assessing the impacts of design errors in construction projects

Abstract Design errors leading to rework and/or design changes are considered to be the primary contributor to schedule delays and cost overruns in design and construction projects. While design errors are deemed prevalent, most design and construction firms do not measure the number of errors they create, thereby having limited knowledge regarding their mechanism to undermine project performance. To address this, a system dynamics model has been developed to capture the dynamics of design errors and systematically assess their negative impacts. This paper reports on the development of the model, and its application to a university building project. The results indicate that design errors can significantly delay project schedule in spite of continuous schedule recovery actions taken by construction managers. The case study also shows that schedule pressure can propagate the negative impact of design errors to numerous construction activities, including those that are not directly associated with the errors. Finally, the case study confirms that the developed model can more rigorously assess the negative impact of design errors, which is often underestimated by practitioners. Based on these results, it is concluded that the developed model can assist project managers in better understanding the dynamics of design errors and recovering delayed schedule, particularly under schedule pressure.

Hybrid System Dynamics and Discrete Event Simulation for Construction Management

Simulations have significantly contributed to the analysis of construction, and Discrete Event Simulation has been a primary means of simulation focusing on Construction Operation. In this paper, the authors address the importance of Construction Context as another realm for understanding and managing construction through representation of overall behavior of construction associated with Construction Operation. The issues raised from representing both Construction Operation and Construction Context together in a simulation model are discussed, and a hybrid System Dynamics and Discrete Event Simulation approach is proposed as a comprehensive simulation framework for that purpose. Briefly, its application to construction is also discussed.

Analysis of Causes of Construction Defects Using Fault Trees and Risk Importance Measures

Defects can have a significant impact on construction performance. A defect is not usually an outcome of a single cause, but rather occurs when multiple interrelated causes combine, forming a defects pathway. Because defects may occur through numerous pathways, the risks of causes can vary in terms of the number (i.e., frequency) of pathways that they take part in and the impact (i.e., magnitude) of the contribution they provide for the formation of these pathways. Several studies have strived to identify generic defect causes; however, re- search on the analysis of the risk of causes in order to develop further defect management efforts is lacking. To address this deficiency, this study aims to develop a methodology to identify and quantify the risk of defect pathways. Specifically, the study uses a fault-tree approach to construct the taxonomy of the defect causes and uses risk importance measures to assess the identified defect causes in terms of frequency and magnitude. Applying the developed methodology to four residential projects in Dubai confirmed its applicability as an effective tool for analyzing the risk of defect causes in construction. An effective defect-prevention strategy is expected to be further developed by applying the methodology to a large number of defect samples in a subsequent study. This paper makes a contribution to knowledge in the area of construction engineering and management by introducing a quantitative model, which opens a gateway for researchers to address the complex nature of defect generation and to better understand the vulnerability of a construction project system to defects. In addition, this paper is of value to practitioners with respect to providing an effective tool to rank the significance of defect causes and to optimize their resources consumed for defect prevention. DOI: 10.1061/(ASCE)CO.1943-7862.0000653.

Identification and Quantification of Non-Value-Adding Effort from Errors and Changes in Design and Construction Projects

In a design and construction project, non-value-adding effort (NVAE; also called non-value-adding activities) is wasted effort that could have been avoided if the project had been more carefully planned, executed, monitored, and controlled. NVAE is considered the main contributor to schedule delays and cost overruns in design and construction projects. Microlevel analyses such as work sampling and resource balance charts have been applied extensively to identify and minimize NVAE. These methods can pinpoint unnecessary steps in a highly repetitive construction activity and are most effective when analyzing activities with low performance variation in each cycle. However, microlevel analyses lack the capabilities to deal with errors and changes that usually result in significant performance variations, although they are a major trigger of NVAE in design and construction projects. To address this deficiency, this paper outlines the development of a system dynamics-based model for analysis on a macrolevel. T...

Modeling and representation of non-value adding activities due to errors and changes in design and construction projects

Non-value adding activities which consume time and/or resources without increasing value, have been considered as main contributors to schedule delays and cost overruns in design and construction projects. While these activities are mainly triggered and proliferated by errors and changes, traditional construction management approaches have not explicitly addressed the impact of errors and changes on non-value adding activities. To capture non-value adding activities due to errors and changes, a system dynamics based simulation model is developed and presented in this paper wherein the impact of non-value adding activities are intuitively visualized in a colored bar chart. The developed model is applied to a bridge project in Massachusetts. The simulation results show that errors and changes resulted in 26.1% of non-value adding activities and 171 days of schedule delays in this project. Based on these simulation results, it is concluded that the developed simulation model holds significant potential to aid better decision-making for controlling non-value adding activities in design and construction projects.

Application of Case-Based Reasoning for Estimating Preliminary Duration of Building Projects

AbstractThe applicability and effectiveness of case-based reasoning (CBR) have been demonstrated in various construction management areas, including bidding, international market selection, safety hazard identification, construction litigation, and preliminary cost estimation. Despite its strong potential as a decision-supporting tool in construction, only a few studies have applied CBR for estimating the preliminary duration that is necessary for the overall success of a construction project. Based on this recognition, this paper develops a CBR model capable of accurately estimating the construction duration in the preliminary stage. The applicability and effectiveness of the developed model are tested through application to 83 multihousing projects. The test results confirm the strong potential of CBR to provide an accurate estimate of construction duration with limited information available in the preliminary stage. This paper is significant in that it provides practitioners with a reliable decision-su...

Project Pathogens Network: New Approach to Analyzing Construction-Defects-Generation Mechanisms

AbstractConstruction defects can exert significant impacts on project performance. These defects are typically traced back to their initiating root causes, formulated as infectious decisions, practices, or circumstances. The root causes often act as pathogens that propagate to spread numerous other risky conditions, thereby making projects prone to defects. Accordingly, it is essential to quantify the pathogenic capacity held by each root cause to determine the scope of potential risk associated with its existence. Although several studies have striven to identify project pathogens, research on determining the most pathogenic causes to develop further defect management efforts is lacking. To address this deficiency, the aim of this study was to develop a methodology that captures the complex mechanisms of defect generation and quantifies their pathogenic capacities in accordance to their position within the network of sequential events leading to defects. Specifically, the study uses a social network anal...

A real-time location-based construction labor safety management system

AbstractThe construction industry continues to record a high number of accidents compared to other industries. Furthermore, the ramifications of construction accidents are growing in terms of both economic loss and loss of life with trends toward larger-scale, more complex projects. For this reason, there is an increasing awareness of the importance of safety management in the construction industry, and the need for more effective safety management techniques. This paper introduces a real-time location-based construction labor safety management system that tracks and visualizes workers’ locations in real-time and sends early warnings to endangered workers. The system is developed by integrating: a real-time locating system (RTLS) for tracking of workers’ location; a location monitoring system for mapping the workers location on a computerized building model; and alarm technology for sending early warnings. The developed system has been applied to an apartment project and an RTLS technology test center in ...

Modeling the dynamics of urban development project: Focusing on self-sufficient city development

Abstract A self-sufficient city can be defined as a city where there is a defined perimeter, inside which lies a population that is self-sufficient: i.e., the economy within the city fully employs the population, and the services and cultural infrastructure within the city are sufficient supply for the population. This paper aims to analyze the dynamics of urban development projects, with a particular focus on the self-sufficient city development policy. To this end, key success factors relating to self-sufficient city developments are derived. A causal loop diagram is then constructed to analyze the interaction between elements of the self-sufficient city development and a system dynamics model is developed to perform quantitative analysis of urban development policies. The results indicate that all urban development policies are related to urban growth, but with varying types and degrees of influence. The ‘business inflow’ and ‘initial education welfare investment’ policies do influence quantitative urban population growth. However, the ‘initial houses’ and ‘initial service facility supply’ policies have arguably greater influence, as they assist in achieving stable urban population growth over time. Based on these results, it is concluded that the developed model has a potential to aid decision makers in assessing the impact of various self-sufficient urban development policies.

Comparative Study of Discrete-Event Simulation and System Dynamics for Construction Process Planning

Discrete-Event Simulation (DES) has been the mainstream in the area of construction simulation. Recently, research has shown the possibility of applying System Dynamics (SD) to the construction management discipline. Unlike DES, which is based on statistical analysis and queuing theory, SD is able to represent the complex system of construction management through capturing feedback effects, managerial actions, and soft variables such as schedule pressure and morale, which are important in determining project behavior. Though SD is capable of representing such variables and relationships, the validity of SD models has often been questioned because when modeling with SD, it is difficult to attain as much detail as when modeling with DES. Therefore, SD has not been fully adopted to simulations in the area of construction management, despite its advantages. To gain widespread use in the construction management area, SD needs to address operational details. In this paper, an SD based earthmoving process model is presented to explore ways in which operation details can be represented using SD. Initially, an SD based earthmoving model is proposed and for the purpose of comparison, and is tested against a DES counterpart model, created using STROBOSCOPE. The tests have shown that the simulation results generated by the SD model are as accurate and reliable as those of the STROBOSCOPE models. The specifics of this comparison are identified, including how the SD model is created from and compared to DES model at an operational level. These research findings support the widespread use of SD in the area of construction management; thus, aiding in the representation of the complexities inherent in construction.