Mehdi Tavakolan

Stochastic Time-Cost-Resource Utilization Optimization Using Nondominated Sorting Genetic Algorithm and Discrete Fuzzy Sets

In a construction project, the cost and duration of activities could change due to different uncertain variables such as weather, resource availability, etc. Resource leveling and allocation strategies also influence total time and costs of projects. In this paper, two concepts of time-cost trade-off and resource leveling and allocation have been embedded in a stochastic multiobjective optimization model which minimizes the total project time, cost, and resource moments. In the proposed time-cost-resource utilization optimization (TCRO) model, time and cost variables are considered to be fuzzy, to increase the flexibility for decision makers when using the model outputs. Application of fuzzy set theory in this study helps managers/planners to take these uncertainties into account and provide an optimal balance of time, cost, and resource utilization during the project execution. The fuzzy variables are discretized to represent different options for each activity. Nondominated sorting genetic algorithm (NSGA-II) has been used to solve the optimization problem. Results of the TCRO model for two different case studies of construction projects are presented in the paper. Total time and costs of the two case studies in the Pareto front solutions of the TCRO model cover more than 85% of the ranges of total time and costs of solutions of the biobjective time-cost optimization (TCO) model. The results show that adding the resource leveling capability to the previously developed TCO models provides more practical solutions in terms of resource allocation and utilization, which makes this research relevant to both industry practitioners and researchers.

Construction project risk assessment using combined fuzzy and FMEA

Effectively managing risk is an essential element of successful project management. It is imperative that project management team consider all possible risks to establish corrective actions in the right time. So far, several techniques have been proposed for project risk analysis. Failure Mode and Effect Analysis (FMEA) is recognized as one of the most useful techniques in this field. The main goal is identifying all failure modes within a system, assessing their impact, and planning for corrective actions. In traditional FMEA, the risk priorities of failure modes are determined by using Risk Priority Numbers (RPN), which can be obtained by multiplying the scores of risk factors like occurrence (O), severity (S), and detection (D). This technique has some limitations, though in this paper, Fuzzy logic and Analytical Hierarchy Process (AHP) are used to address the limitations of traditional FMEA. Linguistic variables, expressed in fuzzy numbers, are used to assess the ratings of risk factors O, S, and D. Each factor consists of seven membership functions and on the whole there are 343 rules for fuzzy system. The analytic hierarchy process (AHP) is applied to determine the relative weightings of risk impacts on time, cost, quality and safety. A case study is presented to validate the concept. The feedbacks are showing the advantages of the proposed approach in project risk management.

Fuzzy Weighted Interpretive Structural Modeling: Improved Method for Identification of Risk Interactions in Construction Projects

AbstractThe construction industry has a major role in the economic development of any country. Because of the nature of the construction industry and its unique characteristics, and the overtime wo...

Long Term Concessions on Public-Private-Partnership Projects, How to Make This Right?

Long term concession agreements as kind of Public-Private-Partnership (PPP) have been applied in infrastructure projects with equity participation by private sector. The concession approach to project financing has many advantages over traditional methods and as many concerns with nontraditional techniques. The growth of demand on financing infrastructure projects with public sector makes these projects deliver to the private sector throughout long term concession agreements. The main purpose of the right in long term concession is to cover infrastructure gap and reduce public concerns and protect the public interest and ,on the other hand, to encourage private initiative and benefit from the involvement of the private sector particularly in the designing, building, financing, operating and maintenance of infrastructure projects. We try to classify the most important criteria of long term concessions in the structure of matrix in four approaches: public objective, project properties, the project implementation and the environmental conditions. We show that various terms of contract can be investigated by considering these criteria in two infrastructure case studies of initial concessions in the United States.

Risk management workshop application: a case study of Ahwaz Urban Railway project

ABSTRACT Effective risk management is a vital part of project management. The previous workshops in the construction industry have shown to suffer from the lack of a comprehensive risk management techniques. This paper aims to investigate the capacity of a workshop as a risk management approach through the analysis of risk management for Ahwaz Urban Railway project. The analysed workshop uses brainstorming, the combination of fuzzy and failure mode and effect analysis and multiple-choice questions to identify, evaluate and determine the best responses to risks, respectively. The workshop examination shows that a workshop gives the organization an opportunity to identify critical risks. Furthermore, it helps the organization staff to have a better understanding of the projects environment and provides chances to improve teamwork. Despite the strengths of the workshop, it has several limitations of its own. The participants should be the projects major stakeholders and the workshop requires time and money. Two of the major limitations of the analysed workshop are time limitation, and lack of risk monitoring and controlling experience. In addition, this study does not investigate the relationship between risks. However, more attempts are needed to address challenges and barriers of risk management implementation in construction industry.

Developing safety archetypes of construction industry at project level using system dynamics

INTRODUCTION Safe behavior and work conditions are a major concern in construction projects. However, accidents occur due to system failures, not a single factor such as unsafe behavior or condition. Construction safety should be investigated by a systematic view capable of illustrating the complex nature of accidents. METHOD The present research aims to detect and categorize behavior patterns recurring in construction safety management continuously. Content analysis and ground theory method (GTM) were adopted to achieve the study objectives. In total, 90 articles were reviewed to explore the factors influencing safety in construction projects all over the world. Furthermore, 20 interviews were conducted on participants with rich experience in construction health and safety. Four archetypes were identified from data collection process, including delay in design, number of subcontractors, cost and safety of project, and supervisors and safety. Each archetype is completely discussed at different steps of dynamic complexity, behavior over time, and the leverage point to show how to deal with the archetype.