Hani Alzraiee

Contractor Selection Model for Highway Projects Using Integrated Simulation and Analytic Network Process

AbstractSelecting the appropriate contractor is a significant step to highway project success. The process of selection is subjected to uncertainty and influence of criteria other than bid price. This paper presents an approach to prioritize competitive contractors at the prebidding stage for highway projects by utilizing the analytic network process (ANP) and Monte Carlo simulation. Both techniques are integrated on a single platform to build the proposed model. Initially, the main quantitative and qualitative criteria affecting the contractors’ selection process are identified and studied. The effective criteria in the selection process were obtained from experts and literature. A structured questionnaire was designed and sent to experts in highway projects. The ANP was used to prioritize these criteria subsequently, and Monte Carlo simulation was utilized to develop the selection model. The applicability of the proposed model was tested using four real cases of highway projects. It was concluded that u...

A HYBRID FRAMEWORK FOR MODELING CONSTRUCTION OPERATIONS USING DISCRETE EVENT SIMULATION AND SYSTEM DYNAMICS

Construction projects are characterized by their dynamic nature and operational details. This paper presents a hybrid simulation methodology; designed to model construction projects. The methodology utilizes Discrete Event Simulation (DES) and System Dynamics (SD). DES has been widely used in modeling construction operations; however, it lacks the ability to model the global aspects of operations being modeled and the cause-effect relations of simulation variables. SD is utilized to circumvent these limitations. Both simulation methods provide valuable decision support but none is individually capable of capturing the holistic nature of the operation being modeled. The developed methodology integrates DES and SD to utilize their respective advantages in simulating construction operations. The developed methodology encompasses five stages: 1) identification of model objectives, 2) decision criteria to assist in selecting simulation methodology, 3) building simulation model and identification of interface variables, 4) computation framework and 5) implementation and testing. The paper describes the essential features of the developed methodology and its computational framework and focuses primarily on the modeling aspects of SD. A case study project is analyzed to demonstrate the use of the developed methodology and to highlight its capabilities.

Methodology for synchronizing discrete event simulation and system dynamics models

Integrating Discrete Event Simulation (DES) and System Dynamics (SD) simulation methods require synchronization of their simulation clocks to ensure that actions are executed in an orderly manner. This paper presents a synchronization methodology for integrating DES and SD models. A hybrid simulation-based method consisting of SD components at the higher decision level and DES components at the lower decision level is expected to benefit from the developed method. The proposed methodology integrates DES and SD models on a single platform, which enhances the simulation of construction operations. It consists of three elements: (1) advancing mechanism, (2) DES advancing algorithm, and (3) messages sequence mechanism. The paper provides a description of the three elements of the synchronization method. An illustrative preliminary experiment that utilizes DES and SD engines is presented to demonstrate the use of the developed synchronization method and to illustrate its capabilities.

Dynamic Planning of Construction Activities Using Hybrid Simulation

Traditional planning methods such as CPM and PERT have been useful tools to manage construction projects. However, the underlying model of these traditional methods often seems to fail to represent real projects as they tend to assume no interrelationship between project components. In reality, project components have complex dynamic feedback process that requires modeling of inherent uncertainty in the execution of these projects. Nevertheless, this dynamic nature and uncertainty have not been explicitly addressed by traditional planning methods. Project failure can be attributed to poor representation of the inner and outer aspects of operations that are responsible for project dynamics. Uncontrollable external forces are often cited but the real cause may be internal such as the feedback process among components of the project. An alternative perspective is offered in this paper through system dynamics (SD) that accounts for the feedback process and discrete event simulation (DES) for modeling the uncertainty. The proposed method utilizes SD method for modeling project dynamics and DES method coupled with CPM network for operational details and uncertainty, respectively. A case study that involves preparing engineering drawings in a design office is used to demonstrate the use of the developed method and to highlight its capabilities. Modeling the dynamic dimension is expected to enhance planning and scheduling of construction operations and to provide a better understanding of the impact of various internal and external factors on project schedule and productivity performance.

Condition Prediction for Chemical Grouting Rehabilitation of Sewer Networks

AbstractDifferent techniques have been used to maintain and rehabilitate pipes and manholes of the sewer networks in the province of Quebec, including several trenchless rehabilitation techniques in the past two decades. In an effort to predict the future performance of trenchless rehabilitations, this paper presents condition prediction models for chemical grouting rehabilitation of both pipelines and manholes in the city of Laval, Quebec, Canada. The models were developed using regression analysis, based on gathered and analyzed closed circuit television (CCTV) inspection reports for the Laval city sewer network. Different defects in the chemical grouting rehabilitated sewer mains and manholes in this city are presented. The developed regression models are capable of predicting the structural and operational conditions; they are also utilized to generate deterioration curves over time for chemical grouting rehabilitation of sewer pipes and manholes based on basic governing factors such as pipe material ...

Condition Prediction for Cured-in-Place Pipe Rehabilitation of Sewer Mains

AbstractAuthorities in Quebec, Canada, have been making considerable efforts to improve sewer networks across the province by using up-to-date technologies. To rehabilitate its sewer mains, Quebec has used several rehabilitation methods including slip lining, cement and epoxy lining, and cured-in-place pipe (CIPP).These replacement and rehabilitation techniques have been developed over the last four decades, with many arbitrary declarations made about the efficiency and performance of different rehabilitation techniques. This paper presents condition prediction models for CIPP rehabilitation of sewer mains. Regression analysis technique is used to develop these models, based on gathered and analyzed closed-circuit television (CCTV) inspection reports for Quebec CIPP rehabilitations. The models can predict the structural and operational conditions of CIPP rehabilitation on the basis of basic input such as pipe material, and rehabilitation type and date. They can also generate curves illustrating condition ...

Assessment of construction operations productivity rate as computed by simulation models

Modeling and simulation tools are used to assist decision-makers to predict essential parameters such as completion duration and productivity rate of construction operations. Two approaches are used, process simulation and system simulation. The first compute parameters based on processes interaction while the second focuses on the complex relationship among project components and their impacts. This paper presents an assessment to simulated project completion duration and productivity rate under traditional Discrete Event Simulation (DES) and modified traditional simulation technique. The evaluation is based on a simulated real case study. The process elements of the case were simulated using (DES) while system elements were simulated using System Dynamics (SD). A significant difference in productivity rate and duration was noticed between the base DES model and the impacted model. The argument presented about the credibility of simulation model outcomes highlight the pitfalls of simulation models and the measures that should be endorsed.