Osama Moselhi

Resource-driven scheduling of repetitive activities

Repetitive activities are found commonly in the construction of high-rise buildings, pipeline networks and highway and housing projects. Construction crews assigned to these activities often perform the work sequentially, moving from one repetitive unit in the project to the next. Because of this frequent crew movement, construction of repetitive activities should be scheduled in such a way as to enable prompt movement of crews among the repetitive units so as to minimize idle crew time. In order to maximize the efficiency of crew utilization, the schedule of repetitive activities should be resource driven, and should satisfy the crew work continuity constraint in addition to precedence relationships and crew availability constraints. This paper presents a flexible algorithm for resource-driven scheduling of repetitive activities that satisfies the three constraints, and considers the impact of a number of practical factors encountered commonly during the construction of this class of projects. The algori...

Automated detection of surface defects in water and sewer pipes

Automation is gaining momentum in industry, particularly in rehabilitation and inspection works of underground infrastructure facilities. This paper describes a model for automating inspection and identification of surface defects in underground water and sewer pipes. The paper describes the current efforts in identification of surface defects in underground water and sewer mains, and presents an automated system designed to assist infrastructure engineers in diagnosing defects in this class of pipe networks. It describes the general architecture of the system and its basic components, and focuses primarily on four modules designed for automating image acquisition, image processing, features extraction and classification of defects.

Web-based integrated project control system

This paper presents a system that supports project time and cost control in an integrated manner. The system utilizes object‐oriented modelling to represent the process of project delivery. A set of control objects is designed to map the process of project control. Eighteen key indicators are considered to represent the resources utilized in each control object and serve as sensors to highlight problematic areas associated with unfavourable performance. A Three‐Tier Client/Sever computer system is designed to implement the developed system. Daily, weekly, monthly and/or yearly, period‐by‐period, and cumulative to‐date project performance reports are generated to provide the status at project, control object and resource levels. An example drawn from the literature is analysed to allow for comparison with the results obtained using the proposed methodology. The example also serves the purpose of demonstrating the use of the proposed system and illustrating its essential features.

Project Selection Considering Risk

A number of procedures have been formulated in recent years for evaluating engineering, procurement and construction projects based on an established set of objectives. These procedures, however, have generally considered either multi-objectives without the risk associated with each objective or a single objective with some form of risk assessment. Decision aid methodologies that permit the consideration of both multi-objectives and risk have generally been associated with complex mathematics and high computational effort. The purpose of this paper is to present a simple, yet comprehensive methodology for the selection of a project under risk, avoiding time consuming analyses. The method considers multi-objective decision criteria and takes into account the uncertainties associated with each individual objective. The method is based on multi-attribute utility theory for modelling the selection criteria and treats uncertainty in a similar way to that used in Program Evaluation and Review Technique (PERT). ...

A decision support tool for construction bidding

A reliable estimate of markup is essential for successful bid proposals. This paper presents a decision support model for construction bidding. The developed model can assist contractors in estimating markup, and owners and/or their agents in evaluating bid proposals. The model is generic and can be used as a tool to evaluate different alternatives in engineering, procurement, and construction. It utilizes the multi‐attribute utility theory and the analytic hierarchy process and makes use of their advantages. Unlike models developed for similar purposes, the proposed model provides a decision support environment for the two functions; that is, estimating markup and evaluating bids. It also enables the user to construct the decision hierarchy that best suits his/her company’s business environment and bidding strategy in a flexible manner. It accounts for the decision maker’s attitude towards risk. Two numerical examples are presented to demonstrate the use and capabilities of the proposed model.

An algorithm for mobile crane selection and location on construction sites

This paper presents a newly developed algorithm for selecting and locating mobile cranes on construction sites. The algorithm is incorporated into a computer system that integrates a selection module and three databases, dedicated respectively, for cranes, rigging equipment, and projects’ information. This paper focuses primarily on the selection module and its algorithm to support an efficient search for most suitable crane configurations and their associated lift settings. Data pertinent to crane lift configurations and settings are retrieved from the databases and processed to determine the near optimum selection of a crane configuration. The developed selection module features powerful graphics capabilities and a practical user‐friendly interface, designed to facilitate the considerations of user imposed lift and site constraints. The selection algorithm has been implemented within the crane selection module using MS‐Visual Basic programming language. A case example is presented in order to demonstrate the use of the developed selection module and to illustrate its essential features.

RFID+ for Tracking Earthmoving Operations

This paper presents an automated methodology for tracking earthmoving operations in near real time utilizing RFID technology to capture data during construction. It is based on attaching low cost passive RFID tags to hauling units (trucks) and attaching fixed RFID readers to designated gates of projects’ dump areas. The RFID readers will identify and record the time each truck enters or exits one of these gates. The captured data will then be transferred wirelessly from the RFID reader to a computer housed in one of the temporary offices onsite and to the main server in contractor’s head office. The collected data will be analyzed and processed automatically, without human intervention, to calculate the productivity of the hauling unit and report it directly to onsite personnel. Database application is developed to implement and automate the developed methodology in Microsoft Access. The developed database is used to process the data captured by the RFIDbased system to calculate earthmoving productivity in near-real-time. It can also be used in estimating productivity of similar works during planning stage. The developed methodology is expected to facilitate early detection of discrepancies between actual and planned performances and supports project managers in taking timely corrective measures.

Simulation optimization for earthmoving operations using genetic algorithms

This paper presents a methodology for simulation optimization utilizing genetic algorithms and applies it to a newly developed simulation-based system for estimating the time and cost of earthmoving operations. The genetic algorithm searches for a near-optimum fleet configuration that reduces project total cost, and considers a set of qualitative and quantitative variables that influence earthmoving operations. Qualitative variables represent the models of equipment used in each fleet scenario, whereas quantitative variables represent the number of items of equipment involved in each scenario. Pilot simulation runs were carried out for all configurations generated by the developed algorithm, and a complete simulation analysis was then performed for the fleet recommended by the algorithm. The numerical example demonstrates the use of the proposed methodology and illustrates its essential features.

Fuzzy-Based Life-Cycle Cost Model for Decision Making under Subjectivity

AbstractDecision support models are needed to facilitate long-term planning and priority setting among competing alternatives. Life-cycle cost is the most frequently used economic model that considers all cost elements and related factors throughout the service life of the alternatives being considered. These cost elements and related factors are usually associated with uncertainty and subjectivity. As such, it is important to model the uncertainty arising from the assumed data over the service life of competing alternatives. Probabilistic techniques, such as Monte Carlo simulation, are commonly used to deal with such uncertainty or vagueness. However, they have been criticized for their complexity and amount of data required. This paper presents a fuzzy-based life-cycle cost model that accounts for uncertainty in a manner that disadvantages commonly encountered in probabilistic models are alleviated. The developed model utilized fuzzy set theory and interval mathematics to model vague, imprecise, qualita...

Data acquisition from construction sites for tracking purposes

Purpose – The objective of this paper is to develop a tracking and control system that automates the process of data collection from construction sites for fast and accurate measurement of work progress.Design/methodology/approach – The proposed system integrates different data acquisition hardware and software technologies including barcoding, radio frequency identification (RFID), laser distance and ranging (LADAR), digital images, and a tablet PC as integrating media.Findings – The paper briefly highlights the advantages and limitations associated with each technology, and presents a methodology that best utilizes these technologies in an integrated system. At the core of the developed system is its database, which is designed to organize and store data collected from construction sites in a way that supports the developed methodology in progress reporting.Practical implications – The accuracy and timeliness of these reports are crucial for management teams to take corrective actions, if needed, so as ...