WSC 2007 Final Abstracts

A Message-based Architecture to Enable Runtime User Interaction on Concurrent Simulation-animations of Construction Operations
Prasant Vajallu Rekapalli and Julio Cesar Martinez (Purdue University)

Abstract:
This paper describes a preliminary architecture to support user interaction with 3D animations. These interactions are able affect the state of the concurrent discrete-event simulation driving the animation. We first explain how user interaction is conceptually split into user-action and user-intent, and then detail the message-based architecture adopted to support user interaction.

Project Planning Using an Interactive Structured Modeling Environment
Ian Flood (University of Florida)

Abstract:
Planning construction projects typically makes use of the activity network based Critical Path Method (CPM), since it is very simple to use and reasonably versatile. Most other planning techniques are either aimed at specialized types of construction work (such as linear scheduling techniques) or are peripheral tools to be used in conjunction with these tools (such as n-D CAD). Discrete-event simulation has also been used for construction planning, and while it is extremely versatile, it lacks the simplicity in use of CPM and so has not been widely adopted within the industry. This paper goes back to first principles, identifying the needs of construction project planning and how existing tools meet (or fail to meet) these requirements. Based on this, it proposes a new modeling paradigm better suited to contemporary construction project planning. The principles of the method are demonstrated with a range of examples from construction

Ontology-centered Integration of Project Management, Cost and Resource Modeling with Analysis, Simulation and Visualization: A Case Study of Space Port Operations
Paul A. Fishwick and Zachary Ezzell (University of Florida) and Nabeel M. Yousef, David J. Miranda, Haluk Mustafa Akin, Luis Rabelo, and Jose A. Sepulveda (University of Central Florida)

Abstract:
As the size and complexity of space launches continues to grow an architecture is becoming ever more necessary to accurately organize and determine workforce requirements for the involved organizations. The Launch Services Program at Kennedy Space Center has recently begun using a tool developed by the technology consulting firm Booz-Allen Hamilton specifically for this purpose. This paper addresses the possibility of transferring the information developed and organized by the Kennedy Workforce Planning Tool into a standard Microsoft Project document with integrated cost, resource modeling and analysis, simulation and visualization using an ontology-centered approach. The study emphasize on the potential of being able to forecast the workforce resource requirements.

Expecting the Unexpected: Representing, Reasoning About, and Assessing Construction Project Contingencies
G. Ryan Anderson and Nilufer Onder (Michigan Tech) and Amlan Mukherjee (Michigan Technological University)

Abstract:
Planning, scheduling and effective management of contingencies are crucial for the successful management of construction projects. In this paper we explore a mathematical representation of construction processes that can be used to infer alternative futures of a project as it unfolds. The representation has its foundations in temporal constraint networks. We present algorithms that can traverse the network in time, reason about the constraints driving a construction project, and present the combinatorial possibilities of futures that can emerge from one or more constraint violations during project implementation. The algorithms will aid construction managers to anticipate and react to crisis scenarios as they evolve in time. Our broader goal is to use the contingency information and the user responses to reveal the cognitive strategies used by humans to manage complex crisis scenarios.

Agent-based Simulation for Collaborative Cranes
Cheng Zhang and Amin Hammad (Concordia University)

Abstract:
Most of the materials and components for a construction project are lifted by cranes. Much research has been done for path planning, motion control, and online navigation to reduce conflicts and improve efficiency. This paper proposes a new simulation approach based on agents to coordinate crane operations where two cranes are working together. Agents can dynamically control the kinematic action of the two cranes respecting the functional constraints for safety and efficiency of operations. A simulation model is under development using a case study to investigate the feasibility of the proposed approach.

Communication and Process Simulation of Set-based Design for Concrete Reinforcement
John-Michael Wong, Kristen Parrish, Iris D. Tommelein, and Bozidar Stojadinovic (University of California, Berkeley)

Abstract:
Two discrete-event simulations are developed to assess the feasibility of improving the delivery process of reinforced concrete structures. The simulations represent the resource and information flows necessary for supporting set-based design of reinforcing bars used in concrete. Set-based design enables the exploration of feasible solutions for longer in the design process than is otherwise affordable using point-based design, so as to allow for input from several project participants early on and at the same time. The simulations use the canonical example of selecting longitudinal reinforcement for a beam-column joint. The first simulation uses EZStrobe(c) to model the amount of time necessary to converge to a satisfactory design solution using set-based vs. point-based design methods. The second simulation uses XML data exchange and state machines in a service-based architecture to analyze the required information flows for communicating design sets. This enables the exploration of a meta-language to express design goals.

Process Flowcharting and Simulation of House Structure Components Production Process
Haitao Yu and Mohamed Al-Hussein (University of Alberta) and Reza Nasseri (Landmark Master Builder Inc.)

Abstract:
Stimulated by the success of management innovation in the manufacturing industry culminating in lean production, many homebuilders attempt to model the construction process on manufacturing. Currently, much of the focus has been on the use of factory-built structural components, which reflects the inherent characteristics of the residential construction industry that homebuilders construct high volumes of houses with similar structures. However, many such attempts failed due to operation management problems. This paper presents a hybrid approach that combines process flowcharting and simulation for helping prefabricators analyze and improve their production process. In the research, the process flowchart and process activity chart are used to identify opportunities for process improvement, and simulation models are built in Simphony, a Special Purpose Simulation (SPS) tool, to do what-if analysis and to predict productivity. The results of this study indicate that process flowcharting coupled with simulation is an effective way to plan process improvement.

Construction Noise Prediction and Barrier Optimization Using Special Purpose Simulation
Anupama Gannoruwa and Janaka Ruwanpura (University of Calgary)

Abstract:
Construction projects produce serious environmental pollution and great annoyance to the neighbouring community due to construction noise. This paper presents an application of the special purpose simulation (SPS) language using Simphony software to predict the noise levels generated by construction equipment, tools and machinery at a given reception point for a certain barrier length, as well as the related cost of the barrier wall. To illustrate an application of the developed model, an example has been developed for different noise sources and different activities. The information obtained from the simulation model output will help to utilize the model as a planning tool for optimizing the length and location of noise barriers around a construction site. The tool can be useful for a contractor to develop a noise-control plan using mitigation measures that are acceptable to the owner.

Modeling and Representation of Non-value Adding Activities Due to Errors and Changes in Design and Construction Projects
Sangwon Han (University of Illinois at Urbana-Champaign), SangHyun Lee (University of Alberta) and Mani Golparvar Fard and Feniosky Pena-Mora (University of Illinois at Urbana-Champaign)

Abstract:
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. 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. To address this, 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.

Special Purpose Simulation Template for Workflow Analysis in Construction
Sivakumar Palaniappan, Anil Sawhney, and Howard Bashford (Arizona State University) and Kenneth Walsh (San Diego State University)

Abstract:
Workflow analysis is an important component in the simulation of construction operations. It involves creating a specific number of work requests for a crew every time period, computing outputs such as work arrival rate for a downstream crew and plotting work in process (WIP). These outputs are not directly provided in many construction simulation software tools. Determining these outputs is generally considered a time consuming and tedious undertaking. Developing modeling constructs that automate the computation of these workflow outputs will be useful for construction modelers. This paper presents a special purpose simulation (SPS) template developed for workflow analysis. The SPS template consists of four modeling constructs that implement the workflow analysis functionalities mentioned above. The SPS template logic was verified using two simulation experiments. Use of this SPS template for analyzing different workflow based issues as well as to test the production management principles in construction is also highlighted.

Simulation Tool for Manpower Forecast Loading and Resource Leveling
Mikhail Hanna and Janaka Ruwanpura (University of Calgary)

Abstract:
Mega projects are lengthy complex endeavors that require significant planning by management, engineers and construction personnel to ensure the success of the project. Companies, both client and contractor, are reporting significant cost and schedule overruns. Lack of project scope definition and planning are the primary characteristics of this problem. Simulation helps decision makers identify different possible options by analyzing enormous amounts of data. Computer simulation can be used effectively to analyze the resource loading and manpower requirements needed to complete a task in a given time frame, based on current progress levels. This paper discusses a simulation tool for optimization of manpower forecast loading and resource leveling. The model is capable of optimizing resource requirements for a petrochemical project, based on standard discipline requirements and involvements. Tests of this tool have produced exceptional results; currently, the system is being modified to incorporate historical data within the simulation.

Permutation-based Elitist Genetic Algorithm Using Serial Scheme for Large-sized Resource-constrained Project Scheduling
Jin-Lee Kim (Missouri Western State University)

Abstract:
This research paper presents a new permutation-based Elitist genetic algorithm using serial schedule generation scheme for solving a large-sized multiple resource-constrained project scheduling problem, which is one of the most challenging problems in construction engineering. A key aspect of the algorithm was the application of the elitist roulette selection operator to preserve the best individual solution for the next generation so as to obtain the improved solution. Serial schedule generation scheme was applied to generate a feasible solution to the problem. Results for large-sized project network problems were pre-sented to demonstrate the performance and accuracy of the algorithm. The computational results indicate that the proposed algorithm not only produces reasonably good solutions for the resource scheduling problem over the heuristic method and other GA, but also able to solve large-sized multiple resource-constrained project scheduling problems applicable to the construction industry.

Program Planning Under Uncertainty
Kabeh Vaziri, Paul Carr, and Linda Nozick (Cornell University)

Abstract:
Task durations are subject to uncertainty which can be influenced by the resources assigned. Also, commonly there is the opportunity to assign workers to tasks that require a secondary skill they have. When workers use their secondary skills they are not as efficient as workers for which that skill is their primary skill, however they can contribute to the completion of the task. This paper provides the means for program managers to heuristically optimize the allocation of their skilled workers among individual tasks on several competing projects when the task durations are uncertain and workers have multiple skills.

Simulation and Uncertainty Modeling of Project Schedules Estimates
Ivan Ourdev, Simaan AbouRizk, and Mohammed Al-Bataineh (University of Alberta)

Abstract:
Project management involves various sources of uncertainty that affect planning, execution schedules, and cost. At the same time, the influx of information can be employed to reduce the uncertainty. This can be efficiently accomplished within the framework of the Bayesian approach. This approach also has the advantage of providing a seamless synthesis of information coming from the field with information generated by data enhancing simulations. We demonstrate the use of this approach in an on-line simulation that augments a real-life monitoring and planning system for managing tunneling construction projects.

Qualitative Simulation of Construction Performance Using Fuzzy Cognitive Maps
Manjula Dissanayake and Simaan AbouRizk (University of Alberta)

Abstract:
The construction process is subject to an array of influences, both from internal and external environments, which makes the process performance uncertain and difficult to predict. To deal with uncertainty, simulation is widely applied in construction process modeling. Most of the applications, however, are restricted to quantitative models due to limited qualitative simulation capabilities. In this paper, Fuzzy Cognitive Maps (FCM) are proposed as a means for modeling and controlling complex construction performance–related problems qualitatively. They provide an effective tool for answering what-if questions during the construction planning phase.

Optimal Work Breaks in Deterministic and Probabilistic Repetitive Projects
Photios G. Ioannou and Chachrist Srisuwanrat (University of Michigan)

Abstract:
An effective way to reduce the duration and cost of projects with repetitive activities is through the relaxation of resource continuity and the introduction of work breaks at strategic points between repetitive project units. This paper describes the problem and introduces the basic concepts for determining the optimal location and duration of work breaks for both deterministic and probabilistic activity du-rations. The procedure is described in detail and is applied to an example project with 9 activities with probabilistic durations that repeat over 10 similar work units. The solution employs concepts from the Repetitive Scheduling Method (RSM), the Sequence Step Algorithm (SQS-AL), and is modeled in STROBOSCOPE, an activity-based simulation system. Numerical and graphical results explain the process and the underlying time and cost tradeoffs.

Optimal Scheduling of Probabilistic Repetitive Projects Using Completed Unit and Genetic Algorithms
Chachrist Srisuwanrat and Photios G. Ioannou (University of Michigan)

Abstract:
In this paper we introduce the completed unit algorithm (CU-AL), a probabilistic scheduling methodology for repetitive projects. The algorithm has two main advantages, simplicity and short computational time, that facilitate and expedite its use in simulation modeling and optimization. An integration between CU-AL and genetic algorithm (GA) is established to optimize the problem of maximizing profit for repetitive projects with probabilistic activity durations. This integration between CU-AL and GA is explained in detail through an example project with 5 activities and 10 repetitive units. A simulation model for this project is developed in Stroboscope, an activity-based simulation system. The optimization is performed by ChaStrobeGA, a Stroboscope add-on using genetic algorithm to optimize the overall objective function of project profit. Discussion of the results provides insight into the tradeoff between maintaining and relaxing resource continuity constraints in order to maximize expected project profit.

Flexible Modeling of Linear Schedules for Integrated Mathematical Analysis
Gunnar Lucko (The Catholic University of America)

Abstract:
Developing and analyzing schedules is essential for successfully controlling the time aspect of construction projects. The critical path method of scheduling is by far the most widely use scheduling technique in the construction industry. However, several problems related to its concept and use have been identified in the literature. The lesser known linear scheduling method has much potential for handling the rich information that project managers handle on a daily basis. While being well-suited to linear and repetitive projects, it has been a predominantly graphical method without a comprehensive underlying mathematical model. This paper introduces a new method based on singularity functions using Macaulay bracket notation. It makes beneficial use of the strengths of these functions, including their flexibility and clarity, while remaining intuitive and requiring only basic geometry and algebra knowledge from users. An example from the literature is re-analyzed step-by-step and compared successfully with the critical path method.

Enabling Smooth and Scalable Dynamic 3d Visualization of Discrete-event Construction Simulations in Outdoor Augmented Reality
Amir H. Behzadan and Vineet R. Kamat (University of Michigan)

Abstract:
Visualization is a powerful method for verifying, validating, and communicating the results of a simulated model. Lack of visual understanding about a simulated model is one of the major reasons inhibiting contractors and engineers from using results obtained from discrete-event simulation to plan and design their construction processes and commit real resources on the job site. The fast emerging information technology makes the use of modern visualization applications more appealing to engineers and scientists in different domains. This paper presents the design and implementation of an Augmented Reality (AR) visualization application together with an authoring language that allows the creation of outdoor AR animated scenes of simulated operations while featuring complete user involvement and interaction. The application is based on the concept of scene graphs. It also uses a unique general purpose data transmission method to communicate with hardware components of the system.