(CTCI), a top 200 global design firm and contractor, in the ... Director is a computer software system, which is designed to not only provide user-friendly interfaces ...
Development and Application of 4D Construction Simulation Tools
Yuan-Fu LIAO1, Shang-Hsien HSIEH2, Shih-Chung KANG2, Chuin-Shan CHEN2, Cheng-Tao YANG3, Hon-Lin CHI2, Wan-Chun CHI2 and Ching-Hua, YU1 ¹ CTCI Corporation, Taipei, Taiwan ² Department of Civil Engineering, National Taiwan University, Taipei, Taiwan 3 National Center of Research for Earthquake Engineering, Taipei, Taiwan
Abstract: This paper reports the experiences in developing Construction Director, a 4D plant construction simulation system, in a collaborative project between the CTCI Corporation (CTCI) and National Taiwan University (NTU). Construction Director is a computer software system, which is designed to not only provide user-friendly interfaces and functionalities to ease the user’s task in defining the link between the objects of the 3D plant or building model and the activity items in the construction schedule, but also to support animated and visual reviews of construction progress. This paper summarizes the experiences in developing Construction Director, and the lessons learned from the application of Construction Director to a high-rise building project. Key words : 4D CAD, Construction simulation, Construction plan review
1
INTRODUCTION
In the past decade, 4D CAD technology, which binds 3D models with their corresponding construction schedules in its simplest form, has emerged rapidly. This is mainly due to the increasing recognition from the construction industry of the benefits of using the 4D CAD applications; such as, increased productivity, improved project coordination, and the optimization of on-site resource allocation. The realization of 4D CAD technology has also been greatly accelerated by the availability of powerful commercial 4D CAD tools, for example, Bentley’s Navigator1, Intergraph’s SmartPlant Review 2 , Common Point’s Project 4D, and ConstructSim3 (Sheppard, 2004). Moreover, many research efforts have been carried out to advance the 4D CAD technology from simple 4D animation of construction progression to interactive 4D simulation of alternative construction processes (e.g., McKinney et al., 1996; Collier and Fischer, 1996), and even to nD CAD that integrates 4D models to project information in dimensions beyond 3D space and time (e.g., Lee et al., 2003; Tanyer and Aouad, 2005). Although many successful projects that employed 4D technology for construction management have been reported, 1 More information can be found at http://www.bentley.com/ 2 More information can be found at http://ppm.intergraph.com/ 3 More information can be found at http://www.commonpointinc.com/
it is still a challenge to introduce this new technology to a large-scale construction firm where staff are accustomed to in-house working procedures. The smooth transition from existing working flows to those involving 4D technologies usually requires careful planning and trial-and-error costs. This paper presents the experiences of CTCI Corporation (CTCI), a top 200 global design firm and contractor, in the development and application of 4D construction simulation tools. CTCI has a breadth of experiences in the planning, design, and construction of refineries, petrochemical plants, general industrial plants, and power plants throughout the world. Currently, CTCI usually employs Intergraph’s Plant Design System (PDS) for 3D plant design and construction, and SmartPlant Review (SPR) for interactively reviewing and analyzing the 3D models of a plant. Although some 4D CAD simulation capabilities are supported by the ScheduleReview function of the Construction module of SPR (complementary software), CTCI staff still feel the need for an additional and more user-friendly, flexible, and intelligent 4D CAD capability. This is in order to facilitate more efficient and effective 4D simulation and management of construction progress and to allow for better integration with CTCI’s project resource management systems. A two-year collaborative research project between CTCI and the Computer-Aided Engineering (CAE) Group in the Department of Civil Engineering at National Taiwan University was initiated in April 2005. In the first year, researchers in the CAE group developed a software tool, called Construction Director, to facilitate binding (or linking) the objects in the 3D building model with the activities (or work items) in the construction schedule. The
tool was built on top of the existing SPR software, which is frequently utilized by CTCI engineers, so that it can be easily adopted by CTCI engineers in their current workflow for visualizing the construction progress on computers. In the second year, Construction Director was extended to include functions for the management of schedule-related information and an additional tool, called Erection Director, which allows the simulation of detailed erection activities at operational levels. This paper discusses how the 4D simulation tools (including both Construction Director and Erection Director) and their major components were designed and built to fulfill CTCI’s requirements. In addition, this paper presents an application example in which Construction Director is applied to and evaluated for the management of a building construction project.
2
KEY REQUIREMENTS FOR CONSTRUCTION DIRECTOR
Although several commercial products have powerful functionalities for 4D simulations, often they cannot be easily adopted and customized to satisfy the needs of a specific consulting or construction company, such as CTCI, because each company has its own software environment for managing 3D models, scheduling, and other 4D related data. In this work, major system requirements for the development of Construction Director are identified to better satisfy CTCI’s needs. They are summarized as follows (Hsieh, et al., 2006a): Functions for Binding between Schedule and 3D Model: The system should provide user-friendly interfaces for the construction planner to bind the 3D construction objects with the work items in the construction schedule. Because the plant design tasks performed in PDS are typically divided among different engineering fields, for example, structural engineering or piping engineering, the 3D objects are usually grouped by the engineering system, such as structural system or piping system. This grouping method is very different from that of 4D construction planning, in which construction planners usually group the work items by the daily or weekly schedule. Therefore, the system should provide powerful search functions and grouping tools to support regrouping of tasks.
objects. The hierarchy of the activities and work items may be displayed and managed using a tree structure. Visualization and Animation of Construction Progress: The system should be able to display and animate the construction progress on SPR’s user interface. In the animation, a set of colors should be used to present the construction statuses of the 3D objects.
3
DESIGN AND IMPLEMENTATION OF CONSTRUCTION DIRECTOR
Object-oriented technologies, including design patterns, object-oriented design and programming, were introduced to the development of Construction Director. The design of Construction Director applied multiple design patterns (Gamma, 1998) to increase maintainability and reusability of the system. Figure 1 illustrates the basic framework of the system design. The framework consists of two major parts: the KernelFacade (Gamma, 1998) and Graphic User Interface (GUI) subsystems. The KernelFacade subsystem defines a higher-level and unified interface to the C-Style (that is, using the C programming language) SPR API. It also helps develop SPR’s searching function (Search Engine) and visualization function (Animation Engine). The GUI subsystem consists of two components: Schedule Tree and Models List. The Schedule Tree component uses a directory tree as an interface to manage the hierarchy and attributes of the activities and work items in a construction schedule. The Models List component employed both folder-like and list-like interfaces for managing and displaying 3D construction objects.
Fig. 1 Design of Construction Director Functions for Linking Existing Management Software: The system should be able to import (export) the construction schedule information from (to) either Microsoft Project or Primavera Project Planner (P3), or both. It should also provide some editing capabilities for renaming, adding, and deleting the schedule items as well as modifying the attributes of individual schedule items. Two types of schedule items are needed: activities and work items. An activity is a top-level entity for grouping work items. Both the activity and work item may contain one or more work items. Only the work items are linked to the 3D construction
Construction Director is implemented using the Microsoft .NET (MS.NET) environment. Although SPR API supports both the Visual Basic and C/C++ programming, the C++ programming language was selected in this work because it has better computational performance. In addition, the C++ programming language allows us to integrate the Microsoft Foundation Class Library (MFC) more easily, while MFC was used to implement the graphical user interfaces of Construction Director.
4
FEATURES OF CONSTRUCTION DIRECTOR
4.1 4D Project Management For managing the activity tree and its work items in Construction Director, the user can create new items and easily change the relationships among activities and work items through drag-and-drop mouse operations. If the user double-clicks on an activity or work item, a dialog box displays in which the user may edit the attributes of the activity or work item. Also, the users are allowed to export and import a complete or partial activity tree from and to project management software such as Microsoft Project or P3. This is achieved through the use of the Project XML format, a general format for exchange data between different software tools. Figure 2 shows the user interface of Construction Director. The upper toolbar (Frame A) consists of icons for quick access to a set of tools. The left-hand side window (Frame B) is used to manage the activity tree of a construction schedule, and the centre window (Frame C) serves as a working area to facilitate the 4D binding tasks, while the right-hand side window (Frame D) is used to manage the grouping of 3D construction objects. For binding the 3D objects and the work items, users can simply drag and drop the 3D object into the target work item. If the work item does not yet exist in the activity tree, the user can still drag and drop the 3D object to the target activity and the system will automatically create a new work item under that activity. This feature is particularly helpful when the user needs to link a group of 3D objects to the target activity. In addition, two different icons indicate whether a 3D object has been assigned to a work item (see Figure 2 for the icons in the ELEM_NAME column). The yellow flower icon is used to indicate that the 3D model has been assigned to a work item, while the question mark icon is used to indicate that the 3D model has not been assigned to any of the work items.
model are highlighted with different colors. Each color represents a different construction status of the object. The users are allowed to define the color scheme to suit their needs. Table 1 shows the color scheme selected in Construction Director.
Fig. 3 Various colors display the construction status of 3D objects as the time progresses
Table 1 Color Schemes for Illustrating Different Construction Statuses Color
Construction Status
Pink
The construction had been completed before the given time interval
Red
It is currently under construction
Yellow
The construction has just been completed
Blue
The construction has been completed within the given time interval
Orange
The construction has not been started yet
4.3 Earned Value Management
Fig. 2 The User Interface of Construction Director 4.2 Construction Simulation After the binding has been completed, Construction Director can be used to animate the construction progress, as shown in Figure 3. The animation runs at a user-defined time interval. During the animation, the 3D objects in the plant
Construction Director also allows users to manage the earned value which is a quantitative measurement to define the working progress of a project. As work is performed, it is "earned" on the same basis as it was planned, in dollars or other quantifiable units such as labor hours. Comparing earned value with the planned value measures the dollar value of work accomplished versus the dollar value of work planned. Any difference is called a schedule variance (SV). Comparing the value earned for the work performed with the actual cost incurred for the work performed provides an objective measure of cost efficiency. Any difference is called a cost variance (CV). Using the earned value process, the management team can rapidly compare how much work has actually been completed against the amount of work planned to be accomplished (PMBOK, 2004). Figure 4 shows the user interface of Earned Value Management provided in Construction Director. The upper window (Frame A) provides an integrated view of cost and
schedule performance. The left side window (Frame B) is used to show the analysis Information of Earned Value Management, such as Actual Cost of Work Performed (ACWP), Budgeted Cost for Work Scheduled (BCWS), Cost Performance Index (CPI), Schedule Performance Index (SPI) and so on, the right-hand side window (Frame C) shows all curves together which is a typical EVM line chart.
total floor area of approximately 33,000 square meters. It commenced in January 2007 and completion is expected in December 2008. At the time of writing the paper (April 2007), the completed stages are the foundation piles, diaphragm wall and the first floor slab. The main steel structure will be installed from April to December 2007.
Fig. 5 The User Interface of Erection Director Fig. 4 The User Interface of Earned Value Management 4.4 Erection Director Erection Director is designed to simulate and visualize critical erection activities. It allows construction planners to test drive the crane in a virtual world. This will help us identify any problematic or unsafe operations and avoid them in the field. Erection Director provides a physics-based simulation for the crane in the virtual world. It simulates and calculates in the runtime to provide accurate force capacity, collision detection, and dynamic feedback due to the inertia force during the crane operation. Figure 5 shows the user interface of Erection Director. The layout of windows displayed on the interface can be adjusted: windows added, discarded, split, resized or repositioned by the user. The left window and lower middle window are the scenes of the virtual construction with different view points. Users can manipulate the crane model using the mouse and keyboard. Real-time information is displayed in the upper-right window. It includes crane status, current loading and the warning signals for collision or overloading. During the operation of the erection activity, the working scquences can be recorded and replayed by using the animation controls shown on the bottom-right view.
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APPLICATIONS AND BENEFITS
Construction Director was applied to the CTCI building project (as shown in Figure 6), in order to examine the pros and cons of the tool used in a practical project. 5.1 Project Description This project is a building project, which has 20 floors (17 floors above the ground and 3 floors underground) and a
Fig. 6 CTCI Building Project 5.2 Application of Construction Director Before introducing Construction Director, the creation of a 3D model of the building project was needed. A CTCI engineer used Intergraph’s Plant Design System (PDS) and spent two weeks creating the 3D model. It includes walls, columns, beams, slabs, doors, curtain walls and stairs. Then he imported the 3D model into Construction Director. The following four steps were required to create the 4D model of the project: STEP 1: Create the Construction Activity Tree Users create the activity tree by hand or import schedule data from P3 or MS Project (as shown in Figure 7). STEP 2: 4D Binding Users bind the construction activity and 3D objects using Construction Director (as shown in Figure 8). STEP 3: Pre-Construction Simulation When the 4D model is completed, we can simulate the
construction status using Construction Director (as shown in Figures 8 to 12). STEP 4: Show Construction Status When users input the actual construction date to the assigned activity, Construction Director can show the differences between the planned status and actual status in different colors (as shown in Figure13 and Table 2).
Fig. 10 Status 2: Install Diaphragm Wall
Fig. 7 Creating the activity tree
Fig. 11 Status 3: Install Steel Structure
Fig. 8 4D Model Binding
Fig. 9 Status 1: Install Foundation Pile
Fig. 12 Status 4: Finished
Fig. 13 Planned versus actual status Table 2 Color schemes for showing the difference between planned status and actual Status Color Yellow Red Blue Green purple
Planned versus actual status Finished Working Not started yet Delay for start Delay for finish
5.3 Benefits Various benefits were identified in using the 4D tool for the project. They are summarized as follows:
Construction Director allows for verifying the feasibility and constructability of a construction schedule during early planning stage. Construction Director is an effective communication tool between disciplines. Construction Director helps construction managers arrange preliminary tasks more accurately. Construction Director allows us to precisely estimate the cost according to both 3D models and the schedule. Construction Director improves visibility of problematic activities during construction progress. The construction progress can be stored and become a case study for training purposes in the future.
5.4 Technical Problems On the other hand, some technical problems were observed during the creation of the 4D model. They include:
It is difficult to model detailed 3D objects (such as rebars) and temporary facilities (such as tower crane and scaffold). Some parts of critical activities, such as applying construction permits, which do not have a strong relationship with 3D models, are difficult to repres ent properly. Although Construction Director has provided several methods to batch procedures, it is still time consuming to connect 3D models with the schedule.
Some elements in the building information model cannot reflect the reality of the construction site.
6
CONCLUSIONS
The use of Construction Director has significant potential benefits for the construction industry. Construction Director can have a positive impact on both pre-construction and the construction phases, while having the power to assist planners in producing improved planned projects and to see how their plan will be unfold. In addition, Construction Director enables planners to predict potential problems at each construction stage, which could have considerable costs and time benefits. This paper detailed the development processes of Construction Director and explained the benefits and technical problems encountered in a real building project. The experience from the case study can become a reference for the future developers, especially for those who will develop computer tools for creating building information models for large-scale constructions. ACKNOWLEDGMENT The financial support from the CTCI Foundation is gratefully acknowledged. The authors would like to thank Mr. Wen-Han Lee of the CTCI Corporation, and Mr. ShianJeng Weng and Ms. Pei-Shiuan He of National Taiwan University for their assistance in the development of Construction Director. REFERENCES Collier, E., and Fischer, M. (1996), “Visual-Based Scheduling: 4D Modeling on the San Mateo County Health Center,” Proceedings of the Third Congress on Computing in Civil Engineering, Anaheim, CA, USA, June 17-19, 1996, 800-805. Gamma, E., Helm, R., Johnson, R., and Vlissides, J. (1998), Design Patterns, Addison Wesley, 1998. Hsieh , S . H . , Chen, C . S . , Liao , Y. F. , Yang, C . T. , and Wu, I. C., (2006a) “Experiences on Development of a 4D PLANT Construction Simulation System”, Proceedings of the 11th International Conference on Computing in Civil and Building Engineering, June 1416th, 2006, Montreal, Canada. Hsieh , S . H . , Chen, C . S . , Liao , Y. F. , Yang, C . T. , and Wu, I. C., (2006b) “Construction Director: 4D Simulation System for Plant Construction”, Proceedings of the 10th East Asia-Pacific Conference on Structural Engineering and Construction, August 3-5th, 2006, Bangkok, Thailand. Lee, A., Marshall-Ponting, A. J., Aouad, G., Wu, S., Koh, W. W. I., Fu, C., Cooper, R., Betts, M., Kagioglou, M., and Fischer, M (2003). “Developing a Vision of nD-enabled Construction,” The Center of Excellence for Construct IT, University of Salford, UK. McKinney, K., Kim, J., Fischer, M., and Howard, C. (1996), “Interactive 4D-CAD,” Proceedings of the Third
Congress on Computing in Civil Engineering, Anaheim, CA, USA, June 17–19, 1996, 383–389. PMBOK Guide (2004), “A Guide to the Project Management Body of Knowledge”, Third Edition, PMI, 2004. Sheppard, L. M., (2004) "Virtual Building for Construction Projects," IEEE Computer Graphics and Applications, Vol. 24, No. 1, 6-12. Tanyer, A. M., and Aouad, G. (2005), “Moving Beyond the Fourth Dimension with an IFC Based Single Project Database,” Automation in Construction, Vol. 14, Issue 1, 15-32.
