Chapter 5 - Construction Scheduling: a Latin American Perspective

Constructing the Future nD Modelling Edited by: Ghassan Aouad, Angela Lee and Song Wu This essential book introduces the concept of nD modelling, which takes the theory of computer modelling of the built environment to n dimensions. nD modelling utilises a decision support tool for systematic assessment and comparison between various design parameters such as cost, accessibility, maintainability, sustainability, crime, energy, whole life costing, acoustics and scheduling among others. Constructing the Future is a comprehensive book which provides a global perspective on the concept of nD modelling and examines its impact on construction, from development to application. The text offers a critique of competing views that seek to justify (or ignore) the role of nD modelling in the future of construction as well as describing developments in this area which are already happening worldwide. Presenting a thorough critique of competing views as well as providing guidance on best practice, Constructing the Future is a bold, well-grounded and illustrated title introducing construction management professionals and researchers to this exciting new development in the quest for a single building and product model.

Part 1: nD Modelling: The Concept 1. nD Modelling: The Background 2. Engineering Design 3. Lessons Learned from Ten Years of Conceptualising, Developing, Introducing and Using nD BIMs Part 2: nD Modelling: The Scope 4. Planning and Scheduling Practices in the UK 5. Construction Scheduling: A Latin American Perspective 6. nD in Risk Management 7. Construction Safety 8. Automated Code Checking and Accessibility 9. Acoustics in the Built Environment 10. nD Modelling to Facilitate Crime Reduction 'Thinking' within the Project Briefing Process Part 3: nD Modelling: The Application 11. Data Classification 12. Management of Requirements Information in the nD Model 13. Information Management in nD 14. Data Visualisation 15. Legal Issues of nD Modelling 16. Interactive Experimenting of nD Models for Decision Making 17. Technology Transfer 18. The Role of Higher Education in nD Modelling 19. Designing Fit-for-Purpose Schools: The nD Game Part 4: nD Modelling: The Future 20. nD Modelling: Where next? 21. An Ontology to Integrate Building and Urban n-Dimensional Data 22. Modelling Cities 23. nD in 2D. Concluding Remarks

Contents

November 2006: Hb: 0-415-39171-7 £95.00

Construction Scheduling: a Latin American Perspective Leonardo Rischmoller, Universidad de Talca, Chile Introduction There is consensus among practitioners and academics that Construction Projects involve a high degree of uncertainty that ideally could be reduced if timely, effective and efficient Construction Planning and Scheduling (P&S) is carried out (Figure 1). However, despite the unanimous assertion about the importance of P&S, the agreement on the benefits that good P&S can bring to a construction project and the problems that bad or non-existent (i.e. improvising) P&S can produce; the compliance of projected construction costs and schedules are an exception rather than a norm in construction projects, showing that the results of P&S are not as effective as it is expected or even desired. Figure 1 illustrates how the ability to influence costs in a construction project is bigger while earlier the involvement in planning and scheduling..

Figure 1 Ability to influence cost in construction projects (CII, 1986) Research carried out by the Production Management Center (GEPUC) in Chile shows that on average, and despite some exceptions, the percentage of Planned Activities Completed (PPC) in Chilean construction projects barely reach 60% (Figure 2) and only a few companies, where new management approaches has been applied in the last five years (e.g. Last Planner System), have been able to increase plan reliability, remaining however in average below the 70% PPC level. Similar PPC data has been found in countries outside Chile (e.g Ballard, 2000)

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Figura 2 percentage of Planned Activities Completed (PPC), average by contractor (Source GEPUC 2003). Considerable research effort has been invested during the last few decades in developing or adapting methodologies and theoretical approaches to better carry out construction planning and scheduling (e.g. CPM, PERT, etc.). The reality has shown that these very important theoretical approaches have not been completely successful when applied to real projects, becoming partially impractical and sometimes used more as a good theoretical framework (a reference) than a solid guide to project execution and later control. Fifty to seventy percent of compliance with project plans and schedules are used to be considered good results and 100% of compliance is considered a utopia. The special characteristics of the construction industry and other arguments are posed as a logic explanations to this results sustaining that nothing can be done for further improvement. As such, more user-friendly and more powerful software tools have been developed that try to overcome the theory-practice dilemma described above, promising the ability to, for example, create rapidly and easily CPM bar charts or PERT diagrams, including resources and cost information and providing mechanisms to carry out an optimum construction project control leading to timely decision making and optimum project performance. These tools are mainly developed to automate existing and sometimes new (e.g. last planner system) theoretical approaches. This stance that the tools just merely aid the automation process, thus underestimates the importance of the tools and subordinate its existence to the goodness of the theoretical approaches. At the end a new dilemma, tools-practice, arises resulting in most construction project executors still relying on spreadsheet and paper based solutions to perform construction P&S rather than taking advantage of available tools specially designed to support construction P&S. Construction Planning and Scheduling (P&S) can be then considered as a process that has traditionally been approached within theory-practice and technology-practice dilemmas which has led the industry to conform with percentage of Planned Activities Completed (PPC) data below 70% as very good results. In this scenario, academic groups, software/ systems vendors and construction executors seems to be running in parallel rather than converging through a common goal of improving construction P&S. In this chapter, the theoretical background and some practical experience that has emerged from research on how to improve construction P&S using Information Technology is presented. The need and opportunity of a new approach to construction scheduling within a multidimensional (nD) context due to new available and coming technology will be discussed.

The traditional construction scheduling process Gantt bar charts depicting a list of interrelated activities or tasks each with a certain duration calculated using rates or resources assignment are central to traditional construction scheduling processes. The theory behind Gantt bar charts and similar approaches has led us to focus first in the efficiencies of individual activities, using historical productivity rates to support time estimates, floats, resources allocation, costs, etc. The focus is then changed to the relationships between activities in a cumbersome process which, early or late, escapes from our mind capacity to review, understand and use the Gannt bar chart to control and reschedule our project if necessary during construction execution. This neither induces parts to do what is good for the system as a whole nor direct managers to the point that needs their attention, steering the project leader away and sometimes leading even to failure of projects. Other techniques and approaches to carry out construction scheduling (e.g. line of balance, last planner system, etc.) conceived also under solid theoretical frameworks suffer from the same lack of 100% practical applicability and the emerging levels of uncertainty, complexity and variability inevitably lead to move away from proactive to reactive behaviors increasing as you come near to the jobsite and workface. Uncertainty at the jobsite is reflected in the form of urgent requirements, non-consistent constructive sequences dependant on immediate available resources (Alarcón and Ashley, 1999), lack of coordination in the supply chain, project scope changes, quality failures, etc. The combined effect between uncertainty and complexity in a project produces variability (Horman, 2000). High levels of variability and uncertainty lead to inconsistent estimations and assumptions, and thus general project performance deterioration. Current practices make use of material inventories, time and cost contingencies, excess of labor and equipment capacity, etc., for example, to deal with variability and uncertainty in intuitive and informal ways (Gonzalez et al, 2004).

Figure 3 The traditional construction scheduling process (From Fischer & Kunz, 2004)

A lot of safety (i.e. floats, contingencies, etc.) is added into construction schedules in order to protect the project from the uncertainty and also from the variability associated with the traditional construction scheduling process. Safety is added to the project as a whole, and safety is also added to each and every step of the project. Not too much understanding of this issue of safety embedded in the planning of a project has been carried out and safety included not very rationally has become a normal part of the scheduling process. For estimating the duration of every activity in the schedule, ‘realistic estimates’ are given according to their worst past experience. Time estimates become then a self-fulfilling prophesy and once they are established, with all their safety, there is little positive incentive, if any, to finish ahead of time, but there are plenty of explanations required when the project is delievered late. There is no point asking how much safety is included in the project because people believe that they give realistic estimations. The problem is in what they call realistic. The higher the uncertainty, the higher the resulting safety. Whenever a step in a project is a collection of several tasks, each done by a different person, the boss of the project asks each person for their own estimates, adds them up and then adds his own safety factor on top. Safety is inserted into the time estimates of almost every step of a project using time estimates based on a pessimistic experience.. The larger the number of management levels involved, the higher the total estimation, because each level adds its own safety factor. The estimators also protect their estimations from global cut. When you add it all up, safety must be majority of the estimated time for a project. Unlike in production where work centers are protected with inventory, in construction projects, scheduled activities are protected with safety time. In production if there is a stoppage, inventory does not disappear. In projects, time is gone, forever. The Core Process A ‘core process’ means a chain of tasks, usually involving various departments or functions, that deliver value (products, services, support, information) to external customers. Alongside the core processes, each organization has a number of ‘support’ or ‘enabling’ processes that provide vital resources or inputs to the value-adding activities. While the idea of a core process may seem pretty straightforward - and it is - it is interesting that this key organizational ‘building block’ is a relatively recent idea, one of the breakthrough concepts of the Six Sigma system (Pande et al, 2000). Independently from the tools, techniques and methods to capture construction knowledge and transform it into a construction schedule, a number of questions remain associated to what the construction scheduling core process should be:

• What will at the end need to be constructed? • How much of this or that will be constructed? • and When will it be constructed?

The mental and practical construction scheduling process is guided by the answers to the above questions. But independently of the project type, the answers to these questions seem to be tied to a common approach focused in calculating activities durations, resources, costs and depicting the relationship between these activities through graphical representations (e.g. networks, gannt charts, etc.) developed by specialized personnel. Currently, construction scheduling is usually a task that involves only specialized estimators and schedulers concentrating on everything related to the construction scheduling process rather than various departments or functions and support or enabling processes working together to deliver value. The resulting schedule is then passed to the contractor who must convert the schedule into practical tasks concentrating on everything, which sometimes is synonymous with not concentrating at all. Then if project leaders use early starts, they will lose focus. If they use late starts, focusing is not possible at all. There are no mechanisms, rules, and tools that will enable project leaders to focus.

Existing techniques and supporting tools Existing scheduling methods and techniques used by the construction industry are based undoubtedly on sound theoretical knowledge which in some cases come from and are also used very successfully in other industries (e.g. aeronautics, manufacturing, etc). Paper, pencil and electronic calculators have given up its starring role as supporting tools for these scheduling methods and techniques to computer based supporting tools, i.e., software. For example, specialized software to develop ‘easily’ and ‘fast’ CPM bar charts, PERT networks and Pure Logic Diagrams are commercially available and used with some success in several industries but in construction. These software tools are developed following the scheduling method or technique that they try to automate. There are also some scheduling techniques, i.e., Line of Balance, for which software tools are not as widespread but there are several specific efforts around the world trying to automate these construction methods and techniques. Existing scheduling methods and techniques used by construction are an important part of every project and it would be unfair to sentence them as poor. Most of the built environment that we see around us have been constructed using these methods. However, since at the end a constructed project reflects that the contractor has been effective in achieving a construction project ‘main’ goal, this ‘success’ in achieving our goals, i.e., a constructed project, has led us to conform with the low levels of efficiency of the scheduling process accepting them as ‘normal’ and believing and even feeling that it is an utopia pretending to improve to 100% PPC (percentage of Planned Activities Completed) levels. The need of change The construction scheduling process in its traditional form to a great extent is the result of the traditional tools and techniques used for their preparation combined with the related working process. This traditional approach has to some extent led to focus in the efficient preparation of complex bar charts and other forms of representation but not necessarily at its practical use. Dominant ideas associated to existing tools and work processes have been with us for decades providing us with a way of looking at construction projects. Whatever way one tries to look at how construction projects are executed today, is likely to be dominated by the ever present but undefined dominant ideas associated to traditional tools, techniques and work processes that have accompanied us for decades. Unless one can pick out the dominant ideas, one is going to be dominated by them. If one cannot pick out the dominant ideas, then any alternatives one generates are likely to be imprisoned within that vague general idea (de Bono, 1970). There is nothing wrong in the logic behind traditional construction planning and scheduling. However, there are new efforts tending to build around themselves meanings, contexts and lines of development that represent conscious efforts to pick out the dominant ideas in the construction industry projects processes development, acting as active changing agents trying to push the construction industry to adopt new available technology under a proactive approach instead of waiting to be taken by the storm of new technology (Sawyer, 2004). New available technologies and production principles bring an opportunity to re-think the construction scheduling process and generate alternatives to the ‘traditional’ approaches. These alternatives consider the multidimensional (nD) context of construction projects, moving away from vague general ideas and existing tools and work processes to more explicit and realistic ways to carry out construction planning and scheduling. Construction scheduling as it is carried out today has not provided a truly proper control mechanism that can help keep project managers focused. And if project leaders are not focused or doesn’t maintain focus, the probability that emergencies will turn the project into a fiasco is high. Everybody knows what a control mechanism is: it measures the progress of the project. The problem is that by the time the progress report indicates something is wrong, it is usually too late. A project report might tell you that ninety percent of the project is finished in one year and then, the remaining ten percent takes another full year (Goldratt, 1997).

The ‘traditional solution’ for this problem has been the addition of safety to our assumptions (e.g contingencies, floats, buffers, etc.) in schedules. The safety introduced in schedules (i.e. cost and time) are not the result of bad assumptions but they are the result of our lack of ability to consider the multiple dimensions involved in the construction execution. For example, constructability issues or space-time constraints are difficult to represent into a bar chart. Once safety is introduced into a construction schedule activity, there is no rush to start it until the last minute so that the activity is executed in the assigned period of time and using the assigned resources, including all the safety, which in this way more than used becomes wasted. The dependencies (e.g. predecesors and succesors activities) between activities sometimes cause delays to accumulate and advanced to be wasted, and again all the safety we put into the schedule becomes vanished. We need a much better way to manage our projects in which we could visualize what is beyond a bar chart and keep project mangers focused. An nD construction scheduling process New information technology tools provide the opportunity to undertake the construction scheduling process in a completely different way with regard to how it is accomplished today. Commercially available visualization tools not only allow a greater understanding of the geometry of the project by looking at time in more realistic three-dimensional (3D) computer aided design (CAD) models. When the construction of a 3D CAD model is carried out or guided by those who will be in charge of the construction of the project in real life, the 3D model can be divided in pieces that later on can be associated to construction activities in what is known as 4D modeling. The use of 4D models in an iterative process where at some point construction planners decide if a 3D CAD model represents a constructable design or the design need to be refined and/ or if a 4D model represents a construction schedule that is executable or it need to be refined, has been referred by Rischmoller et al, 2002 as the 4D-PS (4D Planning and Scheduling) work process. The combination of technology, methods and procedures by which to conduct 4D planning pioneered in the first 4D application on a live project in Chile (Rischmoller et al, 2000) rendered significant and demonstrable savings in man-hours and materials, giving solid credence to the assertion that 4D technology is viable and cost-effective. Research efforts around the world has arrived to the same conclusion and 4D modeling is now in the process of crossing over the boundary between academic research and practical implementation by the construction industry (Heesom and Mahdjoubi, 2004). 4D considers the time as the fourth dimension which when added or linked to a 3D CAD model or a 2D digital representation of the project activities (Rischmoller and Valle, 2005) leads to the formation of a 4D model that can be shown in a display device where the spectator can see four dimensions simultaneously. Other dimensions, like for example the cost, the materials quantities take off coming from the 3D model pieces, the temporal-spatial relationships and all the design information useful from the construction planning and scheduling perspective are to some extent implicitly considered when using 4D modeling. However, these and other dimensions could be considered not only implicitly but also explicitly into an nD model. An nD model is an extension of the building information model by incorporating all the design information required at each stage of the lifecycle of a building facility (Lee et al, 2003). Thus, a building information model (BIM) is a computer model database of building design information, which may also contain information about the building’s construction, management, operations and maintenance (Graphisoft, 2003). From this database, different views of the information can be generated automatically, views that correspond to traditional design documents such as plans, sections, elevations and schedules. As the documents are derived from the same database, they are all coordinated and accurate – any design changes made in the model will automatically be reflected in the resulting drawings, ensuring a complete and consistent set of documentation (Graphisoft, 2003).

The nD model concept was developed as one of the main results of the funded 3D to nD modelling project at the University of Salford. The core ideas behind this concept can be traced back maybe ten to twenty years ago (Bertelsen, 1992). However, the advances in research on Information Technology in construction, the availability of new tools and the maturity of the industry to use these tools, have led to conclude that the nD concept could start the process of crossing over the boundary between academic research and practical implementation by the construction industry sooner than expected. Virtual Design and Construction at Stanford University, Scenario Based Project Planning by FIATECH and Building Information Modeling (BIM) by Autodesk are samples of some world class research approaches, strategies, and organizations dealing, to some extent, with the same ideas behind the nD concept. In Chile, Rischmoller et al 2000, proposed the Computer Advanced Visualization Tools (CAVT) concept as a new concept that should lead to face options and opportunities offered by IT with a revitalized creativity and in a constructive fashion, when dealing, not only with visualization issues, but mainly with engineering and construction management. Computer Advanced Visualization Tools A 1997 study focused on the full range of IT use revealed that design firms tended to equate information technology with Computer Aided Design (CAD) (Fallon, 2000). Engineering managers have clearly become more interested in the topic of integrating CAD technology effectively into their work processes and in the specific features required to make CAD effective for everyone in the firm, not just drafters (Fallon, 2000). CAD is however an acronym that in itself is tying us to the past and limiting our ability to develop creative thinking regarding IT developments and their application to engineering and construction processes. The broad spectrum in which the CAD acronym is used today does not match the original concept behind it, limited to receive aid during the design process. A new broader concept that shall lead to new ideas and improvements is needed. 2D CAD has almost completely replaced the drawing board, 3D CAD modeling enjoy a ‘well’ developed approach in most AEC/ EPC leading companies, and 3D Visualization has been identified by CAD vendors as the most obvious advanced capability of CAD products that will provide more share of existing CAD market (Philips, 1999). 4D CAD is a technology starting to cross over the boundary between research and practice. Common to all these approaches is their ability not only to represent visually, the final products aimed by AEC/ EPC industry (i.e. 3D model), but also the processes (i.e. 4D model) needed to be carried out to achieve the final products. This, jointly with the need to represent not only the visual animation information, but also underlying information led to the CAVT concept development. CAVT is defined as ‘the collection of all the necessary tools, which allow for the visual representation of the ends and the means of AEC/ EPC needed to accomplish an AEC/ EPC design and construction project.’ CAVT defined in such a broad sense provides a definition that could evolve over time, since it is not tied to any particular tool. And even CAVT is mainly related with the visual aspect of project representation, it is not limited to such approach, which constitutes only its ultimate output. The CAVT definition also considers underlying information about facility components and activities that might lead to a 3D rendering, or a 2D plot, or a bill of materials, or a work order report, or a virtual reality environment, each coming from a unique product and process model representation, which can be visualized through a computer based display device. CAVT understood as a concept aligned with the nD concept demands rethinking construction product and process modeling processes into new approaches that should be not only supported, but intrinsically linked to CAVT. Product Modelling – The Digital Reality According to traditional rationalistic philosophy, the difference between ‘reality’ and our understanding of that reality is not an issue, because it claims that there exists a rather simple

mapping between the two. Our ability to intelligently act in the world around us is due to the mental images or representations of the real world that we have in our minds. In fact, studies have shown that we receive approximately 80% of our external information in visual form (Intergraph, 1998). The level of detail and realistic views that 3D product models can achieve by using CAVT in the construction industry, and that will be achieved in the near future, makes it sometimes difficult to differentiate them from reality. Furthermore, computers allow going beyond the visual aspect of the objects represented and attach to them all kind of attributes and links. In this way, physical properties (i.e. material, mass, density, inertial momentum, etc.) and other characteristics of the 3D product models become an inherent part of them. Environment lights coming from different sources and directions and the response of the objects to them (i.e. shadows, reflections) can complement 3D models representations to make them even much more realistic. Product models are not now then just geometric representations of an intended project, but they indeed ‘exist’ digitally into a computer, which lead us to name them Digital Realities (DR). Naming of a project product model as Digital Reality has more than semantic implications. The process of design varies from trying to replicate the future by representing it with the use of computers, to an iterative transformation of a Digital Reality in a new process of refining it. This new approach is developed concurrently in a common, collaborating and multidisciplinary digital dimension, pursuing an optimum and constructible design. The Digital Reality is in this way ‘dynamic’, unlike a 3D product model, which is ‘static’. Furthermore, future easier and faster CAVT should lead to facilitate the construction of the Digital Reality within the computer, and even outside it with devices like, for example, the workbench response table at Stanford University (Koo and Fischer, 2000). Future widespread use of CAVT make us envision the result of the design stage as not only geometric information in 3D models, but also complete construction planning and scheduling visualization models (i.e. represented in complete nD models) which may include scope and cost beside time (Staub and Fischer, 1999) and where construction activities, tasks durations, resources and costs could be linked and/ or obtained from a project product model (i.e. 3D model and databases). We also envision construction tasks being completely transformed when narrowing the degree of uncertainty existing currently at the job site. CAVT shall transform the way we execute the work at the jobsite (i.e. reporting in real time though CAVT and associated hardware mobile devices) so as to have no resemblance to anything we know today in the construction industry. So Digital Reality spoken in two words goes beyond the traditional product modeling definition and oppose to Virtual Reality. If prizes were awarded for best oxymoron, virtual reality would certainly be a winner (Negroponte, 1995). Virtual as opposite to Reality states a big contradiction of both words together. ‘Walkthroughs’ into a 3D CAD model produces a sense of ‘being there’, even without using electronic glasses and gloves, typical common devices of virtual reality technology. The Digital Reality could represent to the construction industry the foundation over which completely new paradigms for the design and construction processes can emerge, transforming the way AEC/ EPC projects are developed even today with the ‘widespread’ use of Information Technology. Process Modelling Designers develop digital realities, and contractors need to construct these digital realities. This can also be done digitally before going to the job site. The construction industry relies on processes of varying complexity to accomplish every task it is related with. These processes are the means that allow the transformation of abstract information into a physical reality, an important goal of a construction project. Simulations have been used widely to represent construction industry processes. In general, simulation refers to the approximation of a system with an abstract model in order to perform studies that will help to predict the behavior of the

actual system (Alciatore, 1991). A previous modeling effort is essential to develop any simulation task. Model development efforts must invariably consider the general modeling technologies upon which new models will be based on (Froese et al, 1996). Within the computer graphics and visualization context, in the last years 3D modeling has reached a high level of development in the AEC/ EPC industry, specially in the Plant Design industry where 3D and shaded models have become an inherent part of most of the design process. And currently available CAVT provide the most advanced technologies to visually model the construction process, by allowing the development of 4D models. However, despite its availability, this advanced CAVT feature has not been widely implemented yet in AEC/ EPC projects. A comprehensive study of theoretical and practical approaches of 4D modeling around the world and through several case studies carried out in Chile, lead us to conclude that this is the technology that will trigger the major changes expected from CAVT in the way to an nD Construction Schedule. 4D models reflect the realities of project execution more closely than the approaches used in practice today (Fischer and Alami, 1999). Available 4D modeling tools can be used to support construction planning and scheduling. Field personnel knowledge introduced into 4D models, can be used to generate project schedules with computer software. Furthermore, when 4D application is carried out included into work processes specially designed to take advantage of 4D modeling, it can be proved that using 4D is productive and cost effective (e.g. Rischmoller et al, 2001). Thanks to computer advances, it is expected that CAVT will continuously reduce the construction process modeling effort. CAVT and 4D modeling technology are commercially available today, yet we are not taking fully advantage of them. In the future it is expected that the CAVT and nD approaches will allow the visualization of the mapping scheme developed to support the relationships between the different hierarchical representations of design, cost, control and schedule information represented at different levels of detail (Staub and Fischer, 1999). In this way, AEC/ EPC projects, which are highly complex systems with a high degree of connectivity between objects and attributes, will become every time more explicit with CAVT application not limited to the design stage, but also to the construction phase of AEC/ EPC projects. The next benefit should extend the CAVT and nD approaches to the whole life cycle of AEC/ EPC projects. This will reduce complexity and uncertainty, allowing for increasingly more realistic models of products and processes within the AEC/ EPC industry. The nD Construction Schedule The combination of product and process modeling theoretical backgrounds, coupled with the use of available CAVT, can lead to a new construction schedule development process understanding and design based on Information Technology advances. This new approach to construction scheduling can consider now more dimensions than just the time (e.g. quantities take-off, space-time constraints, etc.) with some effort required to overcome the lack of interoperability of currently available CAVT coming from different software vendors. It is expected that in the future the nD Construction Schedule development process will be the result of a single nD modeling effort using interoperable software and specially designed new work processes. Since 2003, nD modelling is a research topic that has started to gain momentum and interest worldwide. While the 3D to nD research project, at the University of Salford, aims to develop a unique multi-dimensional computer model that will portray and visually project the entire design and construction process, enabling users to ‘see’ and simulate the whole-life of the project, research about CAVT in Chile pursue the same objective but focused in how to predict and plan the construction process using mainly 3D and 4D commercially available CAVT to develop nD Construction Schedules. The research approach to nD or CAVT used in Chile uses

the following commercial tools: Autodesk Architectural Software to ‘build’ 3D models taking as point of departure 2D drawings usually made in AutoCAD software. Primavera Project Planner software is used to develop the traditional construction schedule, while Intergraph’s SmartPlant Review software is used to link the 3D model pieces to the construction schedule activities obtaining 4D models. This research approach cohabits with several IT problems, like for example interoperability, which are not the main part of the research focus. The main objective of the research carried out in Chile is the work processes development needed to take full advantage of available CAVT for nD construction scheduling development and planning and control improvement. Another important objective is the creation of awareness about the future nD tools and work processes that is generated while researching about how to implement and take advantage of available tools. The research about nD carried out in Chile can the be considered from a ‘pull’ perspective since it is created into the industry creating awareness that shall contribute to accelerate industry adoption of the future results coming from the 3D to nD research project which at some time will be ‘pushed’ into the industry. The goal of improving construction management though new approaches to construction scheduling achieved either from ‘push’, ‘pull’ or both kind of efforts together shall at the end help to improve the decision-making process and construction performance by enabling true ‘what-if’ analyses to be performed to demonstrate the real cost in terms of the variables of the design issues. Conclusion New IT tools will not only help to automate the things we are doing - continuing doing the same faster - but a big transformation in the way we work is expected in the next years as a result of the application of IT advances to the construction industry. nD Modelling, VDC, BIM and FIATECH are examples of established labels for world class research efforts tending to build around themselves meanings, contexts and lines of development that represent conscious efforts to pick out the dominant ideas in the construction industry projects processes development, focusing with unprecedented opportunity and precision mainly on answering to the questions: What will at the end need to be constructed? How much of this or that will be constructed? and When will it be constructed?, these research efforts act as active changing agents trying to push the construction industry to adopt new available technology under a proactive approach instead of waiting to be taken by the storm of new technology (Sawyer, 2004). Information Technology for the AEC/ EPC industry involves the integration of all product development processes and the management of the information flow between them, irrespective of the data models chosen in the different implementations of one and the same process (Scherer, 1994). Product and process modeling are the main topics related with the former approach, that have gained more attention in the last years within IT research in the AEC/ EPC industry. Although the use of building electronic product and process models is not widespread in the industry at the present time, its need is seen to be self evident. Central to product models is the visual representation of the project product, commonly associated to some 3D CAD modeling effort. Different approaches have extended the ‘physical’ representation of the project product, to include not only geometric information within it, but also the relying data which support the different activities during the several phases involved in an AEC/ EPC project. Process modeling has been trying to represent the detailed tasks and transformation of specific entities among simultaneous activities oriented to complete a design into a constructed facility. In the construction industry, product and process modeling efforts have been mainly related with the academic community. Product and Process models coming from the academic world, are however very different from 3D models being developed within the AEC/ EPC industry, especially those dedicated to design. The expectations of real projects are focused on the results and the tools to achieve the results. The tools are mainly the available hardware, software and skills needed to use them. The knowledge about product and process

modeling coming from the academic community, has been usually overlooked or developed in a tacit fashion, more guided by the common sense, than for an ordered approach based in techniques, methodologies or prototypes coming from the academic community. More recent research efforts like CAVT and nD modeling and the availability of more powerful and easy to use tools tackles these issues under new approaches that may help to traverse the line from theory to practice faster than expected. New tools require ever diminishing ‘computer’ skills from engineers, who don’t need to be ‘computer operators’, but they can focus more on engineering, achieving results faster and with less effort than only a few years ago. CAVT and nD application to the AEC/ EPC industry should allow the necessary break between the results and the tools, creating a niche where the accumulated knowledge about product and process modeling could fit, providing great benefits to the AEC/ EPC industry, and starting a new phase of research from a practical perspective, instead of the prototype testing approach used commonly to date allowing for the attainment of levels of integration never seen before. Traditional construction scheduling approaches have proved not to have the capacity to produce and make it easily and timely available the information needed for a latter effective and efficient construction control and execution reflected in a high Percentage of Planned Activities Completed. nD poses barriers and opportunities associated to big transformations which for example could lead to relegate traditional construction scheduling approaches like the CPM in which the critical path has become a bottleneck, a constraint of a project. The big change of working with a nD construction schedule can lead to lose less time on the critical path itself but exploiting this constraint and subordinating everything else to it. Most problems that impact the critical path do not occur on the critical path itself, then subordination is not a nicety, it is a must (Goldratt, 1997). Another big change is that using nD Modeling it is possible to alter the order in which the different level of detail schedules are developed for a construction project. Using nD and CAVT it is possible to develop first the more detailed schedule and then obtaining the master schedule grouping activities in this more detailed schedule. The master schedule can then be adjusted to project requirements and the detailed schedule reviewed in an iteratively process. This opposes to the way scheduling is carried out today in which the detailed schedule follows the master schedule development effort and rarely one goes back to review the master schedule deeply, but makes the maximum effort to adjust the detailed schedule to the master schedule. And finally a very important change is that Visualization, Planning, Analysis and Communication capabilities embedded in a new nD construction scheduling development process can improve the traditional scheduling process to the extent that this schedule could finally be used as a real production control mechanism that could lead to tackle problems proactively and re-schedule the project as necessary. Referenences Alarcón, L.F. and Ashley, D. B. (1999). Playing Games: Evaluating la Impact of Lean Production Strategies on Project Cost and Schedule. Proceedings of IGLC-7, University of Berkeley, California, U.S.A., 26-28 July. Alciatore, D., O’Connor, J., Dharwadkar, P. (1991). A Survey of graphical Simulation in Construction: Software usage and application. Construction Industry Institute Source Document 68. Ballard, G. (2000). The Last Planner System of Production Control. Ph.D. Dissertation, School of Civil Engineering, Faculty of Engineering, The University of Birmingham, Birmingham, U.K. Bertelsen, S. (1992). The Mouse’s Opinion-on the building design documents. NIRAS Consulting Engineers and Planners, Denmark

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