Infrastructure Solutions White Paper Moving to Model-Based Design Choosing Between 2D and 3D Do you really have to choose between 2D and 3D? The answer is no, but it is important to know why. Over the past few years engineering design technology has begun an important transition: from automating traditional 2D drafting processes to developing 3D models as the basis of design. The building industry began this transition more than ten years ago, and today that industry is moving even further with building information modeling, or BIM This transition has brought valuable benefits to the building industry, such as improved coordination of drawings, faster communication of design alternatives, and reduced field rework (For more detailed information on BIM, visit www.autodesk.com/bim.) Those gains can now be realized in the engineering and construction industries as well. It is not a question of 2D versus 3D; the methods need not be mutually exclusive, even in the context of a single project. For Civil engineering and construction professionals using 3D modelbased design software like Autodesk Civil 3D, you can get the benefit of both 2D and 3D Model-Based Design To understand model-based design, you need to think beyond 3D. In model-based design, you create a data model of a proposed site development or road from which work products are generated: site volumetrics, road sections and profiles that are dynamically linked, parcel topologies, dynamic grading plans, conceptual what-if presentation models, design development drawings, and construction documents that might include plans, profiles, staking plans, details, reports, and presentation graphics. Each deliverable is created from a central data representation of the site or road itself. By using model-based design methods, civil engineering professionals can create a more complete design model that includes important nongraphical data, 2D and 3D geometric data, as well as information regarding functional relationships, such as the association between a road and the right-of-way and abutting parcels. By creating a road model instead of multiple, unrelated CAD drawings, you are developing a single data set from which all project documents are generated, improving coordination between the various work products and disciplines. For example, if you move the road, other elements such as profiles, cross sections, parcels, and daylight points all update automatically instantaneously (see Figure 1). The digital design data generated from the model not only supports design and construction phases, but can also be used in downstream project phases to support the complete infrastructure lifecycle. www.autodesk.com/civil-engineering 1
Finished drawings are derived from data in the model. Changes to alignments result in updated profiles, cross sections, alignment drafting, and so forth. Changes to parcel geometry result in updated tables, labels, and graphics. Surfaces are derived from a variety of 3D source data. If a point changes, the surface can update. Points are broken in groups for use throughout the entire project. Figure 1: Dynamic relationships of model-based design With a model-based approach, the amount of design information is consistent with the design process stage. A road representation, for example, may be a single centerline (during planning); a complete centerline, edge of pavement, shoulders, and right-of-way (late pre-design, design documentation); and a fully detailed road model (construction phase), without reentry or multiple inputs. The centerline object is simply modified and expanded to contain the next level of design information and detail consistent with the current phase of the project or that required by the project team member making the change. And the data model evolves accordingly; a design phase transition no longer means starting from scratch with new drawings and deliverables. This evolution reduces the possibility of coordination errors and makes graphic representation of objects consistent throughout the design deliverable set. Benefits for Designers and Engineers For designers and engineers, model-based design enhances project quality through improved coordination not only among plans, profiles, aspects, and take-offs but also between disciplines. For example, when the engineering model is shared across disciplines, you can use 3D functionality to easily identify interferences between sewer and water lines, drainage plans, street intersections, and more. Because all disciplines work from the same model, interdisciplinary coordination is improved and problems can be resolved before construction, reducing the cost and time required for rework. The same design data, used in 3D, enhances visualization of the site or road design to better communicate with clients and others, helping to ensure that the work product satisfies the client s expectations and the public s needs. www.autodesk.com/civil-engineering 2
Approval for civil engineering projects requires fast and effective communication of various design proposals to a diverse audience. A model-based design approach can help you communicate design ideas internally to the project team and externally to the client, public agencies, reviewers, and others crucial to the success of a project. Benefits for Construction Professionals Consider this quote from McAninch Corporation, an Iowa earth-moving and utility construction contractor: Because accurate three-dimensional models are required to represent grading surfaces for GPS-equipped machines, contractors must either obtain 3D models from designers or create models themselves based on 2D drawings. McAninch generally prefers to obtain digital designs rather than recreate them. This quote shows how 3D modeling is changing the entire lifecycle of a project, not just the design phase. A 3D model enables project teams to alleviate spatial coordination problems because designers, engineers, and construction firms are using a single data set at a 1:1 scale, ensuring that everything fits together properly. By using a 3D model, teams can more easily and costeffectively review the effect of change in the field and in the office when revisions are made during the design and construction phases. Using model-based design, architectural firms have already demonstrated a 10 percent savings in construction costs and believe they can save up to 20 percent by solving problems before they get to construction. The civil engineering and construction side can easily realize these gains as well. Mistakes found late in the process have a much greater impact and are more expensive to correct. Because a model provides a visual 3D representation of the project, problems that would normally not be seen in 2D can be uncovered and resolved much earlier in the process, saving you and your client time and money. Benefits for Owners and Operators Perhaps the most significant benefit of model-based design is the usefulness of the digital design data throughout the infrastructure lifecycle. The data generated from the engineering model can be applied to short- and long-term infrastructure maintenance, emergency management and response, what-if expansion planning, road or building renewal, resource management, environmental analysis, and other infrastructure management functions. These capabilities are not possible with traditional CAD or GIS packages or paper. The model becomes the centerpiece of infrastructure operation and management and is an investment in data with a high return. Figure 2 shows the benefits of moving from file-based systems, where information is passed between proprietary systems, to the model-based approach, where information is added to the model as needed. www.autodesk.com/civil-engineering 3
Land base Survey Engineering or CAD Dept. Design and Drafting GIS Dept. Mapping Customer Service Billing Maintenanc e Dept. Work Order Operations Dept. Outage Land base Survey Engineering or CAD Dept. Design and Drafting Central Database The Model GIS Dept. Mapping Customer Service Maintenance Dept. Operations Dept. Billing Work Order Outage Figure 2: Process support for the total infrastructure lifecycle www.autodesk.com/civil-engineering 4
The Evolution of Digital Design Autodesk s approach improves the design process from conceptual design through design development and visualization to production of construction documents and provides useful digital design data for downstream use throughout the infrastructure lifecycle. This approach enhances communication and collaboration among all project stakeholders. But implementing this vision requires that engineering and construction industry work processes move beyond drafting to model-based design. The larger opportunity to improve processes throughout the infrastructure lifecycle lies in taking advantage of digital design data to facilitate the planning, design, construction, and management of the infrastructure asset, such as roads, sewers, water lines, and housing developments. The following table compares the stages of digital design evolution with their effects on process, representation, and deliverables. Evolution Drafting Model-Based Design Integrated Infrastructure Lifecycle Approach Process focus Drafting Design Planning, design, bid, build, operate, manage Principal representation medium 2D drawings and paper Data yielding either 2D or 3D model views and visualizations Mixed media data model with 2D and 3D geometric data as integral part Key work product Individual construction drawings Coordinated construction drawing set derived from single infrastructure model Comprehensive data model from which reports, plans, and paper can be produced easily As you can see in the table the move to model based design lays the foundation for an integrated lifecycle approach. The model itself now drives the process down stream with more efficiency and accuracy resulting in the same design information being used by many more down stream users. This step bridges the existing data chasm between drafting and the need for real time intelligent design information. Model-based design methods produce richer, more highly structured data that is useful beyond the design phase. In this engineering model, not everything needs to be represented in 3D. A mixed media model can contain 3D elements when necessary, but 2D continues to play a significant role in areas such as civil construction details. The intent is to provide a variety of tools and options that enable you to work in 2D, 3D, or both, and to support the engineering design process and infrastructure lifecycle. The Autodesk Solution Autodesk provides a design solution for the civil engineering and construction industries that improves the engineering design process and generates digital data that is useful throughout the infrastructure lifecycle. Autodesk solutions include tools for planning, drafting, conceptual design, design development, visualization, production of coordinated construction documents, increasing communication and collaboration throughout the project lifecycle. Autodesk s model-based design strategy enables you to adopt this approach at your own pace, using traditional drafting methods while moving to model-based design as appropriate. www.autodesk.com/civil-engineering 5
It s not about choosing between 2D and 3D. It s about choosing the right approach to get the job done as effectively as possible with powerful, flexible tools that accommodate your work process. With the Autodesk solution you get that, and more. Autodesk is a registered trademark of Autodesk, Inc., in the USA and other countries. All other brand names, product names, or trademarks belong to their respective holders. 2004 Autodesk, Inc. All rights reserved. www.autodesk.com/civil-engineering 6