September 05, 2005
A Hybrid Approach to As-Built Design: Combining 3D CADD with Laser Scanning - Responding to Hurricane Katrina
Please note that contributed articles, blog entries, and comments posted on AECcafe.com are the views and opinion of the author and do not necessarily represent the views and opinions of the management and staff of Internet Business Systems and its subsidiary web-sites.
About this Issue .
Welcome to AECWeekly! This week, AECCafe and AECWeekly would like to extend our sympathies to those who have suffered and lost loved ones as a result of the massive destruction wrought by Hurricane Katrina. The absolute destruction of homes and lives cut a swath across the Deep South from Florida through Mississippi and New Orleans, wrecking havoc in yet unimaginable ways. The recovery effort will take time, and will require enormous resources.
New Orleans Mayor C. Ray Nagin stated that he believes New Orleans will not be functional for months. It has been estimated that the total cost of damage may reach upwards of $25 billion. And that is just one city - many others suffered greatly as well.
Oil production in the Gulf of Mexico has been shut down. With the resulting drop in production, gasoline shortages developed in some areas of the country, and prices surged above $3 a gallon. To counteract this rise in prices, the Department of Energy said it would release oil from the nation's strategic reserve to offset the production losses.
Already in the works this week before the hurricane made landfall, was our story on 3D CADD and 3D laser scanning, which is of specific interest to power, process and offshore designers and engineers.
One of the toughest challenges, particularly in the area of process, power and offshore engineering and design, is the issue of retrofitting existing facilities. Since 3D CADD hasn't been around that long, most plants and facilities were built using 2D non-electronic documentation, which may or may not be altogether accurate to begin with. And even if it was accurate when constructed, over time many changes have been made to the facility, typically without updating the as-built documentation. Read about how 3D laser scanning can be used along with 3D CADD to boost productivity and cut costs dramatically in this week's Industry News.
AECWeekly is a news magazine featuring important industry news profiles, a summary of recently published AEC product and company news, customer wins, and coming events. Brought to you by AECCafe.
AECWeekly examines select top news each week, picks out worthwhile reading from around the web, and special interest items you might not find elsewhere. This issue will feature Industry News, Acquisitions/Agreements/Alliances, Announcements, Appointments, Name Changes, New Products and Upcoming Events.
AECWeekly welcomes letters and feedback from readers, so let us know what you think.
Susan Smith, Managing Editor
A Hybrid Approach to As-Built Design:
Combining 3D CADD with Laser Scanning
By Susan Smith
For the sake of this article we will be referring to CADD with double “Ds” as in “computer aided design and drafting,” since so much of design engineering is comprised of both drafting and design.
For designing new facilities in recent years, 3D CADD has been an invaluable tool that ensures design standards and best practices are embedded and enforced, thereby making sure the documentation is accurate and consistent. In addition, 3D CADD models have the advantage of being electronically transportable to engineering design teams around the world. Other data, such as facility information, can also be linked with the visual 3D CADD model so it can be easily found. Moreover, construction phase rework is virtually eliminated, which cuts down on costs and schedule delays.
But 3D CADD can't be used for everything today. One of the toughest challenges, particularly in the area of process, power and offshore engineering and design, is the issue of retrofitting existing facilities. Since 3D CADD hasn't been around that long, most plants and facilities were built using 2D non-electronic documentation, which may or may not be altogether accurate to begin with. And even if it was accurate when constructed, over time many changes have been made to the facility, typically without updating the as-built documentation.
Further, even if electronic 2D documentation was available, a 3D model cannot be easily generated from traditional 2D CADD. Therefore, creating a 3D CADD model for an existing facility requires time-consuming manual modeling. Even if 3D CADD models are available, they can be inaccurate or incomplete as they typically use idealized representations of space and features, assuming all angles are 90-degrees. Additionally, details such as gusset plates, packaged equipment, field routed utility systems, instrument conduit and cabling are usually omitted. It is these “real-world” imperfections and details that cause the majority of construction rework..
So, it's understandable why contractors are more excited about a new building opportunity than a revamp. On the other end of the spectrum, project managers are tasked to control project costs while being challenged with unknown rework costs on maintenance and modification projects that may or not be budgeted in the original estimate. To avoid these issues, the re-creation of as-built data should occur early in the project lifecycle so that reliable information is available from the beginning of the project.
Collecting As-built Data
Once the as-built laser scan data has been collected, it can be combined with 3D CADD models to provide the existing plant conditions for design and create entities in the 3D CADD package. It can also be used to take measurements from point to point and find details such as pipe centerline, angle and outer diameter, for example. When dealing with existing structures, this allows for only those parts of the structure that need work to be remodeled, rather than having to remodel the entire structure.
3D CADD models can also be imported and displayed within the 3D laser model for visualizing proposed modifications for design and constructability planning, to compare and validate CADD models against the as-built laser documentation, and to share proposed updates with project team members who aren't CADD software users.
As in 3D mechanical models, these 3D CADD models can be clashed against the 3D laser model to see if there are potential interferences or dimensional “busts.” This way, potential design clashes can be identified and eliminated early on in the design process, before they find their way to construction.
3D laser models can also pick up features such as packaged equipment details, field routed utility systems, and instrument conduit and cabling where they are visible and provide accurate dimensions. This helps ensure that clashes against even the smallest plant details are identified and eliminated as well as assists with the routing of new pipe, conduit, etc.
One of the other great features is that it is possible to scan plant structures safely, even in areas that are hard to see or are congested, where actual physical access would be dangerous or impossible. In this way, the use of 3D laser modeling also eliminates the need to put large numbers of team members in jeopardy of exposure to hazardous conditions.
You can find the full AECCafe event calendar here.
To read more news, click here.
-- Susan Smith, AECCafe.com Managing Editor.