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|Federal Highway Administration > Publications > Public Roads > Vol. 65· No. 6 > See It Before It's Built|
See It Before It's Built
by Richard E. McDaniel
Imagine your client is the park superintendent for a national park. To help move visitors in and out of the area, a new road needs to be built to augment the existing one. You propose three design options: a bridge that allows for an arch design, a high-clearance bridge requiring long columns, or a low-clearance bridge. The client now needs to decide which design would suit the park best.
Wouldn't it be nice if the client could actually see the bridge—exactly as it would look after construction and against the actual backdrop of the park—before making a decision?
The Federal Highway Administration (FHWA) provided precisely that service for the National Park Service's Natchez-Trace Parkway in Mississippi. The park people were interested in a bridge spanning historic Old Agency Road. But residents living nearby were concerned, among other things, about the impact of constructing a bridge over this tree-lined roadway. Paul Schneider, John Seabrook, and myself, all with FHWA's Eastern Federal Lands High Division's (EFLHD) Location Branch, showed them a dozen different options—using different bridge colors and types. We also showed them what it would look like without any landscaping, and what it will look like in 5 years after vegetation has grown.
These days, clients do not need to attempt to visualize designs in their minds, and they do not have to pay a fortune to obtain artist's renderings of the various options. All they need to do is have their tech folks produce a design visualization for the project.
Get the Picture
Design visualization (DV) technology enables engineers to depict how facilities like bridges, roadways, sidewalks, and buildings will look after they are completed. The DV images can be displayed on computer screens or in large, high-resolution color photographs. To do this, the engineers match a photograph of the construction location with a three-dimensional (3-D) computer-generated model of the proposed design. What emerges is a composite view of the proposed highway facility superimposed on the photograph of the construction location. In addition to still pictures, 3-D animation software makes DV video simulations possible as well.
DV can be used for any aspect of roadway design, including construction of new bridges and roadways and modification of those facilities. Although the processes used in DV have been available for some time, the technology has become more feasible only in recent years— thanks to rapid advances and falling costs in computer technology. Before the requisite technology was available, the only way to produce visualizations was for an artist to draw them by hand. Today, with high-end graphics workstations and software available at reasonable costs, such manual work is no longer required. And computer technology allows for much greater precision compared with hand-drawn simulations.
Connecting with the Layman
DV technology not only helps engineers during their planning process, but also it serves as an effective way to communicate clearly design implications to non-engineers. Thanks to this technology, highway engineers now are able to take their composite drawings to public meetings and present them to non-engineers with ease.
Engineers can show different alternatives for various types of bridges, alignments, and other possibilities and provide decision-makers with a better understanding of what the completed facility will look like before they actually make a decision. This technology provides decision-makers with better information to base their decisions on.
The layperson, even when shown sophisticated 2-D engineering drawings, often has difficulty conceptualizing what the constructed facility would look like. Making decisions without fully grasping the design implications often causes problems down the line. After construction work has started, making changes is either impossible or very expensive.
Dan VanGilder of FHWA's EFLHD Technical Services Branchwitnessed an excellent example of the impact of DV technology on decision-making during a road project at Manassas Battlefield National Park in Manassas, VA. The project involved lowering the grade of a section of a roadway with poor sight distance. Early in the development of the project, the engineers explained to the local residents that the present road was hazardous because motorists driving down the hill could not see traffic stopped at the intersection.
Before VanGilder's DV presentation, citizens in the area were not convinced that the project was necessary. But then he showed a video simulation of a vehicle driving down the hill as it currently was configured, demonstrating that motorists could not see vehicles at the intersection. After that, he showed a DV simulation with the grade lowered, which demonstrated that this improvement would enable the driver to see the intersection clearly. After the presentation, the viewers said that they appreciated the safety concerns and acknowledged that the project would benefit the local population. The DV demonstration thus became a crucial factor in obtaining approval for the project, which has since been completed successfully.
Getting the Best Solutions
Another impact of DV is that decision-makers feel more comfortable allotting the extra project funds needed for the more visually pleasing designs, having seen the alternatives in life-like 3-D images. The DV presentations also can be posted on the client organization's Web site, enabling a broad audience to view them.
The technology helps in pre-assessing the environmental impacts of new structures. A section of a proposed mountain road, for example, may either be supported by a bridge or by lower-cost earthworks encased by a retaining wall on either side. Both alternatives can be demonstrated with a PowerPoint® presentation, showing the different options, environmental impacts, and cost associated with each option.
Similarly, DV can be used for viewing the anticipated progress of the re-vegetation of a construction area. Users can take existing trees and generate a computer image of their progression to see what they will look like in 5 or 10 years.
The DV technology helps in evaluating the impact of roadway widening projects. For one such project, the client wanted to see the impact the widening would have on a historic stone house in Manassas Battlefield Park. I examined a design that included shoulders and one with curbs. After viewing the impacts of both designs, it was decided the best option was to widen the road using the curbs.
A variety of techniques are used in DV, including simple computer painting programs, photomontage, video overlay, and 3-D animation. A computer paint program enables the user to copy an image from a photograph of a completed design onto an existing photo in order to create an image of a new proposed design. Photomontage enables the user to place a view of a 3-D computer model, rendered with photo-realistic materials, into an existing photograph precisely at the proper location and viewing angles, again creating an image of the proposed design. Producing dramatic before-and-after photos is as simple as displaying the existing photo and the DV photo.
Video overlay merely extends the photomontage concept by placing a view of a video image into an existing photograph. The result is a view of the design with live action movement, which adds a heightened sense of realism.
Finally, 3-D animation, also sometimes called "drive-through" or "fly-through," is a powerful and flexible method for viewing a design project in virtual reality. Computer software is used to place "cameras" or views into the 3-D computer model. The camera views can be static or allowed to move through the model. The software also allows for the inclusion of other animated objects in the computer model, such as automobiles, trains, and pedestrians. The 3-D model uses photo-realistic materials, lighting effects, shadows, and reflection. The camera views are scripted so that the resulting images simulate a video taken from within the 3-D model. Music can be added. The final animation is a truly dramatic presentation of a project design.
Hardware and Software Requirements
Still photograph DV can be carried out using any modern desktop computer, but video animation typically calls for more specialized high-end workstations. The data for each picture frame need to be "crunched" at high-speeds, such as 30 frames per second. A few years ago, we had to let the computers process the information overnight to produce an animated simulation. Now, thanks to the tremendous increases in computing power, what used to take 12 hours takes only an hour.
My own hardware consists of a Silicon Graphics visual workstation equipped with duel Pentium III 550 megahertz Xeon processors, 1 gigabyte of RAM, and two 18 GB hard drives. Also required are a tape drive (for data backup), a professional desktop editor videocassette recorder, a color video monitor, a CD duplicator, and a large-format color plotter.
Typical software required is a suite of multimedia software like Photoshop,® Premiere,® PageMaker,® and Illustrator® software from Adobe® Systems. Also required are roadway design software products like GEOPAK,® and Computer-Aided Design and Drafting (CADD) such as MicroStation.® For landscaping, to create different images of trees, for example, I use Onyx Tree. TM To create animated images of people and objects (e.g., trucks, signs), a software like ModelVisionTM is useful. For making the final presentation to clients, software such as Microsoft PowerPoint,® Corel® Presentations,TM or Adobe Premiere® can be used.
I regularly execute DV projects for the National Park Service, Forest Service, the U.S. Department of Transportation, and other clients. I also have done work for local jurisdiction bodies like the Washington, DC, city government and local county governments, and also the Virginia Department of Transportation.
Recently FHWA's Eastern Federal Lands Highway Division carried out a simulation for several congressmen, involving a proposed tunnel for a section of E Street, which runs along the White House's south side. The congressmen wanted to know the potential aesthetic impact of the tunnel (desired for security reasons) on the surrounding architecture, including the White House. I prepared a photomontage visualization, presenting the congressmen with alternative views of the proposed structure.
Such is one of the many examples of the DV's uses. The technology is fast becoming an indispensable tool for highway construction organizations, benefiting not only engineers but also non-technical officials and the public. The technology is proving how the old adage that a picture is worth a thousand words is still very true.
Richard McDaniel is CADD/Design Visualization Coordinator for the Technical Services Branch of FHWA's Eastern Federal Lands Highway Division (EFLHD). During 13 years at EFLHD, he has received more than 30 FHWA Special Act Awards for graphics and design visualization work. Examples include:
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