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Automated bridge design: Washington DOT implements a fully-functional graphics management system.

Mr. Stoddard is a structural engineer in charge of computer applications for the Washington DOT's Bridge and Structures Office. Mr. Rudeen is a transportation engineer, responsible for customizing the graphics management system within the DOT.

With more than 3000 bridges spanning mountains, rivers, and lakes and more than its share of challenging natural events--avalanches, earthquakes, volcanos, flooding, and hurricane force winds, the Washington Department of Transportation's (DOT) Bridge and Structures Office stays busy designing and maintaining its extensive statewide bridge system. To help ensure that bridges meet safety and functional requirements--and that bridges withstand a variety of forces threatening their stability--the DOT implemented computer assisted drafting and analysis systems that are increasing the productivity and effectiveness of designers and drafters. Figures indicate that productivity has more than doubled in some aspects of design, primarily through the implementation of workstations and systems that have allowed designers unlimited access to powerful tools necessary for the production of contract bridge designs.

Overall, the office's new systems have brought consistency, convenience, and flexibility to the bridge and structures office it did not previously enjoy. In the past, isolated, piecemeal computerized systems had been put in place, including an older, more traditional computer aided design and drafting (CADD) package. The new systems have streamlined the office's automated design and drafting capabilities by creating libraries of "objects" that meet state design standards and offering the additional ability to complete the complex calculations required for effective bridge design. Numerous specialized menus -- including a menu-driven user interface designed specifically for the occasional, ad hoc user--allow design/drafting professionals to lay out geometrics, reinforcements, and coordinate geometry (COGO) dimensions as well as do property and section calculations. To date, the system has been used to design a variety of bridge types: reinforced box girder, reinforced T-beam, post tension box girder, cable stayed, curved steel plate girders, and concrete segmental bridges as well as concrete floating bridges that are frequently impacted by torrential rains and flooding.

Project History

Since 1983, the bridge and structures office has had a CADD package in place; however, since the office sought to migrate to an automated system that would offer far greater capabilities--including use by virtually all departmental personnel--the office began exploring new solutions. The previous CADD system created severe bottlenecks and resulted in long turnaround times among drafters. For years, the office was dependent upon a few drafters and technicians to provide plotted drawings. Often, personnel could not obtain their own plots. Consequently, we determined that the proposed system needed to be both easy-to-use from a design/drafting perspective as well as be accessible to all employees responsible for structural design and drafting.

In 1989, the office issued a Request for Proposal for CADD, structural modeling, and office automation packages that could take advantage of the Windows environment. The specifications required that these systems support designers and drafters as well as various other personnel. That summer, the office initiated a comprehensive evaluation program on various CADD systems that offered superior, state-of-the-art drafting and structural modeling capabilities on powerful workstations.

In August 1989, the office selected EDS, (Maryland Heights, Missouri) Graphic Data System (GDS), a feature-based soft ware package that creates and manages objects as they exist in the real world. Users can now extract information from the computer based on how they logically think. They are then able to deal with real-world objects and the relationships of these objects. The system provides DOT personnel the drafting capabilities required to streamline the bridge design process plus the capacity to perform detailed geographic information system (GIS) mapping, analysis, and modeling. Through the combination of computer-aided drafting, computer-aided engineering and GIS analysis functionality, the DOT now has three systems in one. This offers the opportunity to save money and eliminate the need to learn multiple packages since integrated, common data elements are shared by the three different applications. The new system provides access to and manages everything from one-line sketches through complete drawings. As a result, we have reduced duplicated efforts since small, isolated databases are all tied into GDS, offering any number of users the ability to use the same information base. Today, the functionality GDS provides has become the single most important component to the bridge and structures office of the Washington DOT.

For example, the year-long pilot project to test the new system's capabilities provided an interesting scenario. The Loma Prieta earthquake shook California and damaged or collapsed parts of California's viaduct system. Because Seattle's Alaskan Way Viaduct is similar in age and appearance, the new systems analyzed and reported on the seismic vulnerability of the double deck viaduct, giving the bridge and structures office analytical capabilities that most other computer aided design and drafting (CADD) systems can,t deliver. Since then, the combined flexibility to draft and design bridges, while conducting complex geometric calculations, has proven time and again to be of significant benefit. This cohesion is helping designers support other projects. No longer do notes and scratch pads accompany drawings. Today, drafters receive accurate scale drawings to more effectively coordinate work loads and to ensure an integrated product.

Establishing the System

Initially, purchasing was staggered over four-month cycles to accommodate training and funding requirements. Today, the bridge and structures office has implemented 34 Digital Equipment Corp. (DEC) workstations running DEC Windows: 11 for drafters, 20 for designers, and 3 for management. Additionally, several PCs using DEC Pathworks local area network are also used that take complete advantage of the system's capabilities.

While GDS is a powerful program directly from the box, the office has added many custom features to its system. For example, special project directories have been created that incorporate bridge standards. Users can move files, objects, or drawings between directories This allows designers and drafters to copy whole sheets or details using a "union" command that copies existing information into new files that can be tailored as required for a new bridge design. Greek characters are also easily established within the system, giving users the ability to choose a given symbol with the touch of a button. Standardized, easy-to-use menus let users pick individual design elements--line styles, objects, etc. Additionally, the ability to create any imaginable line style is a powerful feature to the system.

A special interface was created that does not require an extensive memorization of commands. Using this menu, casual, occasional users can select the appropriate function and begin work in any application area. In addition, an automatic redlining capability also saves time by eliminating the manual checks necessary to ensure that design specifications meet state requirements.

Among the most important benefits of the system has been its ability to complete complex geometry calculations and dimension checks directly within the program. This has allowed bridge technical advisers, who have responsibility for resolving construction site problems, to use the system to resolve dimension and geometry problems that arise on the site. COGO techniques, bearings, distances, and offsets can all be depicted and analyzed visually, giving users a unique representation of a design, from one integrated package.

Some Unique Applications

Secured Stamp and Signature. One unique Washington DOT application is an automated process for electronic stamping and signature of designs. This application has created a completely secure environment that will continue to be tested in hopes of guaranteeing that this electronic stamping and selection process is completely authentic and meets state requirements.

Design and Rating System. The bridge and structures office has set up an in-house designed bridge design and rating system. The system simply runs a truck icon across a bridge to find out load resistance factors by measuring capacities. Written in C using DEC's Windows (although it can operate on multiple platforms), this system can be integrated with the GDS/GIS package, providing users with the ability to fully access this system from within GDS. With the office's goal to quickly rate each statewide bridge, this integration could help to complete the often manually tedious job of approving routes for special overload permits.

CEAL. Field data is currently collected using CLM Corporation's (Tampa, Florida) CEAL program, an automated system that provides digital terrain modeling capabilities and engineering analysis required for effective roadway design. Users input terrain conditions and from there develop road design templates. Currently CEAL data are translated into the field office's CADD system and then transferred to GDS; however, the bridge and structures office plans to use an EDS interface package to provide a direct one-to-one relationship between CEAL classification codes and GDS objects. Ultimately, this interface will eliminate the added step of translating CEAL data into the field office's CADD package, then to the bridge and structures office's GDS.

AUTOCAD. Because many outside consultants utilize AutoDesk's (Sausalito, California) AutoCAD, the ability to translate between the two systems became very important. With GDS, these translations were easy. This capability helps the office more effectively manage the efforts of designer and drafters contracted by the office and allows internal staff to adapt to any modifications to these designs.

3-D Modeling. The system can also provide complete architectural renderings and 3-D solid modeling. This easy-to-use application establishes a visual, graphical picture of a bridge site so users can inifiate alternatives during the design phase of the structure.

A Look to the Future

The ability of this automated system to expand into a fully functional GIS that would develop a statewide graphical representation of the entire roadway and bridge system will be investigated. This would let the office maintain a visual model of the entire road and bridge network. Personnel could effectively inventory and maintain detailed data above and beyond the designs currently held in the system. Further, the office envisions a link between the current system and a future imaging system as well as links between GDS and the statewide inventory of bridge structures (SWIBS) to provide for easier information sharing.

These systems have provided significant benefits, primarily in achieving higher productivity with more than double the work of a few years ago, reducing the costs associated with the DOT's previous systems, and allowing the office to respond to change more quickly. These benefits are putting the bridge and structures office in a strong position to handle bridge design and drafting needs well into the future.
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Title Annotation:Department of Transportation
Author:Stoddard, Dick; Rudeen, Jeff
Publication:Public Works
Date:Jun 1, 1993
Words:1700
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