Keeping the civil data chain intact: object-based 3D civil software matures

CADalyst, June, 2004 by Andrew G. Roe

When PC applications first became accessible to civil engineers and surveyors in the early 1980s, many began to seek field-to-finish solutions. Firms sought ways to collect field survey data digitally, send data to designers for use in an office setting, and then reverse the process to send design data back to the field for staking and construction.

In reality, the process has been far from seamless. Even with improved communication between field data collectors and design software, a certain amount of manual data entry or data manipulation remains necessary before designers can use the data with CAD software. Additional data entry is often required to transform conceptual designs into usable construction plans, and then to convey design information to the field.

The process is still not perfect, but the industry is closing the gap on maintaining a continuous data chain. More intelligent design software is helping the cause, as are handheld applications that provide field access to data once limited to desktop computers.

Object-based Software

Designers are often caught in the middle of the datastream, tweaking field and office data before, during, and after design. The domino effect--when a single design change affects several portions of a project--is particularly bothersome, requiring manual editing of lines, text, and other CAD entities.

Object-based software, such as Civil 3D from Autodesk (www.autodesk.com), helps automate this process, says James Wedding, information technology manager at Jones & Boyd, a Dallas engineering, surveying, and planning firm. With key components of land development projects represented as intelligent objects, instead of generic entities such as lines, arcs, and text, design changes are not as painful. A parcel of land, for example, is a cohesive object, with geometric characteristics and labels associated with it (figure 1). When a designer moves a lot corner, the other components of the parcel move accordingly, and the labels update automatically.

[FIGURE 1 OMITTED]

Dynamic updating has greatly aided the development of what-if scenarios for designing land development projects, says Wedding. "The parts know they belong to each other," he says, noting that adjustments that previously took 10-15 minutes are now done instantaneously.

Civil 3D also includes objects for points, alignments, profiles, sections, and surfaces. Its grading groups provide a collection of related grading objects, allowing designers to model building footprints and easily generate proposed grading contours and section views (figure 2). If the building footprint changes, proposed contours, earthwork volumes, and other data dynamically update to reflect the change.

[FIGURE 2 OMITTED]

Autodesk launched Civil 3D in late 2003 as an introductory product for Autodesk Civil Design subscribers. Many features, such as the grading object, are still being refined, and Autodesk doesn't plan for it to replace the Land Desktop and Civil Design products any time soon. For now, Civil 3D will primarily be used in conjunction with Land Desktop, says Dave Simeone, Civil 3D product manager. Autodesk's development plans are still evolving, but sometime in the future, Civil 3D could encompass Land Desktop and Civil Design as a stand-alone product. The timing depends largely on how quickly the industry embraces the object-based approach. "It's a significant shift in the way our customer base has worked," says Simeone. "The market will tell us what the time-frame is."

Field Ready

As design software has matured, so have capabilities for exchanging data with field personnel. FDOT (Florida Department of Transportation), a primary user of MicroStation and GEOPAK from Bentley Systems (www.bentley. com), has worked with Bentley for several years on streamlining processes for generating quantities such as concrete, asphalt, signage, and landscaping items to include in construction contracts. The public agency helped shape development of Bentley's Quantity Manager, a stand-alone tool that manages quantities generated by the Design and Computation Manager feature of GEOPAK.

Using Quantity Manager, FDOT eliminates most paper-based processes for documenting quantities (figure 3). The agency uses the GEOPAK Design and Computation Manager to calculate quantities based on design data and then exports them to Quantity Manager. Users can also load manually generated quantities for nongraphical elements into Quantity Manager.

[FIGURE 3 OMITTED]

FDOT and other users have also used Quantity Manager to exchange data with Trans*port, a software suite developed by the American Association of State Highway and Transportation Officials (www.aashtoware.org) to manage transportation projects. Users can import standard pay items from Trns*port for use in Quantity Manager, as well as the federal and state funding splits for pay item quantities on individual projects. Bentley introduced Quantity Manager for GEOPAK last year, and this year plans to release a version to complement InRoads, Bentley's civil engineering suite that works with MicroStation and AutoCAD.