Blurring the CAD/GIS lines in preliminary design

Much has been written about the collection, housing, and use of Geographic Information Systems (GIS). Traditionally, these systems have been used by municipalities and state and federal government agencies as a means to manage built assets. More recently, these same agencies have begun making this data available to the general public for other uses through web portals. A new workflow can reduce the number of iterations and data transfers between engineering design software and GIS in the preliminary design phase of civil engineering projects.

Integrate GIS data directly into the CAD design process

Product application
LandSketch for Highways allows engineers to coordinate with GIS data to improve the efficiency of the route-creation and selection process.

GIS in planning
In many organizations, large or small, planning and environmental professionals use GIS to analyze project alternatives for environmental impacts, feasibility, and cost effectiveness.

Enacted in 1970, the National Environmental Policy Act (NEPA) requires federal agencies to compile an Environmental Assessment as part of any construction project in order to determine the need for an Environment Impact Statement (EIS), also referred to as an Environmental Impact Study or Report. The purpose of this process is not to prohibit or restrict the government from harming the environment, but rather to ensure that the deciding body is fully informed of the environmental aspects and consequences prior to making a decision on the project. Prior to its passage, this type of evaluation was normally overlooked and took a backseat to the financial evaluation and technical factors. Since then, many states have also adopted their own versions of this policy and require some form of environmental report to ensure informed decision making.

The list of environmental considerations is lengthy, and most of the items often must be taken into account. Examples of items considered include land use, schools, churches, recreation facilities, right-of-ways, historical and archeological sites, endangered species, wetlands, streams, rivers, floodplains, woodlands, farmlands, energy, and utilities.

To arrive at a preferred project alternative, it is often necessary to create many alternatives and iterate the designs multiple times. This usually involves coordinating with other professionals (within the same firm or with outside consultants) who possess the skills and technology to arrive at preliminary designs. The disconnect between planners who have the GIS analysis tool (and no design tools) and the engineer who has the sophisticated design tools (but not the GIS tools) creates an inefficient workflow. Passing the data between systems is prone to errors and flat out takes too much time.

One company’s GIS use
Bernardin, Lochmuller & Associates, Inc.’s (BLA) need and use of GIS in preliminary design highlights the importance of a well-defined and up-to-date GIS workflow. Founded as a transportation planning firm in 1980, BLA has evolved into a full-service survey, planning, engineering, and environmental firm serving clients throughout the United States and abroad.

Transportation projects commonly require submission of an EIS because of the impact on the human environment. And as part of the NEPA process, multiple alternatives for the project (complete with all pertinent environmental information) must be considered and made available to public officials and citizens for input before any actions are taken.

Unfortunately, most engineering/planning firms have not fully realized the potential that lies in using this environmental GIS data because of disparate systems and traditional “silos” of information.

Brian Litherland, P.E., chief of highway design at BLA, provides the following insight into the preliminary development of a highway corridor: “The current workflow must involve close coordination of the highway engineering department and the environmental services department to ensure the most cost-effective and least impactful design. The old process began with the engineers laying out an alignment and providing the alignment data to the environmental department for a field review. After the field review, comments were received back from the environmental department regarding what impacts were found. Then, revisions would be made to the alignment to avoid or minimize impacts and the field review and comment process would start over again.”

In this traditional workflow, there are several bottlenecks. During the initial alignment layout, the designer could benefit from knowing as much environmental data as possible before the first iteration is ever given to the environmental group. Second, the back and forth iterations between the groups are fraught with data conversions between disparate systems. Third, the inefficient field reconnaissance slows the alternative evaluation process significantly. Last, the planners, designers, and public cannot easily collaborate on selecting the preferred alternative. Rather than working as a team, they work independently, which causes lengthy delays and potentially expensive errors.

Importance of GIS in engineering applications
“Some of the bottlenecks in the preliminary route-selection process have been removed with the advent of digital aerial mapping. And the GIS system has allowed the potential impacts to be known up front before the engineering begins, saving an initial trip or two to the field,” said Litherland. But, while some things have improved with technology, not everything has been addressed.

Litherland added, “There has not been a real efficient method that allows the engineers to layout their alignments, construction limits, and right-of-way and to get quick feedback as to the impacts that particular alternative has on the environment. The process still involves exchanging data back and forth between the environmental department’s GIS system and the engineer’s CAD system. The result is still the same, a disconnect between the actual engineering data and the environmental GIS data that requires an iterative process to determine if the impacts were avoided or how much they were lessened.”

Litherland envisions changing that disconnect using a new software application from Eagle Point Software Corporation. LandSketch for Highways improves the efficiency of the route-creation and selection process with specific tools to quantify environmental impacts, area takes, and rough earthwork.

“LandSketch for Highways offers the first real opportunity to unite the engineering task with the environmental assessment/documentation tasks,” Litherland said. “LandSketch allows the engineer to coordinate with the environmental group’s GIS data at the beginning, before the alignment is developed. Critical hot spots are identified within the graphic environment in which the engineered alignments are being generated, so that those areas can be avoided from the beginning.”

Figure 1: GIS data overlaid with aerial imagery.

Figure 1 shows the convergence of aerial imagery with GIS information superimposed. Property boundaries, land use, and wetland delineations are part of the data that is critical to consider in the environmental assessment.

Figure 2: Planners and engineers visualize critical areas involved in each route alternative.

Figure 2 illustrates how the planner or engineer benefits from being able to visualize this information while laying out route alternatives. And with the connection to the GIS data, environmental impacts can be quantified and reported on without leaving the system (see Figure 3).

Figure 3: Impacts are clearly indicated for each route alternative.

Litherland points out that the real efficiency gains are through the utilization of this data and the advances in technologies that can take advantage of it during this very collaborative process. “The speed at which LandSketch is able to generate the construction limits, right-of-way, and subsequently the impacts on the environmental features of an alternative, will allow our engineers to instantly know how the alternative performs compared to other alternatives,” he said.

New technologies are blurring the CAD/GIS line for engineers and planners. Tools that are available for the preliminary design and planning phase, such as LandSketch, link not only traditional basemap drawings, but also information-rich GIS data. This connection is allowing for quicker, more-informed decision making during the initial corridor layout and all the way through final alternative selection.

Obviously, finding problems with a design late in the design process is much more costly than finding them early. Planning and design departments collaborating early and in the same software package allows for the early discovery of problems, leading to more cost-effective designs faster.

Steve Biver is civil product line manager, Eagle Point Software Corporation.

Posted in Uncategorized | January 29th, 2014 by

The comments are closed.