Civil engineer’s perspective
Rose: Don’t we wish that everyone thought like an engineer? Well, actually, no we don’t. If we all thought the same, we would never see the flaws in our own thinking—that’s why working as a team has so many benefits. That said, it does help if each profession understands a little bit about what the other is trying to achieve.
On a recent project, our surveyors located a series of manholes on an existing sewer line. This data was then entered into our GIS layer of the sanitary sewer system to provide some planning data. We needed to determine if the existing gravity sewer system was deep enough to serve a proposed development, and we needed to model the system to see if we had sufficient capacity to accept the additional flow.
The data we got back from the GIS department showed manhole locations, manhole identifying numbers, and the depth to the invert of each pipe as the field survey crew had measured it, but no rim or invert elevation. We met with our GIS professionals and explained what information we needed, why it was important to us, and what we were going to do with it. This helped a great deal. Once they understood exactly what we needed, they knew what information to look for in the survey data and how to provide it to us. And once we understood how they were getting the information from the survey crew, we were able to work out a solution. The information existed; it just was not where the engineers could easily see it.
So what do engineers wish GIS professionals understood? The easy answer is, we wish they knew everything we were thinking without us having to communicate our thoughts. But since that’s not realistic, a better idea is to sit down together and talk about exactly what we need, which allows us all to get the data we need, first time, every time. This would make our jobs easier and allow us to be more responsive to our clients’ needs. And that’s what we all want.
Jackson: If engineers understood the basic differences between GIS and CAD, they would not expect a GIS professional to create a "drawing" in GIS and "make it look and feel like CAD."
CAD is a drafting/drawing computer tool, and GIS is a mapping, analysis, database computer package used by geospatial professionals. In their basic form, CAD and GIS may look alike to some folks, but they behave very differently and require a completely different set of skills to produce high-quality results. CAD requires the technician to work in a "what you see is what you get" (WYSIWYG) environment. GIS’s real power comes from behind the drawing or map, because the database is the driving force for what you see on the screen. These are two totally different approaches to getting the job done. And if you don’t know how each is set up, you won’t know which one to use for which job.
A good example of not using the right tool for the right job is when GIS professionals are asked to "label the features—just like CAD—and then give me the data." To a GIS professional, labeling and label positions are considered graphical components and that type of task is more efficiently done in CAD. Also, when people ask for "the data," I never know exactly what they mean. Does that mean they want an Excel file? Or does it mean they want a map of what the data is showing? Using CAD terminology to explain GIS requests—or thinking that CAD and GIS are virtually the same—is a common challenge that GIS professionals wish engineers understood.
So how do you decide which is the most effective tool to get the job done? Include the GIS professional from the beginning of the project. That way, you can decide, together, which tool—CAD or GIS—is the most productive and offers the best results for you, your project, and your client.
Gordon Rose, P.E., senior project manager at McKim & Creed, has 30 years experience in water distribution, wastewater collection and treatment, stormwater management, and planning. Janet Jackson, GISP, heads McKim & Creed’s GIS activities company-wide. Contact Rose and Jackson at firstname.lastname@example.org. McKim & Creed is an engineering, surveying, and planning firm.