The BIM That Binds

The collaborative power of information-driven modeling software.

By Aidan Ackerman, ASLA 

3-D view example. The power of BIM in coordinating design and construction information is most evident when developing multiple views and annotations from a single model. Image by Sasaki.

It’s a familiar scene in landscape architecture offices of all sizes: Around a conference table, a debate arises about the benefits and drawbacks of adopting a Building Information Modeling (BIM) work flow. The advantages of BIM adoption are rarely as obvious as the drawbacks. The popular architecture-centric Autodesk Revit software lacks functional landscape modeling tools, though it has a library of building objects such as floors, windows, doors, and roofs. Vectorworks, a more landscape-focused BIM software, does not exchange files directly with Revit, an obstacle that impedes digital collaboration with architects. Regardless of the software being used, the up-front costs of adopting BIM, such as software and training expenses, can quickly eat up profits. Yet despite these challenges, landscape architects are beginning to include BIM in their digital toolboxes. A recent survey by the American Society of Landscape Architects’ Digital Technology Professional Practice Network, with Benjamin George, ASLA, of Utah State University and Peter Summerlin, ASLA, of Mississippi State University, found that 21.8 percent of the 480 ASLA members who responded said their firm currently uses Revit, and 30.6 percent were interested in adopting a BIM work flow. Of those currently using Revit, 12.39 percent use the software daily, and 11.06 percent said it is extremely important to their work flow.

The “B” in BIM stands not for an architectural building but for the process of building something, an acronym that hints at BIM’s strengths in capturing the construction feasibility of a design project. BIM models contain information such as material assemblies, structural details, and quantities, all coordinated in a single file that can also be used to generate plans, sections, perspectives, and detail drawings. BIM is a popular and established work flow for architects: In a 2018 survey of more than 2,000 architecture firms, the American Institute of Architects found that 45 percent of architecture firms use BIM for billable projects, an increase from 40 percent in 2015. The largest area of growth in BIM adoption is among firms with fewer than 10 employees, which increased to 34 percent in 2017 from 28 percent in 2015. The report also shows that 71 percent of architecture project revenue comes from BIM projects, with no major differences across firm sizes or areas of specialization. With greater numbers of architects adopting BIM, landscape architects have begun to forge their own path toward this complex technology.

The main draw of using BIM for landscape architects lies not in its modeling prowess, but rather in the ways it enables communication among designers. Landscape architects who work with architects typically encounter frustration when it comes time to share files, largely owing to the lack of file coordination between the architect’s BIM models and the landscape architect’s AutoCAD drawings. This lack of coordination means that the architecture and landscape architecture designs occur in separate parallel work flows. To exchange files, architects will convert their three-dimensional BIM model to a two-dimensional CAD plan, reducing a complex building model to a simple drawing that lacks important information. The landscape architect, in turn, will supply a two-dimensional CAD drawing to the architect, who will insert the drawing into the three-dimensional BIM model. This process is repetitive and time consuming, but it also results in designs that are continually out of sync with each other, requiring seemingly endless revisions just to keep the building and the landscape aligned.

Section example. Image by Sasaki.
Enlargement plan example. Image by Sasaki.

I have spent the past year interviewing several dozen leading landscape architects in the United States and Europe about this issue, attempting to understand why BIM is gaining traction in the profession. In the conversations I’ve had with landscape architects, Revit is mentioned most frequently as the BIM tool of choice, especially for projects that involve collaborating with architects. The benefits of Revit are significant, with a single modeling and documentation environment that offers the ability to share work between team members easily. However, resources for landscape architects who want to learn Revit are scarce. One website has become the go-to resource for many of the landscape architects I interviewed: landarchBIM, a site dedicated to documenting and sharing methods of using Revit for landscape architecture. The site was created by Lauren Schmidt, an associate at GGN in Seattle, who wanted to share her BIM knowledge with other landscape architects. “I see BIM as the future of the AEC industry,” Schmidt says. “I was frustrated by the lack of resources out there for helping landscape architects learn Revit, and so I’m doing as much as I can to help move that forward with my website.” In her own design work at GGN, Schmidt has seen firsthand the benefits of using BIM in collaboration with architects. “You’re sharing your design process with the architect,” she says. “You can see much more quickly when things change in the design compared to simply receiving an exported two-dimensional file, which is where a lot of information gets lost.”

Ease of information sharing doesn’t always translate to an even playing field between designers. On many projects, changes to architecture still have a certain primacy. “From a collaboration standpoint, the basic elements of communication are still the same using Revit as they were using AutoCAD,” Schmidt says. “The landscape changes are still chasing the building’s changes. But overall, design changes do happen in a more centralized way, and design iteration is much more rapid than without BIM.” Although progress is slow, it does seem as though the use of BIM is changing the ways architects approach collaboration with landscape architects. “Architects have gotten much more used to seeing the landscape as a part of their design process,” Schmidt says. “Once they are used to landscape architects’ using Revit, they really start to rely on us being part of the BIM work flow.” Despite Revit’s usefulness, Schmidt finds that she still needs to use other software for parts of the design process. “There have been plenty of times when I’ve needed to pull something out of Revit to study in AutoCAD, or in hand drawing,” she says. “You can never truly leave AutoCAD behind.”

Problem: Using a modified floor feature to model sloped hardscape in Revit results in triangulated hardscape with a distorted paving pattern. Image by Sasaki.
Resolution: Drawing a custom paving pattern in CAD and linking it to Revit enables the paving pattern to read correctly in plan view. Image by Sasaki.

How should landscape architects start learning to use BIM? “Revit is a challenging software with a lot of layers and hidden features,” Schmidt says. “You can’t just go in and start working—it’s not the most intuitive software.” She suggests that landscape architects can strengthen their BIM skills by learning coding and programming. “Revit was created by a handful of architects who wanted better software,” she says. “If landscape architects want better BIM tools, we need to take matters into [our] own hands. No one else is going to do it for us—our profession is too small.”

BIM’s collaborative nature often requires landscape architects to address details and construction issues in the early stages of project development. Phyllis Zhou, ASLA, a landscape architect at AECOM in Chelmsford, Massachusetts, finds that BIM tools immediately present her with all of the information about a particular design feature. This can be a benefit or a drawback, depending on the design phase. “With Revit, you cannot hide information. If a detail is there, it’s there—you can’t pretend you didn’t see it,” Zhou says. She acknowledges that AutoCAD remains an important tool for landscape architects, and says she embraces AutoCAD as a piece of the BIM process instead of rejecting it in favor of an entirely Revit-based work flow. “Even if the entire project is not modeled in BIM, we still benefit from using it even just as a study tool,” Zhou says. “Revit gives a really good sense of scale, as well as offering a great rendering base.” She often finds herself working in AutoCAD daily, while also exchanging Revit files with architects weekly. To accomplish this work flow, she relies on some techniques for converting files between programs without losing information. To link or import an AutoCAD file into Revit, she will make use of shared coordinates, using them to remember the positions of the various files being used in a project. This enables the AutoCAD file to be used as a base to build three-dimensional geometry in Revit. For projects that involve significant grading, she uses Autodesk Civil 3D’s ability to turn two-dimensional AutoCAD linework into an accurate three-dimensional topographic surface. Once she has created the three-dimensional topography in Civil 3D, she will use the Site Designer for Revit extension to import it into her Revit model.

The Revit model for Smale Riverfront Park Vine Street Plaza in Cincinnati embodies the complexity of the coordination required among landscape architects, architects, structural engineers, MEPs, and fountain designers. Image by Sasaki.

Revit expertise has allowed Zhou to gain insight into the opportunities that present themselves when landscape architects use BIM. “Every time we exchange files with architects, we have the opportunity to engage in a conversation about the design changes that have occurred,” Zhou says. “When we use Revit, we no longer need to ask the architect repeatedly for exports from their model. This has the effect of the architect being more willing to talk about their building changes and the way [the building] interfaces with the landscape, rather than feeling like their only interaction is responding to requests for floor plans.” These positive interactions are further improved by the use of BIM 360, Autodesk’s cloud-based coordination solution that automatically updates in real time. “BIM 360 will notate and highlight the changes between drawing sets,” Zhou notes. “This helps us keep track of design changes as they occur, instead of one or two weeks later when you exchange drawings with the architect.” Zhou has also found that using Revit enables rapid decision making during the construction project. “Often during construction, a lot of effort is spent just trying to understand what the problem is,” she says. “With Revit, all of the designers and clients are collaborating together in Revit, and it becomes very easy for everyone to understand why a certain decision needs to be made.”

The BIM work flow can require adherence to absolute technical accuracy, even during preliminary design work. “With Revit, we are accountable for every line we draw, because every line represents an actual object with real information attached,” says Chris Golden, a landscape designer and an associate at CRJA-IBI Group, a landscape architecture design and environmental planning practice in Boston, who uses Revit frequently for landscape architecture projects. The result of this accountability, Golden says, is that his team is able to provide architects with its exact design intentions. “Using Revit leads to better informed decision making, allowing the entire team to get to a higher level of design understanding much more quickly,” Golden says. “I’d like to believe that we achieve a better collaborative product in the end.” He acknowledges that Revit has major limitations when used for landscape design.

A section perspective of the West End North Towers garden garage project in Boston. The project’s infrastructural complexity necessitated the use of Revit for landscape design. Image by CRJA-IBI Group.

“Terrain modeling has been a challenge, and we end up using some other programs to do some of our grading. It’s just not something Revit does that well,” Golden says. A recent BIM project at CRJA-IBI Group, the West End North Towers in Boston, involved the redevelopment of an existing garden garage to a 44-story residential apartment tower and adjacent landscape. “With the garden garage project, we initially built a Revit model to prove the grading in theory, but to do a true grading plan we exported the Revit file to CAD, imported it in Autodesk Civil 3D, and manipulated the contours.

“We verified all of our slopes and pitches in Civil 3D, because what we were doing with grading in Revit wasn’t really working.” This lack of landscape modeling functionality can require time-consuming work-arounds. “Sometimes we have to model a simple shape representing a more complex element, then cut a section through it and fill in information by hand,” he says. “Revit doesn’t do well with elements that landscape architects model all the time, such as walls that don’t have a consistent top-of-wall elevation, or that don’t end in a perfect 90-degree angle.”

However, these limitations haven’t stopped the landscape architects at CRJA-IBI Group from achieving their design goals with Revit. “There hasn’t been anything that we have shied away from yet,” Golden says. The benefits of Revit in construction documentation have become especially clear when working on a project that uses AutoCAD. “It really saves us time to work in Revit,” he says. “In AutoCAD, if a wall shifts six inches, we have to mark that on four different plans, then update several different plan sheets.” The need to repeatedly mark each change manually in AutoCAD stands in stark contrast to the single-touch efficiency of Revit. “In Revit, our labeling updates with each schedule change. And during construction administration, Revit marks the changes that have occurred to a sheet, and also updates the calendar date and revision cloud for us.” This can mean that small changes that would take several hours to update and convey in AutoCAD can take just a few minutes in Revit. “We have the ability to track our changes and update our labels almost automatically,” Golden says. “The confidence Revit gives us is invaluable.”

Aidan Ackerman, ASLA, is an assistant professor of landscape architecture at the State University of New York College of Environmental Science and Forestry.

CORRECTIONS: The print version of this article omitted the names of three collaborators on a recent software utilization survey conducted with Benjamin George, ASLA, and Peter Summerlin, ASLA: Matt Wilkins, ASLA; Eric Gilbey, ASLA; and Nathan Qualls, ASLA. We regret the omission.

This article stated that Vectorworks software does not exchange files directly with Revit. In fact, users can directly import Revit Project File (RVT) and Revit Family File (RFA) files into Vectorworks, though files created in Vectorworks must be exported in the IFC format to be imported into Revit. 

2 thoughts on “The BIM That Binds”

  1. Hey!
    I have designed in Revit since 2006 as a landscape designer, as a love-hate relationship. I’m now using it with over 10 years of experience and can’t think of designing any other way. I went from F this, to I love this and would love to share the journey

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