During the last several years, 3D modeling in the transportation industry has gained attention with many agencies, consultants, and contractors having different understandings of what information 3D models can provide. Contractors of past have viewed 3D models as solely a public involvement tool. Transportation consultants have considered 3D models as products only vertical engineers use for Building Information Models (BIM) and don’t have much use in the horizontal world. Transportation agencies have previously viewed 3D models as an extra cost and effort for a pretty picture or movie that is not geometrically accurate.
But these views are changing. Today’s 3D design models increasingly are viewed as important tools that offer a design-centered approach to visualize accurate information. These 3D models are now used to develop the design of transportation projects to help engineers and stakeholders make more informed decisions and deliver better projects. 3D design mitigates risk, reduces time in alternative design exploration, develops quantities faster, and, overall, 3D models convey the design intent in a mathematically accurate and digestible format.
Older, traditional design models were created after the design was complete, often by a graphic artist through interpretation from an engineer or designer. Continuously changing designs and decisions resulted in a significant investment in time and computing power to reproduce the changes in the visualization model. These models were only as realistic as the artist’s interpretation. Today’s 3D models are created with realistic effect directly by engineers. The design model visualization is a direct by-product of the engineer’s intended design calculations. The visualization is as accurate as the engineer’s construction intent.
Developing 3D designs today
In many transportation projects around the world, Bentley’s MicroStation is a common product used to create design plans. Bentley’s OpenRoads Technology, found in many of its products, brings 3D design to a new level of automated or semi-automated changes that allows engineers to quickly develop designs and visualize the effect of changes not only to their own discipline, but also to other disciplines.
Lockwood, Andrews, and Newnam, Inc. (LAN), which works extensively on transportation projects, has used this technology to adjust designs to avoid potential change orders during construction. Previously, this was done by studying cross-section cuts every foot and reviewing them closely over a longer period. Today’s OpenRoads 3D model allows the engineer to quickly flag clashes between discipline elements.
A benefit LAN has experienced often from 3D design modeling is the effect of changing roadway geometry and its ripple effects on existing or proposed utilities and underground storm sewer systems. As the drainage engineer develops the 3D design model of these systems, a roadway engineer can see the associated changes by simply referencing these models into their environment. There is no need to develop detailed plan sets with drafted notes prior to sending the design to other disciplines.
Design intent is streamlined through improved model references. When a roadway profile change is required, the storm drain or utility pipe is adjusted or a horizontal alignment change is made. The 3D design model provides accurate information for engineers to collaborate and make decisions. If a path is chosen to progress the design, parts of the model are automated or semi-automated to carry through changes throughout the design. This reduces a significant amount of time spent in design review and also in alternative design exploration.
Alternative design exploration
As an engineer chooses a path to progress the design in this immersive model environment with other engineers, changes are immediately processed and visualized. Changes in the roadway model may not only affect the drainage or utility engineer, but also the bridge engineer. The bridge engineer can reference these files in real time during design and flag possible vertical clearance issues. The bridge engineer can also offer alternative design ideas that can be vetted quickly. Bentley’s OpenRoads rules (or relationships) can help automate some tasks to provide a more comprehensive design alternative in a fraction of the time taken previously.
LAN has used these tools to determine both constructability and material cost feasibility on various projects. An alternative design would require a designer to draft an alignment and the edges of pavements, curb, etc., and calculate quantities from 2D plan and profile views with a significant amount of time devoted to drafting. In today’s 3D models, these quantities are calculated from each model for linear, area, or volume quantities and can be compared faster than ever before. Plan alignments and profiles can still be adjusted in 2D for ease of use by the designer, but in a quick and effective dynamic view.
In a recent diamond interchange project, LAN produced a model and calculated retaining wall, bridge, pavement, and earthwork quantities. The same day, the crossing highways were flipped in an alternative design. Automated retaining walls were created from the constraints developed within the software. Similar quantities were calculated for comparison and an informed decision was made to move forward with the original design.
Communicating the design
As mentioned before, communicating design intent in the past has typically been done on hand-drafted paper or on 2D CAD-developed paper plans. Someone with industry experience would then study the plans and visualize the project. Often, specific design elements that the designer wanted to convey may be missed or overlooked by the reviewer mentally visualizing the project. With the designer and the reviewer on different pages, communicating design intent and addressing stakeholder concerns becomes an even bigger challenge.
Also, visualization software required heavy-duty computing power, an experienced user who may or may not have an engineering background, and a significant amount of time invested into each model. Consequently, these models would often only be used for high-profile projects with large budgets.
Current design-centered 3D modeling software such as OpenRoads, Autodesk REVIT, or Autodesk Civil3D allows design intent to be communicated faster and easier. The software is more intuitive, easier to use, and more accessible than ever before. 3D visualizations are the direct by-product of engineering calculations. The increased use of 3D models helps increase collaboration among not only engineers, but also stakeholders, politicians, and the public. Since everyone understands the intent of the project better, work-sharing and problem-solving workshop scenarios help foster closer relationships between these stakeholders.
A case in point: During a meeting, a client requested the design team to determine the cost difference between using a retaining wall, a concrete side slope, or purchasing right-of-way, expecting an answer later in the week. Within 10 minutes during the same meeting, the designer was able to show the client what the project would look like in each scenario and a rough cost comparison between the three scenarios. Visualizing the design in 3D helped inspire new ideas and increased collaboration between the client and consultant.
Training young engineers-in-training (EITs) and staff is easier when the concepts you are trying to teach are easily visualized as well. The previous generation of engineers would conceptualize everything in 2D and often have difficulty grasping certain 3D design concepts in mind, using Excel, or even drafting the elements in plan, profile, or cross section. Using 3D design methodologies, EITs can be taught concepts and the ripple effect of design changes throughout the life of the project. A realistic, visualized model is much more impactful than a stack of papers with lines.
The new generation of 3D design models in the transportation industry are far from perfect. Adoption of new technologies in transportation tend to move slower than other civil fields, but it is improving nationwide. Pilot projects in many states are beginning to see the benefit of stakeless jobs — construction projects based on digital information and often using 3D design models in automated machine grading/paving.
Contract language and national/statewide standards regarding 3D design can be improved and adopted. On some current projects, a 3D design is developed, then converted down to 2D plan sets. The winning contractor would then recreate the 3D model from the 2D plan sets with inferior information. How can we move more efficiently from design to construction? In some states, the true benefit of 3D design from designer to contractor can be realized only through innovative contracting vehicles such as design-build, construction manager, or general contractor at risk. How can we make this work better for design-bid-build or rather, how can we change design-bid-build to utilize 3D design models?
With the growing popularity of virtual reality (VR) and augmented reality (AR), 3D design models are quickly developing not just for visualization, but also for formwork construction and real-world clash detection. In other industries, VR/AR with real-life application, like construction, are being developed with various software companies such as Microsoft’s Hololens, Occipital Structure, HTC Vive, and even Facebook/Oculus VR.
Martin Bros. recently created a proof of concept by having someone construct a bathroom pod frame with no plans and only using Microsoft’s Hololens. City planners and engineers in Christchurch, New Zealand, have used an app called CityView AR to show where buildings were before earthquakes. Autodesk and Bentley have been developing various products to take advantage of the growing interest in AR and how it can help pave the way of the future in planning, design, and construction.
3D design models help transportation engineers design smarter, faster, and more efficiently than years past. Current models also mitigate risk, reduce time, produce better designs with accurate calculations and quantities, and convey the design intent more effectively than ever before. In addition, they can be used to help train younger staff or foster better collaboration between clients, consultants, contractors, and the public. While the current state of 3D design tools is far from perfect, they provide a better way to deliver projects more efficiently today and in years to come.
Alan Esguerra, P.E., is a senior transportation engineer at Lockwood, Andrews & Newnam, Inc. (LAN; www.lan-inc.com), a national planning, engineering, and program management firm. He can be contacted at firstname.lastname@example.org.