Bridging the Gap Between Tradition and Innovation
The transportation industry, long reliant on 2D drafting and traditional design methods, is beginning to embrace the transformative power of 3D modeling. While other market sectors have made significant advancements in 3D modeling, the transportation realm, particularly within government agencies, has been slow to adopt this technology.
How 3D Modeling Is Used in Transportation Projects
3D modeling provides a comprehensive visual representation of transportation infrastructure, such as roads, bridges, tunnels, and railways, which allows stakeholders to better understand how the design will look and function in a real-world setting. Designers can integrate various project components, including utilities, drainage systems, and surrounding landscapes, to ensure compatibility and reduce conflicts. Simulations using 3D models can help assess traffic flow, structural performance, and environmental impacts, enabling engineers to test different roadway alignments to optimize traffic patterns. With 3D models, potential clashes between structural elements, like utilities and beams, can be identified early in the design process. These models are also effective communication tools, making it easier for non-technical stakeholders to visualize and approve designs. Additionally, contractors can use 3D models to plan construction phases more effectively, minimizing disruptions and delays.
Advantages of 3D Modeling Over Traditional 2D Design
3D models provide a more precise representation of dimensions and spatial relationships, reducing errors and omissions in design documentation. They are also easier to share and interpret, which fosters better collaboration among multidisciplinary teams. These highly visual and data-rich models provide the ability to detect and resolve design conflicts during the modeling stage, which reduces costly revisions during construction and enables informed decision-making by showcasing the project’s impact and feasibility in greater detail. 3D models can be integrated into Building Information Modeling (BIM) systems, supporting the project through its entire lifecycle—from design and construction to maintenance and operations. Advanced 3D modeling tools can analyze environmental factors, enabling designers to optimize for sustainability and reduce ecological impact.
The Evolution of CAD to 3D Modeling
Traditional computer-aided design (CAD) systems have long been a staple in the engineering world. While initially CAD was merely an electronic drafting board, it was a significant improvement over manual drafting due to its ease of modification. However, these early systems were limited in their ability to convey meaningful information beyond basic visual representation.
The next evolution of CAD involved adding intelligence to these lines and shapes. Tools like Civil 3D allowed users to represent real-world elements such as roads and walls, building up from simple lines to more complex structures. This was a significant step forward, but the real game-changer came with model-based CAD.
Model-based CAD systems enable users to create detailed, intelligent models of structures. This approach was quickly adopted by the architecture and housing industries, where smart programs could simulate real-world conditions and optimize designs. Mechanical CAD followed suit, revolutionizing the design and manufacturing of complex parts and assemblies.
Challenges and Innovations in Transportation
Despite the clear advantages, the transportation sector has been slower to adopt 3D modeling. Highways and transportation infrastructure are complex and not easily defined within a 3D model. Additionally, the design processes established by State Departments of Transportation (DOTs) are deeply rooted in 2D graphics, making the transition challenging.
At RETTEW, we recognize these challenges but also see the immense potential of 3D modeling. We have pioneered the use of mechanical design tools for bridge modeling, where bridges are treated as assemblies of parts, similar to cars. This innovative approach has proven very successful, as demonstrated by our work on the Pennsylvania Turnpike Northeast Extension project. By enhancing software through scripts and codes, we have streamlined the design process, allowing for rapid adjustments and improvements in subsequent projects.
Expanding 3D Modeling Across RETTEW
In January 2020, RETTEW was awarded an engineering services contract by the Pennsylvania Turnpike Commission (PTC). As part of that contract, we were assigned the NB-550 bridge replacement project in January 2021. Preliminary engineering commenced in March 2021, followed by the final design phase in April 2022, and construction consultation in July 2023. The project scope included all necessary engineering services to replace the bridge carrying State Route 1001 (Hatchery Road) over the Northeast Extension of the Pennsylvania Turnpike in Penn Forest Township, Carbon County.
This was one of the PTC’s pilot projects using 3D modeling under their Digital Delivery initiative. The existing single-span steel beam bridge’s substructure was failing, necessitating its replacement. RETTEW evaluated several alternatives and ultimately selected a two-span prestressed spread box beam bridge, featuring a wall pier and mid-height abutments on spread footings, with concrete slope walls between the shoulder edge and the abutments’ face. We provided a vast array of services, including surveying, highway engineering, bridge engineering, 3D modeling, digital delivery consultation, and construction consultation. Additionally, we supervised and coordinated sub-consultants for right-of-way coordination, utility coordination, erosion and sedimentation planning, and traffic control planning.
Navigating the digital delivery and 3D modeling components was the most challenging aspect of this project. RETTEW met with the PTC and its digital delivery consultant monthly during preliminary engineering and bi-weekly during final design. We provided a 3D model of the bridge that served as the legal document for contractors to bid on the project, along with 2D plans for roadway, cross sections, erosion and sedimentation, traffic control, signing and pavement marking, and an abbreviated structure plan set. This project exemplifies our dedication to leveraging cutting-edge technology to deliver innovative and efficient engineering solutions.
Leading the Way Forward
Our goal at RETTEW is to continue pushing the boundaries of what is possible with 3D modeling. We are working closely with the Pennsylvania Department of Transportation (PennDOT) and the PTC to advance model-based design and digital delivery. While these agencies are still adapting to new methodologies, we are ahead of the curve in leveraging our expertise to drive innovation and efficiency.
The future of engineering lies in intelligent, model-based design. By championing this approach, RETTEW is not only enhancing our own capabilities but also setting new standards for the industry. As we continue to refine our techniques and expand our use of 3D modeling, we are committed to delivering exceptional results for our clients.
Conclusion
3D modeling is more than just a tool; it is a paradigm shift in how we approach design and engineering. At RETTEW, we are proud to be at the forefront of this transformation, using cutting-edge technology to deliver innovative solutions. As we look to the future, we remain dedicated to advancing our capabilities and setting new benchmarks for excellence in the industry.
