It is complex to model structures such as tunnels and viaducts that are controlled by an alignment and profile. Put that in an environment where the alignment changes often, and the structural engineer, using a tool like Revit software, finds it hard to accommodate that change. AutoCAD Civil 3D software is great for designing the alignment and profile — with complex curve elements and subassemblies for the mass modeling of complex structures — but we need Revit software for the detailed concrete modeling.
Solutions to the challenge involving export/import of data between software have helped, but they present their own new challenges. This is where writing Dynamo scripts comes into play, providing integration and coordination between AutoCAD Civil 3D software and Revit software to give an interactive and dynamic modeling environment that can integrate structures like stairs and the MEP (mechanical, electrical, and plumbing)-required equipment.
Understanding the Linear Structures Modeling Challenge
Dar have a long history in BIM for buildings and have executed many projects for hospitals, commercial premises, hotels, and sports facilities: architectural, structural, and MEP disciplines author their project BIM models and use the models for downstream processes such as design review and coordination, drawing production, visualization, and cost estimation.
However, BIM in the infrastructure environment has proven to be more of a challenge, with BIM standards less well defined than for buildings, while clients are increasingly demanding BIM deliverables (e.g., coordinated models) in addition to drawings. Linear structures are a particular case in point: known workflows were a hybrid of 2D CAD and 3D BIM, which would no longer be acceptable, and the discipline design teams were at breaking point to manage modeling tasks that supported the mandated BIM workflows.
Dar decided to initiate a project with Autodesk to develop processes for the coordinated design of tunnels, viaducts, and retaining walls across the design disciplines of transportation, structures, architecture, and MEP. This article presents some of the results of that project.
Requirements Gathering and Prioritization
The project that was selected for this linear structure proof of concept is a large new airport in the Middle East, in concept design stage and moving into detailed design. Hundreds of kilometers of tunnels are planned in this airport to enable passenger, baggage, and service vehicle movement. The adopted platforms are Civil 3D for transportation modeling (runways and taxiways, roads, surface modeling) and Revit for the other disciplines related to linear structures.
A two-day workshop was held between Autodesk experts and Dar BIM team members to gather and prioritize the detailed requirements for our project. Dar’s BIM team consists of experts from all design trades who act as a development, training, and support group for project teams in all design offices and are thus familiar with the challenges of current methods. Requirements, challenges, and priorities were scrutinized and grouped to give a clearer picture of where focus during the project needed to be.
As a consequence of this we determined to spend the bulk of our effort on tunnels, many of the challenges we were discussing being common across the structure types anyway, then test the process on bridges and retaining walls, before dealing with their specifics (piers, etc.).
It is complex to model structures such as viaducts and tunnels that are controlled by an alignment and profile. Put that in an environment where the alignment changes often, and the structural engineer, using a tool like Revit software, finds it hard to accommodate that change. AutoCAD Civil 3D software is great for designing the alignment and profile—with complex curve elements and subassemblies for the mass modeling of complex structures—but we need Revit software for the detailed concrete...