the gulch viaducts
Atlanta, GA
Year Built 1920s
Client
Perkins+Wills
Services
Building Documentation - 3D modeling
Our work at The Gulch was one of the most unique projects that we have ever undertaken: a rare request to create an as-built Revit model of several miles worth of elevated viaducts in Downtown Atlanta.
The construction of the Downtown Atlanta viaduct system began in the early 1920s. The viaducts were elevated around one story high and constructed over the railroad system to improve the flow of vehicular and pedestrian traffic in the area. One hundred years later, these viaducts still play a major role in the fluidity of vehicular traffic in Atlanta.
As part of a master plan study, documenting the existing condition of the viaducts was critical for the architect Perkins+Will. The goal of this project was to convert the point cloud provided by the client into an accurate 3D site model that would be used in conjunction with any design models created for the study.
The greatest challenge lay in devising a way to use Revit - a tool that was not designed for modeling roadways - to achieve the level of detail and accuracy required by the client. After a period of trial and error, RCM managed to develop a model that satisfied the needs of its client. Most elements were modeled at LOD 300 with a represented accuracy of between 5/8” and 2”. To achieve the specified level of accuracy, the paved surface was adjusted every 10 to 20 feet.
As we all know, long-span structural elements are prone to deflection. During the modeling process, we found several elements that had deflected past the represented accuracy range allowed by the project. Tagging each element within the model provided a clear communication solution that cautioned the designer to carefully study any elements of lower accuracy. Using this solution, accuracy validation could be easily achieved by importing the laser scan data into the model as needed.
Key Characteristics
Seamless integration with client’s standards
Model developed 100% in Revit
The model was solely based on laser scan data
+/- 2” represented accuracy