A very interesting article by engineers from Sundt Construction, Tempe, Arizona, about applying some of the techniques used in vertical construction (tall buildings) to horizontal construction (highways, roads bridges). It’s particulary interesting because it is another example of the convergence of BIM and geospatial technology.

One of the efficiencies that is gained in the construction of tall buildings is that with the exception of one or two ground level floors, the foundation and top floors, floor designs are identical.  Horizontal construction is more complex than vertical construction because of ground topography and existing infrastructure.  Because of this complexity Sundt says that horizontal construction could benefit more than buildings from building information modeling (BIM). Sundt uses the term “virtual design and construction technology (VDC)” for BIM for horizontal construction, others use “BIM for infrastructure”.  Sundt has been working to transfer lessons learned in vertical BIM to highways and bridges.

A VDC project begins with a site model built on a 3D laser scan, typcially accurate to within a millimeter. Horizontal projects have to be very concerned with existing underground infrastructure.  The clash detection technology used in vertical projects to detect interferences between water, HVAC, structural and other subsystems can be used in a VDC project to avoid clashes with water, wastewater, electric power, telecommunications, and other underground infrastructure.  This highlights the importance of having an accurate 3D geospatial model of underground infrastructure, which is still lacking in many jurisdictions.

One of the ways VDC projects can achieve a degree of repeatability is through “subassemblies” which are used to parametrically model features, road surfaces, retaining walls, typical road details, bridges, grading standards, rail tracks, and utilities. With a digital terrain model (DTM) a VDC model can be used to calculate every foot of trench from exact existing elevations and exact trench depths and apply a slope formula to figure out the exact amount of excavation required.  And VDC models can be provided directtly to construction subcontractors enabling them to more easily add schedules (4D); and budget (5D) to the 3D model.

Sundt says that VDC is an improved process for collaboration between all players in the construction process including owners, surveyors, designers and engineers, and construction contractors.  In the future Sundt plans to create construction-ready VDC models for horizontal projects because they have the potential to transform the construction process, from surveying to paving to recording as-built information.

CE NEWS in the August print edition will be also be publishing an article that will include some of Sundt’s BIM for infrastructure projects in the U.S.