May 18, 2009
Back to the future
Construction drawings were once works of art. Not for their detailed precision or extensive notes and documentation, but simply for their expressive representation of a building. In those days, ideas evolved from sketchy schematics to roughly scaled preliminaries, with time to review alternatives and think through their constructability.
Final drawings were inked with ruling pens on pressed linen using T-squares, triangles and curves to shape beautiful illustrations of the building. The result was a set of drawings based on a thoughtful process that was fundamental to the pride and challenge of a team of good draftspersons.
This was also an era when builders and drafters could take the time to collaborate and work together to shape a building during its construction. The finished drawings were no more than a starting point for a working relationship between skilled tradesmen and women who could take pride in abilities that they had acquired through years of apprenticeship and training.
With the advent of time saving instruments like parallel bars and drafting machines, ideas continued to be drawn, but the speed and versatility of these new instruments meant details could be discussed and noted on the drawings entirely within the designer’s office. In other words, rather than rely on open relationships on the jobsite, drafters began detailing the “requirements” for the constructions before the drawings reached the field.
This ability to presuppose the input and experience of the builder meant construction drawings soon lost their place as the start of a conversation. Working drawings became contract documents, with detailed notes and specifications penciled onto sheets of vellum outside any input from a builder — collaborative opportunities for mutual cooperation were quickly forgotten.
Then computer aided design (CAD) became an essential drafting tool silencing even the skilled draftsperson. With the advent of CAD, once open drawing-board-conversations between skilled designers were inadvertently lost to the memory of a machine. Newly trained CAD operators labored in “virtual” isolation to manipulate lines and letters, using templates and libraries of graphic data with conversations limited to redlined corrections and data input. What little construction knowledge that could be exchanged was dulled by the monitors of isolated work stations.
The latest technical development takes this breakdown in any collaborative approach one step further. With building information modeling (BIM), software publishers promise that a set of two-dimensional documents can be “parametrically” generated from detailed design models. With the expanding power of graphical computers, hundreds of sheets of drawings and thousands of pages of specifications can now be automatically extracted from three-dimensional databases, leaving little time for any discussion.
Silenced by the technology
Ironically, both the builder and the practiced draftsperson are now silenced by a widening technical gap. Worse yet, the computer operators who build these parametric models are even further removed by the same technology. As the puppets of project management, they have been reduced to performing tasks with limited understanding of the nuances of the real-world constructability or the implications of the plans automatically generated by their computers.
In response, large construction companies have installed their own graphical work stations. Operators struggle to generate preconstruction and as-built models using the same design software to anticipate and resolve conflicts and problems that may occur in the field. The use of this software by constructors indicates a commitment to cutting edge information technology, even though the real value of these programs is its advertised potential to automatically convert 3D models to 2D contract drawings (parametrically). Not something many builders need or want in the real world.
The challenge of course is to respond to the potential of this new technology, without losing the exchange of ideas and interaction fundamental to discovering solutions in the construction process. Like the once skilled draftsperson, professional builders can easily be buried by a protracted learning curve, cut off by a technology that blurs the essence of what it means to be a builder.
Construction models are not BIM
A construction model graphically defines scope and anticipates real-world conflicts and alternatives with little need for two-dimensional drawings. These models mix sequence animations and assembly and process simulations to communicate ideas spontaneously in an ongoing construction process.
Important is that a construction model differs from a designer’s BIM model. While in theory a detailed BIM model incorporates the subassemblies necessary to produce a set of contract documents, a construction model intends to graphically represent ideas in support of a continuing conversation in real-time construction.
In practice, the construction modeling process helps builders think through and visualize more than the finished assembly. It is fundamentally a tool to hypergraphically plan and anticipate the impact of change and the values of different approaches to the same result. In other words, construction models embody the means and methods that interact and evolve with the variable of real-world construction.
The strength of a construction model must therefore be in the simplicity of its production. Any technical distraction, other than to directly represent a construction concept and clearly illustrate a series of actions, only distracts from its communicative potential for the seasoned builder.
Keep it simple
A three-dimensional construction model must therefore be absolutely dead simple to build. The software must reduce the production of the construction model to the essence of its value to hands-on builders. This means learning the program must be intuitive, requiring no more than an hour or so to gain proficiency, yet capable of generating the kind of detail that can be used in a variety of interactions.
To meet these requirements there are several 3D programs, any one of which could serve the needs of different builders and all of which are free. These programs range from basic modelers with simple sets of construction tools like DeleD and 3Dbase to photorealistic modelers like POV Ray, Blender3D, and TrueSpace from MicroSoft.
Of course, the most popular 3D modeling program and perhaps the most intuitive for hands-on construction modeling is Google SketchUp.
In the end, the choice of the modeling program is really unimportant. The most important requirement of a construction model is the model builder’s underlying and fundamental understanding of the construction process. From this basis, a construction model can communicate an approach, plan a process, and think through alternatives.
Like the early pen and ink drawings of our graphic tradition, the resulting three-dimensional images will then focus the conversation on the actual construction, helping all the project players, on and off the jobsite, to literally see and share the same point of view.