1. The Handmade Era
Recall the time when everything was crafted by hand: hand-drawn sketches, handwritten documents, and manually created tables. These three essential types of information—graphics, text, and data—were all produced manually. Often, all this information was consolidated into one set of drawings. In the earliest days, there were no separate design documents (except for structural calculations, which required calculation sheets); only a set of drawings was used.
If you were to review hand-drawn engineering drawings today and made a mistake, you would have to scrape the error off with a blade. If you scraped too hard or too much, you could easily ruin the drawing. This process was tedious and unforgiving. I am not sure if hand drawing is still taught in universities nowadays. When I was at university, our teacher insisted we not use CAD, claiming that hand drawing would improve our “hand feel”—perhaps a concept borrowed from architecture? As civil engineering students, we wondered what “hand feel” had to do with us.
Drawing errors in this era—what we called “image comparison”—were handled by stacking sheets of tracing paper (transparent sulfuric acid paper) from different engineering disciplines and manually checking for conflicts with the naked eye. This required a certain level of spatial imagination. For those who struggled with spatial thinking, this process was particularly challenging and discouraging.
2. The CAD Era
With the advent of the CAD era, things changed: drawings were created using CAD software and printed, documents were prepared in Word, and data tables were managed in Excel. This era is still ongoing, and you can easily witness its practices today. While CAD could technically be used to create documents and tables, the formats of these three software tools—CAD, Word, and Excel—are completely incompatible.
In the CAD era, “image comparison” was mostly replaced by CAD’s multilayer function, which allowed users to overlay different disciplines’ drawings on the computer. However, due to small screen sizes, many still preferred to print drawings and review them on paper. The limitation of screen size persists even into the BIM era.
Although this era is named after CAD, it was not just about CAD. Excel played a crucial role, especially in calculations—whether for quantities, cost estimation, or structural analysis. Everything that required calculation relied heavily on Excel. When I completed my college graduation project in 1998, I used Excel to create about 20 tables and implemented semi-automated structural calculations. This approach frustrated those who did manual calculations, and some even wanted to “kill” me for it. Eventually, we reached a compromise: I helped many classmates do their calculations on the computer. Our teacher opposed the use of Excel, believing it would hinder the development of mechanical concepts. I countered that letting computers handle calculations would free up time for us to learn more concepts.
This was the first wave of computer-driven transformation in the construction industry. On the surface, it seemed technology-driven, but in fact, it was the result of long-standing demands meeting previously insurmountable technical barriers—such as drawing, calculation, and information management. Once these obstacles were overcome, these needs could finally be met.
During this period, China’s first discipline-based company was born—the BIM PKPM system, developed by the China Academy of Engineering. Initially, it focused on structural design—drawing and calculation (with built-in graphics and calculation engines). Later, it expanded to architecture, water supply, electrical, HVAC, cost estimation, and project management. Internationally, the development of CAD and FM (facility management) software (document + calculation) accelerated, but true integration with CAD was rare—Archibus, for example, achieved some integration, known as “BIM based on management.” Autodesk’s CAD became the de facto standard and synonym for CAD in this era, and many industry-specific software solutions based on CAD emerged both domestically and internationally. Some, such as ArchiCAD—the first BIM software for architectural design—even came with their own graphics engine.
3. The BIM Era
We are currently undergoing this transformation, and many conditions have improved compared to the past. I recently read a 1995 report from several manufacturers discussing the main challenges in BIM development, such as graphics software, standards, hardware, and storage methods. Most of these issues have now been resolved, but some difficulties unique to China remain.
Let’s first discuss how BIM relates to previous methods:
(1) The graphics part has evolved from 2D CAD software to more mature 3D modeling software, with REVIT as a representative. The information embedded in these models is not necessarily greater than in CAD (in the 2D era, heights were indicated by elevation, while other heights were expressed using a mix of graphics, text, and data). However, the visualization in 3D has improved significantly. At this stage, BIM essentially serves as a blueprint, now rendered in 3D.
Domestically developed Zhongwang CAD still cannot compete with Revit regarding 3D graphics engines. Even though PKPM is based on professional BIM and has its own graphics engine, it is reportedly still difficult to use effectively.
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