I have read with interest articles and blog posts lamenting the poor productivity of construction and the need to get in step with mass production manufacturing. While this is an interesting topic and would appear to be a viable observation, I believe that on closer inspection it is not. The design and construction of buildings addresses a certain type of need and mass production a very different one.
There are about 40-50 well-known companies that direct the design and manufacture of automobiles for the entire world. Many of the larger ones include multiple lines of cars and trucks that are branded and marketed to specific segments. Retaining overall control, they typically contract out the manufacturing (and sometimes design) of many components and sub-assemblies to other manufacturers, coordinating the delivery and integration of parts for final vehicle assembly.
The cost and effort to design a vehicle is amortized across thousands or millions of nearly identical units, unlike a building where the design is generally constructed one time
The term "mass production" came into use in the 1920's to describe the large scale production of standardized parts and products. As a process, it was nearly perfected by Toyota by the 1980's. It utilizes complex and tightly orchestrated processes in order to realize efficiencies. While there is much to learn from manufacturing, the AEC industry is not in the mass production business.
WHY IS THERE A BUILDING INDUSTRY?
By contrast, most buildings are individually designed and constructed to meet the needs of a specific client for a particular site in a certain area or region. The client generally wants a building tailored to their needs and takes an active role in the design process. They exercise control over most aspects of the project related to the budget and schedule and retain the right to delay decision making or change their minds.
Some clients still consider employing an architect and design team to be a commission, not unlike engaging an artist
The resulting design is typically bid competitively amongst multiple contractors to obtain the best value (ahem, lowest price). Alternatively, a construction manager or design-build firm may be engaged early in the process but still utilizes a similar bidding effort to select most or all of the sub-contractors.
Every project also employs a specific combination of designers and constructors. With a few exceptions, It is unlikely that the same AEC team will work together again, missing the opportunity to collectively learn and improve.
Applying this client driven model of service to mass production quickly creates issues. Let's look again at the automobile industry. With this paradigm, like a building project, each prospective car owner now has opportunity to change options as to the size, layout, features and performance characteristics of their new vehicle to meet their particular needs. They also retain the right to change their mind during the manufacturing process itself. It takes little imagination to see that this approach will immediately introduce significant slowdowns to production rates with a corresponding increase in cost. The benefits of mass production are lost.
ON THE OTHER HAND
The converse is equally problematic. The variety of buildings around the world are a testimony to the creativity of people working with the limitations of available financing, building technologies, skills and materials. The unique needs of clients and their individual preferences along with many other factors all contribute to the richness of the built environment we see. We appreciate the varied buildings and urban fabric of Prague, San Francisco and Greenwich Village - especially when compared to many post World War 2 American suburbs where a focus on efficiency, commoditization and cost have led to a general blandness.
A BETTER COMPARISON
Rather than contrasting construction to mass production, a better comparison would be to the design and manufacture of the custom tooling used in the manufacturing plant itself. It is a capital intensive effort, often for the development of specialized, one-of-a-kind (or few of a kind) pieces of equipment. Design specifications for the tooling may change along the way, as it is fine tuned for what the manufacturer will produce (automobiles, aircraft, plastic bags, food products, etc.).
ISSUES AFFECTING CONSTRUCTION PRODUCTIVITY
Are we overlooking opportunities within the design and construction industry where improvements affecting productivity might occur? I think so. One area I have never seen an article or a seminar presentation specifically address is constructability - the mechanics of assembly or how elements and assemblies of the building will fit together.
Contexture - the act, process or manner of weaving parts into a whole - Webster's Dictionary
There are several components to this, the first being practical knowledge of building systems themselves, second, the ability to integrate them with a degree of elegance and an understanding of the assembly process itself. Too often designs are not readily constructible or just impractical to build. This can have a significant effect on the time to fabricate and install as well as schedule and cost.
I had a discussion with a steel detailer who shared that complicated perimeter slab edges (lots of ins & outs) on elevated floors were more costly to fabricate and install (especially in a union environment). On that particular project we re-worked the exterior façade design slightly to allow for mostly straight runs of steel edge angle. Separately, the structural engineer redesigned the roof framing to eliminate the majority of connections requiring moment welds. Both efforts simplified the buildings construction.
Unfortunately, in the United States, the architectural profession today shows little interest in how buildings are put together, preferring to focus on big picture aesthetics and trendier aspects. Projects often move so quickly that there is limited time to think through the building itself resulting in a lot of "trigger work" being required. The increased focus on BIM modeling as an end in itself sometimes creates a confusion of goals where an accurately modeled building may not reflect good construction practices.
BIM models are useful for quantifying materials but do not convey the complexity or build-ability of a design. This is not unlike the difference between "information" and "wisdom".
Mass production by definition is the manufacture of nearly identical items and it requires singular control over many parameters to be efficiently done. The construction of buildings involves the management of multiple factors that often change and are out of the contractor's direct control.
Here are several issues I have seen that can hinder construction productivity.
- Project complexity - unrealistic expectations and conflicting goals
- The "speed of time" - needing to progress work while decisions lag or change
- Design fee pressure - the new constant
- Limitations inherent in the bidding and contracting process which limit their value proposition for skilled workers and final building systems selection
- Over reliance on technology