Variation in construction often refers to the inconsistent processes that ultimately lead to

crews at the workface waiting for work or work waiting for workers. This unreliable workflow

is often caused by a project environment that is lacking in resources. As illustrated in Figure $1,$

the six elements or resources needed include information, tools, equipment, people, materials

and environment. All resources needed for the project must be synchronized to avoid

problems that cause a deviation or fluctuation in the performance of crews and$/$or disruptions

or delays for downstream crews. Therefore, it is imperative that we identify the sources of

variation and take action to eliminate them in order to have a consistent workflow on the

project. Generally, most variations can be categorized as either external or internal. External

sources of variation $($also known as special cause variation$)$ include environmental conditions

$($weather$),$ equipment breakdowns, material delivery interruptions, delays in submittals and

design errors. Internal sources of variation $($also known as common cause variation$)$ are often

more related to individual crew member performance, such as motivation level, safe working

practices, experience level, and following inconsistent processes. In both cases, it is up to the

project management team to create the proper project environment that addresses these

causes of variation.

A corporate culture must be established by company leadership as one of support for the

project teams. Likewise, it is up to the project leadership to ensure that all six elements are

provided as needed, when needed, to support the work crew$$s efforts to perform in the most

efficient and effective manner possible. As illustrated with the foot prints, project leadership

must get out of the office and observe the crews at the workface in order to ensure all

elements are in place.

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Figure $1.$ The $6$ Elements of Efficient & Effective Work. $($AGC LCEP Unit $7)$

A goal of lean thinking is to have a continuous and reliable flow of work where workers are

not waiting for work and work is not waiting for workers. Examples of continuous flow include

information $($construction documents, submittals, request for information, etc.$),$ supply chain

$($procurement and delivery of materials$),$ and jobsite activities $($work in process$).$ Reliable

workflow from one trade to another is very important in maintaining project cost and time

commitments. Reliability is the long$-$term consistency of a system. Knowing that workflow is

reliable indicates that we can establish a predictable start$/$release of work.

To better understand the variation effects on operations, the Lean Construction Institute

created the $$Parade of Trades$$ simulation. The $$Parade of Trades$$ uses thirty$-$five $(35)$ chips

to move through an entire construction process to create a final project. The amount of work

each trade will process depends on the roll of the die. With this activity, each participant will

execute a role within a construction project. There are seven roles for each team: Concrete,

Masonry, Fa$$ade$,$ Carpentry, Plumbing, Electrical and Painting. Once the simulation is

completed, be prepared to discuss the following questions.

Questions:

$1.$ What are the key points or lessons learned from this activity?

$2.$ How is this simulation like a real construction project?

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$3.$ What kind of variations do you see in a typical project $($external or internal$)?$ Try to list

two of each type.

$4.$ How can buffers $($inventory$,$ capacity and schedule$/$plan$)$ be utilized to minimize

variation in production?

$5.$ How can the lessons learned from this simulation be applied to construction projects?