Lean Construction - Lean Construction FAQs

Lean Construction FAQs

• Answers provided by Lean Construction Institute (LCI) Executive Director Greg Howell and Academic Forum Chairperson Tariq Abdelhamid -

1. What is Lean Construction?

Lean Construction a different way to see, understand and act in the world. For example, waste in current practice is normally understood as labor utilization. Learning to see contingency as waste is the big step we need if we are to make a step change in construction, one commensurate with managing inventory just in time.

Lean Construction is a philosophy - it is something that people do. Lean Construction a comprehensive system of ideas that lead to the flawless delivery of the built environment. This philosophy is practiced using the Lean Project Delivery System, which continues to evolve as more is learned from practice and research.

2. Is Lean Construction just applying Lean Production in construction?

No. Lean Construction started as an attempt to reform the way work in projects is managed. Once it was appreciated that work moves between specialists in construction by the administrative act of making an assignment, it was possible to adapt principles and practices direct from Toyota Production System. However, Lean Construction is more than Lean Production in Construction. The project-oriented execution of construction projects made it necessary to develop unique methods and tools for construction.

3. When did Lean Construction begin?

LC began with two main insights. First, the inability of the current planning system to produce reliable workflow. Second, the lack of a theoretical understanding of what is production in construction. This was in the middle 1980s to early 1990s. A more formal start could be identified as the first meeting of the International Group for Lean Construction in 1993. Lean Construction remains to be a research and practice area in constant flux.

4. What are the major differences between a project run based on Lean Construction and one that is not?

Lean works because the work on the project is designed and managed by those who do it. LC designs and activates the network of commitments necessary to deliver the project.

The “tragedy of the commons” is prevented. This tragedy results because individually rational decisions are destructive to the overall project. Instead of local optimization driven by labor utilization, Lean Construction targets system optimization that is driven by throughput. Work on Lean Construction projects is deliberately and systematically organized to maximize the project and not the pieces, and commercial terms are adjusted to align interests, and promote improvement and minimize risk to the involved parties.

Another difference is that the construction process, the building operation and maintenance, and the recycling/salvage needs are inputs to the design and not outputs of it; inputs needed to start the work are provided and issues (waste) that prevent finishing started work are eliminated; problem solving and learning is the job of those involved in the project and not just part of the job; Where possible, materials are brought to the site in the same way concrete is; The aim is for a zero punchlist and not to zero-out the punchlist.

5. Building Information Modeling (BIM) aims to build a collaborative relation between designers and constructors, so how is that different from LC?

BIM is technology. It doesn't aim, it does make possible different conversations because it is a great tool for spatial representation of design. LC structures those conversations and connecting design, logistics and installation. LC designs and activates the network of commitments necessary to deliver the project. It is necessary to enable Lean Construction ideals but not sufficient.

6. Is Lean Construction like Leadership in Energy & Environmental Design (LEED) where you have to commit to a certain level of compliance and the project is checked against that?

No. Lean is a way to manage and improve work. LEED and GREEN are value propositions - an end. Lean Construction is the means to better arrive at that end.

7. What percentage of the US construction industry is adopting it?

There is no definitive way of knowing. The number of LCI state-based chapters are increasing which reflects an increased interest in the industry. The corporate and individual membership of LCI is increasing, again indicating interest is rising. The AGC of America Building Division has began to develop Lean Construction training for construction site professionals. AGC estimates that one in seven contractors is using Lean Construction. According to LCI, there is still time to be an early adopter.

8. Is Lean Construction accepted more in other countries than in the US?

There is significant implementation in Germany, UK, Denmark (the longest running with strong Union support), Sweden, Brazil, Chile, Peru, Taiwan, Malaysia, India, Egypt, Israel, and Nigeria.

9. What is the primary difference between Lean Production and Lean Construction?

• Lean production is the inspiration for lean construction, but cannot be grafted onto construction.

• Production & construction are different; construction is more like ship-building or airplane-building, where the workers move and the product is stationary instead of the product moving between stationary workers like in production.

• In production, typically the same part is produced in mass volume. This is not the same as construction, unless major generalizations are made (i.e. a wall is a wall, even if made of different material and on different projects). So, Lean Construction focuses heavily on the similarity in the process of constructing more so than on the product of construction.

• Sven Bertelsen (a Lean Construction Scholar) encouraged the move from construction on to project production in general because he sees the project as the basic form of production where mass production is just the simplified version Toyota and Shingo demonstrated as new thoughts but construction has to establish its own thinking.

• Lean Production primarily focuses on the reduction of the time from order, of any transaction be it assembly, billing, supply, etc, to delivery. This reduction of time is achieved by the elimination of waste (the unproductive use of resources) that is captured in the mnemonic word “ DOWNTIME”. Respect for people and continuous improvement guides the reduction of waste. Lean Construction has been inspired by this but also by other paradigms. Production in construction is conceptualized as a transformation of inputs to outputs through a flow process of materials and information that is directed at maximizing value to the client. Lean Production is not about maximizing value to the client, otherwise, the Cadillac would cost the same as the Chevy, the Lexus would cost the same as the Camry, etc. Lean Construction also draws on the new theories regarding project management as well as social science, and complexity theory. A construction project is considered as a project-based production system.

10. Can the concept of Heijunka be used in construction? Why?

• Heijunka = production leveling. Production leveling for a manufacturing plant relies on being able to “create” stable demand, so that the Takt time for the plant is constant. Toyota does this through its marketing and sales division. The TPS is quite vulnerable otherwise. Of course, it is not always perfect but they strive for this stability, especially with tactics such as mixed-model production.

• Construction is project-based and the requirements needed to complete a project are known – the quantities are known, with a time and budget constraint. A construction project needs stability and reliability in the workflow so that it is not going in fits and stops. This is achieved using the Lookahead and weekly work planning process with a constraint screening process (elements of the trademarked Last Planner System), and not just an FYI (for-your-information) coordination meeting. The act of keeping a workable backlog is designed to keep work flowing and progressing.

• The use of the line of balance (linear scheduling, flow lines) is a nice tool to visualize the production rates of different activity and avoid the interruption of work as well as the problem of overproduction. However, in Lean Construction it is not desirable to have one crew finish too fast or too slow.

• Crew balancing is not an example of heijunka. Crew balancing may lead us to locally optimize at the expense of the system throughput.

11. Contrast “lean work structuring” with “work breakdown structure”.

• A WBS should not be used as the sole planning tool for a project. It is a great brainstorming tool to understand the project. It is probably the best scheme to develop a MASTER schedule. The problem is using it for more than what it is capable of. Project cost and project duration can't be determined by simply working the WBS. The WBS is looking at activities in an independent fashion in support of transformation thinking. The WBS assumes that optimizing the part will optimize the whole – reduce the part cost and duration and you will reduce the cost and the duration of the whole. Get the lowest price and the shortest time for drywall separate from electrical and plumbing and you find on site that the work of these three trades is so intertwined that the cost and duration you received for drywall was a pipe dream.

• A WBS is a tool to use in Lean Work Structuring.

• LWS is thinking production, operation, maintenance, and recyclablity during design. It also focuses on work package (not trade or contract packages), i.e. the wall, or the ceiling, and how that work will be accomplished throughout its upstream and downstream stages.

12. What are the differences between project control and production control?

• Project control monitors progress using lagging indicators such as schedule and cost variance. It is sometimes too late to do anything about the project going off-track or it takes too much to get it back on track. So, project control is reactive. Think of the stock market. The DJI - Dow Jones Industrial Average – only informs about what has happened to the market after the fact. It’s like taking the temperature of a patient – it indicates whether a person has fever but not why.

• In Lean Construction, production control is practiced with an aim to make things happen to prevent the project from having a fever. Production control is pro-active because work is facilitated by removing the known process and system constraints.

13. Is Value Stream Mapping (VSM) a tool for construction?

VSM has a place in construction. And this applies to many other tools and techniques that are being used to enable Lean Construction ideals, but are not widely known or shared by those practicing them. The Last Planner System is one example.

As far as VSM is concerned, it provides a big picture view of the flow problems in whatever system is under study. It's a flow improvement tool and not a process improvement tool (flow kaizen vs. process kaizen). A great bottleneck finder.

VSM has been applied to reduce the time for processing specialty contractor payment applications (from 40 days to 5 or so – see IGLC11 in a paper by Mastroianni and Abdelhamid). An architecture office also is using it for streamlining the submittal and show drawings review and approval process because of delays and complaints by contractors. An example for application on a construction site is that of a construction company that specializes in suspended ceiling and drywall installation. They used VSM to identify time that drywall sheets and tiles spend before being put in place. They used the results to justify the cost of using a temp warehouse (supermarket) close to the site and deploying a pull delivery system. The result, using the SAME installation process, was less time per SQFT because material handling was almost down to single touch – from the truck to the installation location. Interestingly, they then used work sampling techniques (as described in Oglesby, Parker and Howell 1989) to improve the dry walling process itself.

In Brazil, VSM is being used mostly by academics. As any other tool developed for manufacturing it needs some adaptation in order to become useful for construction. Researchers at the University of Campinas (UNICAMP) have developed some innovative applications of VSM for administrative and design processes and also as part of production system design of construction projects. They have published a few papers in previous IGLC conferences.

14. Is Integrated Project Delivery the same as Lean Construction?

No. In fact, the ideals of Lean Construction are enabled by using the Integrated Project Delivery approach. IPD is necessary but not sufficient. In other words, just having an IPD will not guarantee meeting the Lean Construction ideals. IPD is defined on this page (scroll up).

IPD is a Relational Contracting approach that aligns project objectives with the interests of key participants, through a team-based approach. The primary Team Members would include the Architect, key technical consultants as well as a general contractor and key subcontractors. It creates an organization able to apply the principles and practices of the Lean Project Delivery System.] (Matthews and Howell 2005). IPD is defined at http://www.leanconstruction.org/glossary.htm. For more information see http://www.leanconstruction.org/lcj/V2_N1/LCJ_05_003.pdf