Lean construction boosts productivity

Emphasis of design and construction planning is shifted from
specific tasks to the interrelationship of activities

December 01, 2000 |

The process of designing and constructing a building is markedly different from that of manufacturing a product. But adapting lean production-management concepts from manufacturing for use in construction has the potential to substantially increase the efficiency of delivering buildings, say its proponents.

"Lean construction" is a concept espoused by the Lean Construction Institute of Idaho (see "Learning about lean construction," page 32). Gregory Howell, a civil engineer, is its executive director. In the late 1980s, he and Research Director Glen Ballard began to investigate the performance of project planning systems. They discovered that on a typical U.S. construction project, only about half of the assignments planned to be performed in a given week are actually completed (see charts on page 30).

Against this background, Howell and Ballard saw a potential for applying the work of Lauri Koskela, a researcher with VTT Building Technology in Espoo, Finland, to the construction industry. Koskela recommend that construction theory be revised to focus on optimizing the project by considering the flow of work between activities and the creation and delivery of value.

Making quality assignments

The "last planner" system of production control is a key element of lean construction. The last planner is the person who makes assignments to direct workers. It is the last planner's responsibility to make only "quality" assignments-those that are well defined, in the best available sequence and sized to available capacity. The performance of the planning system itself can then be measured and improved by tracking the percentage of assignments completed, identifying the root causes of planning failures and taking action to prevent recurrence.

Linbeck Construction Corp., based in Houston, a member of the Lean Construction Institute, was one of the first U.S. contractors to adopt the methodology. Ed Beck, a Linbeck vice president, outlined its basic tenets. Projects consist essentially of "conversion" activities and "flow" activities, he explains. Conversion activities are those that add value to the end product, such as the conversion of information to design, from design to details and from details and materials into a structure.

"Most of our thinking and planning in design and construction is focused on conversion activities, as demonstrated by schedules, contracts, cost reporting and other documents that concentrate on specific work tasks," Beck says. "However, most design and construction problems, inefficiencies and waste result from breakdowns in the flow of activities." For example, Beck cites the "false economy" associated with the "large-batch" phenomenon, which may be the result of poor planning, late deliveries or lack of cooperation.

"We do a lot of queuing, or waiting until enough material has been assembled to process it. An enormous amount of time is devoted to batching and queuing, compared to the amount of time spent adding value to a project," says Beck. When planning is unreliable, bottlenecks occur and are merely pushed downstream, Beck notes. For example, the closure of a wall is delayed because of an inadequate number of electricians. The painters are therefore delayed, but still must complete their work by inspection time. "At some point quality is sacrificed, and rework becomes inevitable," Beck says.

Instead of eliminating the cause of unreliable work flow by correcting the planning system, construction teams are more likely to push ahead in order to keep people busy. This out-of-sequence work compounds the problem because it makes subsequent work more difficult.

Beck says the implementation of lean construction consists of the following steps: Defining what is valuable to the client; planning a sequence of activities required to deliver the defined values; achieving an efficient flow of work; and performing work only when it is needed to advance these values. The final step is to seek perfection through the continuous application of the preceding steps. The ultimate goal is to avoid "muda"-the Japanese term for waste-of time, talent, money and energy.

Renovation is a pilot project

A pilot lean-construction project was Linbeck's renovation of Rice University's 1925 chemistry building to house the biochemistry and bioengineering departments. The architect for the $21 million project was FKP Architects of Houston.

The building was gutted to its load-bearing masonry exterior walls, says Kathleen Jones, Linbeck's project manager for the Keck Hall project. The physical challenge was to provide a laboratory facility that could meet current codes within a structure that has floor heights of only 13 feet, instead of 16 feet to 20 feet, which is typical for new buildings of this type.

A demanding schedule was the other major challenge. Linbeck initially told the university that construction would take 14 months. However, to meet Rice's academic schedule, the contractor was given only 11 months.

Time savings was the biggest benefit of using lean construction concepts because they helped to generate teamwork among the subcontractors, according to Jones. Each of the major subcontractors implemented lean principles.

Subcontractors typically want to complete their work as quickly as possible so they will be less likely to experience interference from other contractors, Jones observes. At the outset of the Rice project, the plumbing subcontractor was installing glass piping before the mechanical contractor could install stainless-steel risers, an operation that requires welding. The plumbing contractor was concerned that the latter operation would damage the glass pipe. To remedy the situation, Jones emphasized to both parties that the interest of the project took precedence over individual subcontractor schedules, and reminded them that their companies had committed to the lean construction process. The job flowed smoothly after that, she says.

To keep contractors from getting in each others' way, schedules and look-ahead plans were reviewed weekly to determine the order in which each firm would perform its work. To make this work, an honest and accurate appraisal of when the work can be completed is extremely important.

Jones recalls a statement at a lean construction seminar that the potential is best demonstrated in handling a crisis situation.

Lean applications expanded

Elsewhere, Oscar J. Boldt Construction Co. of Appleton, Wis., is using lean construction as general contractor for the $14 million Taycheedah Correctional Institution under construction in Fond du Lac, Wis. Paul Reiser, Boldt's vice president of production, said the company adopted the methodology to enhance productivity, but "realized it is much more than a productivity improvement program. It's a different way of delivering facilities."

Last fall Boldt set a goal of implementing lean construction approaches on five projects over the ensuing year. After only 10 months, it was applying the concepts to 20 projects. "It has performed that well for us," Reiser notes. "Now we're starting to move from production upstream into the design phase. We're also getting more suppliers involved, so it's becoming a supply-chain-management tool."

Koby Scheel is project manager with the Taycheedah project's architect, a joint venture of Milwaukee firms Kahler Slater Architects Inc. and Zimmerman Design Group. He reports that as a result of subcontractors' adoption of a lean philosophy, weekly progress meetings that normally last more than an hour have been reduced to half an hour.

Fast-track and high-tech

A contractor and a designer who became acquainted through the Lean Construction Institute teamed up to implement lean construction on the renovation of a Hewlett-Packard facility in Fort Collins, Colo., to accommodate the relocation of functions from the West Coast. Fort Collins-based design/builder Neenan Co. and Portland, Ore.-based architect Industrial Design Corp. could not begin design and construction until February 1998, and completion was required in five months. Each firm had an independent contract with the owner.

Hewlett-Packard, an owner with an extensive knowledge of construction costs, budgeted $4.5 million for the project. It was delivered for $3 million, according to Michael Daley, an architect with Neenan.

Growth seen for lean concept

Howell predicts that owners and product suppliers will influence the adoption of lean construction. He notes that a number of suppliers-including Kohler, Pella and Cold Spring Granite-are implementing lean practices.

Other factors that Howell says bode well for the acceptance of lean construction are that owners want their projects delivered more quickly while they are delaying decisions in order to respond to changes in their markets. And as projects become more complex, specialty contractors will be providing more input relating to both design and construction.

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