RT-191 defined lean construction as: “the continuous process of eliminating waste, meeting or exceeding all customer requirements, focusing on the entire value stream, and pursuing perfection in the execution of a constructed project.” This research identifies the core principles of lean production, compares and contrasts the manufacturing and construction industries, and identifies the potential for implementing lean principles in the construction industry as well as a questionnaire for Self-Assessment of Lean Behavior.
Using lean concepts as a foundation, RT-191 first defined the nature of value-adding actions and waste. The research documents the definition of Value Adding (VA), Non Value Adding but Required (NVAR) and Non Value Adding (NVA) activities with case studies outlining the Value Stream for Structural Steel and Process Piping.
A significant finding was the large amount of waste activities (defined as anything that takes time, resources or space but does not add value to the product or service delivered to the customer) in construction as compared to manufacturing. The research determined that only 10 percent of field construction activities add value. If a contractor could improve the value-adding portion 5-20 percent, the lean contractor would have a significant competitive advantage.
RT-191 interviewed lean manufacturers, early adopters of lean construction methods, and academics and theorists from around the world. Using all of this information led to the identification of five lean construction principles that can significantly benefit both owners and contractors.
- Customer focus
- Culture and people
- Workplace organization and standardization
- Elimination of waste
- Continuous improvement and built-in quality
RT-191 found that lean behavior among construction contractors usually is confined to the first two principles. The remaining three principles are more difficult to implement, particularly because of the vast differences between the manufacturing and construction industries. Also, the use of those last three principles, even among contractors actively pursuing the lean ideal, is rare because to be truly lean requires changes to every aspect and every level of an organization. Regardless, construction’s processes can be improved, and applying lean principles should be considered. Becoming lean is a long-term, comprehensive commitment that requires a cultural change for the organization.
1 : Large Amount of Waste Activities
A significant finding was the large amount of waste activities (defined as anything that takes time, resources or space but does not add value to the product or service delivered to the customer) in construction as compared to manufacturing. The research determined that only 10 percent of field construction activities add value. According to lean manufacturing standards, NVA activities consume between 50-75 percent of the productive time and NVAR work on the typical construction job consumes between 20-25 percent of the productive time, which is much higher than that experienced at a typical manufacturing plant. (RS191-1, p 16)
Waste in Construction Processes include:
- Excessive material handling
- Rework
- Design errors
- Conflicts between trades
- Conflicts between other contractors
- Ineffective supply chains
2 : Differences Between Construction and Manufacturing
The research notes similarities and differences between “manufacturing principles” and “construction principles.” Below are samples of the findings. The complete list is detailed in the research. (RS191-1, p 5)
Customer Focus
- Constructors do not control the entire supply chain.
- The largest constructors control only one percent of the market, whereas in manufacturing the largest manufacturers may control 20 percent or more.
Culture/People
- High turnover results in less opportunity for training.
- Construction workers are craft skilled; in manufacturing they are process specialized.
Workplace Standardization
- Construction has a fluid organization at the project level.
- The configuration of the production environment changes all of the time, more difficult to maintain visual management systems.
Elimination of Waste
- To a large extent the production sequence is discretionary.
- Material flow is not steady-state; supply lines are different at different project locations.
Continuous Improvement/Built-in Quality
- High turnover/less opportunity for training.
- Ability to develop a quality-tracking program is difficult.
The primary issue common to this list is the much greater degree of discretionary behavior and larger amounts of uncertainty that is evident in construction. Whereas in manufacturing, production systems are defined by and controlled by the configuration of the production line, in construction the production system is defined by project managers and the individual workers.
3 : Reasons for Applying Lean Principles to Construction
Regarding the construction production process, this research indicates that typically construction activities are only 10 percent value adding. If a contractor could improve the value-adding portion to just 5, 10, 15, or 20 percent, the lean contractor would have a significant competitive advantage. (RS191-1, p 17)
Rewards to “Go Lean”
- Reduce waste / improve efficiency
- Improve safety
- Lower cost
- Reliable Schedules
- Fewer defects / less rework
5 : Path Forward to Becoming Lean
The suggested method of establishing a foundation of lean in an organization is as follows: (RS191-1, p 19)
- Establish management commitment at the highest levels in an organization. If leaders are not committed, the resources to insure that lean is successful are not likely to be available.
- Identify a champion who has a mandate to lead.
- Train personnel at all levels in the theory and practice of lean.
- Identify the improvement opportunities that are specific to the organization. The organizations in this study each found some “targets of opportunity” that could be remedied fairly easily and that these successes helped to spur greater interest in lean.
Once these initial steps have been taken, the following is the suggested path:
- Identify waste in field operations
- Drive out the waste
- Standardize the workplace
- Develop a lean culture
- Get your client involved with the lean transformation
- Continuously improve
6 : Implementation Tool #1
RS191-1, Lean Wheel
The wheel is a tool to simplify and organize the lean principles into a format that is easily communicated to and understood by those new to lean theory. At the highest level the wheel organizes lean ideas into five lean fundamental principles, and is further divided into sub-principles. (RS191-1, p 7)
RS191-1, Lean Principles for Construction
A comprehensive assessment of the applicability of lean construction principles to the construction process.(RS191-1, p.22)