10. Conclusion
This research seeks to confirm the following objectives: (1)
Determine the implementation of lean ideal; (2) Identify the
source of wastes classified under lean construction industry;
(3) Examine general perceptions of the construction industry
with the lean construction principles of practices; (4) Study
reduction and elimination of wastes as classified under development
of Last Planner System as a technique of lean construction
implementation and to evaluate the effectiveness of
implementing last planner to increase plan reliability; (5)
Examine the relationship between lean construction and performance
improvement programs in construction organizations;
and (6) Analyze the characteristics of successful
performance improvement programs, and develop a model
that identifies three critical elements: (a) Time spent on
improvement, (b) Improvement skills and mechanisms, and
(c) Improvement perspective and goals. The authors identify
different ways to structure improvement program: outcome focused
(such as Critical Success Factors) and process-focused
(such as Lean Construction). The paper discusses the implications
of the different perspectives and argues that they lead to
different improvement approaches each reflecting different
paradigms for the nature of the change. The authors propose
that result-focused improvement programs may be a barrier
to the adoption of Lean Construction. The paper proposed a
dynamic model of performance improvement process. The
model examined the factors affecting the process and their
interactions. The paper proposed that: (1) Direction of the
improvement effort is strongly influenced by the structure
and goals; and (2) Result-focused programs have limited ability
to address complex systemic problems. One question for future
research is what drives a contractor to establish a resultfocused
or a process-focused program. It appears that specialty
contractors are more familiar with the process-perspective
because of their familiarity with productivity
improvement studies (which is a process analysis of a relatively
simple problem). On the other hand, general contractors are
more likely to emphasize overall project results. Future research
also needs to (1) Develop and validate a more complete
model of performance improvement; (2) Further examine the
behavior of improvement process over time; and (c) Use the
model as a starting point for system redesign by adding loops
and breaking links.