5. Construction wastes
Construction management suffers many problems and the
majority is practical which need to be solved or better understood.
As a result, the construction industry is overwhelmed
by delay and often has suffered cost and time overrun. Alsehaimi
and Koskela [35] reported that the poor project management
was a dominant and common reason for delay in
construction projects. Consequently, these problems associated
with management, in particular, should be understood,
and efforts need to be directed toward developing solutions
and more efficient methods of operation [36]. The introduction
of new production philosophies in construction requires new
measures of performance Koskela [3], such as waste, value, cycle
time or variability. UK studies indicated that up to 30% of
construction is rework, only 40–60% of potential labor effi-
ciency, accidents can account for 3–6% of total costs, and at
least 10% of materials are wasted. The cost of rework in Australian
construction projects has been reported as being up to
35% of total project costs and contributes as much as 50% of a
project’s total overrun costs. In fact, rework is one of the primary
factors contributing to the Australian construction
industry’s poor performance and productivity [37]. In general,
a very high level of wastes/non-value added activities is assumed
to exist in construction, and it is difficult to measure
all waste in construction. Several partial studies from various
countries have confirmed that wastes in construction industry
represent a relatively large percentage of production cost. The
existences of significant number of wastes in the construction
have depleted overall performance and productivity of the
industry, and certain serious measures have to be taken to rectify
the current situation. Waste measures are more effective to
support process management, since they enable some operational
costs to be properly modeled and generate information
that is usually meaningful for the employees, creating conditions
to implement decentralized control. Fig. 3 shows the
waste percentages of time in manufacturing and construction.
Waste has been defined by Alarcon [39] as ‘‘Anything different
from the absolute minimum amount of resources of
materials, equipment and manpower, necessary to add value
to the product.’’ In general, any losses produced by activities
that generate direct or indirect costs but do not add value to
the product from the point of view of the client can be called
‘‘waste.’’ Waste is measured in terms of costs; other types of
waste are related to the efficiency of the processes, equipment
or personnel, and are more difficult to be measured because the