A Study of Lean Construction Practices in Gaza Strip

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Material Productivity = Total Output / Amount of Material Machine Productivity = Value of production / Amount of work (Yahia, 2004). 2.6.9 The Five Why's: Five whys as part of lean manufacturing is a problem solving technique that allows you to get at the root cause of a problem fairly quickly. It was made popular as part of the Toyota Production System (1970’s.) Application of the strategy involves taking any problem and asking “Why - what caused this problem”. The benefits of the 5 Whys are as follows: • It helps to quickly identify the root cause of a problem. • It helps determine the relationship between different root causes of a problem. • It can be learned quickly and does not require statistical analysis to be used. 2.7 Construction Waste A number of definitions of waste are available. In general, Alarcon (1994), Koskela (1992) and Love et al. (1997) argued that all those activities that produce costs, direct or indirect, and take time, resources or require storage but do not add value or progress to the product can be called waste. These waste categories are measured as a function of their costs, including opportunity costs. Furthermore, other types of waste are related to the efficiency of process, equipment or personnel. Non value-added activity (also called waste): Activity that takes time, resources or space but does not add value.(koskela et al., 1992). Waste in the construction industry has been the subject of several research projects around the world in recent years (Formoso et al., 1999). The study by Skoyles (1987) in the UK also suggested that all those involved in the construction process contributed to waste. This includes those who design materials, plant and building; those who specify and communicate, for example, the quantity surveyors and head office staff; and particularly site managers and site operators. Therefore, the responsibility for minimizing waste should be shared by all parties involved in construction projects, including: • All managers in building organizations, not only site managers, • Those who design, manufacture and supply merchandise and plant used in construction, 22
• Those who design buildings, • Those who specify, describe and account for the works, and • Those who provide briefs pay for and use buildings. Graham and Smithers (1996) believed that construction waste could occur during different project phases: • Design (plan errors, detail errors and design changes), • Procurement (shipping error and ordering error), • Materials handling (improper storage, deterioration and improper handling on and off site) • Operation (human error, trades person, labors, equipment error, accidents and weather), • Residual (leftover and irreclaimable non-consumables), and • Other (theft, vandals and clients actions). Despite variations in construction projects, potential material waste is caused by similar inefficiencies in design, procurement, material handling, operation or residual on-site waste such as packaging (Formoso et al., 1993 and Gavilan and Bernold, 1993). Research also indicated that clients could be a source of waste through careless inspection procedures and variation orders during the process. Initially, carelessness at the design stage can lead to excessive waste which creates a need to over order to avoid a shortage of materials on site (Graham and Smithers, 1996). Waste in construction is not only focused on the quantity of waste of materials on-site, but also related to several activities such as overproduction, waiting time, material handling, processing, inventories and movement of workers (Formoso et al., 1999; Alarcon, 1994). Consolidating research from authors (Alarcon, 1995; Alwi, 1995; Koskela, 1993; Robinson, 1991; Lee et al., 1999; Pheng and Hui, 1999), the main categories of waste during the construction process can be described as: reworks/repairs, defects, material waste, delays, waiting, poor material allocation, unnecessary material handling and material waste. In Chile, a research study from 1990 to 1994, focusing on waste was conducted to identify the most relevant factors that produce waste of productive time in building construction works (Serpell et al., 1995). The study concluded that waiting time, idle time and travelling time, indicated as the main subcategory of noncontributory work (waste), explained 87% of the total value of waste. Another 23
Page 1: The Islamic University of Gaza Dean
Page 4 and 5: Acknowledgment I would like to expr
Page 6 and 7: ABSTRACT This research deals with t
Page 8 and 9: 2.5.6 Increase Output Flexibility .
Page 10 and 11: Appendices Appendix (A): Daily Repo
Page 12 and 13: List of Tables Table 2.1: Conceptua
Page 14 and 15: List of Figures Figure 2.1: Reducti
Page 16 and 17: 1.1 Statement of the Problem Most o
Page 18 and 19: 2.1 Lean Construction History Chapt
Page 20 and 21: 2.3 Impact of Lean Construction Acc
Page 22 and 23: Table 2.1 Conceptualization of lean
Page 24 and 25: for measuring the percent plan comp
Page 26 and 27: 2.5.6 Increase output flexibility F
Page 28 and 29: � The more wastes inherent in the
Page 30 and 31: 3. System requires the need to deve
Page 32 and 33: the work flow, material flow, produ
Page 34 and 35: • Straighten Next, materials were
Page 38 and 39: investigation showed that 25 percen
Page 40 and 41: 7. Poor technology of equipment. 8.
Page 42 and 43: 2. Unnecessary material handling. 3
Page 44 and 45: inventory (Wrong storage of materia
Page 46 and 47: Main Activity Mobilization and exca
Page 48 and 49: 4. Sort the candidates in order of
Page 50 and 51: 4.2 Project Activities Lean constru
Page 52 and 53: Table 4.2 represents the resources,
Page 54 and 55: Main Activity Slab work Building wo
Page 56 and 57: 4.4.1 Mobilization and excavation T
Page 58 and 59: 4.4.4 Neck column Table (4.6) shows
Page 60 and 61: 4.4.7 Ground beam The twelve proces
Page 62 and 63: 4.4.10 Ground floor slab The eleven
Page 64 and 65: No. 9 10 11 Table 4.14 Non-value ad
Page 66 and 67: 4.5 Remove or Reduce the Influence
Page 68 and 69: The result by using arena simulatio
Page 70 and 71: Table 4.17 Simulation results No. A
Page 72 and 73: Table 4.17 Simulation results (Cont
Page 74 and 75: 4.5.3 Foundation Table (4.20) shows
Page 76 and 77: 4.5.7 Ground beam Table (4.24) show
Page 78 and 79: 4.5.11 Column first floor Table (4.
Page 80 and 81: 4.6 Identify the Cause of Waste Tab
Page 82 and 83: Percent of value adding time 35% 30
Page 84 and 85: Table 4.33 Total project duration N
Page 86 and 87:
Then, the processes with the greate
Page 88 and 89:
number of workers to 12 workers sho
Page 90 and 91:
Activity Process Ground floor Colum
Page 92 and 93:
Actual project duration was 6000 ho
Page 94 and 95:
Date Process Assigned Process Compl
Page 96 and 97:
5.1 Conclusion Chapter Five Conclus
Page 98 and 99:
References 1. Abudallah Fawaz , (20
Page 100 and 101:
27. Graham, P. and Smithers, G., (1
Page 102 and 103:
51. Serpell, A.; Venturi, A. and Co
Page 104 and 105:
Appendices (A) Daily report Date Ac
Page 106 and 107:
04/09/2003 06/09/2003 07/09/2003 08
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18/12/2003 20/12/2003 21/12/2003 22
Page 110 and 111:
11/04/2004 12/04/2004 13/04/2004 14
Page 112 and 113:
Appendix (B) Arena Simulation Compu
Page 114:
Appendix (C ) Simulation result of
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A Study of Lean Construction Practices in Gaza Strip

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