A Study of Lean Construction Practices in Gaza Strip

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3. System requires the need to develop general accounting systems, special cost system, and general costs concepts System. 4. Some company do not accept the idea of the application of the system of production costs in time because of its high cost, which occur at the beginning of the application of this system by the preparation of administrators and workers and by changing company dealings with both suppliers and customers. 5. Administrators are not convinced about the change from existing systems to a system of production costs in time because they fear its application failure. 6. Closures is the biggest problem facing the economic side to provide materials as the stock in this system is equal to zero, and in the case of the closure, we will not find materials to be used by the contractor and consequently activities are halted. 2.6.2 Last Planner System Ballard (2000) indicates that Last Planner System (LPS) is a technique that shapes workflow and addresses project variability in construction. The Last Planner is the person or group accountable for operational planning, that is, the structuring of product design to facilitate improved work flow, and production unit control, that is, the completion of individual assignments at the operational level. In the last planner system, the sequences of implementation (master schedule, Reverse Phase Schedules (RPS), six-week look ahead, Weekly Work Plan (WWP), Percent Plan Complete (PPC), constraint analysis and variances analysis). The goals of last planner are to pull activities by reverse phase scheduling through team planning and optimize resources in the long-term. This tool is similar to the Kanban system and production leveling tools in lean manufacturing. 2.6.2.1 Master Schedule The master schedule is an overall project schedule, with milestones, that is usually generated for use in the bid package. RPS is produced based on this master schedule. 2.6.2.2 Reverse Phase Scheduling (RPS) Ballard and Howell (2003) indicated that a pull technique is used to develop a schedule that works backwards from the completion date by team planning; it is also called Reverse Phase Scheduling (RPS). They also state that phase scheduling is the link between work structuring and production control, and the purpose of the phase schedule 16
is to produce a plan for the integration and coordination of various specialists’ operations. The reverse phase schedule is developed by a team consisting of all the last planners. It is closer to reality than the preliminary optimal schedule which is the master schedule. However, without considering actual field factors in the RPS, the RPS is less accurate than the WWP. 2.6.2.3 Six-Week Look Ahead (SWLA) Ballard (2000) indicated that the tool for work flow control is look ahead schedules. SWLA shows what kinds of work are supposed to be done in the future. In the look ahead window, week 1 is next week, the week after the WWP meeting. The number of weeks of look ahead varies. For the design process, the look ahead window could be 3 to 12 weeks (Ballard 2000). All six-week-look ahead durations and schedules are estimated based on the results of the RPS, and constraints are indicated in order to solve the problems before the actual production takes place. SWLA is distributed to all last planners at WWP meetings. Lean look ahead planning is the process to reduce uncertainty to achieve possible constraint free assignments (Koskela et al., 2000). 2.6.2.4 Weekly Work Plan (WWP) Should, Can, and Will are the key terms in WWP (Ballard 2000). Weekly Work Plan (WWP) is produced based on SWLA, the actual schedule, and the field condition before the weekly meeting. Along with this plan, manpower from each trade will be adjusted to the need. • Should: Indicates the work that is required to be done according to schedule requirements. • Can: Indicates the work which can actually be accomplished on account of various constraints on the field. • Will: Reflects the work commitment which will be made after all the constraints are taken into account. The WWP meeting covers the weekly schedule, safety issues, quality issues, material needs, manpower, construction methods, backlog of ready work, and any problems that can occur in the field. It promotes two-way communication and team planning to share information on a project in an efficient and accurate way. It can improve safety, quality, 17
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 32 and 33: the work flow, material flow, produ
Page 34 and 35: • Straighten Next, materials were
Page 36 and 37: Material Productivity = Total Outpu
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
Page 108 and 109:
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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