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Analysis of the Acceleration of Time and Cost of Construction Projects with Additional Work Hours /
Overtime and Labor Using the Time Cost Trade Off
Method Patricia Kanicia Djawu, Ayu Rosita
Faculty of Engineering, Mercu Buana University Jakarta, Indonesia [email protected], [email protected]
Abstract
The existence of significant cost and time deviation on the project indicates poor project management. This research discusses the time acceleration in the implementation of a high rise building project (Hight Rise Building) with the Time Cost Trade Off method. The author will use analysis with two methods, the first is the questionnaire method (validation and reliability tests) with the help of the SPSS program, and the second is the time cost trade off method by comparing the additional work hours of 4 hours (alternative 1) and the addition of labor ( alternative 2) with the help of the Ms. Excel program. With the results of data analysis, the ranking order of each factor that causes project delays is obtained. Factors that are the main cause of delays in the Rr Choco Plant - Banten project, namely design changes by the owner, shortages of manpower, delays in delivery of work equipment, changes in materials, and work accidents to workers. From these factors several alternative solutions have been suggested. As for the time cost trade off analysis, it is found that the estimated time for the acceleration of project implementation is from the normal duration of 93 calendar days, after the crash duration there is an acceleration of the time to 70 calendar days. With a time efficiency of 23 days / 2% of the initial total schedule.
Keywords:
crash duration , project acceleration, questionnaire, SPSS, time cost trade off.
1. Introduction
Controlling construction projects is an activity or systematic effort to determine targets in accordance with planning objectives, comparing implementation with planning, and making necessary corrections so that costs, resources and time can be used effectively and efficiently in order to achieve construction project objectives. which is desired. So that with project control, construction project deviations, losses incurred, and project delays that may occur can be avoided (Duc-Hoc, 2019).
Delays in project work often occur due to differences in site conditions, design changes, weather effects, and errors in planning. Project delays can be anticipated by accelerating (crashing) in its implementation, but must pay attention to the cost factor. It is hoped that the additional costs incurred should be as minimal as possible and still pay attention to quality standards. Acceleration (crashing) of implementation can be done by adding more hours of work, more productive tools, increasing the number of workers, and faster construction methods (Priyo, M., Sumanto, 2016).
In this case study, the project development experienced a delay in work, namely 13.08% of the cumulative plan of 58.10% so that it would result in the postponement of the completion of the Structural and Architectural work, while the Contractor targets the handover of the Building Unit to the Owner in July 2020 and to avoid fines. contractor penalty due to late work. To find a solution to this, it is necessary to carry out an analysis of the acceleration of the implementation of the Structural work so that the project construction can be completed on time.
1.1. Stages of Problem Identification
Per the end of March 2019 based on the weight of the S-Curve, the work progress has a deviation of - 13.08% from the cumulative plan of 58.10%. In addition, the data obtained from the field shows that the workforce from the Formwork subcontract has experienced a very large decline with an average of 15 people in February 2019 and 12 people in August 2019. So that progress has decreased.
1.2. Scope and Limitation of the Problem
In general, the scope to be discussed in this study are as follows:
1. Time acceleration analysis using two methods, namely the questionnaire test method using SPSS 24 and themethod Time Cost Trade Off on projects that are experiencing delays (M.Andi Wahyudi, 2020).
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A
A A A
2. Analysis of costs arising from the acceleration of the duration of the project so that thecan be known direct and indirect costs .
2. Research Methods Study 2.1. Sites The Study
location of the office & workshop construction project Rr Choco Plant - Banten is located in the Cikande area - Banten.
2.2. Data collection
The data needed in this study include:
1. Project planning drawings.
2. Project implementation schedule (time schedule) in the form of an S curve to determine the normal duration in accordance with project implementation.
3. Details of the Cost Budget (RAB) 2.3. Research Process
Figure 1: Flowchart of the Stages of Study
3. Results and Discussion of 3.1. Independent
Variables Variables in a study consist of several components, namely the treatment, factors and attributes that are studied and a conclusion will be drawn from the results of the research assessment. Based on the literature study the research variables can be seen in the following table:
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Tabel 1. Independent Variable / Sub
Variable Indicator
Techical
(X1) Change in design during implementation
(X2) Lack of rough manpower (builders)
(X3) Lack of trained manpower and management to support construction implementation
(X4) Productivity of work equipment
(X5) Productivity of use heavy equipment as a supporting tool
(X6) Design errors made by planners
(X7) Delays in delivery of work equipment
(X8) Change in material from, function and spesification
(X9) Delays in material delivery
(X10) Owner delays in decision makin
(X11) Procedure long material inspection
(X12) Problems that occur during implementation
(X13) Lack of worker supervision
(X14) There are material change by the Owner, due to design errors by the planner
(X15) Work accidents that occur to workers
(X16) Lack of worker attendance
(X17) Incompleteness of providing detailed shopdrawing / work drawings
(X18) Experience of field managers
(X19) Lack of design of engineering planner (X20) Difficulty in installing certain materials
Non Teknis
(X21) Convoluted biocracy in project operations (X22) Negotiation and licensing on contracts
(X23) Lack of communication between owners and planners in planning (X24) Amount of material used unsuitable supplier sent
(X25) Conflict between contractor and consultant (X26) Financial administration to contractor
(X27) Material price increased, insuffcient allocation of funds
(X28) Late payment of workers
(X29) Payment system for workers not according to contract, due to reasons certain
(X30) Poor quality of materials
(X31) Damage to materials in storage
(X32) Insufficient contractor capital
(X33) Quality of work control
(X34) Level of labor wages
(X35)
There is theft of work equipment in the field
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Table 2. Independent Variables
Variable / Sub Variable Code Indicator
Non-Technical (X21) Convoluted biocracy in project operations (X22) Negotiation and licensing on contracts
(X23) Lack of communication between owners and planners in planning (X24) Amount of material used unsuitable supplier sent (X25) Conflict between contractor and consultant (X26) Financial administration to contractor
(X27) Material price increased, insuffcient allocation of funds
(X28) Late payment of workers
(X29) Payment system for workers not according to contract, due to reasons certain
(X30) Poor quality of materials
(X31) Damage to materials in storage
(X32) Insufficient contractor capital
(X33) Quality of work control
(X34) Level of labor wages
(X35) There is theft of work equipment in the field
3.2. Descriptive Statistical Test The
results of descriptive analysis are presented in each variable. The following is a tabulation of the results of the descriptive analysis of the independent variable (X) for the factors that cause delays in a construction project which can be seen in the table below:
Table 3. Results of the Analysis of
Rank Variable Indikator Sum Mean
1 Change in design during implementation X.1 168 4.54
2 Lack of rough manpower (Builders) X.2 144 3.89
3 Delays in delivery of work equipment X.7 141 3.81
3.3. Cost and Time Exchange Analysis with Additional Hours of Work / Overtime
To facilitate understanding Regarding the results of the analysis that has been carried out can be seen in Table below:
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Table 4. Results of Rank Analysis
No Work Item Work Volume Duration of
work
Total
A B (A:B) = C
A. Productivity / Day ( Before Crashing )
1 Work under struktur
- Work Concrete 9.61 m³ 70 day 13.73 m³/day
(Concrete pile cap, TieBeam, Pedestal Column, PitLift)
2 Work upper structure ( 1St Floor - Rooftop)
- Work Concrete 13.73 m³ 93 day 14.76 m³/day
- Iron Work 1.41 kg 93 day 15.19 kg/day
- Work formwork work 1.19 m' 93 day 12.83 m'/day B. Produktivitas / Jam (Sebelum Crashing)
1 Pekerjaan Struktur Bawah
- Pekerjaan Beton 13.73 m³ 8 jam 1,716 m³/jam (Beton Pile Cap, TieBeam, Kolom Pedestal,
PitLift) 2 Pekerjaan Struktur Atas (Lantai 1 s/d
Lt.Atap)
- Pekerjaan Beton 19.61 m³ 8 jam 2,451 m³/jam - Pekerjaan Pembesian 2.18 kg 8 jam 27.25 kg/jam - Pekerjaan Bekisting 17.04 m' 8 jam 2,130 m'/jam C. Produktivitas / Hari (Sesudah Crashing)
1 Pekerjaan Struktur Bawah
- Pekerjaan Beton 13,731 m³/hari
(Beton Pile Cap, TieBeam, Kolom Pedestal, PitLift)
2 Pekerjaan Struktur Atas (Lantai 1 s/d Lt.Atap)
- Pekerjaan Beton 19,611 m³/hari
- Pekerjaan Pembesian 2,289 kg/hari
- Pekerjaan Bekisting 17,041 m'/hari
D. Crash Duration 1 Pekerjaan Struktur Bawah
- Pekerjaan Beton 49.00 hari
(Beton Pile Cap, TieBeam, Kolom Pedestal, PitLift)
2 Pekerjaan Struktur Atas (Lantai 1 s/d Lt.Atap)
- Pekerjaan Beton 70.01 hari
- Pekerjaan Pembesian 61.73 hari
- Pekerjaan Bekisting 70.01 hari
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Table 5. Results of Rank Analysis
No Work Item Work Volume Duration of
work
Total
A B (A:B) = C
B. Productivity / Hour (Before Crashing)
1 Work under struktur
- Work Concrete 13.73 m³ 8 hour
1,716
m³/hour (Concrete pile cap, TieBeam, Pedestal Column,
PitLift) 2 Work upper structure ( 1St Floor -
Rooftop)
- Work Concrete 19.61 m³ 8 hour 2,451 m³/hour
- Iron Work 2.18 kg 8 hour 27.25 kg/hour
- Work formwork work 17.04 m' 8 hour 2,130 m'/hour C. Productivity / Day (After Crashing)
1 Work under struktur
- Work Concrete 13,731 m³/day
(Concrete pile cap, TieBeam, Pedestal Column, PitLift)
2 Work upper structure ( 1St Floor - Rooftop)
- Work Concrete
19,611
m³/day
- Iron Work 2,289 kg/day
- Work formwork work 17,041 m'/day
D. Crash Duration
1 Work under struktur
- Work Concrete 49.00 day
(Concrete pile cap, TieBeam, Pedestal Column, PitLift)
2 Work upper structure ( 1St Floor - Rooftop)
- Work Concrete 70.01 day
- Iron Work 61.73 day
- Work formwork work 70.01 day
a. Calculating daily productivity, with the formula: Prod. Day = Volume / Duration of Work b. Calculating productivity per hour, with the formula: Prod. . Per Hour = Prod. Day / 8 Hours c. Calculate daily productivity after crash.
d. = (8 hours x prod. Per hour) + (decrease in performance x prod. Per hour)
e. Calculating crash duration, with the formula: Crash Duration = Vol. /Prod. Day After Crash f. Calculating the total crash cost
g. As for the calculation of costs due to additional working hours, overtime can be formulated as follows:
Normal wages of workers per day = Productivity per day x Unit price of workers Normal wages of workers per hour = Productivity per hour x Unit price wages of workers 4 hours of worker's overtime costs =
(1.5 x normal hourly wages (first hour of overtime) + (2n x normal hourly wages (for the next hour of overtime)wages per day
Crashcost of workers'=Normal wages of wages per day + cost of overtime per day
Total crash cost = Crashcostper day x crash duration
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Table 6. Results of Rank Analysis N
o
Analysis Method
Normal Duratio
n (Hari)
Crash Duratio n (Hari)
Normal Cost (Rp)
Crash Cost (Rp)
Time Efficienc
y
Cost Efficienc
y
Research Result
1 Additional 4 hours of overtime
work (alternative1
)
93 70
7,065,423,055.5 8
7,852,222,213.1
7
2% -7,0% - Normal Duration:
93 days --> Crash Duration: 70 days; -
Normal Cost:
7,065,423,055.58 -->
Crash Cost:
7,850,470,061.75; - Time Efficiency: 2%;
- Cost Efficiency: - 7,0%
2 Additional
workforce (Alternative
2)
93 70
7,065,423,055.5 8
7,983,031,179.7
9
2% -7,1% Normal Duration: 93 days --> Crash Duration: 70 days; -
Normal Cost:
7,065,423,055.58 -->
Crash Cost:7,983,031,184.0
0; TimeEfficiency:
2%; Cost Efficiency:7,1%
4. Conclusions and Suggestions 4.1. Conclusion
a. Factors Causing Delays in Work in the Choco Plant Project - Banten
The results of the questionnaire test above obtained the ranking order of each variable, which can be seen in the following table:
Table 7. Independent Variables (Continued)
Rank Variable Indikator Sum Mean
1 Change in design during implementation X.1 168 4.54
2 Lack of rough manpower (Builders) X.2 144 3.89
3 Delays in delivery of work equipment X.7 141 3.81
b. Project Implementation Costs After Acceleration
The results of the above analysis show that the estimated time for the acceleration of project implementation is from the normal duration of 93 calendar days, then after the crash duration there is an acceleration of the time to 70 calendar days. With a time efficiency of 23 days / 2%.
1. Method of adding 4 hours of overtime work (Alternative 1)
From the normal cost of Rp. 7,065,423,055.58, - (excld VAT), then after the crash cost there was an increase in costs to Rp. 7,852,222,213.17, - (excld VAT). With an over cost of Rp. 786,799,157.59, - / 7.0%.
The cost slope is Rp. 34.208,659.03, - 2. Method of adding labor (Alternative 2)
From the normal cost of Rp. 7,065,423,055.58, - (excld VAT), then after the crash cost there was an increase in costs to Rp. 7,983,031,179.79, - (excld VAT). With an over cost of Rp. 917,608,124.21, - / 7.1%
Cost slope of Rp. 39.896.005.40, -
4.2. Suggestion
Based on the results of the accelerated duration analysis that has been carried out, it can be suggested as follows:
1. It is expected that in the implementation of the project it can pay attention to the work included in the critical trajectory which allows delays in theschedule implementation.
2. Performing routine supervision & control is also maximized, as well as recording the actual progress then comparing it to the planned activity time.
3. Make regular daily, weekly & monthly reports.
115 Refferences
Duc-Hoc, D. (2019). Multi Objective Symbiotic Organisms Optimization For Making Time Cost Trade Off in Repetitive Project Scheduling Problem, National Taiwan University of Science and Technology, Taiwan.
M.Andi Wahyudi. (2020). Analisis Percepatan Proyek Menggunakan Metode Cost Trade off. Dengan Penambahan Jam Kerja Lembur Dan Tenaga Kerja Menggunakan Metode Time Cost Trade Off’.
Universitas Mercu Buana.
Priyo, M., Sumanto, A. (2016). ):Analisis Percepatan Waktu Dan Biaya Proyek Konstruksi DenganPenambahan Jam Kerja (Lembur) Menggunakan Metode Time Cost Trade Off: Studi Kasus Proyek Pembangunan Prasarana Pengendali Banjir. Universitas Muhammadiyah.
