Optimization of The Use Truck Mixer on The

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Optimization of The Use Truck Mixer on The

Effectiveness of 3 Batching Plant PT Wijaya Karya Beton Ready Mix Concrete – High Speed Railway Project

Febby Dwiyanti Afriyani, Anjas Handayani

Faculty of Civil Engineering and Planing, University of Mercubuana Jakarta, Indonesia

[email protected], [email protected]

Abstract

The demands of high productivity make each Batching Plant has a big target to be achieved. In addition, the longer the use of the tools used, the greater the costs that must be incurred. The purpose of this paper is to analyze the need for the number and type of truck mixers needed to be more effective and efficient. The data used in this study are primary and secondary data, which are then mapped from each truck mixer in each batching plant by making 3 alternatives. The method used in this research is the literature method, the observation method and the interview method. The calculation results from this study obtained the optimal time needed to complete the Ready Mix Concrete - High Speed Railway project, which is 253 days or about 8 months 13 days with the operating cost of using a mixer truck of Rp 20,529,650,218, cheaper than the real condition. in the field, which is Rp.

22,426,477,127, the difference is Rp. 1,896,826,909 with a cost efficiency of 8,458 %. With the composition of heavy equipment mixer trucks, namely 17 units at Batching Plant Karawang, 11 units at Batching Plant Baros, and 10 units at Batching Plant Walini.

Keywords:

Composition, Cost, Productivity, Time, Truck Mixer

1. Introduction

Projects that can generally be defined as specific activities that are limited by time, human resources, tools, materials and money, with the presence of tools are very helpful, where projects have very limited time and their implementation is accelerated (Febrianti & Zulyaden, 2017). The use of heavy equipment in foundry work will certainly increase the cost of carrying out the work, therefore, the use of heavy equipment on projects is very necessary, especially in foundry work because it is very helpful to complete the casting so that the planned time can be achieved maximally (Jawat & Rahadiani, 2018).

With high productivity demands, each Batching Plant has a big target to achieve. In addition, the longer the use of the tools used, the greater the costs that must be incurred. For this reason, it is necessary to analyze the number and type of truck mixer usage needed to be more effective and efficient (Semaan 2016).

It is known that the implementation of the Ready Mix Concrete – High Speed Railway project has a planned production volume of concrete supply in the period of March 2020 of 118,826 m³ of a total volume of 1,220,000 m³ in 3 Batching Plants. However, the realization recorded in the March 2020 period was only 47,676 m3. Based on the plan data and the realization of the concrete supply, there has been a delay.

Based on the plan data and the realization of the concrete supply, there has been a delay. With different casting distances in each batching plant and the composition of heavy equipment mixer trucks, there are only 38 units and unevenly spread over 3 Batching Plants. So, it becomes interesting to study so that an analysis can be carried out in order to optimize the composition of the use of mixer trucks in the 3 Batching Plants by maximizing the number of existing units. In this research, a deeper study will be conducted regarding the optimal cost and time required for each batching plant.

1.1. Learn Literature 1. Project Management

Project management is planning, organizing, leading, and controlling company resources to achieve predetermined short-term goals. Project management grew because of the urge to seek a management approach that suits the demands and nature of project activities, an activity that is dynamic and different from routine operational activities. The project management concept requires a single person in charge who serves as a central source of information related to the project, integrator, and coordinator of all activities and participants according to the interests and priorities of the project.

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The concept of project management also aims to create an era of linkage between planning and control. This is mainly due to the rapid change in activities and takes place only once. The formulation and implementation of the project management concept through gradual evolution starting from the expediter, coordinator, to the form we currently encounter (soeharto 1999)

2. Construction Management

Construction management is an effort carried out through a management process, namely planning, implementing and controlling project activities from start to finish by allocating resources effectively and efficiently to achieve a satisfactory result according to the desired target. Management in a construction is a tool to streamline and streamline activities on the project. The parameters used are time and cost functions of each construction project activity. (Nugraha 1985)

3. Heavy Equipment Management

Machine selection and control management is the process of planning, organizing, leading and controlling the machine to achieve the specified job objectives. Several factors must be considered in the selection of heavy equipment, so that errors in equipment selection can be avoided, including: the function to be carried out, the capacity of the equipment, the operating method, the limitations of the method used, the economy, the type of project, the project location, the type and power support soil and field conditions. (Fatena Rostiyanti 2008)

a. Heavy Equipment Functional Classification

What is meant by functional classification of tools is the division of these tools based on the main functions of the tools. Based on their function, heavy equipment can be divided into seven basic functions, including land processing equipment such as dozers, scrapers, and motor graders; digging tools such as excavators, backhoes, draglines, and clamshells; material transport equipment such as dump trucks and cranes; material transfer equipment such as loaders and dozers; compaction tools such as tamping rollers, pneumatic-tired rollers, and compactors; material processing equipment such as crusher, concrete batch plant and asphalt mixing plant; material finishing equipment such as concrete spreader, asphalt paver, motor grader and compactor. (Fatena Rostiyanti 2008)

b. Heavy Equipment in Various Construction Project

Every construction project requires several types of heavy equipment, but not all existing machines. The types of projects that generally use heavy equipment are building projects, ports, roads, irrigation, and others.

(Fatena Rostiyanti 2008)

c. Definition of Heavy Equipment

Heavy equipment is a large machine designed to carry out construction functions such as earthworks and moving building materials. Heavy equipment generally consists of five components, namely the implement, traction device, structure, power source and transmission (power train), and control system.

d. Truck Mixer

Truck mixer (concrete mixer) is a tool/machine used to mix and deliver bulk concrete. Mixer trucks or commonly known as molen trucks have various types with the same function, namely transporting concrete from one location to another by maintaining the consistency of the concrete so that it remains liquid and does not harden in transit. Truck mixer is a special transportation tool for ready mix concrete which is used to transport ready mix concrete from the Batching Plant to the foundry location. (Hidayat Saefudin, Achmad Mudianto 2004)

4. Heavy Equipment Source

In the world of construction, heavy equipment used can come from various sources, including heavy equipment purchased by contractors, heavy equipment leased by contractors, and heavy equipment leased by contractors. (Fatena Rostiyanti 2008)

5. Definition of Productivity

Productivity is defined as the ratio between output and input, or the ratio between production output and total resources used. In construction projects, the productivity ratio is the value measured during the construction process, can be separated into labor costs, materials, money, methods, and tools. The success or failure of a construction project depends on the effectiveness of resource management. (Febrianti, D., & Zulyaden, 2017) 6. Cost Efficiency

According to P.Malayu (1994) efficiency is "the best comparison between inputs (inputs) and outputs (results), between benefits and costs (between the results of implementation and the sources used), as well as optimal results achieved with the use of limited resources". The budget that has been made by management should be analyzed further, whether it needs to be done efficiently or not in its implementation later. Efficiency of the budget is a form of control carried out by the company against the budget that has been made before the work is carried out.

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7. Construction Project Delay

Delays in construction projects can be minimized when the cause can be identified. In dealing with the possibilities that occur during project implementation, appropriate steps must be prepared. Barriers that can cause delays in time performance on construction projects include: ineffective and efficient allocation of resource placement, limited number of workers, insufficient equipment, bad weather conditions, and inappropriate work methods. (Kiswati, S., & Chasanah 2019)

2. Research Methodology

In this research, the data sources needed are primary data and secondary data. The method used in this research is the literature method, observation method and interview method. The dependent variable used in this study is the optimization of the amount of heavy equipment used for truck mixers, while the independent variables are the cost of using the tool and the productivity of the tool. The results of the selection of these variables come from interviews and analysis of planning and realization.

3. Result and Analysis

3.1. Data Description

The data used in this study are primary and secondary data. Primary data is data obtained directly from direct observations in the field, while secondary data itself is data obtained from agencies related to this research. Based on a survey conducted directly in the field, some data obtained in the field in the form of truck mixer cycle time data, mixer truck rental prices, fuel prices, casting volume, casting distance, tool working hours and so on.

The amount of heavy equipment truck mixers in the original conditions in the field (existing) used in each batching plant is different. The Batching Plant Karawang has 4 mixer truck units, the Baros Batching Plant has 16 truck mixer units, and the Walini Batching Plant has 18 truck mixer units. With a total number of truck mixers in 3 batching plants, there are 38 units. For standard working hours applicable in each batching plant in one day is 7 hours/day.

3.2. Data Analysis 1. Cycle Time Calculation

The data in the cycle time such as loading time, filled vehicle travel time, empty vehicle travel time, loading and unloading time is obtained by observing in the field and calculating the time using a stopwatch. Example on a truck mixer Y01:

Load time (Cms) = 5,767 minutes

Transport time to project site (tam) = 104,582 minutes Return time from project site (tk) = 64,549 minutes Unloading time (tb) = 7,231 minutes

Unloading waiting time (tt) = 3,483 minutes Cm = Cms+ tam+ tk + tb + tt

Cm = 5,767+ 104,582+ 64,549+ 7,231+ 3,483 Cm = 185,607 menit

2. Truck Mixer Productivity Calculation

In calculating the productivity of the mixer truck, a direct review of the cycle time is carried out. This is done because the path passed by the mixer truck has different terrain and the speed of the mixer truck is not stable, so a direct review is needed so that the calculations are in accordance with the conditions in the field. The following is the productivity calculation on the truck mixer Y01:

Truck mixer work efficiency (Et) = 0,75

Cycle time (C_mt) = 185,607 minutes P = ((60×E_t)/C_mt)×M

P = ((60×0,75)/185,61)×1 P = 0,242 m³/minutes 3. Time Duration Calculation

The following is the calculation of the time duration at the Batching Plant Karawang :

Volume = 400.000 m³

Average machine productivity = 0,242 m³/menit

Heavy equipment usage time = (Volume)/( Average machine productivity) Heavy equipment usage time = (445.202 m³)/(0,242 m³/minutes × 4 units) Heavy equipment usage time = 413.848,371 minutes

= 985 days (working hours 1 day is 7 hours)

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Table 1 Calculation of Time Duration of Real Conditions in the Field

Batching Plant Volume Average

Productivity

Number of

Tools Time Duration

(m3) (m3/minute) (unit) (day)

Plant Karawang 400.000 0,242 4 985

Plant Baros 420.000 0,359 16 174

Plant Walini 400.000 0,421 18 126

4. Fuel Cost Calculation

The use of fuel used is obtained from a recap of usage records taken from each mixer truck driver. Fuel consumption per hour is calculated from fuel consumption per month divided by the hour meter truck mixer per month. The following is the calculation of the cost of the truck mixer Y01 fuel :

Fuel consumption / hour = 13,11 liters Unit price = Rp 7.859

Fuel cost = fuel consumption per hour × fuel unit price = 13,11 liters × Rp 7.859

Fuel cost = Rp 103.065 /hour

5. Lubricating Oil, Grease and Filter Cost Calculation

The amount of lubricant used is very dependent on the size of the engine, the capacity of the oil crankcase, the state of the piston rings and the length of time for replacement. The following is the calculation of the cost of using lubricants obtained from data on the use of lubricants in the field at the Batching Plant Karawang :

Lubricant usage / day = 1,333 liters Unit price = Rp 69.444

Lubricant Cost /day = 1,333 liters × Rp 69.444 = Rp 92.593/hari = Rp 3.858/hour Tire Cost Calculation

The following is the calculation of the cost of tires at the Batching Plant Karawang : Hourly tire usage = (Tire price)/( Estimated tire life )

Hourly tire usage = (Rp 4.656.000)/(6.840 hours) Hourly tire usage = Rp 681,00 /hour

6. Repair Cost Calculation

In calculating the repair cost, an estimated working hours per year is needed, obtained from the real working hours of the tool per month multiplied by 12 months in one year. The following is the calculation for repair costs on the truck mixer Y01:

Heavy equipment working hours in one year = 2.258,4 jam

Heavy equipment price = Rp 1.095.000.000

Repair cost = (Heavy equipment price ×90% (work hard)/60% (light work))/( standard heavy equipment hours per

year) (Rp/hour)

Repair cost = (Rp 1.095.000.000 ×60%)/(2.258,4 hours) Repair cost = Rp 290.914 / hour

7. Operator Salary Calculation

Operator salaries are paid every month with a different nominal between batching plants. The nominal sample is taken in accordance with the local UMK based on Government Regulation Number 78 of 2015 concerning Wages. The following is a list of operator salary calculations:

Table 2 Operator Salary Calculation

Tools Name

The Amount of

Operator

Operator Salary /Month

Total Operator Salary

Total Operator

Salary

Total Operator Salary

(Person) (Rp) (Rp/month) (Rp/day) (Rp/hour)

Plant Karawang 2 Rp 4.594.324 Rp 9.188.648 Rp 306.288 Rp 43.755 Plant Baros 2 Rp 3.139.274 Rp 6.278.548 Rp 209.285 Rp 29.898 Plant Walini 2 Rp 3.145.427 Rp 6.290.854 Rp 209.695 Rp 29.956 3.3. Alternative Analysis Calculation

1. Analysis of Real Conditions in The Field At the Batching Plant Karawang :

Number of real tools in the field (n) = 4 units

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Productivity per truck mixer in the field (Q)= 0,242 m³/minutes

Productivity of all tools = Q x n

= 0,242 m³/minutes x 4 units

= 0,97 m³/minutes

Total duration of work time = 985 days = 6.897 hours Tool rental fee per hour = Rp 300.000 x 4 units

= Rp 1.200.000 /hour

Tool operating costs per hour = Fuel cost + lubricant cost + tire cost + repair cost + operator cost

= Rp 428.334 /hour

Total cost of tools = (tool rental fee per hour + tool operating costs per hour) x duration Total cost of tools = (Rp 1.200.000 + Rp 428.334) x 6.897 hours

Total cost of tools = Rp 11.231.387.166

In the same way, calculate the total cost of equipment at the baros batching plant and the walini batching plant. So the total cost of equipment for 3 batching plants is Rp. 22,426,477,127 with the longest duration at BP Karawang with 6,897 hours which is converted to 985 days (33 months) if the policy of working hours in 1 day is 7 hours. For a complete recapitulation of real conditions in the field, see the following table :

Table 3 Recapitulation of Total Equipment Costs in Real Conditions in the Field

Batching Plant

Volum e

Numb er of Tools

Productivi ty Per

Tool

Time Duratio

n

Time Duratio

n

Biaya Sewa Alat

Operating Cost

Total Cost of Tools (m3) (unit) (m3/minut

e)

(minut

e) (hour) (Rp/hour) (Rp/hour) (Rp) Plant

Karawang

400.00

0 4 0,242 413.84

8 6.897 Rp

1.200.000

Rp 428.334

Rp 11.231.387.166 Plant Baros 420.00

0 16 0,359 73.135 1.219 Rp

4.800.000

Rp 269.067

Rp 6.178.804.830 Plant Walini 400.00

0 18 0,421 52.773 880 Rp

5.400.000

Rp 303.217

Rp 5.016.285.131

TOTAL Rp

22.426.477.127 2. Alternative Analysis 1

It is known that the number of truck mixers in real field conditions in 3 batching plants is 38 units. The following are some alternative calculations that will be analyzed based on the calculation of tool productivity and equipment operating costs by simulating the number of truck mixer needs in each batching plant.

At the Batching Plant Karawang :

Number of alternative tools (n) = 11 units Productivity truck mixer (Q) = 0,242 m³/minutes Productivity of all tools = Q x n

= 2,658 m³/minutes

Total duration of work time = (400.000 m³)/(2,658 m³⁄minutes)

= 150.490 minutes = 2.508 hours = 358 days

Tool rental fee per hour = Rp 300.000 x 11 units

= Rp 3.300.000 /hour

= Rp 428.334 /hour

In the same way, also calculate the total cost of equipment at the baros batching plant and the walini batching plant with the number of alternative tools that have been determined. With the productivity of each truck mixer and equipment operating costs per hour that are fixed, so the total cost of equipment for 3 batching plants is Rp. 20,716,107,473 with the longest duration at BP Karawang with 2,508 hours which is converted to 358 days or 12 months if policy working hours in 1 day is 7 hours. For a complete recapitulation of alternative 1 analysis, it can be seen in the following table:

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Table 4 Alternative Analysis Recapitulation 1 Batching

Plant

Volum e

Numb er of Tools

Productivi ty Per

Tool

Time Duratio

n

Time Duratio

n

Biaya Sewa Alat

Operating Cost

e)

(minut

e) (hour) (Rp/hour) (Rp/hour) (Rp) Plant

Karawang

400.00

0 11 0,242 150.49

0 2.508 Rp

3.300.000

Rp 428.334

Rp 9.351.301.868 Plant Baros 420.00

0 16 0,359 73.135 1.219 Rp

4.800.000

Rp 269.067

Rp 6.178.804.830 Plant Walini 400.00

0 11 0,421 86.356 1.439 Rp

3.300.000

Rp 303.217

Rp 5.186.000.775

TOTAL Rp

= 4,108 m³/minutes

Total duration of work time = (400.000 m³)/(4,108 m³/minutes)

= 97.376 minutes = 1.623 hours = 232 days

= Rp 5.100.000 /hour

= Rp 428.334 /hour

In the same way, also calculate the total cost of equipment at the baros batching plant and the walini batching plant with the number of alternative tools that have been determined. With the productivity of each truck mixer and fixed hourly equipment operating costs, the total equipment cost for 3 batching plants is Rp.

20,529,650,218 with the longest duration at BP Baros with 1,773 hours which is converted to 253 days or 8 months.

days if the policy of working hours in 1 day is 7 hours. For a complete recapitulation of alternative 2 analysis, see the following table :

Table 5 Alternative Analysis Recapitulation 2

Batching Plant

Volum e

Numb er of Tools

Productivi ty Per

Tool

Time Durati on

Biaya Sewa Alat

Operatin g Cost

e)

(minut

e) (hour) (Rp/hour) (Rp/hour) (Rp) Plant

Karawang

400.00

0 17 0,242 97.376 1.623 Rp

5.100.000

Rp 428.334

Rp 8.972.125.001 Plant Baros 420.00

0 11 0,359 106.37

9 1.773 Rp

3.300.000

Rp 269.067

Rp 6.327.883.276 Plant Walini 400.00

0 10 0,421 94.992 1.583 Rp

3.000.000

Rp 303.217

Rp 5.229.641.940

Total Rp

= 0,242 m³/minutes x 14 unit

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= 3,383 m³/minutes

Total duration of work time = (400.000 m³)/(3,383 m³/minutes)

= 118.242 minutes = 1.971 hour = 282 days

= Rp 4.200.000 / hour

= Rp 428.334 / hour

In the same way, also calculate the total cost of equipment at the baros batching plant and the walini batching plant with the number of alternative tools that have been determined. With the productivity of each truck mixer and equipment operating costs per hour that are fixed, so that the total equipment cost for 3 batching plants is Rp. 20,576.387,338 with the longest duration at BP Karawang with 1,971 hours which is converted to 282 days or 9 months 12 days if the policy of working hours in 1 day is 7 hours. For a complete recapitulation of alternative 3 analysis, it can be seen in the following table :

Table 6. Alternative Analysis Recapitulation 3

Batching Plant

Volu me

Numb er of Tools

Productivi ty Per

Tool

Time Durati on

Biaya Sewa Alat

Operatin g Cost

e)

(minut

e) (hour) (Rp/hour) (Rp/hour) (Rp) Plant

Karawang

400.0

00 14 0,242 118.24

2 1.971 Rp

4.200.000

Rp 428.334

Rp 9.121.087.342 Plant Baros 420.0

00 14 0,359 83.583 1.393 Rp

4.200.000

Rp 269.067

Rp 6.225.658.056 Plant Walini 400.0

00 10 0,421 94.992 1.583 Rp

3.000.000

Rp 303.217

Rp 5.229.641.940

TOTAL Rp

20.576.387.338 3.3. Discussion

After calculating the 3 alternative compositions of the number of tools against the real conditions in the field (existing), then a comparison of the 3 alternatives will be carried out to obtain a more optimal alternative in terms of time and cost. Calculation of heavy equipment used in the field (existing) will be used as a comparison against the alternatives that have been analyzed. From the calculation results of alternative 1, alternative 2, alternative 3 can be seen in the recapitulation results of the comparison of heavy equipment in terms of cost and time in the form of percent (%) can be seen in the following table :

Table 7 Results of Comparison of Alternative Heavy Equipment

The Real

Conditions Alternative 1 Alternative 2 Alternative 3 Total Cost Rp 22.426.477.127 Rp 20.716.107.473 Rp 20.529.650.218 Rp 20.576.387.338

Time 32 Months 25 Days 11 Months 28 Days 8 Months 13 Days 9 Months 12 Days Cost

Efficiency (%)

- 7,627% 8,458% 8,250%

Time Efficienncy

(%)

- 63,636% 74,295% 71,429%

Tools Composition

4 KRW, 16 BRS, 18 WLN

14 KRW, 14 BRS, 10 WLN Description :

- KRW = Batching Plant Karawang - BRS = Batching Plant Baros - WLN = Batching Plant Walini

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From the following table, it can be seen that alternative 2 has a composition of 17 truck mixer units at BP Karawang, 11 truck mixer units at BP Baros, and 10 truck mixer units at BP Walini, these alternatives have the largest cost difference and time difference to the original conditions in the field. For the cost of Rp. 20,529,650,218 with a cost efficiency of 8.458% and working time for 8 months and 13 days with a time efficiency of 74.295%. So it is recommended to use alternative 2 to carry out work on the Ready Mix Concrete – High Speed Railway project.

4. Conclusion

Based on the analysis of the calculations that have been carried out, it can be concluded that by calculating the productivity of each tool and analyzing the composition of the use of a truck mixer, the optimal time needed to complete the Ready Mix Concrete - High Speed Railway project is 253 days or about 8 months. 13 days. The operating cost of the equipment is Rp. 20,529,650,218, cheaper than the real condition in the field, which is Rp.

22,426,477,127, the difference is Rp. 1,896,826,909 with a cost efficiency of 8,458%. 3 After analyzing by trial and error method, the composition of heavy equipment that is appropriate and can be used optimally is in the analysis of alternative 2 because the alternative has the largest cost difference and time difference to the original conditions in the field. With the composition of heavy equipment truck mixers, namely 17 units at Batching Plant Karawang, 11 units at Batching Plant Baros, and 10 units at Batching Plant Walini.

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Kiswati, S., & Chasanah, U. (2019). Analisis Konsultan Manajemen Konstruksi Terhadap Penerapan Manajemen Waktu Pada Pembangunan Rumah Sakit Di Jawa Tengah. Neo Teknika, 5(1).

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Bioghrapy

Anjas Handayani, Lecturer in Civil Engineering. Born in Jakarta on March 9, 1977. Works as a lecturer at Mercu Buana University. He graduated with a Bachelor of Civil Engineering from Mercu Buana University in 1999 and obtained a master's degree in Civil Engineering with a concentration in Construction Management from Pelita Harapan University, Jakarta. Currently teaching several courses such as Project Cost Estimation and Economic Engineering, Construction Management, Construction Quality Management System. Until now, he is also actively working in a subsidiary of a BUMN in Indonesia.

Febby Dwiyanti Afriyani, was born in Depok April 19, 1997. Obtained a Diploma in Civil Engineering with a concentration in Civil Construction Engineering from the Jakarta State Polytechnic in 2018 and is currently continuing her studies to achieve a bachelor's degree at Mercu Buana University. From February 2019 to December 2020 he worked in a BUMN subsidiary as an administration of equipment and currently he works as a government employee in a government agency in the DKI Jakarta Provincial Government Organization since March 2021 until now.