STUDY OF COST AND TIME ANALYSIS USING THE TIME COST TRADE OFF (TCTO) METHOD IN THE CONSTRUCTION PROJECT OF THE OFFICE BUILDING OF A GOVERMENT AGENCY (OPD) IN PASURUAN

In construction project control, the main factors of concern are quality, time and cost control. So it is necessary to use one method in the implementation of its control. This study aims to analyze the time and cost of the Raci OPD Office Building Construction project. The benefit of this research is to anticipate potential delays that occur in the project. The problem limitation is focused on work that has not been completed in the remaining time of the contract period. To analyze time and cost, this research uses Critical Path Method (CPM) and Time-Cost Trade-Off (TCTO) which begins with determining the work network and critical path. TCTO analysis is carried out by shortening the duration of work by adding 3 hours of overtime and calculating the Crash Slope of each job on the critical path. Rescheduling is done by accelerating the work that has the lowest cost The results showed that the most effective rescheduling was carried out on the Lt.3 Installation and Plastering work with the acquisition of an acceleration duration of 8 days. And the total cost required for this acceleration is Rp. 29,441,424, - or Rp. 1,226,726,- per day for 24 days.


INTRODUCTION
A construction project is a series of activities carried out to build a building within a specified time period.The most important goal for contractors as service providers and service users is that construction projects can be completed on time, at the right cost and at the right quality.In the reality of implementing construction projects often face delays in the completion of work.Project delay is the completion of a project that exceeds the time limit specified in the contract.This obstacle causes losses both from the contractor as the executor and the assignor.Therefore, management is needed to control time, quality and cost.Project management is the application of knowledges, skills, tools and techniques in project activities to meet project needs.(PMBOK2017) (Institute, 2017).
Project management is carried out through the application and integration of the stages of the project management process, namely initiating, planning, executing, monitoring, and controlling and finally closing the entire project process (Mantel et al., 2001).In its implementation, every project is always limited by constraints -constraints that affect each other and are commonly referred to as the project constraint triangle, namely: scope of work (scope), time and cost.Where the balance of the three constraints will determine the quality of a project.Changes in one or more of these factors will affect at least one other factor.(PMBOK 2017).
Control is a systematic effort to determine standards in accordance with planning objectives, design information systems, compare implementation with standards, analyze possible deviations between implementation and standards and take the necessary corrective actions so that resources are used effectively and efficiently in order to achieve goals.(Soeharto, 1999).
Controlling a large project involves keeping a close eye on resources, costs, quality, and budget.Controlling also means using feedback loops to revise or change project plans and shifting or reorganizing resources to meet time and cost requirements.
Control measures can be taken in terms of cost and time.Time control can be done by looking at the performance of project implementation that has taken place (Dannyanti, 2010).The implementation of a project can be delayed, accelerated, or on time according to the project plan scheduling depending on the conditions of each project.
One of the methods used is the critical path method (CPM) which is done by compiling a work network.Such a control process can also be carried out on the OPD Office Building Construction Project at the Raci Office Complex, Pasuruan Regency (Sa'adah & Rijanto, 2021) Based on observations during implementation, which until this article was compiled entered week 19, the progress of work in the field still shows a positive deviation value.However, if analyzed more deeply, the deviation value of progress until week 19 is inversely proportional to the average productivity each week.The following is a table of observations made in the last 3 weeks.The work deviation value continues to decrease.In week 16 there was still a deviation of 11.572% but it continued to decline until it remained around 4.051%.And when viewed based on weekly productivity, it also continues to decline as shown in the S Curve.
Based on Primary Data from Supervision Consultant, (2023), from the S Curve, the blue line is the implementation plan, while the red line is the realization.The area between the red and blue lines is the progress deviation value.The more to the right, the narrower the deviation area.So if not anticipated, it will cause a minus deviation, which means there is a delay in implementation.
In addition, if calculated from the remaining time available, there are indications that there will be delays.Because if the calculation of the remaining time is less than 50%, it still has to catch up with the progress of around 60%.So it is necessary to accelerate and anticipate efforts to avoid delays.
This research was conducted as an effort to prevent delays in implementation.So it is expected to be applied so that it can be carried out on time.One of the methods used is the CPM (Critical Path Method) method (Lilyana, 2020).
In the scheduling procedure with the CPM (Critical Path Method) method or critical path method, it is assumed that the duration of a component of project activities is considered to be known with certainty (Danang Prihandoko et al., 2022).(Saputra et al., 2021)This CPM method aims to plan and control a large number of activities that have complex dependency relationships in engineering design, construction and maintenance problems (JAYA, n.d.).
The research begins by breaking down the work into several work components that will be organized into a network (network planning).This network serves to determine the relationship between each work component and its predecessor.From the work network, it will be known which components do not have free time and must be done on time.Then each component is arranged as a critical path.

RESEARCH METHODS
The subject of the research is in the form of data collected from various sources related to the Construction of the OPD Office Building in the Raci Office Complex.The data that will be used as research subjects are time schedule data and RAB from the Implementing Contractor and work progress report data from the Supervisory Consultant in the field.The research location is in the Raci Office Complex, Pasuruan Regency.The OPD Office Building of the Raci Office Complex under construction consists of 3 floors which function as office buildings and are owned by the Pasuruan Regency Government.(Rosyid et al., 2020)The research instruments used are methods of accelerating work including Critical Path Method (CPM) and Time-Cost Trade-Off (TCTO).(Rakasyiwi et al., 2022)Data processing using Microsoft Excel and Microsoft Project 2017 applications.The data used in this study are primary data and secondary data.Primary data is data on the implementation of the OPD Office Building Construction in the Raci Office Complex, which is collected from the Supervisory Consultant.While secondary data is obtained from literature studies that are used as study materials during the research process .Data analysis techniques in this study are Critical Path Method and Time Cost Trade Off (Budianto & Husin, 2021).

RESULTS AND DISCUSSION
From the data collected, a simple analysis has been carried out by comparing the remaining duration with the speed of work implementation to obtain the following initial hypothesis:  Looking at the curve above, for the last 5 (five) weeks, the weekly target has never been achieved.Of course, this will cause a buildup of targets in the weeks behind.

Comparison Of Weekly Average Gains With Remaining Implementation Time
In the table above it can be seen that the average job gain per week is about 3.8%.The remaining time is 10 (ten) weeks, so it can be concluded that with the current average gain, until the end of the work only obtained about 38%.While the target that still has to be achieved in the remaining time is about 50.6%.
Determination of the implementation time is taken from the implementing contractor's work plan data.

IJATEIS | INTERNATIONAL JOURNAL ON ADVANCED TECHNOLOGY, ENGINEERING, AND INFORMATION SYSTEM
https://ojs.transpublika.com/index.php/IJATEIS/E-ISSN: 2828-5425 From the above scheduling, it can be seen that the overall work will end on December 25, 2023.Contractually, the work must be handed over no later than December 21, 2023.So that acceleration efforts need to be made.To carry out acceleration, first determine the critical trajectory of this work.Critical activities are obtained from the table on Ms.Project as follows:

Table 2. Critical activities in the remaining work
From the calculation of the table above, it is found that critical activities occur on the A-I-J-N-O work track which has a Total Slack value equal to 0. So that the Crashing Program can be carried out on these activities, namely: 1. 2nd Floor Concrete Work 2. 3rd Floor Concrete Work 3. 3rd Floor Installation and Plastering Work 4. 3rd Floor Plafond Work 5. 3rd Floor Painting Work

Calculation of Normal and Accelerated Daily Productivity
Normal daily productivity is daily productivity at normal duration in accordance with the initial scheduling.While accelerated productivity is daily productivity after acceleration (Yaqin et al., 2023).acceleration can be calculated by adding overtime working hours of 3 hours per day on all work on the critical path.If a breakdown of each job is carried out, the following work details and labor costs will be obtained: (Source: Data Processing, 2023)

Calculation of Crash Duration, Crash Cost and Crash Slope
After calculating the daily productivity of normal duration and acceleration duration, it can be calculated Crash Duration, Crash Cost and Crash Slope.The steps taken are as follows:

Crash Duration
Crash Duration is the duration of acceleration obtained by adding 3 hours of overtime every day (Oetomo et al., 2017) (Source: Data Processing, 2023)

Crash Cost and Crash Slope
From the data on changes in work duration after the Crashing Program, the costs required to implement the acceleration can be calculated.The costs incurred during the Crashing Program consist of direct costs and indirect costs.Direct costs are costs incurred for personnel wages during acceleration.While indirect costs are additional costs of work carrying capacity that must be incurred during acceleration (Manurung, 2018).
An example of calculating overtime costs on wall painting, ceiling and gypsum work is as follows: 1. Direct Cost Direct costs in the acceleration process are personnel wage costs and overtime costs.Personnel cost data in this study was obtained from the RAB analysis and added to the results of the calculation of personnel overtime wage costs.According to the Labor Law, the calculation of overtime costs is as follows: a.The first hour's wage is 1.5 times the hourly wage.b.The wage for each subsequent hour is 2 times the hourly wage.

Figure 2 .
Figure 2. Scheduling with Ms. Project (Source: Data Processing, 2023) . The OPD Office Building Construction Project in the Raci Office Complex, started on May 26, 2023 with an implementation duration of 210 calendar days with an implementation budget of Rp. 18,335,039,000.00.The OPD Office Building being built is planned to consist of 3 (three floors).

Work Realization Is Still Below The Plan
This temporary observation is carried out by looking at the trend of work achievement in the last 5 (five) weeks, namely weeks 16 to 20.

Table 6 . Crash Cost and Crash Slope Calculation Results
From the table above, the lowest Crash Slope is obtained in the work of Lt.3 Installation and Plastering Work amounting to Rp. 3,680,178, -/ day with the result of an accelerated duration of 8 days.As for the total cost of implementation of the acceleration can be seen in the table below: