Analysis of Ergonomic Factor Measurement for Transjakarta Bus Drivers

Transjakarta transportation accidents have increased from year to year. Transjakarta buses having an accident can result in the driver not feeling comfortable while driving so that the driver experiences a lack of concentration. Therefore, the authors conducted a study that aimed to investigate the ergonomic factors experienced by Transjakarta bus drivers. The author uses the Rapid Upper Limb Assessment (RULA) method by taking 30 Transjakarta bus driver data and by using the Nordic Body Map (NBM) method by taking 30 driver data using a questionnaire. The results of the RULA method have been used to test the correlation using the Minitab software. The results of the RULA on reaching the steering wheel activity were 3-4 which means that further investigation was needed and may require changes to improve. And for the average time to reach the button was 5-6 which means the need for immediate investigation and change. NBM results show that most of them experience pain in the waist so that it is necessary to improve the position of the waist. Correlation Test Results The activity of reaching the button and the activity of reaching the steering wheel is -0.209 and the P-Value is 0.268 so that the results of an inverse relationship between the activity of reaching the steering wheel and reaching the button are found. The greater the activity reaches the wheel, the smaller the activity reaches the button. The correlation found has a very weak relationship between variables.


Introduction
In 2004 Transjakarta was the first land-based vehicle with the Bus Rapid Transit transportation system in Indonesia.Transjakarta is also one of the subsidized programs of the Provincial Government of DKI Jakarta which aims to encourage people to switch to the more economical Transjakarta public transportation to deal with traffic jams.DKI Jakarta has made Transjakarta services a regionally owned enterprise (BUMD).Especially for those who live in locations far from campus, public transportation is a more effective option to avoid traffic jams in Jakarta.Transjakarta buses are one of the main vehicle options chosen by many Binus students [1].Even though the use of public transportation is more costeffective and can reduce congestion, the use of Transjakarta buses also requires attention to safety factors.Transjakarta transportation accidents have increased from year to year.In 2018, 54 accidents were found [2].In 2021, 508 accidents were found [3].In 2022 2 Transjakarta buses experience an accident involving 827 buses.Transjakarta buses having accidents can result in drivers who don't feel comfortable while driving so that drivers experience a lack of concentration.

Sample Size
A sample size estimation was conducted as described by Hulley et al. (2013).A power calculation was conducted based on a critical α-value of 0.05 and a 1-β of 0.2.To reach a power level of 80%, 30 participants were required.

Participants
The author collects data and processes data obtained from observations and questionnaires distributed to 30 sample drivers.The research was conducted at the PERINTIS Transjakarta bus pool which is located at Jl. Perintis Kemerdekaan No.1, RT.1/RW.15,Kayu Putih, Kec.Pulo Gadung, City of East Jakarta, Special Capital Region of Jakarta 13210.

Procedure
Flow chart is a data flow process that is used to assist in conducting a research systematically.The flowchart for research on the ergonomics level of Transjakarta drivers can be seen in Figure 1.Research Flowchart.

Figure 1. Research Flowchart
The researcher identified the main problem factors for the Transjakarta bus accident.Negligent bus drivers are one of the causes of Transjakarta bus accidents.The hypothesis that the author has related to the main problem of the Transjakarta bus accident is the heavy workload of the driver causing human error factors, therefore the authors conducted research related to ergonomics factors using two methods, namely Rapid Upper Limb Assessment (RULA) and Nordic Body Map (NBM).The next step is the author collects data through observation and questionnaires which are distributed to 30 drivers and performs data processing.
The research was conducted at the Transjakarta PERINTIS bus pool which is located at Jl. Independence Pioneer No. 1 RT 01/RW 015, Kayu Putih, Kec.Pulogadung, East Jakarta, DKI Jakarta 13210.Researchers conducted an RULA assessment by measuring the driver's body posture and taking the average from the NBM.Body posture measurements are made when the driver performs two different activities on the left, namely when reaching the steering wheel and when reaching the button.
In the RULA study, it was divided into two, namely the first Arm and Wrist Analysis and the second the Neck, Trunk, and Leg Analysis.In the NBM method, data was obtained by distributing the NBM questionnaire which contained 28 body points filled with any part of the body that was experiencing pain.From the NBM data, an average of which part of the body experiences the most pain.The results of the RULA method were tested for correlation with the help of tools from using the Minitab software to measure the extent of the relationship between the two methods.The next step after completing data processing and analysis of the results of each method was followed by concluding the results of the research that has been done.
Conclusions are reached based on the objectives of this report.After that, the author provided advice to PT Transjakarta to be used as a recommendation and evaluation regarding ergonomic factors to increase the driver's comfort while driving a Transjakarta bus so he can focus on driving.

Rapid Upper Limb Assessment.
RULA stands for Rapid Upper Limb Assessment which is a method used to assess posture, style, movement of an activity from ergonomic risks to the upper body from the abdomen to the neck (Upper Limb) which is used to identify potential risks of injury to workers.RULA was first introduced by Dr. Lynn McAtamney in 1993 and developed by Dr.E.Nigel Corlett and Dr. Lynn McAtamney wrote in a research journal regarding Worker Risk Levels at Work Points.RULA assessment by measuring the angle itself and determining the ergonomic risk value in the form of a score based on the worker's body posture during work activities.After obtaining an ergonomic risk score from the RULA assessment, modifications or improvements to be made that are more comfortable and safe can be given so as to reduce comfort risks.The RULA method provides protection in fast work, work related to the upper body, and identifying efforts that require muscle work related to body posture while working [4].
The process of collecting data by observation was used for RULA assessment using 30 Transjakarta bus drivers by documenting the side view of each activity carried out.Activities that can be documented from the left are when you reach the steering wheel and when you reach the buttons on the left.After doing the documentation, the writer takes a measurement of the driver's posture.Measurements can be seen in Figure 2 Driver Posture Measurements [5].
After taking the measurements the writer conducted a RULA assessment.Assessment is entered in tabular form.The assessment can be seen in Figure 3 The RULA Rating Table for one of the drivers.The assessment only uses 2 activities because these activities can be documented from the left side, and the one on the right is blocked by the body of the bus, so 4 it is difficult to do an assessment or documentation.After documenting as many as 30 samples in an activity the author measures body posture to make an assessment.Assessment can be done using tables.The assessment is divided into two parts, namely the arm and wrist analysis and the neck, trunk, and leg analysis.The first is to assess hand posture when reaching for the wheel [6].After taking the measurements the writer conducted a RULA assessment.Assessment is entered in tabular form.The assessment can be seen in Figure 3 The RULA Rating Table for one of the drivers.The assessment only uses 2 activities because these activities can be documented from the left side, and the one on the right is blocked by the body of the bus, so it is difficult to do an assessment or documentation.After documenting as many as 30 samples in an activity the author measures body posture to make an assessment.Assessment can be done using tables.The assessment is divided into two parts, namely the arm and wrist analysis and the neck, trunk, and leg analysis.The first is to assess hand posture when reaching for the wheel [6].
Stage 1 assesses the degree of shoulder up and down.One of the drivers named Pak Anjur, the position of the shoulders forms an angle of 61 degrees, so he gets 3 points.However, because the position of the hands is resting on the steering wheel, the point is deducted by 1 so that you get 2 points in the first stage.
Stage 2 assesses the position of the shoulders to the left and to the right.In Pak Anjur's position, the shoulders form a 9 degree angle, so that you get 1 point.Stage 3 assesses palm position.In the position of Pak Anjur's palms forming an angle of 21 degrees, so he gets 3 points.Stage 4 assesses the horizontal or vertical palm position.The position of Pak Anjur's palms is horizontal so that he gets point 2. The rating table can be seen in Figure 13 Rating Table .Stage 12 gets a score of 1 based on scores on stages 9 to 11. Stage 12 gets a score of 1 based on the table.Stage 13 gets a score of 1 because the activity repeats more than 4 times per minute.Stage 14 gets a score of 1 because the load is less than 44 lbs or less than 20kg.Stage 15 gets a score of 2 from the addition of stages 12 to 14, so 1+1+0 is 2 points.Furthermore, Stage 8 and Stage 15 are used to determine the final score.From the results of stage 8 to stage 15, a final score of 4 is obtained.A score of 4 means that further investigation is needed, and it is possible to make corrective changes.

Nordic Body Map.
NBM is an abbreviation for Nordic Body Map, which is a method used to find out or identify the level of discomfort or pain in a person's body parts by giving a questionnaire to respondents.NBM is used to find out more clearly which parts of the body are sick or experiencing problems and is used to find out complaints of musculosceletal disorders felt by workers.By using NBM, researchers can identify 28 parts of the body that experience discomfort or extreme pain [7].NBM can help identify areas of the body that are most at risk of injury or discomfort.NBM can provide consistent and useful data in describing musculoskeletal problems.NBM can also be useful for preventing injuries and improving IOP Publishing doi:10.1088/1755-1315/1324/1/0120266 worker health, after early identification, preventive steps can be taken to reduce the risk of musculoskeletal problems in the workplace.The data collection process using the NBM method began with distributing questionnaires to 30 Transjakarta bus drivers.The questionnaire contains 28 body points.To answer the driver's questionnaire, it is enough to check which parts of the body experience no pain, moderate pain, pain, and very pain.

Correlation Test.
The stages of the process are carried out to carry out the Correlation Test.In the first stage, the writer determined the variable data that would be used for the correlation test.The result of using the RULA method was used as a data source that went through a correlation test.The RULA data analysis method used activity data to reach the steering wheel and activity to reach the button.After that, using the Minitab software tools and inputting the data that has been determined.

Rapid Upper Limb Assessment
The results of data from 30 sample drivers with two activities are entered in the table so that they can be seen in Table 1 RULA data.The results of the assessment in Table 1 can be concluded that the average of the activities to reach the wheel is 3-4 which means that further investigation is needed and may require changes in improvement.The average time to reach the button is 5-6, which means there is a need for immediate investigation and change.

Nordic Body Map
The NBM assessment requires 30 questionnaires that are completed by the driver then after that the writer did a summary of 30 questionnaires.The summary can be seen in Table 2 NBM Summary.The data in Table 2 show that most of them experience pain in the waist, so it is necessary to improve the position of the waist.

Correlation Test
The stages of the process are carried out to carry out the Correlation Test.In the first stage, the writer determined the variable data that would be used for the correlation test.The result of using the RULA method was used as a data source that went through a correlation test.
The RULA data analysis method used activity data to reach the steering wheel and activity to reach the button.After that, using the Minitab software tools and inputting the data that has been determined [9].
The results of the input data were followed up by testing the assumptions (normality) using the Minitab software.The assumption test (normality) has a function to determine whether the data is normally distributed or not.Parameters of data that had a normal distribution had a P-Value with an alpha value of more than 0.05 while for data that has an abnormal distribution the alpha value was less than 0.05.The results of the assumption test of the activity variable reaching the button from the use of the RULA analysis method could be seen in Figure 5, which displayed the Summary Report for Button Outreach Activities [10].The results of the variable assumption test to reach the steering wheel from the use of the RULA analysis method can be seen in Figure 5 Table Summary Report for Steering Outreach Activities.

Figure 5. Table Summary Report for Steering Outreach Activities
The results of the identification summary for the activity of reaching the button, the P-Value has a value of 0.005 so that the activity data reaching the button after the assumption test is carried out can be said to be not normally distributed.It can be proven that data that has an abnormal distribution had an alpha value of less than 0.05.
The results of the identification summary for the activity of reaching the wheel showed that the P-Value has a value of 0.005, indicating that the activity data reaching the wheel, IOP Publishing doi:10.1088/1755-1315/1324/1/0120269 after the assumption test, wa proven to have non-normally distributed data.This was confirmed because data with abnormal distribution had an alpha value of less than 0.05.
The conclusion from the identification summary for both variables has data values that are not normally distributed.It can be seen from the data that the P-Value value has an alpha value of less than 0.05.
After carrying out an assumption test or normality test, the two variables can be continued to perform a correlation test using the statistical approach of the Spearman Rho method.The correlation test was carried out to find a relationship between the two data variables having a significant or insignificant relationship.The results of the correlation test can be identified as, if the results of Spearman Rho (+) then x increases and y increases as well if x decreases then y decreases, but if the results of Pearson Correlation (-) then x increases and y decreases, if x decreases then y increases.The results of the correlation test between the two variables can be seen in Figure 6 Correlation Test Results Activity reaches the button and activity reaches the steering wheel.

Conclusion
The benefits of a study discussing workload analysis for Transjakarta bus drivers can be seen as follows: • The comfort level experienced by Transjakarta bus drivers based on the RULA method on average from reaching the wheel is 3-4 which means that further investigation is needed and may require changes in improvement.And for the average time to reach the button is 5-6 which means the need for immediate investigation and change.• The level of comfort experienced by Transjakarta bus drivers based on the Nordic Body Map (NBM) method shows that most of them experience pain in the lumbar region, so there is a need to improve the position of the waist.• Correlation Test Results The activity of reaching the button and the activity of reaching the steering wheel is -0.209 and the P-Value is 0.268 so that the results of an inverse relationship between reaching the steering wheel and reaching the button are found.The greater the activity reaches the wheel, the smaller the activity reaches the button.The correlation found has a very weak relationship between variables.

Figure 2 .Figure 3 .
Figure 2. Driver Posture Measurements Stage 5 uses tables to determine scores and is based on scores obtained from the position of the shoulders and palms.The score obtained at Stage 5 is 4 points.Stage 6 gets 1 point because reaching for the wheel is done more than 4 times per minute.Stage 7 gets 0 points because the steering wheel weighs less than 44lbs or the equivalent of 20 kg.Stage 8 is the sum of stage 5 added to stage 6 and stage 7.So 4+1+0, the result of stage 8 is 5 points.Then do the second assessment, namely Locate Neck Position.Stage 9 measures the position of the neck to the head.Pak Anjur gets a score of 1 point because the position of the neck to the head forms a 9-degree angle.Stage 10 measures the position of the back to the head.Pak Anjur gets a score of 1 because the position of his back to his head forms 0 degrees.Stage 11 gets a score of 1 point because the legs support the activity of reaching the wheel.Stage 12 to get a score must use the assessment table.

Figure 4 .
Figure 4. Summary Report for Button Outreach Activities

Figure 6 .
Figure 6.Correlation Test Results Activity reaches the button and activity reaches the steering wheel