Hazard identification and risk assessment of Abuja rail mass transit

Abstract

1. Introduction

The amount of time spent in traffic in Abuja, Nigeria, has increased in recent years as a result of the city's expanding population. A more dependable and time-efficient method of transportation to suit the travel needs of commuters within the Abuja metropolis is required to address this issue. Rail mass transit systems are constructed to bridge this gap because of the numerous advantages they provide in terms of capacity, safety, weather resistance, reliability and timeliness, which makes them convenient as an object for traffic congestion reduction and passenger safety, among other benefits. Despite the fact that it is beneficial to passengers in urban areas, security concerns have arisen as a result of the high population density in urban areas. Different risk factors may emerge during the operation as a result of the dynamic nature of human thoughts, equipment design failure, internal and external environmental activities and mismanagement of the system. Without careful attention to detail, each one of the aforementioned elements has the potential to produce catastrophic incidents that result in user harm, severe system damage, financial losses, or even loss of lives if not handled properly. The safety-first rule is the most important rule to follow when operating a rail system. Because of this, infrastructure managers must be aware of the hazards that exist in the workplace to guarantee that the system is safe for transporting passengers from their point of origin to their final destination. Consequently, it is critical to identify and evaluate the sources of dangers connected with rail mass transport systems during the early stages of their development and implementation.

A methodical strategy to safeguard health and limit the danger to people, property and the environment is known as hazard identification and risk assessment. A hazard assessment is carried out to determine the presence and characteristics of dangers that may be responsible for accidents, occupational sickness, property loss and damage to the workplace environment [1, 2]. As opposed to the identification and estimation of risks, risk assessment is concerned with responding to the level of exposure that a system has to certain risks. The goal of system risk assessment is to provide evidence-based information and analysis that will allow decision-makers to make educated judgements about how to treat a specific threat. The primary benefit of risk assessment is that it provides information to decision-makers, communicates risks and uncertainties, and complies with regulatory requirements inside the company. This is accomplished by the identification of risks, which then allows system managers to make informed decisions about how to mitigate the risk of losses that may occur. Accepting the risk, minimizing the risk, or investing in adequate internal protective measures that are assessed to be sufficient to minimize the possible losses to an acceptable level, as well as investing in external indemnification [1], are examples of activities that can be performed.

The potential for an unpleasant outcome induced by an incident, as defined by standards [2, 3], can be determined by the likelihood of the incident occurring and its related repercussions, or simply by the effect of ambiguity on objectives. Rail mass transit operates in an environment with random activities that are dependent on human behaviour, as well as in the natural environment, where there is uncertainty as to what line of event or activity will occur along a time horizon, as is the case with air transportation. The measure or chance of a failure occurring is used to determine the likelihood of it occurring. The result or impact of an event's outcome or the impact of an event on an objective is the result or impact of these failures (e.g. fatalities, injuries, property damage, environmental impact, and so on). Risk occurs as a result of early events that can lead to accidents such as collisions and derailments in rail mass transit systems. Human behaviour, equipment failure and other factors all have the potential to be contributing factors.

The methods of risk assessment can be classified as qualitative, quantitative, or semiquantitative [4]. When identifying risk, the qualitative risk technique is straightforward, as it is based on the analyst's expertise and judgement. Checklists, brainstorming, interviews, preliminary hazard analysis, hazards operability and risk sequencing matrices are some of the approaches utilized in qualitative analysis. A qualitative scale is used to describe the occurrences in a semiquantitative risk assessment, in contrast to the quantitative risk assessment. The goal is not to establish realistic risk values, as is done in quantitative assessment, but rather to construct a more expansive ranking scale than is typically obtained in qualitative assessment. Depending on the scale employed, the value assigned to each description may or may not be a true representation of the real magnitude of repercussions or likelihood, and those numbers can only be merged using a formula that takes into account these restrictions [4]. Semiquantitative risk assessment approaches such as failure mode and effect analysis and failure mode and effect critical analysis are common examples. For its part, quantitative risk assessment relies on the availability of historical data to estimate the level of risk in a system, and it reveals changes in the system's existence and system safety [5]. Bayesian network, numerical simulation and Monte Carlo simulation, to name a few methodologies, are used in the quantitative risk assessment of the system under consideration. In addition, numerical analysis of probability and consequences is employed in quantitative risk assessment [6].

The risks associated with urban rail transit are the primary motivators for accidents or accident combinations, which can result in injuries, occupational sickness, the loss of lives and property and the destruction of the transportation system. Many scholars in the railway sector have recognized the need to reduce the frequency of urban rail transit accidents in recent years, and they have been working on ways to do so. The purpose of hazard identification is to confirm the presence and characteristics of dangers in rail public transportation systems [7]. The risk value of a harmful hazard has been divided into four categories, each of which is determined by the likelihood and effects of an accident. The 'Yes' or 'No' judgement approach is used to determine whether the hazard and associated effects are consistent with the known state [8]. By examining accidents both at home and abroad, we were able to determine the occurrence rules of accidents and the mechanisms that cause risk factors. The researchers looked at aspects such as facility factor, environment factor and management factor that could have an impact on operation safety, and they discovered the inherent relationships between the cause processes.

According to the current literature, the degree of hazard and risk is frequently computed in the form of an equation. In the hazard evaluation matrix table, the hazard risk degree is calculated by multiplying the occurrence probability of a hazard accident by the severity of conceivable accidents. The hazard risk degree is then used to calculate the risk score for each hazard. A simple system can be evaluated using the usual hazard risk degree evaluation criteria. The range of values available for these criteria is large, there is no subjective judgement involved and the emphasis is on human-caused injuries.

Several studies on the identification and evaluation of rail mass transit hazards have been done in recent years, mostly in Asia, Europe and the United States, but also in other parts of the world. There is a possibility that the findings and remedies will not be appropriate and specific to the situation in Africa, and particularly Nigeria, due to the differences in environmental conditions and awareness between the various regions. This research is therefore a case-based study that takes Abuja's rail mass transit system (ARMT) into mind. The study's overall goal is to quantify the risk associated with rail mass transit during its early stages of operation to enable infrastructure managers to maintain the track and avoid these risk occurrences from occurring in the future.

ARMT is connected with several risks, which are investigated in this article using a questionnaire interview. The risk matrix is used to determine the level of risk associated with a system [3]. The strategy was chosen because there is a lack of sufficient data to allow for the application of recent risk identification methodologies to be feasible. When applied to a given situation, the risk matrix method is a straightforward and unambiguous approach that defines risks based on the likelihood of their occurrence and the severity of their occurrence, and it can be used to quickly determine which risks can be tolerated and which must be dealt with as soon as possible.

After that, the paper is organized as follows: Section 2 describes the risk identification and evaluation process, Section 3 describes the ARMT system and Section 4 describes the risk assessment of the ARMT system based on human behaviours, equipment failures, environmental factors and management problems. Finally, the conclusion is presented in Section 5, which includes a discussion of the assessment results.

2. Hazard identification and risk assessment

There are five steps to the process of risk identification and risk assessment in this study: establishing the context, identifying the risk, assessing the risk, risk reduction and control and, finally, monitoring and reviewing the risk. (See Fig. 1)

Fig. 1.

Process of risk hazard identification and risk assessment.

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Fig. 2.

Abuja rail mass transit network [9].

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First and foremost, the purpose of this research is to raise awareness of the potential risks connected with the operation of rail mass transit systems during the early stages of their development to assist employees in keeping track of these events and their potential consequences. The understanding of the risk can help to improve the overall safety and dependability of the system.

It is the second stage that determines the level of risk associated with the operation of rail mass transport systems. The identification of hazards is frequently referred to as the ‘heart' of risk management. The proper completion of this operation is crucial because, if certain possible threats are overlooked, they could result in significant human casualties and infrastructure damage. Standards [2, 3] state that risk identification can be accomplished through the following steps: dividing risk identification into manageable portions, developing an inventory of tasks, identifying the hazards involved, taking into account the people factors, the environmental factors, the equipment factors, the management factors, assisting the hazard and recording the hazard identification data.

1. Determine the likelihood of the risk.

2. Determine the severity.

3. Determine the risk scoring matrix.

Table 3 depicts the appraisal and acceptance procedures for each hazard event. The table represent, the relationship between frequency (likelihood) and the severity of the risk. The frequency is represented by a number of linguistic terms, such as ‘incredible', ‘improbable', ‘remote’, ‘occassional', ‘probable', and ‘frequent' while the severity level is described by the terms such as ‘minor', ‘marginal', ‘critical', and ‘catastrophic'. The risk level is however, described with linguistic terms such as ‘negligible', ‘tolerable', ‘undesireable', and ‘intolerable’ as well, to demonstrate the level of the risk and whether it is acceptable or unacceptable. Table 4 explains the conditions for acceptability.

The fourth stage, the risk control process, involves identifying, developing, implementing and continuously reviewing all practicable methods for eliminating or reducing the possibility of an injury, illness, or disease occurring in the place of employment. This stage should involve dealing with all of the identified hazards in the order of priority to which hazards require the most immediate attention. This can be accomplished by either eliminating the danger or replacing something safer for it, applying design controls, implementing administrative controls such as safe work procedures, or protecting employees by guaranteeing competence through supervision and training. Every control measure should have a designated person and a date appointed for the purpose of putting the controls in place. This is done in order to ensure that all necessary safety precautions are taken.

Finally, the processes of hazard identification, risk assessment and control are never completed. As a result, it is critical to conduct regular reviews of the process in order to obtain an effective danger assessment and management measures. Whenever changes occur in the workplace, it is important to conduct a risk assessment by providing additional supervision when new employees with a lower level of skill or knowledge are introduced to the workplace. It is also important to ensure that an evaluation of the risk indicators is carried out by constructing an assessment matrix, which is an analytical tool used to define risk levels by plotting the likelihood of the risk against the severity of the consequences. The risk review is the process of ensuring that risk management is up to date. This includes maintaining an ongoing commitment to risk management, continuously improving the system, adjusting to emerging trends, staying up to date on evolving rail transit risk analysis practice and maintaining continuous communication with external and internal stakeholders.

3. Site description

ARMT is an urban rail transit that operates in the capital city of Abuja, Nigeria. It is the first rapid transit system in the country and West Africa, the second in sub-Saharan Africa after Addis Ababa light rail. The ARMT was completed in 2018 and began operation in July of the same year. The rail network consists of Lot 3 (27.245 km) and Lot 1A (17.8 km),  which is approximately (45.135 km) in total. The yellow line is Lot 3 and the blue line is Lot 1A as shown in Fig. 2. The yellow line travels from Abuja central business district to Nnamdi Azikiwe International Airport. The blue line travels from Idu to Kubwa. A network of 290 km is proposed, divided into six phases or lots. Construction of Lots 1 and 3 have been completed. The proposed Lot 2 will be from Gwagwa Transportation Centre (Metro Station) to Nyanya/Karu, Lot 4 is from Kuje to Karshi with the remaining legs of the transit way line 2. Lot 5 is from Kubwa through Bwari to Suleja, and Lot 6 is from Airport through Kuje and Gwagwalada to Dobi.

Fig. 3.

A bar chart representation of the risk score for each safety factor: (a) human factors; (b) environment hazards; (c) equipment factors; (d) management factors.

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The ARMT currently has 12 stations and 1 depot. The depot or the operation control centre is located at Idu station, according to Lot 3 line and Lot 1A line, which includes functions of communication equipment, equipment technical conditions, train operation, equipment maintenance, traffic organization and so on [11].

For the system to operate safely, the safety management of the ARMT system is operated objectively based on some policies, risk management strategies, emergency response, staff training scheme, safety culture, safety resource allocation, unsafe event correction, responsibility, corrective action, preventive measures and internal supervision. The management of the ARMT system is strictly based on the principle of safety first under the safety management system strategies to ensure the safe operation of the system. Despite all of the procedures that have been put in place, there are still levels of uncertainty that are inevitably risky and must be taken into consideration.

4. Identification of hazards and risk assessment at ARMT

4.1. Source of information

Because there was a lack of quantitative data for the risk analysis, this study was conducted using a questionnaire approach. The questionnaire was distributed to 100 participants, including personnel and passengers at the ARMT, in order to gain an understanding of their perceptions of risk while working and boarding trains at the station. The questionnaire is intended to elicit information about the four safety criteria identified in the literature (human behaviours, environmental influence, equipment failure and management factors). In total, only 60 responses were received from the 100 questionnaires that were sent out to participants. A total of 39 passengers, 20 of whom have used the system more than five times and 19 of whom have used the system more than once, answered the survey's questions. The respondents are comprised of 21 employees with working experience ranging from 1 to 3 years at the ARMT and 39 passengers who have used the system more than once. The approximate mean (average) value of the response is used for the assignment of the likelihood and severity values, which are then used for the risk evaluation of the response. The majority of the decision variables were reviewed based on the responses of the personnel, with only a handful being evaluated based on the responses of the passengers. When determining the likelihood and severity of each probable action for the four safety criteria, we use a scale as described in Table 5. The scale shows the value of the likelihood and the severity which is used to describe the risk score and its significance. All factors listed and evaluated in this paper were obtained during the survey, and compared with those in existing works of literature, organization safety guidelines and traffic organization regulations of ARMT given priority to the factors obtained from the investigation. The studies limit the factors to those related to the response of the participants.

4.2. Human factors

People suffer from a variety of psychological, mental, emotional and personality threats on a daily basis, which might result in major workplace dangers. Human threats come in all shapes and sizes, and they are everywhere. We may wish to distinguish between deliberate and unintentional activities, but doing so only pertains to motive and intent, not to the impact and outcome of the actions. As a result, with the exception of a few instances, we will examine these dangers regardless of whether they are intentional. Terrorism, like war, theft and sabotage, to name a few examples, is defined as something done on purpose. Human behaviour also results from rail transit equipment, facilities and other environmental factors. Even emotion and personality desire are nurtured in society. These internal and external conditions interact with each other to form human conscious and subconscious behaviours, which are complicated and difficult to understand [1]. Table 6 shows the results of our survey, which revealed a number of risk-related indicators at the ARMT. When these actions are combined, they can result in a serious accident. The majority of these issues can be resolved efficiently by implementing a functional safety and security system. Proactive safety culture in the workplace can have a significant impact on overall system safety. Controlling access of unskilled personnel to rail tracks, stations and other areas within the stations that contain sensitive or strategic materials, as well as the operation control centre or server rooms, and other areas within the stations that contain those materials can reduce the likelihood of human error.

4.3. Environmental factors

The environmental factors are the unfavourable natural and sociological factors that have impact on the operation of rail mass transit system. The rail mass transit is operated under an environment full of uncertainties, the environment can be categorized into two, the internal environment and the external evironment. The internal environment include the working environment which integrates human relationships and the physical activities in the work place. On the other hand the external environment consist of the natural and the social environment, such as whether conditions (storms, wind, poor visibility, flood, lightning etc.) and residential activities along the track sections which may include theft/vandalism of track equipments and facilities, terrorist attacks and so on. The combination of such activities can cause serious damage to the entire system and lead to serious accidents which may consequencially lead to serious financial cost.

4.4. Equipment factors

The equipment is the basic foundation for the safe operation of systems; these are components, equipment, or units within entities such as locomotives or track infrastructure, if failed, they can result in a derailment or other accidents. The equipment (rolling socks, signalling, and communication device etc.) and the station facilities (platform, tracks, platform bariers and others) are the most important objects of the system due to their interactions. Active supervision of the safety conditions of the system to identify hazards can contribute significanly to improving the safey, dependability, and availability of the system. Identifying the hazards associated to this equipments and station facilities in the early stage of the system operation can minimize the exposure of the system to serious accidents and potential consequences. The failure factors considered for the risk evaluation in this paper includes signal control failure, switch machine fault, communication device failure, train/rolling stock failure and equipment defects (train door defect). The causes of the failure can be regarded as a result of inadequate maintenance of equipment, inadequate design of the equipment, exceeding the design lifecycle of equipment, or unskillful application and use of the equipment.

4.5. Management factors

Management decisions are extremely effective tools for improving the overall safety of railway operations. Things can spiral out of control when management fails to enforce standards and provide the necessary assistance for helping people succeed in their jobs. Poor personnel/employee education on safety, insufficient provision of safety materials to the employee, insufficient adherence to safety rules by the team during system maintenance and a slow response to hazardous activities at the work environment are the leading causes of accidents that may result from poor system management, according to our survey [12]. So far, efforts have been made by the management to identify potentially hazardous sites on the ARMT system, with around 52 sources of risk identified. Some of these are as follows: (1) the existence of five level crossings along the railway, which are important points that can result in vehicle-train collisions as well as motorcycle and pedestrian accidents; and (2) the presence of a freight train on the line. (3) The flooding that washes away the rail bed and ballast because of the rainstorms during the wet days, exposing the track to degradation, geometry degradation and other issues that could have occurred. (4) There is a fire danger in the operation and control centre and the trains, and a train door malfunction, which can result in passengers being thrown from the train, among other things. (5) Terrorist strikes are a possibility.

Identifying risk in the rail mass transit in the early stage of its operation is significant for the improvement of the safety and reliability of the system. This research has identified the possible risk based on the four safety factors: human, environment, equipment and management.

This research is based on the results obtained from the survey, all evaluation indicators listed in the result tables are obtained from the participants' responses confirmed by existing works of literature [1, 10], and the results are evaluated in Tables 6 to 9. And a bar chart representation of the risk score for each safety factor is shown in Fig. 3. However, not all the hazard indicators that can stem from rail mass transit operation are evaluated in this paper. Refs. [10] and [13] have more details on hazards that concern passenger service, dispatched management, driving organization, operator safety and others.

This research was conducted in two phases. In the first phase, a questionnaire was constructed asking the participants about the possible hazard activities they perceived while boarding and working at ARMT. The response is then compared with the existing hazard factors that have been published in existing literature, and similar hazard factors are selected and grouped into four categories, human behaviour, environmental factors, equipment factors and management. A total of 12 possible human hazards, 7 environmental hazards, 6 equipment hazards and 5 management hazards are identified and confirmed from the survey. Human behaviour has the highest possible risk factor. In the second step, the risk factors are then assigned values as described in Table 5 and sent back to the participants. The approximate mean (average) value of the response is used to assign the final likelihood and severity values, and the risk score is calculated as the product of the likelihood and the severity as shown by equation (1).

Furthermore, as mentioned in the previous paragraph, human-induced hazards are the most dominant hazard sources with the highest number of hazards indicating 12 hazard sources. Those with a risk score of more than 8, which falls in the category that needs more attention (that is intolerable and unacceptable), are: personnel and passenger risk at the platform, risk of failure due to inadequate technical compliance, passenger/operator negligence to safety rules, risk of violation of labour discipline, risk of personnel injury while on duty, intentional damage by passengers or personnel and failure to follow management instruction. Safety training of personnel should be organized quarterly and work briefing should always be done before personnel take on any task. On the other hand, environmental factors such as terrorist attacks, theft/vandalism and obstacles on the track also have a risk score of greater than 8, which requires immediate action. Public awareness through signposts and public announcements of the danger of such acts to the infrastructure can improve the safety of rail mass transit. For the equipment factors, signal control failure, switch machine, failure, communication device failure and the rolling stock failure also had a risk score of more than 8, which requires a frequent physical inspection on their good working condition. Lastly, hidden danger rectification, inadequate response to hazardous activities and inadequate response to emergency situations also had a risk score of more than 8, and the management needs to take quick actions on such events.

Human behaviour is the most dangerous and catastrophic source of hazard as shown by the number of hazards identified and their risk score. Compared to previous research [1], it is revealed that human error involved in the breakdown of the hazards technologies in rail transit increased by 60% in the late twentieth century from 20% at the beginning of the twentieth century, arguing that hazards from the natural environment and equipment breakdown can be prevented by the pre-alarm system and preventive measures.

When a rail transit accident occurs, the passive strategy derived from the hazard identification process is to identify possible hazards in the analysis system and formulate safety recommendations to improve operational safety and prevent a recurrence. An active or constructive safety management program is to control and eliminate identified hazards through further improvements in management measures to prevent accidents.

As an active measure to improve operational safety and reliability of rail mass transit, safety training for personnel should be prioritized, and public education about the dangers of vandalizing the rail infrastructure should be promoted through signposts and maybe radio jingles. Also, all the guidelines provided by the technical support team from China Civil Engineering Construction Corporation should be followed adequately, frequent supervision of personnel is important, and physical inspection of equipment is also key. An active and good organizational culture plays an important role in improving safety as well. Considering the organization culture, the following should be kept in mind: (1) an informed culture in which staff are knowledgeable about human, equipment, management and environment factors that influence the safety of the system; (2) people should be able to report their errors and experience; (3) a learning culture in which individuals must be willing and competent in drawing conclusions from safety information systems and the will to do so. (4) adopting a culture of fairness where mistakes must be understood but deliberate violations will not be tolerated when dealing with high-volume temporary operations or certain types of danger; and finally, (5) shifting from the conventional hierarchical model to a flatter model. However, there should be a clear line between acceptable and undesirable behaviour in order to prevent confusion. In addition, the government should have a long-term strategy for supporting the upkeep of its infrastructure.

In addition, due to personnel's diverse backgrounds, they are the most valuable asset in the mass transit business, but they are also the most dangerous risk in the process as a whole. Because of this, the management team must guarantee that there is effective communication between employees, as well as between employees and passengers, and between employees and the top management team in order to avoid subject factors arising from individual differences. Individual differences can be improved or mitigated by the use of the measures listed. (1) One advantage of ARMT is that it can actively watch how workers work (including conducting sentiment analysis of work communication such as email and instant message) and use those data to anticipate who is most likely to engage in unsafe behaviour. This proactive method can assist the ARMT management team in responding to undesirable conduct before it occurs. (2) The ARMT management team should ensure that the appropriate compliance training programmes are in place and that their efficacy is being monitored. Compliance training should be tailored to individual employees so that they may apply it to their specific responsibilities and situations. (3) Establish a safe environment for employees to air their issues without fear of reprisal. This is critical to provide an effective job briefing. The job briefing is typically performed at the start of a new activity, whenever the activity or working conditions change, or if a new member of the team is brought on board. In addition, using notice posts on station platforms, sections and at level crossings to raise awareness of the potential safety concerns to passengers is essential.

5. Conclusions

To summarize, this research has identified and evaluated the risk associated with ARMT using a semiqualitative risk assessment approach. The results of the study are based on responses of a questionnaire from passengers and personnel at the ARMT. Four safety aspects are considered in the studies: human behaviours, environmental failures, management style and equipment failure, among others. According to the findings of the study, human-related hazards are the most likely risk causes hazards at the ARMT, which has 12 different risk hazard sources. Individuals on the platform and failure to comply with technical compliances were the risks with the highest risk scores of 20 and 16, indicating that the risk is intolerable and that it must be eliminated or reduced as soon as possible by implementing the risk reduction measures described in Table 4. In the context of external environmental risks, terrorism is one of the most vulnerable types. Among the possible equipment failure events that should be prioritized for monitoring to increase safety, signal control failure, switch machine failure and communication device failure are also evaluated.

The identification of hazard occurrences during the early stages of a system's operation has the potential to significantly improve the system's safety and reliability.

ARMT's organization regulations and policies documents, the responses to the survey that was conducted, and the literature cited in this research are the sources of information for this work.

ACKNOWLEDGEMENTS

The National Science Foundation of China (Grand No. 71971220) and the National Science Foundation of Hunan Province, China (Grant No. 2019JJ50829). Their assistance is greatly appreciated.

Conflict of interest statement

The authors declare that there no conflict of interest.

References