RISK ANALYSIS IN THE IMPLEMENTATION OF A MEDALJ STREAM REGULATION PROJECT

Summary: During the construction of the regulation of a watercourse, a large number of unex pected events can occur and increase the risk associated with the project hindering its successful realization. Risk events can result in breaking deadlines, increasing costs, reducing quality, etc. This paper analyzes the risk in the implementation of the Medalj stream regulation project, using the appropriate method that gives the best results for each phase of the risk analysis. Thus, the HAZOP method was used to identify risk events, the risk matrix to define the level of risk, the FMEA method to propose actions to reduce the possibility of risk event occurrence, the Fault tree method to determine the cause of risk event occurrence and the Event tree method to determine possible outcomes of risk events. The obtained results showed that the key risk event was “Only a part of the planned soil excavated”, so the paper will present the results related to earthworks, although the analysis referred to the entire project.


INTRODUCTION
Planning is one of the most significant elements of project management, with each of its phases and subphases, as well as some of its functional domains. The main object of planning is the reduction of risk and uncertainty during the implementation of any project.
According to standard ISO 31000 from 2009, risk is defined as the uncertainty effect on goals. From this definition, every risk has an uncertainty that can be quantitatively and qualitatively expressed, which results in the importance of planning and risk assessment in project implementation. Each potential risk in the near of further future can cause huge consequences for company business, and that is why it should be a mandatory part of business management. According to the above mentioned, it can be said that risk includes two components: an unwanted consequence and uncertainty about a possible consequence (C u p i c and S u kn ovi c, 2010).
Risk management includes a set of management methods and techniques which are used to reduce the possibility of adverse and harmful events that could occur during project realization. It leads to the loss minimization and makes a balance between the reduction of loss probability and expenses that are required for this reduction (J ovan ovi ć, 2008).
Risk management is conducted through several phases: risk identification, risk analysis and assessment, risk response planning, and control of the risk response (J ovan ovi c, 2008).
One of the most challenging phases of this procedure is risk assessment, because it requires excellent knowledge of the system and plenty of time to be implemented in the best way. An important aspect of risk assessment is the choice of the methods by which this procedure will be implemented (Vu j o s evi c, 2008).
The primary causes of risk are long project duration, unpredictability, and today's market dynamism (S u d j i c , 2008). Soil and water resources protection projects are confronted with various risks, which are very difficult to manage. This group of projects also includes river regulation projects, which belong to investment projects

RISK ANALYSIS IN THE IMPLEMENTATION OF A MEDALJ STREAM REGULATION PROJECT
BSc. Petar Nešković, University of Belgrade, Faculty of Forestry (petar.neskovic96@gmail.com) Dr. Nada Dragović, Full professor, University of Belgrade, Faculty of Forestry Dr. Tijana Vulević, Assistant professor, University of Belgrade, Faculty of Forestry BSc. Jelena Panić, University of Belgrade, Faculty of Organizational Sciences Summary: During the construction of the regulation of a watercourse, a large number of unexpected events can occur and increase the risk associated with the project hindering its successful realization. Risk events can result in breaking deadlines, increasing costs, reducing quality, etc. This paper analyzes the risk in the implementation of the Medalj stream regulation project, using the appropriate method that gives the best results for each phase of the risk analysis. Thus, the HAZOP method was used to identify risk events, the risk matrix to define the level of risk, the FMEA method to propose actions to reduce the possibility of risk event occurrence, the Fault tree method to determine the cause of risk event occurrence and the Event tree method to determine possible outcomes of risk events. The obtained results showed that the key risk event was "Only a part of the planned soil excavated", so the paper will present the results related to earthworks, although the analysis referred to the entire project.
Keywords: risk, project management, river regulation, HAZOP, FMEA, event and fault tree analysis where a large number of risk events may occur. These events that lead to project failure could occur in all phases of the project lifecycle, especially in the building phase during the execution of earthwork as the most extensive work concerning the quantity of works executed.
In the current project implementation practice from this domain, risk management has been considered only from the impact of change point of view, i.e. cost increase and a qualitative method was applied -Monte Carlo simulation (Baumgertel et al. 2016, Ba u mgertel et al. 2019.
This paper identifies and analyzes the risk on the example of performing works on the regulation of the Medalj stream. For the realization of each step, the appropriate method was applied. The HAZOP method was used to identify risk events, the Risk matrix to define a level of risk, the FMEA method to propose actions to reduce the possibility of risk event occurrence, the Fault tree method to determine the cause of risk event occurrence and the Event tree method to determine possible outcomes of risk events.

Study area
The Medalj stream is a right tributary of the Drina river in the Municipality of Ljubovija (Western Serbia), with a watershed area of 2.3 km 2 , a flow length of 2 km and an average slope of 18-22%. The Medalj stream intersects the main Ljubovija -Zvornik road, where traffic is stopped due to the oncoming torrential water.
In the aim of the Medalj stream regulation, technical objects have been designed in the form of a regulation with inflow made of stone in cement mortar and three sediment traps (gabion check dam, check dam constructed with stone in cement mortar and dry stone masonry check dam). In addition to technical works, the project also included biological works.

Risk assessment methods
The key phase of risk management relates to risk analysis and risk assessment performed by applying a variety of techniques, methods and tools. The methods used for risk assessment could be divided into quantitative, semi-quantitative (combined) and qualitative methods (G rozd a n o v i ć and S to j i l j ko v i ć , 2013). Quantitative methods provide a quantitative measure of risk based on knowledge of the probability of occurrence of an adverse event and the expected consequences of the realization of the adverse event. In combined methods, the magnitudes (probabilities and consequences) for risk assessment are assessed and ranked by experts. Qualitative methods use qualitative data to assess risk without the necessary knowledge of previous adverse events and describe the risk descriptively (e.g "weak", "medium", "high", "very high"). The choice of the risk assessment method depends on several factors such as the availability of resources and the time required for analysis, the availability and relevance of data, the complexity of the project, the goal of the analysis, etc. (M ern a and A l -T h an i , 2008).
All tools and techniques that can be used for risk assessment, if applied systematically in an appropriate manner, can indicate all the vulnerabilities and errors that exist in the project.
Risk assessment is a very complex process involving several steps (Vu j o s evi c, 2008): 1. Risk events identification; 2. Evaluation of potential risk events based on probability and consequences; 3. Defining the causes of failure and actions for its prevention; 4. Analysis of the system behavior influence on the occurrence of the risk event in the system; 5. Identification of the potential risk event consequences. By applying these steps, weaknesses in the project implementation are analyzed and overcome, as well as human errors that occurred in the work. In this paper, a risk assessment for the Medalj Potok regulation project will be performed by implementing the above steps. An appropriate method is applied for the realization of each step.

The HAZOP method
The Hazard and Operability (HAZOP) methodology is a process hazard analysis technique used for risk identification. This method is a qualitative method whose main objective is to ensure that a catastrophic event is avoided during the life cycle of the system through the analysis of its processes (No l a n , 2008).
The basic steps of the HAZOP method are as follows (No l a n , 2008): 1. Defining structure and goals of the procedure, risk assessment team experts responsibilities, and choices; 2. Identification of the system or process elements, selection of the guide words and definition of the deviations; 3. Identification of the risk events potential causes and consequences, protective measures and actions that should be taken to prevent risk events; 4. Creating reports, monitoring the implemented actions, and examining the need for iteration. In this paper, the HAZOP method is used for the identification of the system or process elements, the selection of the guide words and definition of the deviations, i.e risk events.

The Risk matrix
The Risk matrix is a two-dimensional representation of the likelihood and consequences of the risk event used when these two metrics cannot be estimated with accuracy and precision (B i l a l 2003). The Risk matrix is created as a chart where one axis indicates categories of likelihood (expressed as a probability or frequency) and the other axis indicates the categories of consequences (level of the harm). In the risk matrices, the combination of probability and consequences are compiled in a certain number of categories visualized with different colors (e.g. green, yellow and red) represent the level of risk (e. g. low, medium, high). The example of a 5x5 risk matrix that has five levels of probability and five levels of severity (consequences) is presented in Table. 1.
For each risk event identified using the HAZOP method the level of risk is obtained by multiplying the estimated probability and consequences.

The FMEA method
Failure Mode and Effects Analysis (FMEA) is a method used for the identification of all potential causes of identified risk events, supporting the identification of actions and controls whose implementation could reduce or eliminate the risk (Ostrom and Wilhelmsen, 2012).
If a risk event is identified, the FMEA method could be further used for the identification of the causes of failure, and actions for its prevention applying the following steps (O st ro m and Wilhelmsen, 2012): 1. Identification of elements or activities for the analysis, a decision on the application of structural or functional FMEA, depending on the observed process; 2. Identification of the failure mode, its effects, causes, and actions that will affect each element or activity by creating a FMEA list. 3. Component risk assessment, determination of the risk-priority number (RPN) elements, which are severity, occurrence, and detection of the risk; 4. Prioritizing actions for reduction or elimination of the risk. The result of this method is a failure with the highest RPN number and it gets the priority for defining and realizing action that will reduce the severity of occurrence (No l an , 2008).

Fault Tree Analysis
Fault Tree Analysis (FTA) is a method developed in the 1960s by NASA and the US Department of Defence. It is a graphical model created by deductive reasoning that leads to several combinations of events that cause failure, i.e. adverse events (B i l a l , 2003). The construction of the fault tree is performed only for events that are recognized as significant. If the starting point of the analysis is a result of the previously used FMEA method, the Fault tree could be created only for the risk event that is identified as the most importantthe event with the highest RPN number. After the creation of the fault tree, its qualitative and quantitative analyses have to be performed.
The event with the highest RPN number, the very center of the analysis, is called the top event and it represents an adverse event of the observed system. Besides the top event, it is also important to define the basic and indirect events that are part of the fault tree and they relate to the potential causes of the process top event. An indirect event is a failure that happened as a consequence of the logic gate started by one or more events. The basic event, on the other hand, is an event which on the very end of the branch and it can not be further divided (O st ro m and W i l h e l m s e n , 2012). When creating the fault tree, two types of symbols are used: event and logical gates. Events are used to display top, indirect, and basic events, while logical gates display the connection between them.

Event Tree Analysis
Event Tree Analysis (ETA) is a method used to identify all possible outcomes of an incident that result from a selected initiating event (C raw l ey, 2020).
Adverse events obtained by the fault tree method are further considered applying the Event tree method. This method is used to determine and evaluate the set of events, triggered by an initial event, which may represent an adverse event scenario.
After the inputs are defined, steps in the realization of the analysis are as follows (O stro m and Wilhelmsen, 2012): 1. Identifying all potential scenarios; 2. Identifying the indirect events; 3. Creating an event tree; 4. Determining the risk of the obtained outcomes. By implementing these steps and performing the analysis, as a result, adverse outcomes within the observed system are obtained, the probabilities of consequences, and the requirements that will lead to increased system safety. When it comes to indirect events, i.e. tree nodes, they represent events that have two possible outcomes: success or failure, i.e. positive or negative outcomes and these events are connected by tree branches.
For the event tree, a quantitative analysis is also performed, which involves probability calculation for each of the identified outcomes. These probabilities can be determined if the probabilities of positive and negative outcomes of each event are known. The total probability of the positive outcome is calculated as the sum of probabilities of all positive outcomes of the tree, while the total probability of the negative outcome is calculated as the sum of all negative outcomes, i.e. scenarios in that tree (Ferd o u s et al., 2011).

RESULTS AND DISCUSSION
The first phase of risk assessment in the implementation of the Medalj stream regulation project is the identification of risk events using the HAZOP method. This step starts with the identification of the main elements of the system or process and appropriate guide words. The elements of the system include all groups of works and operations that need to be performed.
In the Medalj stream regulation project, 10 activities were selected -previous works, the excavation of soil for regulation, the transport of excavated soil, the construction of regulation, the excavation of soil for transverse objects, the construction of check dam in cement mortar, the construction of dry stone check dam, the construction of gabion check dam, the construction of the inflowing structure and biological works.
For each activity, the deviations of the system from the project (risk events) are identified using the guide words (such as "not", "more", "part", "other"). Guide words "before" and "after" indicate that the order of execution of activities has not been followed, "part" means that only part of the work has been completed; "no" indicates that activity is not realized; the words "early" or "late" indicate the timing is different from the intention; The word "more" means that the volume of performed work was greater than planned, etc.
The analysis is performed for all activities, but the results are presented only for the activityexcavation of soil for regulation because groundworks have proven to be crucial in the risk analysis of this project (Table 2).
After identifying all possible risk events in the Medalj stream regulation project a risk matrix was formed. The risk matrix compares several risk events and by assessing their probability and consequences, the level of risks is defined and could serve to decide on the risk preventive measures and actions. Table 3 presents the risk events related to the project activity -soil excavation as well as the level of risk.
According to the results, the risk event with the lowest value is (6) is More soil was excavated than planned, while the risk event "Only a part of the planned soil was excavated" received the highest level of risk assessment (16).
After the risk events had been assessed and distributed according to the risk zones to which they belong, the FMEA method was applied to define the event with the highest risk priority number (RPN). Previously, the FMEA method was used to define a failure that indicates all potential errors that have their causes that can or cannot be detected in the process of performing works. In this project, the three causes are detected: the worker error, the problems with mechanization and project error. For causes of failure, the values of the following parameters are determined: the severity of potential effects of failure, the probability of occurrence of failure and the probability of failure detection. By multiplying these parameters that can be evaluated on a scale from 1 to 10, i.e. the risk priority number, whose value ranges from 1 to 1000 is calculated. The problem with mechani-  The results obtained for soil excavation for stream regulation using the FMEA method are presented in Table 4.
Using the Fault Tree Analysis Method, the risk event with the highest RPN value is shown as the top event. Events that represent possible causes of the top, unwanted events of the system are also defined, namely: error of workers, the problem in Project error 6 4 3 72 Figure 1. Fault tree analysis for a top event "Only a part of the planned soil was excavated" mechanization and project error (error in the bill of quantities). Then, lower-level events are defined, and the relations between them are shown by logical operations. For example, worker error is caused by insufficient worker expertise due to inadequate training (due to the disinterest of the worker or instructor) or is the result of worker fatigue and his problems. Ten potential causes of the risk event are identified (Figure 2). After a certain cause of a critical event is determined, its outcomes are analyzed using the Event tree analysis method.
From the constructed event tree, it can be seen that there are five possible outcomes of the top risk event and their probabilities. The probabilities of all favorable and all unfavorable outcomes were calculated using the Event tree analysis method. The probability of a favorable outcome is estimated as 82.5% (50% + 25% + 7.5%), while the probability of an unfavorable outcome is 17.5% (14% + 3.5%).
From the presented results of risk assessment during the implementation of the Medalj stream regulation project, it can be seen that the event with the highest risk is the event "Only part of the planned soil was excavated", with ten identified possible causes and five possible outcomes. The probability of a favorable outcome (excavation was performed according to the project) is 82.5% and an unfavorable one (excavation was subsequently performed and excavation was not performed) is 17.5%.

CONCLUSIONS
Risk assessment in the implementation of the project for the construction of the Medalj stream regulation was performed using quantitative methods: HAZOP, Risk matrix, FMEA, Fault tree analysis, and Event tree analysis. The methods were applied in the appropriate phases of risk assessment during the project implementation, from the manner of its occurrence to the outcome with the probabilities of their occurrence. The research covers all works on the construction of the regula-Слика 2. Анализа стабла догађаја са могућим исходима вршног догађаја и вероватноћама tion facility, and only earthworks are presented in the paper because the probability of occurrence of risky events during their development is the highest. By applying the adopted methods, the critical event with the highest probability of risk was determined, as well as its favorable and unfavorable outcomes. In this way, the risk assessment procedure enables the definition of preventive measures and actions to reduce and prevent potential risks, thus providing an excellent basis for risk management planning in the observed project.
Note: The study is a result of the project funded by the Ministry of Science and Technological Development of Serbia.