JP7454401B2 - Risk assessment methods and risk management methods - Google Patents

Description

The present invention relates to a risk assessment method for quantifying risks and a risk management method using the same in order to provide materials for considering safety measures to reduce risks existing in businesses, facilities, systems, products, etc. The present invention relates to a risk evaluation method and a risk management method suitable for classifying risks into graded levels according to the size of the risks and visualizing the risks of each risk scenario based on the obtained risk levels.

2. Description of the Related Art Conventionally, an event tree analysis method that follows risk scenarios in chronological order has been known as a technique for evaluating risks existing in businesses, facilities, etc. (see, for example, Patent Documents 1 and 2). However, there are some businesses, facilities, systems, and products for which risk assessment using event tree analysis is not appropriate.
On the other hand, the R-Map method is known, which uses the degree of harm (size of disaster) and frequency of occurrence of a risk scenario as parameters, and uses a matrix to evaluate the magnitude of risk (for example, see Non-Patent Document 1). .

Japanese Patent Application Publication No. 2005-327214 Patent No. 4769016

Ministry of Economy, Trade and Industry “Risk Assessment Handbook Practical Edition June 2011”

In the R-Map method, risks are evaluated by dividing them into multiple arbitrary areas such as "unacceptable risk areas," "acceptable risk areas," and "safety areas." Therefore, there is an advantage that the magnitude of each risk can be grasped step by step. However, for example, in the principles of ALARP, which is widely used as a risk assessment method, there is a risk standard A that separates "unacceptable risk areas" (danger areas) and "acceptable risk areas", and "acceptable risk areas". The premise of risk assessment is to determine the risk criterion B that separates the ``safety area'' from the ``safety area''. In addition, even if it is not based on the ALARP principle, in order to judge whether the results of risk analysis are acceptable or not, the basic procedure is to first set risk standards and then evaluate the risks. Become. However, in Japanese society, there is a problem in that it is extremely difficult for a single company to decide on risk standards, especially when disasters involve human lives.

Therefore, even if risks are visualized using the R-Map method, risks can be visualized using methods based on international and domestic standards such as ISO 31000 and JIS Q 31000, which involve comparing the results of risk analysis with risk standards. is often practically difficult to evaluate.
In addition, although the matrix in the R-Map method is useful when evaluating the magnitude of risk, it is difficult to intuitively understand how much risk exists at which risk level. There is.

This invention was made against the above background, and its purpose is to classify risk scenarios into stepwise levels according to the magnitude of risk, regardless of risk standards, and to An object of the present invention is to provide a risk evaluation method that can visualize the risk level of each risk scenario based on the risk level, and a risk management method using the same.
Another object of the present invention is to create a risk map that can intuitively recognize the risk level of each risk scenario, thereby making it possible to understand how risks are reduced in risk management. and risk management methods.

In order to solve the above problems, the present invention has the following features:
A risk assessment method in which the risk level of each risk scenario is determined by a computer based on risk analysis data that aggregates the frequency of occurrence and damage scale for each of multiple risk scenarios set in advance for accidents that have occurred in the past in the evaluation target.
a first step of plotting each risk of the plurality of risk scenarios included in the risk analysis data on a virtual graph with damage scale and occurrence frequency as the X-axis and Y-axis, respectively;
a second step of drawing an equal risk line passing through a risk scenario with the highest risk value (product of occurrence frequency and damage scale) among the plurality of risk scenarios as a maximum equal risk line on the virtual graph;
An iso-risk line that passes through the risk scenario with the smallest risk value among the plurality of risk scenarios is drawn on the virtual graph as a minimum iso-risk line, and an arbitrary number of lines are drawn between the maximum iso-risk line and the minimum iso-risk line. The third step is to equally divide the
a fourth step of assigning a risk level to the risk scenarios belonging to each of the plurality of equally divided areas based on the magnitude relationship of the risk values of the plurality of areas;
The method includes a fifth step of determining a priority order for implementing risk countermeasures according to the risk level assigned in the fourth step.

According to the above-described risk evaluation method, multiple risk scenarios can be classified into graded levels according to the magnitude of risk, regardless of risk standards. As a result, it is possible to visualize the obtained risk level by describing it in a table or graph, for example, and to create a risk map that allows the risk level of each risk scenario to be intuitively recognized. Also, although it is difficult to decide on risk standards, anyone can easily draw the maximum equal risk line Rmax and the minimum equal risk line Rmin, and no matter who does it, the same line can be drawn. I can do it .

Further, according to the above method, there is no need to consider risks in areas where the risk is smaller than the minimum iso-risk line, so the burden on the person conducting the risk evaluation can be reduced.

Further, preferably, the virtual graph is a logarithmic graph in which the X axis and the Y axis are each expressed logarithmically,
The above equal risk line is calculated by the following formula, using a and b as coefficients:
Log ₁₀ y = alog ₁₀ x + b
Let it be a straight line represented by .
According to this method, the risk map can be expressed as a logarithmic graph, so when applied to a wide range of targets, such as railway projects, where the scale of damage ranges from small to extremely large, the risk map can be expressed as a logarithmic graph. The dots indicating each risk scenario do not get too long, making it easier to understand the overall risk situation. Note that when displayed in a normal graph instead of a logarithmic graph, the equal risk line becomes a curved line.

Furthermore, preferably, after the fifth step, a table is created in which the risk level assigned in the fourth step is entered in the risk level column of a list that aggregates the frequency of occurrence and scale of damage for each of the plurality of risk scenarios. Include a step that outputs the output.
According to the above method, a table is output in which the risk level is entered in a list that aggregates the frequency of occurrence and scale of damage for each risk scenario, so the risk level of the risk scenario of interest can be immediately grasped.

Preferably, the method further includes, after the fifth step, a step of creating and outputting a graph in which equal risk lines representing the boundaries of the equal division performed in the third step are drawn.
According to this method, it is possible to intuitively understand whether there are many or few risk scenarios of the same level between the equal risk lines on the risk map, and the trends in risks that exist in the business to be evaluated. .

In addition, the risk management method, which is another invention related to this application, is
After implementing risk countermeasures according to the priority order determined by the above procedure, we collect data on newly occurring accidents and perform risk analysis that aggregates the frequency of occurrence and scale of damage for each of multiple preset risk scenarios. This method repeatedly creates data and executes the risk evaluation method again based on the created risk analysis data.
According to the above method, risks can be continued to be reduced as much as possible by repeating the process of repeating risk assessment and implementation of risk countermeasures according to priorities.

According to the risk assessment method of the present invention, risk maps are divided into graded levels according to the size of risk, regardless of risk standards, and the risk map allows the risk level of each risk scenario to be intuitively recognized. This has the effect of making it possible to understand how risks are being reduced in risk management.

1 is a block diagram showing a configuration example of a risk evaluation device to which a risk evaluation method according to the present invention is applied. (A) is a diagram showing an example of analysis data to be evaluated by the risk assessment method according to the present invention in a table format, and (B) is a diagram showing the risk level and priority order calculated by the risk assessment method according to the present invention. FIG. 3 is a diagram showing an example of a data list in a table format. It is a flowchart which shows an example of the procedure of the risk evaluation method based on this invention. It is a graph showing the initial stage of a risk map created by the risk evaluation method according to the present invention. It is a graph showing intermediate stages of a risk map created by the risk evaluation method according to the present invention. It is a graph showing a final stage risk map created by the risk evaluation method according to the present invention. 4 is a flowchart illustrating an example of a processing procedure executed after determining priorities according to the processing procedure of the risk evaluation method shown in the flowchart of FIG. 3. FIG. 8 is a graph showing a risk map changed by implementing the process according to the procedure of the flowchart in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a risk evaluation method according to the present invention will be described below with reference to the drawings, taking as an example a case in which it is applied to evaluation of risks occurring in a railway business. In the railway business, there are risks arising from different elements such as rolling stock, operation/operation, station/yard work, command operations, tracks, signals/communications, etc., and all risks arising from these elements must be treated together. Although it is possible to do so, the number of risk scenarios will be enormous and the graphs and tables will become complicated and difficult to understand, so it is desirable to perform risk analysis and risk evaluation for each element. In addition, the nature of the risks to be targeted will also differ depending on the regional nature of the natural and social environment, such as the metropolitan area and rural areas, so it is desirable to conduct risk analysis and evaluation for each route or business area. . In the following explanation, an example will be explained in which the present invention is applied to the evaluation of risks occurring in "vehicles", which are one of the elements, in one business area.

FIG. 1 is a block diagram showing an example of the configuration of a risk evaluation device to which the risk evaluation method of this embodiment is applied.
As shown in FIG. 1, the risk assessment device 10 in this embodiment has a configuration similar to a normal computer system, and includes an arithmetic processing unit 11 such as a microprocessor (CPU), RAM, ROM, keyboard, etc. It is composed of a data processing device equipped with an input device 12 such as a mouse, a storage device 13 such as a hard disk driver, a display device 14 such as a liquid crystal panel, a printing device (printer) 15, a bus 16 that connects these functional blocks, etc. has been done. A communication device may be provided to evaluate risk analysis data received via the communication network.

The storage device 13 stores a program for executing the risk evaluation method according to the present invention as well as analysis result data as an evaluation target. The analysis result data is prepared by creating a generalized risk scenario for each target element (e.g. vehicle), such as ``a passenger falls inside the train while the train is running'', and then creating a generalized risk scenario for each target element (e.g. vehicle). Accident data is classified into elements, and the frequency of occurrence and scale of damage (for example, number of casualties) are aggregated for each risk scenario of the target element.

FIG. 2A shows an example of analysis result data to be evaluated in a tabular format. In Figure 2 (A), the leftmost item is the scenario number, the next item is the content of the generalized risk scenario such as "a passenger falls inside the train while it is running," and the next item is the frequency of occurrence (yearly average The next item is the scale of damage (average number of casualties per incident), the next item is the risk value, the next item is the risk level which is the evaluation result, and the next item is the priority for implementing risk countermeasures. It is. Note that the table in FIG. 2(A) contains data before evaluation, so the columns for risk level and priority are blank.

Next, an example of the processing procedure of the risk evaluation method of this embodiment using the risk evaluation device 10 (FIG. 1) will be described using the flowchart of FIG. 3. The process according to the flowchart in Figure 3 involves creating a logarithmic graph that represents the risk distribution of each generalized risk scenario, with the scale of damage on the horizontal axis (X-axis) and the frequency of occurrence on the vertical axis (Y-axis). The main content of this program is to determine the priority of risk countermeasures using a logarithmic graph obtained by using a logarithmic graph. It is implemented by executing. Note that the processing procedure described below is an example and is not limited thereto.

In the risk evaluation process shown in FIG. 3, first, analysis result data of an element to be evaluated is read from analysis result data of accident data stored in the storage device 13 (step S1). Next, as shown in FIG. 4, each generalized risk scenario is plotted on a logarithmic graph with the scale of damage on the horizontal axis and the frequency of occurrence on the vertical axis (step S2). Note that the above graph does not need to be actually displayed on the screen of the display device 14, but is virtually generated inside the arithmetic processing device 11.

Next, attention is paid to the risk scenario with the largest risk value and the risk scenario with the smallest risk value from among the multiple risk scenarios plotted on the logarithmic graph. Here, the risk value is a value expressed as the product of damage scale and occurrence frequency, and the larger this value, the higher the risk of the scenario.

Next, from the risk scenario data (damage scale value and occurrence frequency value), substitute the damage scale value and occurrence frequency value for x and y in the formula Log ₁₀ y = alog ₁₀ x + b, respectively, and calculate the risk value. The values of coefficient a and coefficient b in the above formula are calculated from the conditional formula xi×yi=xk×yk, which indicates that the values are equal (steps S3 and S4). Here, the coefficient a represents the slope of the equal risk line on the logarithmic graph, and the coefficient b represents the size of the intercept of the vertical axis (value of occurrence frequency) of the equal risk line on the logarithmic graph. Furthermore, xi and yi are determined from the coordinates indicated by the risk scenario, and yk is determined from arbitrarily selected xk and risk value xi×yi.

Next, find the scenario with the largest risk value and the scenario with the smallest risk value among all the risk scenarios on the logarithmic graph above, and as shown in Figure 5, the iso-risk line with the largest risk value is The line Rmax is drawn, and the equal risk line with the smallest risk value is drawn as the minimum equal risk line Rmin (step S5). Specifically, for example, calculate the value b of the intercept of the iso-risk line that passes through all the risk scenarios, set the iso-risk line with the largest value of b among all the intercepts b as the maximum iso-risk line Rmax, and The iso-risk line for which the value of is small is defined as the minimum iso-risk line Rmin.

Then, the area sandwiched between the maximum equal risk line Rmax and the minimum equal risk line Rmin is divided into N equal parts, and as shown in FIG. 6, an equal risk line is drawn between the maximum equal risk line Rmax and the minimum equal risk line Rmin. is drawn (step S6). Here, N is an integer of 2 or more, and is selected as an arbitrary number between 10 and 20, for example. FIG. 6 shows, as an example, a graph when the image is divided into 10 equal parts. After that, risk scenarios that exist in the area between the maximum equal risk line Rmax and the equal risk line one below it Rmax-1 are found, and the maximum risk level Rmax is assigned to these risk scenarios (step S7). .

Next, find the risk scenarios that exist in the area between the equal-risk line Rmax-1 and the equal-risk line Rmax-2 that is one level below it, and set the second risk level Rmax-1 to those risk scenarios. (Step S8). Then, it is determined whether or not the minimum risk level Rmin has been reached (step S9), and if it is not the minimum risk level Rmin, the process returns to step S8 and the above process is repeated until the minimum risk level Rmin is reached.

If it is determined in step S9 that the minimum risk level Rmin has been reached (Yes), the process proceeds to step S10, and the priority order of risk countermeasures is determined for risk scenarios within the same risk level. Specifically, when the risk levels are different, priority is determined so that risk countermeasures are implemented starting from the one with the highest risk level. It also determines priorities within the same risk level. The method of determining priorities within the same risk level is arbitrary, and depends on the characteristics of the elements to be evaluated (in general, the characteristics of the business, facility, system, or product to be evaluated). For example, priority may be given in order of increasing scale of damage, decreasing cost required for risk countermeasures, increasing frequency of occurrence, or increasing risk value.

After that, the process proceeds to step S11, and it is determined whether or not there is a request to output a table or a graph. If there is a request to output a table, the process proceeds to step S12, and as shown in FIG. 2(B), each risk scenario is A table is created in which the risk level values and priority values determined in the above steps are entered in the "risk level" and "priority" columns, respectively, and is displayed on the display device 14. On the other hand, if there is a request to output a graph, the process advances to step S13 and a logarithmic graph shown in FIG. 6 is displayed.

As explained above, according to the risk evaluation method of the above embodiment, risk scenarios are divided into graded levels according to the magnitude of risk, regardless of risk standards, and the obtained risk levels are displayed in tables and graphs. It can be visualized by
In addition, it is possible to create a risk map that allows you to intuitively recognize the magnitude of the risk of each risk scenario, and by displaying the risk map in a logarithmic graph, it is possible to create a risk map that allows you to intuitively recognize the magnitude of the risk of each risk scenario. When applied to a wide range of fields, including very large ones, the intervals between dots indicating each risk scenario on the risk map do not become too long, making it easier to understand the overall risk situation.

Furthermore, for example, instead of displaying the risk map as a logarithmic graph and drawing the iso-risk line that passes through the risk scenario with the minimum risk value as the minimum iso-risk line Rmin, a straight line that passes through the origin and is parallel to other iso-risk lines is drawn as the minimum iso-risk line. It is also conceivable to regard this as a risk line and equally divide the area between the maximum equal risk line Rmax and the deemed minimum equal risk line. However, in this case, the risk level will be determined by including the region closer to the origin than the minimum equal risk line Rmin in FIG. 6 (the region surrounded by the origin and the minimum equal risk line Rmin). At this time, the risk scenario is not plotted in the area closer to the origin than the minimum iso-risk line Rmin, so if the risk level is determined by including this area, the risk will be evaluated by including unnecessary areas. Therefore, the accuracy of risk assessment may decrease.

On the other hand, in the above embodiment, the iso-risk line with the largest risk value is defined as the maximum iso-risk line Rmax, and the iso-risk line with the smallest risk value is defined as the minimum iso-risk line Rmin, and the iso-risk line with the smallest risk value is defined as the minimum iso-risk line Rmin. Since the level is set, areas where risks are not plotted are not considered as target areas for risk evaluation, and the accuracy of risk evaluation can be improved.

Next, the process after determining the priority order according to the process procedure of the risk evaluation method shown in the flowchart of FIG. 3 will be described using the flowchart of FIG. 7.
After determining the priorities according to the risk evaluation method shown in the flowchart of FIG. 3, preset risk countermeasures are implemented according to the determined priorities (step S21 in FIG. 7). Here, "risk countermeasures" refers to selecting one or more options and implementing those options in order to modify risks.

Options include, for example, avoiding a risk by deciding not to start or continue the activity that gives rise to the risk, taking or increasing the risk in order to pursue an opportunity, and eliminating the source of the risk. changing the likelihood of a risk scenario, changing the outcome (scale of damage), sharing the risk with one or more others, and retaining the risk through informed decision-making. .

If risk countermeasures are implemented from those with the highest risk level according to the priority order described above, as shown in Figures 8 (A) and (B), the risk will decrease first from the risk scenario farthest from the origin, and the maximum iso-risk line will be reached. As it moves closer to the origin, the width of the risk area becomes narrower. However, in the railway business, for example, as long as trains are operated, risks will never be reduced to zero; implementing risk countermeasures may generate other risks, or risks may increase again as accidents fade.

Therefore, after implementing risk countermeasures, monitoring or observation (review) is performed for a predetermined period of time to collect data on the evaluation target for which risk countermeasures have been implemented (step S22). Thereafter, risks are identified from the obtained data (step S23), the risks are analyzed, and a table showing the analysis results as shown in FIG. 2(A), for example, is created (step S24). Then, the risk management process described above is repeated, such as performing the above-described risk assessment (FIG. 3) again based on the analysis results.

By cycling the process as described above, it is possible to continue to reduce risks as much as possible.
By displaying a risk map (logarithmic graph) as shown in FIG. 6 when performing risk evaluation, it is possible to understand how risks are reduced in risk management.

Although the present invention has been described above based on Examples, the present invention is not limited to the above Examples. For example, in the above embodiment, a logarithmic graph is used to visualize the risk level of each risk scenario, but a semi-logarithmic graph with one of the X-axis or Y-axis displayed as a logarithm, or a normal graph that does not use a logarithm may be used. The risk level can be visualized by In addition, in the above embodiment, the graph is shown in which the horizontal axis is the scale of damage and the vertical axis is the frequency of occurrence, but the horizontal and vertical axes may be reversed.In the graph, the equal risk line passing through the risk scenario with the smallest risk value is Although the minimum equal risk line is used, a line that passes through the origin and is parallel to other equal risk lines may be regarded as the minimum equal risk line to classify risk levels.

Further, in the embodiment, the scale of damage is expressed as "number of casualties/case", but risk evaluation may be performed using other parameters such as "damage amount/case".
Further, in the above embodiment, the present invention was applied to the case of evaluating risk factors in railway business, but the present invention is applicable to operations other than railways, such as buses (including water buses), ferries, and airplanes. It can also be applied when evaluating risk factors in transportation projects.
Furthermore, the present invention can be widely used for risk evaluation in businesses other than transportation businesses, facilities, systems, products, and drug manufacturing industries.

10 Risk Evaluation Device 11 Arithmetic Processing Device 12 Input Device 13 Storage Device 14 Display Device 15 Printing Device 16 Bus

Claims (5)

This is a risk assessment method in which the risk level of each risk scenario is determined by a computer , based on risk analysis data that aggregates the frequency of occurrence and damage scale for multiple risk scenarios set in advance for accidents that have occurred in the past in the subject of evaluation. hand,
a first step of plotting each risk of the plurality of risk scenarios included in the risk analysis data on a virtual graph with damage scale and occurrence frequency as the X-axis and Y-axis, respectively;
a second step of drawing an equal risk line passing through a risk scenario with the highest risk value among the plurality of risk scenarios as a maximum equal risk line on the virtual graph;
An iso-risk line that passes through the risk scenario with the smallest risk value among the plurality of risk scenarios is drawn on the virtual graph as a minimum iso-risk line, and an arbitrary number of lines are drawn between the maximum iso-risk line and the minimum iso-risk line. The third step is to equally divide the
a fourth step of assigning a risk level to the risk scenarios belonging to each of the plurality of equally divided areas based on the magnitude relationship of the risk values of the plurality of areas;
a fifth step of determining a priority for implementing risk countermeasures according to the risk level assigned in the fourth step;
A risk assessment method characterized by comprising: The virtual graph is a logarithmic graph in which the X axis and the Y axis are each displayed logarithmically,
The above equal risk line is calculated by the following formula, using a and b as coefficients:
Log ₁₀ y = alog ₁₀ x + b
2. The risk evaluation method according to claim 1 , wherein the risk evaluation method is a straight line represented by . After the fifth step, creating and outputting a table in which the risk level assigned in the fourth step is entered in the risk level column of a list that aggregates the frequency of occurrence and scale of damage for each of the plurality of risk scenarios. The risk evaluation method according to claim 1 or 2 , comprising: The risk assessment method according to any one of claims 1 to 3, further comprising, after the fifth step, a step of creating and outputting a graph on which is drawn equal risk lines representing the boundaries of the equal division executed in the third step. After implementing risk countermeasures in accordance with the priority order determined by the risk evaluation method according to any one of claims 1 to 4 , data on newly occurring accidents is collected and the data is calculated based on a plurality of preset risk scenarios. A risk management method characterized by repeatedly creating risk analysis data that aggregates frequency and damage scale, and executing the risk evaluation method again based on the created risk analysis data.

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