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Abstract: Transport risk assessment for the environment has two important aspects—problem solving model and solution veracity. Problem solving model is larger understanding of tasks interconnection, which represents in itself partial solution of general risk assessment. Veracity of solution means how the results are consistent with the reality. By researching of both aspects, it rises many unanswered questions. It is concerned about verification and validation of risk assessment results. By risk assessment for the environment it is possible to meet wide variety of more or less good soluble problems. It exists simple problems based on risk assessment of common traffic accidents connected with service charge outflow. On the other site, it exists complex problems of risk assessment connected with dangerous goods transport by traffic or pipelines. By simple problems solving there are not many questions about risk assessment veracity. It is possible to determine traffic accidents frequencies and service charge outflows consequences on the basis of examined events in transportation with great veracity. By complex problems the situation is quite different. The frequencies of large accidents are very low but the consequences for the environment may be large. Both are encumbered by large level of uncertainty. That is why the question is rising. To what degree, it is in these cases correct to make decision based on risk assessment.
Key words: Transport, risk, environment, risk management, uncertainties, probability.
1. Risk Management
Risk management is realized in all human life areas. It takes effect in many standards with the relation to risk whose purpose is to unite terminology, methods and procedures in this area. This fact is possible to document with brief summary of static standards from risk management area:
? ISO/IEC Guide 73:2009 Vocabulary for Risk Management
This directive determines basic risk management terminology, which should be respected in all standards used for risk management in different fields. There are mentioned definitions of generally useable terms respecting risk management. Its main aim is to give support to mutual and consistent understanding of actions statement respecting risk management and logically advised access to this statement, as well as using uniform risk management terminology in processes and systems considering risk management. The directive is intended for:
? workers engaged in risk management;
? workers engaged in ISO and IEC activities;
? workers engaged in elaboration of national or branch standards, manuals, procedures and principles concerning risk management.
It results many another standards from this basic terminological document, which have direct or mediate relation to the risk. Like such as standards example it is possible to mention:
? ISO 13824:2009 General principles on risk assessment of systems involving structures;
? ISO 31000:2009 Risk management—principles and guidelines;
? ISO/IEC 31010:2009 Risk management—risk assessment techniques;
? ISO/IEC Guide 51:1999 Safety aspects—guidelines for their inclusion in standards;
? ISO/IEC Guide 50:2002 Safety aspects—guidelines for child safety.
These mentioned standards represent only small part
of ISO standards concerning risk. More detailed instruction manuals and techniques are in IEC and EN standards. These standards regulate many different aspects of risk.
The principle of risk management is the risk assessment. Risk assessment is the process composed of partial processes, which are risk identification, risk analysis and risk evaluation. The risk assessment process represents the heart of risk management, as shown in Fig. 1.
It is necessary to be aware of the activities are the whole process of risk assessment composed by. It always depends on solved case type. Otherwise it is possible to create general model of risk assessment in accordance with activities description, which have to be done and tools, which are useful for these activities, but activities and tools selection is always specific and valid for concrete case. From the general model of risk assessment, which can not be shown in the paper due to large graphic extent, it is possible to deduce risk assessment model of transportation. This model already contains specific activities. These activities correspond to the solved problems.
2. Verification and Validation of Risk Model
Verification and validation are two terms very often used in technical praxis. These terms are not always understood equally in different areas. Most often these terms mean following processes.
Verification is the process by which the proof is got, and the existing activity was realized according to specified requirements.
Validation is the process by which the proof is got, and the product (service) meets relevant requirements of specifications.
Veracity assessment—solution validity confirmation, is not generally possible to do on the basis of solution outcome confrontation with the reality. So it is necessary to find another way of solution validity assessment of risk general problem of complex system [2].
Useful way is the description of general problem solution with the form of technological risk model, which represents the transformation of risk assessment general process model to the model which is valid for risk assessment of concrete complex system. In our case it is concerned about model for transport risk assessment for the environment.
Risk technological model for concrete case of complex system is possible to put together with different ways. The risk general task is divided(discretized) into partial problems, which are solved by concrete tools and with concrete input data. The generation of specific risk model is shown in Fig. 2. Risk general task is possible to divide into partial problems by other ways. These problems are possible to solve by other tools. The verification and validation problem is by this access solved in several steps:
3. Process Model of Transportation Risk Assessment for the Environment
3.1 Input Information
The transport risk assessment model for the environment needs several types of input information. It is possible to summarize this information to following categories:
Goods characteristics:
? The quantity of transported substance;
? Package;
? Substance physical parameters.
Route characteristics:
? Traffic conditions;
? Meteorological conditions;
? Morphology of surroundings terrain.
Substance dangerousness:
? Toxicity;
? Ecotoxicity;
? Flammability;
? Explosibility;
? Radioactivity.
Affected zone characteristics:
? Population density;
? Representation of single environment elements and its types:
? Atmosphere;
? Soil;
? Surface water;
? Underground water;? Biotic elements (flora, fauna, ecosystems) [3]. Environment elements vulnerability:? Sensitivity;? Significance.
Evaluation criteria:
? Legislative;
? Special.
3.2 Evaluation Procedure
The evaluation requires the application of analysis models. Partial outputs from single steps represent always the input to the next step. It is useful to do the evaluation for short route segments. The total risk is then the sum of risks in single route segments.
At the beginning of the evaluation it is necessary to establish the scenarios determining which environment elements and types of actual conditions will be taken into account by the evaluation. It is also necessary to establish basic and special evaluation criteria for existing problem.
In the first step it is necessary to determine the accident probability. It can generally depend on goods type, traffic situation and actual conditions. It can be different in partial route segments according to its specific characteristics, but it can be set by single value flowing from traffic accident statistics.
Then it follows the calculations of dangerous substances spread into the environment. It is mostly concerned about sophisticated deterministic physical models [4, 5]. But these models are largely different for different environments (atmosphere, soil, surface water, underground water). Large number of physical parameters that these models require and large complexity of detailed solution are the problem. Always it is necessary to accomplish some simplification of mathematical formulation of the problem, which has to respond to requirements for outcome exactness. The outputs are time variable concentration fields of the substance in single types of the environment.
There are very important dose/response models, but
they are in light of the environment at the time not ideal. These models should quantify degree of damage of specific environment element by calculated exposure, which is the function of substance concentration, fire heat flux, overpressure by explosion or radiation and exposure time. Well sophisticated are probit models for human death probability. In case of the environment there is a problem of width spectra of natural environments with different vulnerability against mentioned dangerous parameters of various substances. The outcome is the risk level for single environment elements, so the probability and level of negative effect is in specific point. The quantitative or semi-quantitative risk level for single elements is possible to superimpose for different hazards, most often for accident effects of one vehicle in different transport route segments. The outcome is possible to display on maps.
Final social risk represents the quantification of total potential damage in threatened area. For its assessment it is necessary to identify the representation of assessed environment elements in the area, their range, value and level of their damage in partial areas of their occurrence. It is necessary to suit the quantification procedures to the evaluation purpose. The risk qauntification is simpler for population and financial damage. This financial damage is caused by degradation of farmland quality, agricultural, forest or fishing produce or reduced land efficiency. Much more difficult is the quantification of externalities, which contains services of natural environment for human(clear atmosphere, clear surface waters, countryside), biodiversity preservation, nature reserve and protected areas significance. But also here are some first attemps to financial quantification [6].
By quantitative formulation at the comparable level(e.g. monetary units) it is possible to cumulate risks for single environment elements directly. By semi quantitative formulation it is necessary to determine the importance of single elements, eventually of single evaluation aspects. It is necessary to establish criteria for risk acceptability evaluation. These criteria have to respect legislative notes and also they can include special requirements for specific localities, transport methods, etc.
4. Uncertainties in Transport Risk Assessment for the Environment
Different partial problems are encumbered by uncertainties in varying degrees. Accident probability assessment is based on accident statistic data. It exists some disagreements between different institutions(MDCR, RSD, PP). The thing is not only ordinal difference. Problems can arise by expression of different probabilities on roads of different category and especially in single route segments depending on their local characteristics. The distribution of large set to many smaller may lead to reduction of dependability statistic evaluation.
Many models for dangerous substances spread calculation are available. Pasquill-Gifford models are the most used for gas dispersion. More complicated is the liquid spread calculation at the land surface. Small roughness, which has random character, largely affects liquid diffluence in the landscape. It exists verified infiltration models, but their application is encumbered by large errors. It is becasuse that parameters of such model are changed in dependence on actual conditions. The models of contaminant movement in surface waters are encumbered by smaller error. It is possible to agree that the liquid spread is encumbered by larger uncertainties than the gas dispersion. The range of possible pollution is by real transport vessel volumes restricted to tens or maximal first hundreds meters from the route, so that is why it is mostly possible to consider these deficiencies as acceptable [7, 8].
The uncertainties in exposure dose calculations result mostly from the fact that the procedures(relatively good proof) developed for human population are used. It is not clear how these procedures can be used for various environment elements. It is connected with large uncertainties in
5. Conclusions
Risk assessment for the environment is much more difficult than risk assessment for human. It is necessary to explore risk for single environment elements and their concrete forms, which occur in threatened area separately and then to synthesize total risk.
It is useful to put together the technological risk model. The concrete complex problem is partitioned into the set of consequential and parallel partial problems. These problems are then solved by concrete tools.
Solution procedure of most of partial problems is possible to verify and often also to validate. It is not generally valid for exposure dose assessment and damage level of single nature environment forms.
Validation of whole problem is difficult and practicable only in simple cases, while it is possible to do with partial evaluation.
It is necessary to focus on development of classification tool for evaluation of verification and validation level of risk technological model. It is important especially in cases of extreme low probability of unwanted event and large consequences.
Acknowledgments
This research was supported by the Ministry of Education, Youth and Sports of the Czech Republic, Project No. 2B08011 “Guidelines for Assessment of Transport Ways on Biodiversity and Environment Components”.
References
[1] ISO 31000:2009 Risk Management-Principles and Guidelines, Czech Office for Standards, Metrology and Testing, Praha, 2009.
[2] P. Fuchs, Risk Management of Complex Systems Habilitation Works, Technical University of Liberec, Liberec, 2010.
[3] M. Chytry, T. Ku?era, M. Ko?í, Catalogue of Biotopes of the Czech Republic, Praha, Agency for Nature Conservation and Landscape Protection of the Czech Republic, 2001, p. 307.
[4] Methods for the Calculation of Physical Effects Resulting from Releases of Hazardous Materials (Liquids and Gases), (Yellow Book), 3rd ed., Committee for the Prevention of Disasters (CPR), Directorate-General of Labour of the Ministry of Social Affairs, The Hague, 2005, CPR 14E.
[5] D.A. Crowl, J.F. Louvar, Chemical Process Safety: Fundamentals with Application, PTR Prentice-Hall Inc., A. Simon & Schuster Company, Englewood Cliffts, New Jersey, 1990.
[6] J. Seják, Valuing Functions and Services of Ecosystems in the Czech Republic, F?P UJEP (Faculty of Environment, University of J.E.Purkyně in ústí nad Labem), 2010.
[7] C.S. Simmons, J.M. Keller, Status of Models for Land Surface Spills of Nonaqueous Liquids [Online], PNNL-14350, Pacific Northwest National Laboratory, Richland, 2003, http://www.pnl.gov/main/publications/external/technical_ reports/PNNL-14350.pdf.
[8] J.M. Keller, C.S. Simmons, The Influence of Selected Liquid and Soil Properties on the Propagation of Spills Over Flat Permeable Surfaces [Online], PNNL-15058, Pacific Northwest National Laboratory, Richland, 2005, http://www.pnl.gov/main/publications/external/technical_ reports/PNNL-15058.pdf.
Key words: Transport, risk, environment, risk management, uncertainties, probability.
1. Risk Management
Risk management is realized in all human life areas. It takes effect in many standards with the relation to risk whose purpose is to unite terminology, methods and procedures in this area. This fact is possible to document with brief summary of static standards from risk management area:
? ISO/IEC Guide 73:2009 Vocabulary for Risk Management
This directive determines basic risk management terminology, which should be respected in all standards used for risk management in different fields. There are mentioned definitions of generally useable terms respecting risk management. Its main aim is to give support to mutual and consistent understanding of actions statement respecting risk management and logically advised access to this statement, as well as using uniform risk management terminology in processes and systems considering risk management. The directive is intended for:
? workers engaged in risk management;
? workers engaged in ISO and IEC activities;
? workers engaged in elaboration of national or branch standards, manuals, procedures and principles concerning risk management.
It results many another standards from this basic terminological document, which have direct or mediate relation to the risk. Like such as standards example it is possible to mention:
? ISO 13824:2009 General principles on risk assessment of systems involving structures;
? ISO 31000:2009 Risk management—principles and guidelines;
? ISO/IEC 31010:2009 Risk management—risk assessment techniques;
? ISO/IEC Guide 51:1999 Safety aspects—guidelines for their inclusion in standards;
? ISO/IEC Guide 50:2002 Safety aspects—guidelines for child safety.
These mentioned standards represent only small part
of ISO standards concerning risk. More detailed instruction manuals and techniques are in IEC and EN standards. These standards regulate many different aspects of risk.
The principle of risk management is the risk assessment. Risk assessment is the process composed of partial processes, which are risk identification, risk analysis and risk evaluation. The risk assessment process represents the heart of risk management, as shown in Fig. 1.
It is necessary to be aware of the activities are the whole process of risk assessment composed by. It always depends on solved case type. Otherwise it is possible to create general model of risk assessment in accordance with activities description, which have to be done and tools, which are useful for these activities, but activities and tools selection is always specific and valid for concrete case. From the general model of risk assessment, which can not be shown in the paper due to large graphic extent, it is possible to deduce risk assessment model of transportation. This model already contains specific activities. These activities correspond to the solved problems.
2. Verification and Validation of Risk Model
Verification and validation are two terms very often used in technical praxis. These terms are not always understood equally in different areas. Most often these terms mean following processes.
Verification is the process by which the proof is got, and the existing activity was realized according to specified requirements.
Validation is the process by which the proof is got, and the product (service) meets relevant requirements of specifications.
Veracity assessment—solution validity confirmation, is not generally possible to do on the basis of solution outcome confrontation with the reality. So it is necessary to find another way of solution validity assessment of risk general problem of complex system [2].
Useful way is the description of general problem solution with the form of technological risk model, which represents the transformation of risk assessment general process model to the model which is valid for risk assessment of concrete complex system. In our case it is concerned about model for transport risk assessment for the environment.
Risk technological model for concrete case of complex system is possible to put together with different ways. The risk general task is divided(discretized) into partial problems, which are solved by concrete tools and with concrete input data. The generation of specific risk model is shown in Fig. 2. Risk general task is possible to divide into partial problems by other ways. These problems are possible to solve by other tools. The verification and validation problem is by this access solved in several steps:
3. Process Model of Transportation Risk Assessment for the Environment
3.1 Input Information
The transport risk assessment model for the environment needs several types of input information. It is possible to summarize this information to following categories:
Goods characteristics:
? The quantity of transported substance;
? Package;
? Substance physical parameters.
Route characteristics:
? Traffic conditions;
? Meteorological conditions;
? Morphology of surroundings terrain.
Substance dangerousness:
? Toxicity;
? Ecotoxicity;
? Flammability;
? Explosibility;
? Radioactivity.
Affected zone characteristics:
? Population density;
? Representation of single environment elements and its types:
? Atmosphere;
? Soil;
? Surface water;
? Underground water;? Biotic elements (flora, fauna, ecosystems) [3]. Environment elements vulnerability:? Sensitivity;? Significance.
Evaluation criteria:
? Legislative;
? Special.
3.2 Evaluation Procedure
The evaluation requires the application of analysis models. Partial outputs from single steps represent always the input to the next step. It is useful to do the evaluation for short route segments. The total risk is then the sum of risks in single route segments.
At the beginning of the evaluation it is necessary to establish the scenarios determining which environment elements and types of actual conditions will be taken into account by the evaluation. It is also necessary to establish basic and special evaluation criteria for existing problem.
In the first step it is necessary to determine the accident probability. It can generally depend on goods type, traffic situation and actual conditions. It can be different in partial route segments according to its specific characteristics, but it can be set by single value flowing from traffic accident statistics.
Then it follows the calculations of dangerous substances spread into the environment. It is mostly concerned about sophisticated deterministic physical models [4, 5]. But these models are largely different for different environments (atmosphere, soil, surface water, underground water). Large number of physical parameters that these models require and large complexity of detailed solution are the problem. Always it is necessary to accomplish some simplification of mathematical formulation of the problem, which has to respond to requirements for outcome exactness. The outputs are time variable concentration fields of the substance in single types of the environment.
There are very important dose/response models, but
they are in light of the environment at the time not ideal. These models should quantify degree of damage of specific environment element by calculated exposure, which is the function of substance concentration, fire heat flux, overpressure by explosion or radiation and exposure time. Well sophisticated are probit models for human death probability. In case of the environment there is a problem of width spectra of natural environments with different vulnerability against mentioned dangerous parameters of various substances. The outcome is the risk level for single environment elements, so the probability and level of negative effect is in specific point. The quantitative or semi-quantitative risk level for single elements is possible to superimpose for different hazards, most often for accident effects of one vehicle in different transport route segments. The outcome is possible to display on maps.
Final social risk represents the quantification of total potential damage in threatened area. For its assessment it is necessary to identify the representation of assessed environment elements in the area, their range, value and level of their damage in partial areas of their occurrence. It is necessary to suit the quantification procedures to the evaluation purpose. The risk qauntification is simpler for population and financial damage. This financial damage is caused by degradation of farmland quality, agricultural, forest or fishing produce or reduced land efficiency. Much more difficult is the quantification of externalities, which contains services of natural environment for human(clear atmosphere, clear surface waters, countryside), biodiversity preservation, nature reserve and protected areas significance. But also here are some first attemps to financial quantification [6].
By quantitative formulation at the comparable level(e.g. monetary units) it is possible to cumulate risks for single environment elements directly. By semi quantitative formulation it is necessary to determine the importance of single elements, eventually of single evaluation aspects. It is necessary to establish criteria for risk acceptability evaluation. These criteria have to respect legislative notes and also they can include special requirements for specific localities, transport methods, etc.
4. Uncertainties in Transport Risk Assessment for the Environment
Different partial problems are encumbered by uncertainties in varying degrees. Accident probability assessment is based on accident statistic data. It exists some disagreements between different institutions(MDCR, RSD, PP). The thing is not only ordinal difference. Problems can arise by expression of different probabilities on roads of different category and especially in single route segments depending on their local characteristics. The distribution of large set to many smaller may lead to reduction of dependability statistic evaluation.
Many models for dangerous substances spread calculation are available. Pasquill-Gifford models are the most used for gas dispersion. More complicated is the liquid spread calculation at the land surface. Small roughness, which has random character, largely affects liquid diffluence in the landscape. It exists verified infiltration models, but their application is encumbered by large errors. It is becasuse that parameters of such model are changed in dependence on actual conditions. The models of contaminant movement in surface waters are encumbered by smaller error. It is possible to agree that the liquid spread is encumbered by larger uncertainties than the gas dispersion. The range of possible pollution is by real transport vessel volumes restricted to tens or maximal first hundreds meters from the route, so that is why it is mostly possible to consider these deficiencies as acceptable [7, 8].
The uncertainties in exposure dose calculations result mostly from the fact that the procedures(relatively good proof) developed for human population are used. It is not clear how these procedures can be used for various environment elements. It is connected with large uncertainties in
5. Conclusions
Risk assessment for the environment is much more difficult than risk assessment for human. It is necessary to explore risk for single environment elements and their concrete forms, which occur in threatened area separately and then to synthesize total risk.
It is useful to put together the technological risk model. The concrete complex problem is partitioned into the set of consequential and parallel partial problems. These problems are then solved by concrete tools.
Solution procedure of most of partial problems is possible to verify and often also to validate. It is not generally valid for exposure dose assessment and damage level of single nature environment forms.
Validation of whole problem is difficult and practicable only in simple cases, while it is possible to do with partial evaluation.
It is necessary to focus on development of classification tool for evaluation of verification and validation level of risk technological model. It is important especially in cases of extreme low probability of unwanted event and large consequences.
Acknowledgments
This research was supported by the Ministry of Education, Youth and Sports of the Czech Republic, Project No. 2B08011 “Guidelines for Assessment of Transport Ways on Biodiversity and Environment Components”.
References
[1] ISO 31000:2009 Risk Management-Principles and Guidelines, Czech Office for Standards, Metrology and Testing, Praha, 2009.
[2] P. Fuchs, Risk Management of Complex Systems Habilitation Works, Technical University of Liberec, Liberec, 2010.
[3] M. Chytry, T. Ku?era, M. Ko?í, Catalogue of Biotopes of the Czech Republic, Praha, Agency for Nature Conservation and Landscape Protection of the Czech Republic, 2001, p. 307.
[4] Methods for the Calculation of Physical Effects Resulting from Releases of Hazardous Materials (Liquids and Gases), (Yellow Book), 3rd ed., Committee for the Prevention of Disasters (CPR), Directorate-General of Labour of the Ministry of Social Affairs, The Hague, 2005, CPR 14E.
[5] D.A. Crowl, J.F. Louvar, Chemical Process Safety: Fundamentals with Application, PTR Prentice-Hall Inc., A. Simon & Schuster Company, Englewood Cliffts, New Jersey, 1990.
[6] J. Seják, Valuing Functions and Services of Ecosystems in the Czech Republic, F?P UJEP (Faculty of Environment, University of J.E.Purkyně in ústí nad Labem), 2010.
[7] C.S. Simmons, J.M. Keller, Status of Models for Land Surface Spills of Nonaqueous Liquids [Online], PNNL-14350, Pacific Northwest National Laboratory, Richland, 2003, http://www.pnl.gov/main/publications/external/technical_ reports/PNNL-14350.pdf.
[8] J.M. Keller, C.S. Simmons, The Influence of Selected Liquid and Soil Properties on the Propagation of Spills Over Flat Permeable Surfaces [Online], PNNL-15058, Pacific Northwest National Laboratory, Richland, 2005, http://www.pnl.gov/main/publications/external/technical_ reports/PNNL-15058.pdf.