- Email: [email protected]
Transportation system safety
~64
Recent Publications
REFERENCES Carlson W. L. Age, exposure, and alcohol involvement in night crashes. J. of Safety Res 5(4), National SafeTy Council, (Dec. 1973). Carroll P. S., Carlson W. k., McDole T. [.. and Smith D. W. Acquisition of lnforrnatiorz on Exposure and on Non-Fatal Crashes--Exposure Survey Considerations. Highway Safety Research Institute, University of Michigan, 1971. Koornstra M. J. A model for estimation of collective exposure and proneness from accident data. Ace. Anal. & Prer. 5. 157-173, 1973. Shaw L. and Sichel H. Accident Proneness. Research in the Occurence, Causation and Pret:ention of Road Accidents. Pergamon Press, Oxford, 1971. Tilman W. A. and Hobbs G. E. Accident-prone automobile driver. Am. J. Ps~,chiatry 106(5), 321-331, 1949.
Transportation System Safety. Michael Horodniceanu and Edmund J. Cantilli. Lexington Books, D. C. Heath and Company, Lexington, Mass. 1979. 240 pp. $18.95. This book applies system safety principles and methods to the transportation field, with particular emphasis on highway safety. Much of it is based on previous publications by Horodniceanu, et al., including Transportation System Safety Methodology, a report prepared for the Offce of University Research, U.S. Department of Transportation, November 1976; and A Comprehensive Transportation Safety Methodology, which was prepared by Horodniceanu as his Ph.D. dissertation (Polytechnic Institute of New York, 1978). I counted a total of 49 out of 72 figures and tables in the text which referenced one of these two publications as their source. A serious student of this subject may wish to refer to the original source documents for more detailed information. As the authors state, the intent of this book is twofold: to provide a general understanding of the system-safety approach and its applicability to transportation, and to provide a structure through which organizational safety can be analyzed and safety decisions made. Topics presented include The System-Safety Concept; The Existing Safety Problem in Transportation: A Generic Classification of the Transportation Modes for Safety Analysis; Information Flow: The Feedback Mechanism; Guiding Principles for a Comprehensive Gradatim (step-by-stept Safety Analysis Methodology; A Gradatim Safety Analysis Methodology; The Applicability of the Gradatim System-Safety Methodology: A Case Study; Development of a Safety Control and Allocation Toot for Roadside Improvements; and Conclusions and Future Recommendations. The four Appendices include (A) Job Descriptions for a Safety Director, Safety Representative, Safety Inspector, Safety Training Specialist, and Accident Investigator; (B) Development of a Single-Vehicle Roadside Hazard Fault Tree; (C) The Incorporation of Severity into Fault Trees; and (D) an Allocation Program consisting of a computer program employing the fault tree methodology. The first chapter reviews system safety concepts as they are defined by the National Aeronautics and Space Administration (NASA) and the Department of Defense. A key point in this chapter is that through the use of a systematic approach to safety problem identification. potential hazards can be identified before they produce loss, thus permitting corrective actions to be taken before accidents occur rather than after. Based on the concepts discussed in this chapter, a "gradatim" or step-by-step safety analysis methodology for transportation was developed in Chap. 6. Chapter 2 reviews the existing safety problems in transportation and sets the stage for introducing the systems approach to seeking problem solutions. Chapter 3 presents a classification of the transportation modes by operational characteristics as a basis for improving the process of identifying accident causes. Chapters 4 and 5 provide an in-depth explanation of the bases for the proposed system safety methodology. I found particularly interesting the authors' discussion of measurement and the evaluation process. The issues and problems in transportation safety performance measurement are correctly described. The ability to establish safety goals, policies and objectives; to analyze existing safety levels; and to allocate funds for additional safety improvements requires a valid, reliable and practical means of measuring safety. Closely related to measurement is the criterion problem-What should be used as a measureable entity'? As the authors point out. there is difficulty in defining appropriate criteria within a single transportation mode and in defining a common measurement index that is equally suitable to all transportation modes. Problems 'ari,c
Recenl Publication,;
365
when the ultimate criteria of fatalities and injuries are used (e.g. exposure, sensitivity, statistically rare, etc.). To alleviate these problems, the authors suggest using intermediate or proxy criteria (e.g. reductions in driving speed) which can be assessed by means of behavior observation surveys. The authors suggest using the classical experimental research model to assess the effectiveness of an instituted safety program change. In the transportation field, some of the newer analytical techniques for evaluating the effects of safety interventions, such as the Box-Jenkins-Tiao method of interrupted time series analysis using the general class of Auto Regressive Integrated Moving Average (ARIMA) models might be more appropriate for evaluation purposes than the classical research model involving random assignment to experimental and control groups. The heart of the text is Chap. 6, where the Gradatim Safety Analysis Methodology is discussed in detail. The methodology presented in this chapter is a compendium of management techniques, guidelines, checklists, and analytical techniques designed to provide the analyst with the tools necessary to assess the status of safety either in a proposed transportation system (organization) or an ongoing operational one. Chapter 7 applies the Gradatim System Safety Methodology to the highway safety field through applications of the principles of the approach at different levels of government and private industry. A detailed analysis of operating toll highway facilities is performed in Chap. 8, where a model is developed for setting roadside safety improvements in priority order, using fault tree analytical techniques. Finally, Chap. 9 presents a summary and conclusions and indicates future research avenues for further improving safety in transportation. This book presents a well-written, interesting, and thorough commentary on safety issues and analytical techniques involved in the various transportation modes, with special consideration given to highway safety problems. The applications presented involve all aspects of safety, starting with individuals and organizations and concluding with a procedure for making management decisions concerning the allocation of funds for safety improvements. The step-bystep, or "gradatim" methodology for safety analysis, wile really not conceptually new to those familiar with system safety methodology, provides a good beginning for an overall, comprehensive approach to safety in transportation. It considers safety as a collective effort at various organizational levels, integrating managerial and analytical techniques and bringing them together as a focal point for safety measurement, prediction, and control. The method provides managers and safety professionals with tools for analyzing safety within an existing organization, developing guidelines for incorporating and integrating safety into new organizations, and facilitating and documenting safety issues for proper decision-making. The methods discussed provide an organized procedure for anticipating failure events. There are some problems in applying analytical techniques such as fault tree and other system safety analysis tools to human behavior-based problems (as opposed to hardware-based problems), For example, in applying system safety methodologies to traffic safety problems involving the driver, vehicle, roadway and environment the analyst often encounters difficulty in determining the probabilities necessary to properly utilize the analytical techniques. Lacking the data needed to determine probabilities quantitatively, the researcher must resort to opinion or the collective judgement of persons experienced in the field. The reliability of these estimates is often questionable. As the authors state, "The gradatim transportation systemsafety methodology is simply the basis for further research and development which will eventually lead to detailed guidelines for safety organization on a modal basis... To increase the utility of the methodology as a safety research tool, the establishment of a functional relationship between its various elements should be pursued." The authors further state that "The integration of accident severity in all such fault trees should also be researched to enable decisions to be made based on risks rather than simple probabilities" (an example of the incorporation of severity into fault trees is provided in Appendix C). I agree with the authors' statement that the techniques presented provide a basis for further research and development before detailed, practical guidelines can be established for safety analysis and safety organization use in the various transportation modes. In spite of these qualifying remarks, in my judgement the checklists, analytical methodologies, and other information presented in this book provide a very useful and systematic approach to analyzing and solving safety problems in the transportation field. Gradatim system
366
Recent Publications
safety methodology provides a good starting point and holds much promise for upgrading the safety level within the various transportation modes. I recommend that the book be read and digested by all safety professionals and program managers concerned with transportation safety in all modes. WlLI.Ia,M E. TAP,RANTS
National Highway Traffic Safety Administration U.S. Department of Transportation
BRIEF NOTICES A Comparison of the Automatic Shoulder Belt~Knee Bolster Restraint System with the Lap and Shoulder Belt System in VW Rabbits. George Y. H. Chi and Donald W. Reinfurt. University of North Carolina Highway Safety Research Center, Chapel Hill, North Carolina, 1981. 113 pp. The primary objective of this research was to assess the serious and fatal injury reducing effectiveness of the VW Rabbit automatic shoulder belt/knee bolster system using statewide police-reported accident data. The analyses were aimed at answering questions about (ll injury rate differences (manual vs automatic); (2) restraint usage rate differences; (3) performance differences between system sysems (when used); (4) the proportion of injury rate reduction attributable to restraint usage rate differences; and (5) adequacy of state accident data to carry out such investigations. The study data consisted of 10,336 accidents involving VW Rabbits during the period 1975-1979 in New York, North Carolina, Maryland, Colorado, Alabama and South Carolina. The analyses generally involved the following: (1) investigation of potential biases arising from missing belt usage cases: (2) identifying confounding variables by variable screening and then smoothing the data using weighted least squares procedures for categorical data: and (3t examination of the components of the overall serious injury rate reduction, namely components due to usage rate differences, belt system differences and sample variation. For the primary analyses involving data from New York, North Carolina, Maryland and Colorado, the range of usage rates was 16.6-41.6~ for manual belts vs 43.1-73.7~ for automatic belts. Occupants in automatic belt Rabbits experienced 20-30c~ fewer serious injuries than their counterparts in Rabbits with conventional 3-point belt systems. The overriding factor for this reduction was the increase (at least two-fold) in the belt usage rates in the automatic belt Rabbits. When used, the two belt systems were found to be equally effective in preventing serious injuries.
Driver Behavior Research--Needs and Priorities. I.R. Johnston and D. R. Perry. Re~earch Report ARR 108. Australian Road Research Board. Victoria, Australia, 198(t, 39 pp. Driver behavior research is defined as research directed at describing, classifying, understanding and predicting the behavior of the driver in the operation of the road transport system. Evaluating the effectiveness of driver control measures is thus excluded from this reviex~. The "task-demand" and "cognitive-motivational" models of driver behavior are examined to bring out the influence of personal factors in driver decision-making, risk-taking and hence actual on-road behavior. A case is made for a greater research effort into the behavioural, as well as the situational, determinants of variability in on-road behaviour. Research into individual differences is then reviewed, covering personality, skills and driving style. A case is made for more research into transieiit"states rather than "personality" traits: composite measures of perceptual functioning rather than basic visual and motoi abilities: and the systematic investigation of normative patterns of on-road driving behax iour. Major research needs identified include a shift in emphasis from accident-related to n~rm'a/
Recent Publications
REFERENCES Carlson W. L. Age, exposure, and alcohol involvement in night crashes. J. of Safety Res 5(4), National SafeTy Council, (Dec. 1973). Carroll P. S., Carlson W. k., McDole T. [.. and Smith D. W. Acquisition of lnforrnatiorz on Exposure and on Non-Fatal Crashes--Exposure Survey Considerations. Highway Safety Research Institute, University of Michigan, 1971. Koornstra M. J. A model for estimation of collective exposure and proneness from accident data. Ace. Anal. & Prer. 5. 157-173, 1973. Shaw L. and Sichel H. Accident Proneness. Research in the Occurence, Causation and Pret:ention of Road Accidents. Pergamon Press, Oxford, 1971. Tilman W. A. and Hobbs G. E. Accident-prone automobile driver. Am. J. Ps~,chiatry 106(5), 321-331, 1949.
Transportation System Safety. Michael Horodniceanu and Edmund J. Cantilli. Lexington Books, D. C. Heath and Company, Lexington, Mass. 1979. 240 pp. $18.95. This book applies system safety principles and methods to the transportation field, with particular emphasis on highway safety. Much of it is based on previous publications by Horodniceanu, et al., including Transportation System Safety Methodology, a report prepared for the Offce of University Research, U.S. Department of Transportation, November 1976; and A Comprehensive Transportation Safety Methodology, which was prepared by Horodniceanu as his Ph.D. dissertation (Polytechnic Institute of New York, 1978). I counted a total of 49 out of 72 figures and tables in the text which referenced one of these two publications as their source. A serious student of this subject may wish to refer to the original source documents for more detailed information. As the authors state, the intent of this book is twofold: to provide a general understanding of the system-safety approach and its applicability to transportation, and to provide a structure through which organizational safety can be analyzed and safety decisions made. Topics presented include The System-Safety Concept; The Existing Safety Problem in Transportation: A Generic Classification of the Transportation Modes for Safety Analysis; Information Flow: The Feedback Mechanism; Guiding Principles for a Comprehensive Gradatim (step-by-stept Safety Analysis Methodology; A Gradatim Safety Analysis Methodology; The Applicability of the Gradatim System-Safety Methodology: A Case Study; Development of a Safety Control and Allocation Toot for Roadside Improvements; and Conclusions and Future Recommendations. The four Appendices include (A) Job Descriptions for a Safety Director, Safety Representative, Safety Inspector, Safety Training Specialist, and Accident Investigator; (B) Development of a Single-Vehicle Roadside Hazard Fault Tree; (C) The Incorporation of Severity into Fault Trees; and (D) an Allocation Program consisting of a computer program employing the fault tree methodology. The first chapter reviews system safety concepts as they are defined by the National Aeronautics and Space Administration (NASA) and the Department of Defense. A key point in this chapter is that through the use of a systematic approach to safety problem identification. potential hazards can be identified before they produce loss, thus permitting corrective actions to be taken before accidents occur rather than after. Based on the concepts discussed in this chapter, a "gradatim" or step-by-step safety analysis methodology for transportation was developed in Chap. 6. Chapter 2 reviews the existing safety problems in transportation and sets the stage for introducing the systems approach to seeking problem solutions. Chapter 3 presents a classification of the transportation modes by operational characteristics as a basis for improving the process of identifying accident causes. Chapters 4 and 5 provide an in-depth explanation of the bases for the proposed system safety methodology. I found particularly interesting the authors' discussion of measurement and the evaluation process. The issues and problems in transportation safety performance measurement are correctly described. The ability to establish safety goals, policies and objectives; to analyze existing safety levels; and to allocate funds for additional safety improvements requires a valid, reliable and practical means of measuring safety. Closely related to measurement is the criterion problem-What should be used as a measureable entity'? As the authors point out. there is difficulty in defining appropriate criteria within a single transportation mode and in defining a common measurement index that is equally suitable to all transportation modes. Problems 'ari,c
Recenl Publication,;
365
when the ultimate criteria of fatalities and injuries are used (e.g. exposure, sensitivity, statistically rare, etc.). To alleviate these problems, the authors suggest using intermediate or proxy criteria (e.g. reductions in driving speed) which can be assessed by means of behavior observation surveys. The authors suggest using the classical experimental research model to assess the effectiveness of an instituted safety program change. In the transportation field, some of the newer analytical techniques for evaluating the effects of safety interventions, such as the Box-Jenkins-Tiao method of interrupted time series analysis using the general class of Auto Regressive Integrated Moving Average (ARIMA) models might be more appropriate for evaluation purposes than the classical research model involving random assignment to experimental and control groups. The heart of the text is Chap. 6, where the Gradatim Safety Analysis Methodology is discussed in detail. The methodology presented in this chapter is a compendium of management techniques, guidelines, checklists, and analytical techniques designed to provide the analyst with the tools necessary to assess the status of safety either in a proposed transportation system (organization) or an ongoing operational one. Chapter 7 applies the Gradatim System Safety Methodology to the highway safety field through applications of the principles of the approach at different levels of government and private industry. A detailed analysis of operating toll highway facilities is performed in Chap. 8, where a model is developed for setting roadside safety improvements in priority order, using fault tree analytical techniques. Finally, Chap. 9 presents a summary and conclusions and indicates future research avenues for further improving safety in transportation. This book presents a well-written, interesting, and thorough commentary on safety issues and analytical techniques involved in the various transportation modes, with special consideration given to highway safety problems. The applications presented involve all aspects of safety, starting with individuals and organizations and concluding with a procedure for making management decisions concerning the allocation of funds for safety improvements. The step-bystep, or "gradatim" methodology for safety analysis, wile really not conceptually new to those familiar with system safety methodology, provides a good beginning for an overall, comprehensive approach to safety in transportation. It considers safety as a collective effort at various organizational levels, integrating managerial and analytical techniques and bringing them together as a focal point for safety measurement, prediction, and control. The method provides managers and safety professionals with tools for analyzing safety within an existing organization, developing guidelines for incorporating and integrating safety into new organizations, and facilitating and documenting safety issues for proper decision-making. The methods discussed provide an organized procedure for anticipating failure events. There are some problems in applying analytical techniques such as fault tree and other system safety analysis tools to human behavior-based problems (as opposed to hardware-based problems), For example, in applying system safety methodologies to traffic safety problems involving the driver, vehicle, roadway and environment the analyst often encounters difficulty in determining the probabilities necessary to properly utilize the analytical techniques. Lacking the data needed to determine probabilities quantitatively, the researcher must resort to opinion or the collective judgement of persons experienced in the field. The reliability of these estimates is often questionable. As the authors state, "The gradatim transportation systemsafety methodology is simply the basis for further research and development which will eventually lead to detailed guidelines for safety organization on a modal basis... To increase the utility of the methodology as a safety research tool, the establishment of a functional relationship between its various elements should be pursued." The authors further state that "The integration of accident severity in all such fault trees should also be researched to enable decisions to be made based on risks rather than simple probabilities" (an example of the incorporation of severity into fault trees is provided in Appendix C). I agree with the authors' statement that the techniques presented provide a basis for further research and development before detailed, practical guidelines can be established for safety analysis and safety organization use in the various transportation modes. In spite of these qualifying remarks, in my judgement the checklists, analytical methodologies, and other information presented in this book provide a very useful and systematic approach to analyzing and solving safety problems in the transportation field. Gradatim system
366
Recent Publications
safety methodology provides a good starting point and holds much promise for upgrading the safety level within the various transportation modes. I recommend that the book be read and digested by all safety professionals and program managers concerned with transportation safety in all modes. WlLI.Ia,M E. TAP,RANTS
National Highway Traffic Safety Administration U.S. Department of Transportation
BRIEF NOTICES A Comparison of the Automatic Shoulder Belt~Knee Bolster Restraint System with the Lap and Shoulder Belt System in VW Rabbits. George Y. H. Chi and Donald W. Reinfurt. University of North Carolina Highway Safety Research Center, Chapel Hill, North Carolina, 1981. 113 pp. The primary objective of this research was to assess the serious and fatal injury reducing effectiveness of the VW Rabbit automatic shoulder belt/knee bolster system using statewide police-reported accident data. The analyses were aimed at answering questions about (ll injury rate differences (manual vs automatic); (2) restraint usage rate differences; (3) performance differences between system sysems (when used); (4) the proportion of injury rate reduction attributable to restraint usage rate differences; and (5) adequacy of state accident data to carry out such investigations. The study data consisted of 10,336 accidents involving VW Rabbits during the period 1975-1979 in New York, North Carolina, Maryland, Colorado, Alabama and South Carolina. The analyses generally involved the following: (1) investigation of potential biases arising from missing belt usage cases: (2) identifying confounding variables by variable screening and then smoothing the data using weighted least squares procedures for categorical data: and (3t examination of the components of the overall serious injury rate reduction, namely components due to usage rate differences, belt system differences and sample variation. For the primary analyses involving data from New York, North Carolina, Maryland and Colorado, the range of usage rates was 16.6-41.6~ for manual belts vs 43.1-73.7~ for automatic belts. Occupants in automatic belt Rabbits experienced 20-30c~ fewer serious injuries than their counterparts in Rabbits with conventional 3-point belt systems. The overriding factor for this reduction was the increase (at least two-fold) in the belt usage rates in the automatic belt Rabbits. When used, the two belt systems were found to be equally effective in preventing serious injuries.
Driver Behavior Research--Needs and Priorities. I.R. Johnston and D. R. Perry. Re~earch Report ARR 108. Australian Road Research Board. Victoria, Australia, 198(t, 39 pp. Driver behavior research is defined as research directed at describing, classifying, understanding and predicting the behavior of the driver in the operation of the road transport system. Evaluating the effectiveness of driver control measures is thus excluded from this reviex~. The "task-demand" and "cognitive-motivational" models of driver behavior are examined to bring out the influence of personal factors in driver decision-making, risk-taking and hence actual on-road behavior. A case is made for a greater research effort into the behavioural, as well as the situational, determinants of variability in on-road behaviour. Research into individual differences is then reviewed, covering personality, skills and driving style. A case is made for more research into transieiit"states rather than "personality" traits: composite measures of perceptual functioning rather than basic visual and motoi abilities: and the systematic investigation of normative patterns of on-road driving behax iour. Major research needs identified include a shift in emphasis from accident-related to n~rm'a/