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REPORT OF THE

SUBCOMMITTEE ON SYSTEMS SAFETY ANALYSIS

INTRODUCTION

As discussed in the Interim Report, systems safety analysis is a highly sophisticated and recent product of the aerospace industry which enables the influence of a great many variables to be considered in evaluating their impact on a specified event. The Task Force established a Systems Safety Analysis Subcommittee in order to analyze available rail accident data using these techniques. It was expected that this effort would have the potential of suggesting countermeasures capable of substantially reducing risks as well as identifying issues requiring additional research and exploration.

The Subcommittee organized a special action group consisting of AAR professional staff, shipper industry experts, and the consulting firm of Booz, Allen & Hamilton to conduct the analysis. The study, from May through September, 1978, was conducted in close consultation with the Subcommittee.

DISCUSSION

At the outset, it is important to recognize that the recommendations presented in this report are based on limited data, and therefore, should be viewed only as a first step toward completion of a total systems safety evaluation. It is hoped that the work of this Subcommittee will provide a solid foundation on which further research and analysis can be based as more and better data become available.

From the study to date, it appears that about 35% of all freight trains contain hazardous materials. Only about 7.5% of all accidents, however, involve trains carrying hazardous materials and only 1% of all accidents involve a release of hazardous materials. These releases appear to be a fairly constant proportion of the number of accidents in general. Currently, there are about 115 such releases per year. The number of major accidents; that is, accidents involving a release and resulting in a fatality or over $500,000 damage, varies from zero to five per year. Compared to some other transportation safety problems, this represents a relatively good safety performance. Another encouraging trend is that while the total number of releases may be increasing, the number of major accidents is remaining fairly constant. It also appears that the causes of these major accidents are random and not representative of the overall distribution of train accident causes.

Mainline derailments are more likely to involve a release of hazardous materials than yard derailments. In this type of accident, track problems have been identified as the most frequent cause, but there are so relatively few accidents involving a release that upgrading all track conditions is likely to cost many times the savings from accident prevention without insuring total elimination of track failures. It would thus seem appropriate to consider improved track and vehicle inspection and maintenance activity on selected hazardous materials movements.

Some aspects of train makeup and operating practices such as the position of hazardous materials cars in trains, and train speed and length were examined. Analysis to date does not indicate that any further restrictions are justified, but analysis will continue as better data become available.

Releases of hazardous materials also occur as a result of leaks. Studies made by the Bureau of Explosives indicate that about 150 railroad employees are injured each year due to leaks. Generally, these leaks result from failure to secure valves and fittings, deterioration or absence of gaskets, or corrosion.

CONCLUSIONS OF THE STUDY TO DATE

The following is a summary of the major conclusions of this study to date: 1. Over 90 percent of hazardous materials releases in accidents occur as a result of derailments. Preliminary risk assessment identified rail and track geometry, truck components and wheels as the leading causes of derailments which resulted in the release of hazardous materials.

2. The effects of many train operating characteristics, such as length and speed, cannot be adequately assessed from available data. No further general system restrictions on train speed, hazardous materials car position in train, or train length can be justified on the basis of the preliminary analysis made in this study.

3. When traffic density permits, some railroads appear to operate trains of
hazardous materials cars under conditions which improve safety. An
evaluation of these conditions to determine their potential for risk reduc-
tion and more widespread applicability will require data for comparative
analysis. These data should include at least the following:

a. accident data (accident reports, cost estimates, train consist);
b. exposure data (hazardous materials carloads, total carloads,
tons, total number of units, mixed and run-through trains, number

of unit, mixed and run-through trains carrying hazardous materials);

c. track data (maintenance practice, characteristics, class, density,

terrain);

d. mechanical data (safety inspection, journal bearing lubrication procedures, mechanical defect detection systems); and

e. operations data (train speed, length, weight, makeup, switching, special handling).

4. Large volume, high center of gravity covered hopper cars appear to have a higher probability of derailing from track-related causes than other cars.

5. Journal bearings and truck components appear to have a higher probability of contributing to tank car caused derailments than other components.

6. Tank car improvements to improve bottom outlet protection may lead to reductions in hazardous materials releases from accidents. 7. Leaks from hazardous materials cars can be reduced by improved design, maintenance, and operation of valves and fittings, and improved inspection by shippers and railroads.

8. With better data, additional use can be made of risk management techniques, but these techniques cannot be expected to resolve all issues.

9. Due to the widely dispersed nature of causes, reduction of hazardous materials releases by correction of each of the specific causes may require a very extensive program and involve very large expenditures. Accordingly, countermeasures designed to reduce the severity of hazardous materials accidents such as shelf couplers, head shields, and thermal insulation, appear to provide the more effective risk management approach.

10. The projected effect of protection systems now being adopted must be

taken into account in the analysis of other countermeasures. For example, the adoption of shelf couplers, head shields, thermal insulation and bottom outlet protection on certain types of tank cars will reduce the number of releases; at the same time, these changes may reduce the effectiveness of other proposed countermeasures.

RECOMMENDATIONS AND ACTIONS

Based on the above study and conclusions, the Subcommittee on Systems Safety Analysis presents the following recommendations for action programs and further analytical studies:

1. Data requirements, data sampling approaches, and risk management systems will be assessed on a continuing basis. This activity will be conducted in cooperation with all interested agencies and organizations to facilitate the design and execution of improved accident data reporting systems. Contact with NTSB and DOT has been made to explore common approaches to improving data collection and analysis systems.

2. As appropriate data become available, continued efforts will be made to identify significant causes for hazardous material releases and to conduct comprehensive analyses of those countermeasures that will reduce such releases.

3. An approach will be developed to gather data necessary to evaluate the effectiveness of various safety practices. Procedures or operations which materially improve safety will be identified and disseminated to all railroads.

4. Successful guidelines shown to improve hazardous materials safety should be applied as practicable to other hazardous materials movements.

5. Shippers and railroads have been advised that preliminary analysis has shown that certain specific items appear to contribute to releases in a disproportionately large manner and that appropriate attention should be given to:

a. improvement in the quality of rail and track geometry, inspection and maintenance;

b. improvement in the quality of tank car components and journal bearing inspection and maintenance;

c. improvement in the quality of inspection and control of tank car valve and fitting closures;

d. effect on safety of large, high center of gravity covered hopper cars

without adequate snubbing devices.

With the decision of the Task Force to cease its operations, the Systems Safety Analysis Subcommittee has recommended that its work be continued. Its activities would be performed under a cooperative agreement between the Chemical Manufacturers Association, the Association of American Railroads and the Railway Progress Institute to establish and support a "Systems Safety Task Force." Work is now underway toward formation of this group.

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