This guide is intended for use by those undertaking the development of fire hazard assessments for rail transportation vehicles and products contained within rail transportation vehicles.
This guide provides information on an approach to develop a fire hazard assessment, but fixed procedures are not established. Any limitations in the availability of data, of appropriate test procedures, of adequate fire models, or in the advancement of scientific knowledge, will place significant constraints upon the procedure for the assessment of fire hazard.
A fire hazard assessment developed following this guide must specify all steps required to determine fire hazard measures for which safety thresholds or pass/fail criteria can be meaningfully set by responsible authorities. It is preferred that such exercises have input from various sources.
Outcomes: Use and Application. A fire hazard assessment developed as a result of using this guide should be able to assess a new product being considered for use in a certain rail transportation vehicle and reach one of the conclusions listed in 4.4.1-4.4.4.
New Product Safer than Product Currently in Use. The new product is safer, in terms of predicted fire performance, than the one in established use. In this case, the new product is desirable, from the point of view of fire safety.
New Product Equivalent in Safety to Product Currently in Use. There is no difference between the predicted fire safety of the new product and of the one in established use. In this case, use of the new product provides neither advantage nor disadvantage, from the point of view of fire safety.
New Product Less Safe than Product Currently in Use. The new product is less safe, in terms of predicted fire performance, than the one in established use. In this case, a direct substitution of products would provide a lower level of safety and the new product would be undesirable, and should not be used, from the point of view of fire safety, without other compensatory changes being made.
New Product Different in Safety to Product Currently in Use. A new product that is less safe, in terms of predicted fire performance, can nevertheless be made acceptable if, and only if, it is part of a complete, comprehensive, fire safety design for the rail transportation vehicle. Such redesign of the vehicle should include other features such as use of an alternative layout or increased use of automatic fire protection systems, that demonstrably produce the same or better safety for the complete design. In such cases, a more in-depth fire hazard assessment would have to be conducted to ensure that the entire design achieves the safety goals, and the new product would be acceptable only as part of the larger, approved design.
The new product could offer some safety advantages and some safety disadvantages over the item in established use. An example of such an outcome could be increased smoke obscuration with decreased heat release. In such cases, a more in-depth fire hazard assessment would have to be conducted to ensure that the advantages outweigh the disadvantages, and the resulting overall level of safety is no less than that provided by the traditional approach (see Table X1.1 and Appendix X1).
Following the analysis described in 4.4, a fire hazard assessment developed following this guide would reach a conclusion regarding the desirability of the new product studied. It is essential for the results of the assessment to lead to a design that is at least as safe as the one being replaced.
1.1 This is a guide to developing fire hazard assessments for rail transpor......
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