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A wide variety of methods exist in the field of accident investigation. The challenge to find the cause for each and every accident has perpetuated a complicated and fundamental debate. In spite of the different paradigms, the many branch specific investigation methods, decades of accumulated and documented accident investigation experience, the diversity in taxonomy of causal factors, and an increasing depth of general systematic analysis tools, there are still causal factors missing out. A recent study identifies language issues as an underestimated danger. Dutch Labour Inspectorate records identify procedures and communication as an important causal factor area for major accidents. Accident investigation method taxonomies that are frequently used in The Netherlands, were investigated on the content related to language issues. Language issues are found to be either present less than proportional with observed accident rates or not present at all in frequently applied accident investigation classification systems. Hence a new taxonomy problem was found in Dutch accident data. Language issues need more attention in accident investigation methods., (Copyright © 2011 Elsevier B.V. All rights reserved.)

This article further elaborates the findings by Reniers et al. in 2007 and 2008. A discrete-time approximation is presented to determine the severity of a major accident threat triggering immediate evacuation and its expected resulting costs. By implementing the proposed mathematical model, precautionary evacuation decision problems can be tackled in a realistic way, i.e., allowing for major accident threats with limited duration. Furthermore, the model is moulded into a working procedure which was used to develop software to solve the suggested algorithms. A case-study is provided and the results obtained by application of the methodology are discussed. Using a (realistic) discrete-time approximation computer simulation, we found that ignoring option characteristics may produce suboptimal intervention decisions in shutdown settings.

This paper may be regarded as the second part of a larger article. The basic decision model developed in the first part of the article by Reniers et al. [G.L.L. Reniers, N. Pauwels, A. Audenaert, B.J.M. Ale, K. Soudan, Management of evacuation in case of fire accidents in chemical industrial areas, J. Hazard. Mater., 147 (2007) 478-487] is extended to determine both the optimal time and the optimal mode to stop the ongoing activities in case of a major fire possibly giving rise to an escalating event. Chemical plants have multiple modes to stop their production processes, differing with respect to the resulting costs, and with respect to the required time and personnel to complete the shutdown operations. The existence of an additional and more economic (but slower) shutdown mode might encourage the decision maker to stop the production processes earlier, in a less intervening manner, whereas the availability of an additional faster (but less economic) shutdown procedure might stimulate the decision maker to stop the production processes later, in a more intervening manner.

Trade-offs between economic and safety arguments exist in the operation of chemical installations, should knock-on calamities induced by fire accidents occur: a sudden installation shutdown might result in substantial economic losses, but may be needed to ensure safety. Due to the very rare nature of domino effect risks induced decision problems an adequate evacuation decision aid model to be used by plant safety management does, to the best of the authors' knowledge, not exist. This paper develops a tentative approach to calculate the economic gains and/or losses linked to the decision problem whether or not, and when, to evacuate chemical installation(s) threatened by possible domino effect risks. The proposed model is illustrated by a case-study based on empirical data.