Semi-quantitative risk analysis

Semi-Quantitative Risk Analysis Reduction Options 150... 

For those issues or transportation scenarios requiring more detail and insight than a qualitative approach offers, the next level of analysis is a semi-quantitative evaluation. A semi-quantitative risk analysis includes some degree of quantification of consequence, likelihood, and/or risk level. Once evaluated, through the combination of consequence and likelihood, a risk-based decision can be made from the analysis or additional refinement in consequence or likelihood may be necessary. This refinement of the risk analysis may rely on additional information included as part of a semi-quantitative analysis or, as warranted, on some minimal level of quantitative techitiques described in the next chapter. 

Table 4.4 summaries the results of the qualitative risk analysis. Three of the raw materials operations (chlorine, butadiene, and acrylonitrile) and three of the products/wastes (chlorine cylinders, herbicides, and aqueous HCl) were screened out for further risk analysis. Therefore, four chemical movements were escalated for a more detailed semi-quantitative risk analysis... 

One of the major benefits of a semi-quantitative risk analysis is that the technique can be applied and results understood by a wide range of stakeholders in the transportation field. Unlike full quantitative approaches, these types of risk analyses do not require specialized risk management experts. Even with the ease of application, however, personnel involved in these activities need to be knowledgeable in the operations under evaluation and the use of semi-quantitative... 

Certain factors may require some degree of weighting or quantification in a risk analysis. Table 4.5 presents factors associated with the consequences and likelihood that may need to be considered in a semi-quantitative risk analysis. 

While qualitative techniques represent a very basic analysis, with little modification, they can be expanded and evaluated in a semi-quantitative risk analysis. Additionally, events and scenarios elevated for further analysis can be further evolved by considering the range of potential consequences (small to large) and/or likelihood (low to high probability of occurrence). 

XYZ Chemical Example—Semi-Quantitative Risk Analysis... 

To complete this analysis a corporate risk management representative came to the facility to lead a local team through a semi-quantitative risk analysis methodology. The interdisciphnary team, which had received background information on the risk matrix and the semi-quantitative method that will be used, consists of... 

Similar to the process defined for semi-quantitative risk analysis in Chapter 4, quantitative risk is a function of consequence and likelihood. Decisions are made regarding the resnlting risk level and the need for additional risk mitigation based on a comparison of the resnlts to a set of criteria. The QRA process is illustrated in Figure 5.1. The differences between a QRA and the other simpler techniques are ... 

Due to the potential impacts and safety record of some of the carriers, corporate commissioned a QRA of all pesticide tank truck operations that were escalated as a higher-risk issue from the semi-quantitative risk analysis. The focus of this example is on a single origin-designation pair from the Asian facility. 

Semi- Quantitative Risk Analysis (Chapter 4) Faciiity Levei Qualitative risk analysis resulted in the escalation of four of the nine chemical/ mode transportation operations from the Asian facility Increased detail resulted in screening out two of the chemical movements Bulk chlorine and pesticide recommendations developed Rerouting Repackaging... 

The results of the semi-quantitative risk analysis focused on a segment of the chlorine (ton container) route through the medium population density and the entire bulk pesticide transportation route. The recommendations developed for consideration included ... 

As part of the semi-quantitative risk analysis report to corporate, the analysis team included an evaluation of the recommended risk mitigation options. For chlorine, the second recommendation was not practical because the end user required ton containers thus, the transport of smaller cylinders was not an option for the customer. Therefore, this recommendation was removed from further consideration. Since ton containers are shipped via truck, an alternate route was discussed with the carrier—a new route that eliminated passing near higher-population densities with little change in the distance or conditions of the route. 

Uncertainty assessments in a semi-quantitative risk analysis, with application to health care... 

We will use an example to illustrate the main features of the semi-quantitative risk analysis approach. The aimofthe analysis is to estabhsh a risk picture covering all the dimensions (A, C, C, U, P, S, K). 

The numerical scores to be used in a (semi-) quantitative risk analysis have to apply to the factors severity, probability and detectability. The scale may be linear or non-linear, for instance logarithmic. Addition or multiplication of these scores will lead to risk scores. These can be put in a priority sequence the harm with the highest scores should be dealt with the highest priority (efforts and formalities). And the score can also be compared with a fixed limit, for instance in case of a decision if any action has to be taken at all. 

The semi-quantitative risk analysis of ground water source earmarked for the emergency supply of population has been carried out. The analysis of water source hazards caused by natural events, breakdowns and ordinary anthropogenic activities proved that the risk is either negligible or acceptable with regard to all the identified hazard/sensitivity pairs and all the incorporated criticality elements... 

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