Likelihood risk reduction options

Options for Risk Reduction Risk Reduction Category Likelihood Risk Reduction Option Additional Considerations... 

Societal risk is calculated to detemtine the likelihood of accidents involving multiple impacts. As shown in Figure 5.7, the F-N relationship is presented as a log-log plot with the x-axis representing the scale of the consequence in terms of N impacts and the y-axis representing F, the likelihood or expected frequency of N or more impacts. If available, an F-N curve can be plotted along with societal risk criteria for comparison, and to identify if risk reduction options need to be considered. 

Risk reduction options for the safe transportation of hazardous materials can include a decrease in the potential consequence, the likelihood of an in-transit incident (accidental or non-accidental causes), or a risk reduction option that impacts both conseqnence and likelihood. Options to rednce transportation safety risk can be gronped into the following four major categories ... 

Risk reduction options must be evaluated to understand how the additional security measures will affect the safety of the operation, as well as how additional safety measures could impact security. For example, rerouting a chemical shipment around a major metropolitan area for security purposes may result in an important change in the route. This change could result in a significant increase in the route length, with an overall increase in the likelihood of a transportation accident. This change in the safety risk profile needs to be compared to the benefits of the change... 

Therefore, risk reduction options that have the potential to influence the consequence, likelihood, or both should be considered. Table 7.2 lists some commonly applied risk reduction options for consequence reduction. In addition to consequence risk reduction options. Table 7.3 lists commonly applied options for likelihood reduction. As can be seen, there is some overlap between these tables because some risk reduction options may impact both the consequence and the likelihood. These lists are not exhaustive, but provide an example of several preshipment options, as well as additional considerations when evaluating these types of risk reduction measures. 

An example of this process is illustrated in Figure 7.2. In this example, an operation was evaluated with a base case risk level of I, or a higher risk that required consideration of risk reduction options. Three risk mitigation options were developed and evaluated. As can be seen, one option reduced the consequence (Option 1), one option reduced the likelihood (Option 2), and one option reduced both consequence and likelihood (Option 3). Option 3 resulted in the greatest risk reduction benefit. While the options that reduce only consequence or likelihood did reduce risk (movement across or down the matrix), the resulting level of risk, as defined on the risk matrix, did not change from risk level I. Therefore, purely on a benefit basis, Option 3 provided the greatest risk reduction. 

Figure 7.3 shows another example that compares a base case level of operational risk with two risk reduction options using quantitative risk analysis techniques. This F-N curve from Chapter 5 illustrates that both options reduce the likelihood and the potential maximum consequence(s). However, Option 2 results in the greatest risk reduction benefits of lower maximum impacts and lower frequencies. Since both options result in risk reduction, as compared to the baseline, an additional cost-benefit analysis would be required to determine which (if either) of these two options should be considered for implementation. 

Risk reduction recommendations from the analysis of pre-shipment options may be the result of any or all of the parameters of the risk equations. As described in Chapter 3, risk is a function of the consequence and likelihood of the specific transportation scenario(s) under evaluation ... 

Risk Measures Ways of combining information on likelihood with the magnitude of loss or injuiy such as risk indices, individual risk measures, and societal risk measures. Risk Reduction Development, comparison, and selection of options to reduce risk to a target level, if needed, or as needed. 

To be effective in preventing illness and injury or damage to property and the environment, one must have an understanding of the hazard restraint control options. One must be able to evaluate hazards and controls in various ways. Hazards need to be evaluated to determine what factors are related to an undesired event. There is a need to evaluate the risk associated with each hazard event (likelihood of the event occurring and the extent or severity of results). There is a need to identify and evaluate each control option. It is important to estimate the cost to implement control(s) and the cost and risk reduction that the controls can achieve. One must estimate the potential effectiveness of the control(s). 

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