Target level of safety

This paper has examined problems associated with the specification and realisation of functional safety requirements for the human elements of a system for which a target level of safety is specified at the service level. It was shown that the high-level allocation of functions to hardware, software or humans must be done by taking human performance and limitations into account and a generic approach was presented for the specification of both service-level and system-level safety requirements down to the allocation of functions and safety requirements to subsystems. 

Absolute-, compliance with a defined target - eg a numerical Target Level of Safety (TLS) - or portion thereof Such criteria are usually quantitative ... 

Absolutely as eomplianee with a (numerical) target level of safety ... 

The unmitigated risk is "undesirable" on a scale with a target level of safety of 10 (1.00 E-8) being at the top end of the ALARP region. Such risks are only tolerated if further risk reduction is impracticable or the cost of risk reduction... 

Information about current national and international standards and regulations A target level of safety of say 1. OOE-8 must be achieved (this is not yet met with 3.66 E-7 postulated)... 

Frequencies (or probabilities) of hazardous events Inability to evacuate has been advised as the "top event" and several cut sets (B1, B2 CI and BS) need to be reduced to meet the target level of safety... 

It uses safety integrity levels (SILs) for speeifying the target level of safety integrity for the safety functions to be implemented by the E/E/PE safety-related systems. 

In most cases, mass-produced electrical, electronic or programmable electronic products and other devices and intercoimections that are often used to assemble an EPS catmot be expected to have EM emissions and/or immunity characteristics that are adequate for all of the possible EM enviromnents that an EPS might experience. Therefore, it is inqjorlant to recognise that EM and/or physical mitigation measures, applied at the level of the equipment, system and/or installation, are often an effective way to achieve the required characteristics for the target level of safety risk. 

A social problem may arise if in choosing their target levels of safety individual travelers fail to take into account fully any benefits or costs accruing to others. If effects external to individuals, externalities, exist and they are not considered by the individuals, then the resulting level of traffic safety will be inappropriate for society as a whole. The policy concern is that motorists are not safe enough because of external benefits of safety (external costs of accidents) which they ignore. 

Even if travelers fully consider all benefits and costs of their actions and are well-informed a social safety problem may arise if individuals cannot process properly information about risks. The individual benefit-cost approach sees people who can evaluate the target level of safety which they have chosen. The approach sees people who have the ability to compare their subjective estimates of risk being experienced to their target level and respond to any gap between the two. The criticism of safety decisions which we should take most seriously is the challenge to individual competency. 

As stated in Chapter 2 the focus of the individual benefit-cost approach is on the roadway user s choice of a target level of safety and choice of ways of achieving that safety. For expositional purposes the approach is couched in terms of motorist behavior and striking examples. The approach applies, however, to all roadway users and includes subtle responses which may occur over extended periods of time. The approach is general in that mandated technological changes and responses based on psychophysiological arousal are incorporated. ... 

Risk-Benefit Target-setting schemes for countries to establish levels of safety in national territories that go beyond minimum EU standards Member State permitting option for controlling occupational exposures Prioritisation method for regulatory decision-making... 

Safely management has a positive effect on the performance of safety, competitiveness and economic finance (Femandez-Muniz et al. 2009). Many companies strive to maintain a high level of safety management, because they see it as a necessary competitive advantage. Business targets should be used to guide the company s safety efforts because they are a key factor for competitiveness, but also an important part of quality in business (Lanne 2007). 

After the measurement of levels of safety, targets for improvement will be agreed by the workforce. 

In phase I clinical studies, vorapaxar (SCH 530348) demonstrated excellent safety and tolerability. In pharmacodynamic platelet aggregation studies, the compound showed a robust >90% inhibition of platelet aggregation at all tested doses for a sustained period of time [38]. The target level of platelet aggregation throughout the 28-day treatment period was maintained by a 2.5 mg once-daily maintenance dose. 

A deterministic approach to defence in depth does not explicitly consider the probabilities of occurrence of the challenges or mechanisms (an explanation of these terms is given in Section 3.1) nor does it include the quantification of the probabilities of success associated with the performance of features and systems for each level of defence. However, in the future this deterministic approach can be further complemented by probabilistic safety analysis (PSA) considerations (system reUabihty, probabilistic targets, etc.), to provide an adequate level of safety ensuring a well balanced design. 

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