Safety performance measurement Defined

A framework assists in the development of a safety performance measurement program by establishing well-defined performance measures, identifying all areas of safety performance, and documenting procedures for implementing the program. 

Before the intervention proper begins it is necessary to establish the baseline, that is to define the existing level of safe behaviours, against which improvements can be measured. To do this, observations are taken and the safety performance measure is calculated for a period of some four weeks before any feedback is given by the observer. This baseline safety performance measure is the average safe behaviour for the complete four-week period. At this point, when the baseline measure has been established, we would normally hold a review meeting with the observers. This has a number of purposes ... 

Different definitions can have different purposes. For instance, OECD (2003) defines a safety performance indicator as a means for measuring the ehanges over time in the level of safety (related to ehemieal aecident prevention, preparedness and response), as the results of actions taken . Skogdalen et al. (2010, p 109) similarly consider a safety performance indicator to be a means for measuring the changes in the level of safety (related to major accidentprevention, preparedness and response), as a result of actions taken . These definitions reflect that they are made for comparisons over time to demonstrate developments as results of actions. Accordingly, they are not made for comparison between countries and they do not give attention to the needs of special users of the indicators. 

But, no statistical, historical performance measurement system can assess the quality of safety in place that encompasses low probability-high consequence incidents since such events seldom appear in the statistical history. Example A risk assessment concludes that a defined catastrophic event, one that has not happened and is not represented in the statistical base, has an occurrence probability of once in 200 plant operating years.)... 

It is clear that proactive safety control is needed. Safety audits measure the management work being done to control losses, and are therefore vital performance indicators in the safety system. An audit will define what work needs to be done to improve safety and health management. 

Leadership by the top management is most important. They shall lead by personal involvement to set example and shall inspire aU members of the organisation (seniors and juniors) to meet the goals of the company towards TQM approach and should instil values for safety, pollution control, and quality. The leadership shall provide guidelines and directions to subordinates that are understood by aU and create well-defined systems, as well as methods for their implementation and performance measures for achieving those goals. 

A quantitative target for measuring the level of performance needed for safety function to achieve a tolerable risk for a process hazard. It is a measure of safety system performance, in terms of the probability of failure on demand. There are four discreet integrity levels, SIL 1-4. The higher the SIL level, the higher the associated safety level and the lower the probability that a system will fail to perform properly. Defining a target SIL level for a process should be based on the assessment of the likelihood that an incident will occur and the consequences of the incident. Table S.2 describes SIL for different modes of operation. 

Quantitative Risk Assessment. Previous sections in this chapter dealt with the identification, measurement, and mitigation of hazards in a chlor-alkali plant. Plant safety and Responsible Care programs define the objectives of continuous improvement in safety performance. The discussion of mitigation immediately above naturally leads on to the larger question of the most direct and cost-effective approach to this improvement. 

Identifying problem areas The safety mechanism that is geared for performance measurement and feedback takes its cue from the facility inventory of critical behaviors. Problem areas can be defined as those workplace behaviors that deviate from the expected critical behaviors. 

The team that developed Process Safety Research for the 2Century expressed the elusive nature of understanding process safety culture in these words. "The safety culture of an organization has a significant impact on its safety performance. Although the level of safety culture of a work community can be subjectively observed immediately after entering that community, an objective measure is difficult to define. Moreover, establishing effective improvement, if needed is not an easy task... [6]. ... 

A final observation concerns the importance of the nurse in bringing the problem into focus. None of these workers would have dared claim compensation, and so none of the injuries was defined as a lost-time injury. Consequently the problem did not show up in the lost-time injury records which are conventionally used to measure safety performance. These workers did, however, feel able to approach the nurse on the job for painkillers and other palliative treatment. It was only as a result of these treatments that the extent and nature of the problem became evident. It was the medical treatment data which made it clear that something had to be done, and it was the nurse who blew the whistle. In the absence of a site nurse Robbie would presumably have been able to injure and sack several more workers with impunity. 

Safety functions are defined by lEC 61508-4 as operating in the high demand or continuous mode of operation if the demand rate is greater than one per year or greater than twice the proof test frequency. In this case, as discussed below, the measure of the safety performance of the safety function is the limit of hazard rate, h, that achieves tolerable risk. The relationship between the quantified safety performance and the SIL is given in lEC 61508-1 table 3, see Figure 2. 

Although the system is not specifically mentioned in the overall safety and health policy, in most cases, its function and responsibilities are spelled out in a safety management standard on near miss incident reporting, which is a stand-alone document. A safety standard is defined as a measurable management performance. Each element of the safety management system should have a written standard that describes the actions, duties, goals, objectives, and responsibilities for each element. 

Objectives must be based upon performance measurements, which are milestones that tell if the person did or did not perform his or her assigned safety-related task as defined. 

Health and safety performance, as measured by injury rates, is naturally variable. There can be minimal change in management activities, yet performance can and often does vary naturally between limits that are statistically defined by past performance. Figure 2.6 represents monthly fluctuations of the mean incident rate, which is the average of all monthly rates. 

The traffic-safety work has been organised into a number of result areas in order to make it more focused. SNRA has defined performance indicators for each area to follow up on progress. There is a known relationship between the changes within each area, as measured by the performance indicator and the risk of traffic accidents. Table 28.2 shows an overview of some of the performance measures and the goal for each for year 2000. 

Table 28.2 Performance indicators for different traffic-safety areas. Detailed performance measures have not been defined for the traffic environment...

The process safety time is defined as the period of time between a failure occinring in the EUC or the EUC control system (with the potential to give rise to a hazardous event) and the occurrence of the hazardous event if the safety function is not performed. It follows that a safety system must perform its measurement and logical responses in less than the process safety time. Some of the spare time available within the process safety time can then be utilized to perform diagnostic checks as illustrated in Figure 5.19. 

There is an additional benefit from defining minimum acceptable accident-performance measures. Responsible firms will be deterred from myopic behavior if there are clearly stated minimum performance standards that they can meet that would obviate scrutiny by the FRA. From a societal point of view it is much more beneficial to state these minimal objectives in terms of safety outputs rather than by the existing system where acceptable performance is stated in terms of the minimum quality and quantity of safety inputs. The benefit comes from the ability of railroads to use their managerial ability to achieve at least the minimum level of safety by using the most efficient combination of safety inputs. 

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