Measurements accident severity rates

Unfortunately the measure of safety performance has traditionally been accomplished only by means of accident rates, such as Injury Frequency Rate (IFR) or Severity Rate (SR), that are typically categorized only... 

One or more indices describing incident performance according to various units of measurement (e.g., disabling injury frequency rate, number of lost-time accidents, disabling injury severity rate, number of first-aid cases, or dollar loss). It may also refer to a summary statement describing incident performance. 

The second view is macroscopic. In case more than one event is evaluated, an aggregation of the single events is possible in order to assess the overall effects. If the sample under investigation happens to contain accident and non-accident events, an accident rate or prevention rate can be calculated as ratio of frequency of accidents (or one minus accidents) with a measure by frequency of accidents without the measure. Summary statistics can also be computed in non-accident events by statistically evaluating the indicators defined on the physical level. In comparison to a baseline without measure the change due to a specific safety measure can be evaluated at the desired level of detail. Within the accident group, rates for specific injury severities as well as a fatality rate can be estimated. 

Before the accident at Three Mile Island Unit 2 (TMI-2) in 1979, protective action decisions would often be based on real-time environmental measurement of dose rates following a release. Once this dose rate was measured, a projected effective dose could be calculated. This effective dose could then be compared to the intervention levels and the appropriate protective action could be selected. There is a serious problem with this approach by definition, environmental measurements are obtained ctfter a release. Thus, they cannot be used to initiate protective actions before the release. Moreover, even if field measurements are taken shortly after release initiation, much time can be consumed in the process of selecting and implementing appropriate protective responses. After gamma dose-rates are assessed, it is necessary to select an action, obtain the concurrence of off-site authorities, and transmit warnings to the population at risk—who must prepare to evacuate and then drive out of the risk area. The result is that for severe releases the protective action may be taken too late to be effective. 

Any simple measurement of performance in terms of accident (injury) frequency rates or accident/incident rate is not seen as a reliable guide to the safety performance of an undertaking. The report finds there is no clear correlation between such measurements and the work conditions, in injury potential, or the severity of injuries that have occurred. A need exists for more accurate measurements so that a better assessment can be made of efforts to control foreseeable losses. 

TABLE 1.7 U.S. fatalities, nonfatal days lost (NFDL) Injuries, total accident incident rates (IRs), and severity measures for underground and surface mines by sector, 1995 (Reich and McAteer 1997a, b, c, d, e)... 

There are various ways to measure the resuits of work being done to prevent accidents. The effects of having an accident include, for example, injuries, iiinesses, anguish suffering, financial losses, increased insurance costs, poor productivity, absenteeism, production deiays, high labor costs, machinery downtime, and poor community image. Two types of measurements of results are commonly used. The first, and by far the most common, tracks accident frequency and severity rates. The... 

There are many good reasons for using accident frequency and severity rates. As mentioned earher, these measurements of results are part of any effective safety management program. When accident frequency and severity rates are properly used, they can lead to an increased commitment to preventing accidents. Several of the most obvious benefits of frequency and severity rates are ... 

The early phase is defined by the time period during which there is the threat of a significant release. The time interval between the recognition of an accident sequence and the start of the release can extend from about half an hour to about a day and the duration of the release may be between half an hour and several days. In this phase the information based on the analysis of data and predictions being from the nuclear installation and some limited environmental measurements of off-site exposure rates and airborne concentrations from the plume may become available. Thus, the... 

Leachability of a waste form is perhaps the most important criterion in considering accident situations. In the absence of salts, some of our cement products may approach the low leachability of glass. After experimenting with several methods for measuring leach rates, we selected the... 

The nominal accident rate per million platform hours was determined to be 3.34 for majors, 3.01 for large independents, and 2.08 for small independents. Similarly, the weighted accident rate that distinguished between accidents according to their severity was 8.00 for majors, 5.35 for large independents, and 3.85 for small independents. Differences between majors and independents measured in spills were found to be similar but more extreme, with rates of 255 barrels spilled per million platform hours for majors and 24 barrels for independents. 

The term "composite index" is used throughout this thesis to mean the combination of several indicators. The "indicator" itself is a measure derived from variables. In this study the indicator is not any measure and it is normally used to show the level of performance in the country. The indicator can be presented as an average or accident rate. The term "risk" better emphasises the accident rate. 

In chapter three, the theoretical background to all the potential macro-factors that could contribute to road accidents was presented. The relationship between each factor and the probability that road accidents may occur on the national level was conducted. One special criterion to select suitable indicators was used. This has enabled me to determine the key macro-performance indicators in road safety. It has become clear that the chosen indicators must be easy, available, measurable, and comparable worldwide. Moreover, these indicators must be able to indicate/monitor the country s progress over time in road safety and allow international comparisons. The obtained set of indicators was listed and summarised in Table 3.2. The next step was to understand and explain the main published macroscopic studies and models that are used in describing and comparing the road safety development internationally. I have divided the reviewed models into cross-sectional models (time-independent models) and (time-dependent models). A starting point in this direction was to investigate Smeed s equation, particularly in the relation between motorisation and fatality rates. Several models for... 

Various forms of accident data are collected by organisations and a number of standards indices are used, e.g. rates of accident incidence, frequency, severity and duration. Accident data are based on information compiled from accident reports. As such, they are a reactive form of safety monitoring and should not, of course, be used as the sole means of measuring safety performance. However, they do indicate trends in accident experience and provide feedback which can be incorporated in future accident prevention strategies. The following rates are used ... 

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