Showing papers by "Lisa Dorn published in 2019"

Behavioural culpability for traffic accidents

Abstract: This study presents a description of the concept of behavioural culpability, a step-by-step manual for using it, and an empirical test of a suspected mis-classification of culpability. Behavioural culpability is defined as whether the driver’s actions contributed to a crash and that non-culpable crashes are not caused by any specific behaviour and can only be predicted from exposure. Drivers with non-culpable crashes are therefore a random sample of the population. However, if the criteria for culpability and/or the individual judgements are not reflective of the principle of behavioural culpability, no fault drivers will not be a random sample of the driving population. To test the predictions from the definition of randomness in a sample assumed to have sub-optimal coding, the categorization of crash involvement undertaken by a British bus company was tested for associations between at fault and no fault crashes, age and experience. As predicted from the low percentage of at fault accidents in the sample, correlations between the variables indicated that a fair percentage of at fault crashes had been coded as no fault of the bus driver, suggesting a too lenient criterion. These results show that within fleet-based companies, culpability for a crash is probably allocated for legal reasons, which means that the predictability of accident involvement taking into account individual differences is not fully utilized. The aim of behavioural culpability coding is to increase effect sizes in individual differences in safety research and to improve our capability of predicting accident involvement.

Bus drivers who leave; were they more crash-involved?

Abstract: Turnover is usually considered to be a safety problem for companies, but can also be an advantage, if those who leave are less safe than those who stay. This problem has rarely been investigated for bus drivers, where the financial and human costs of crashes are high. This study tested whether bus drivers who left their jobs had more crashes than those who remained, using company records. Several analyses were run, using crashes per number of days worked, the absolute number of crashes in a specific time period, as well as the ratio of culpable to non-culpable crashes. Drivers who left the company, except those who retired, had forty percent more crashes than those who stayed, but were also less experienced, which explained part of the difference. Results were similar regardless of analysis performed. Turnover may be a problem for bus companies due to the costs of recruitment and training, but this study suggests that there are benefits for turnover too. Fleet-based companies would probably gain more by improving driver selection methods than trying to retain drivers with a high crash rate, as a natural selection process seems to lead to the safest drivers staying with the company.

Experience as a Safety Factor in Driving; Methodological Considerations in a Sample of Bus Drivers

Abstract: Experience is generally seen as an important factor for safe driving, but the exact size and details of this effect has never been meta-analytically described, despite a fair number of published results. However, the available data is heterogeneous concerning the methods used, which could lead to very different results. Such method effects can be difficult to identify in meta-analysis, and a within-study comparison might yield more reliable results. To test for the difference in effects between some different analytical methods, analyses of data on bus driver experience and crash involvement from a British company were conducted. Effects of within- and between-subjects analysis, non-linearity of effects, and direct and induced exposure methods were compared. Furthermore, changes in the environmental risk were investigated. Between-subject designs yielded smaller effects as compared to within-subjects designs, while non-linearity was not found. The type of exposure control applied had a strong influence on effects, as did differences in overall environmental risk between years. Apparently, “the effect of driving experience” means different things depending upon how calculations have been undertaken, at least for bus drivers. A full meta-analysis, taking several effects of methodology into account, is needed before it can be said that the effect of driving experience on crash involvement is well understood.

Bus driver accident record; stability over time, exposure and culpability

Abstract: The tendency for drivers to have a stable accident record over time was tested in a population of bus drivers. Analyses included investigations of the effects of responsibility for the cras...