The Development of the Bus Driver Risk Index™
The development of the Bus Driver Risk Index™ was funded by Arriva Bus UK, the Economic and Social Research Council and the Department for Trade and Industry in a three year research programme from 2001 to 2004.
The aim of the Cranfield University research was to develop a psychometrically-based assessment of bus and coach driver behaviour that could be used for recruitment and driver risk assessment purposes. The research programme therefore set about creating the Bus Driver Risk Index™ using the accepted research and statistical methods for the development of such an instrument. All phases of the research programme have been published and references are provided for further reading.
For Phase one, in-depth individual interviews with bus and coach drivers from around the UK were conducted in order to identify themes for use in question (referred to as item) development. The interviews were informal in terms of their structure, although a guideline schedule was developed and all were recorded in full (Garwood and Dorn, 2003). The intention was to get the bus drivers to talk freely about their everyday experiences and not to bias the topics for conversation. The main themes were identified and items were developed using the words and language used by bus and coach drivers.
For Phase two, bus and coach drivers from the UK completed modified versions of the Driver Stress Inventory (DSI) and the Driver Coping Questionnaire (DCQ), measures of individual differences in vulnerability to driver stress and choice of coping strategies. Factor analysis of the DSI responses indicated differences between car and bus drivers. Three of the five factors were replicated and the original factors of Thrill Seeking and Dislike of Driving were reversed in their loadings and became Safe/Cautious Driving and Enjoyment of Driving respectively. Factor analysis of the DCQ responses indicated considerable overlap with all five original factors being replicated (Dorn and Garwood, 2004). This meant that, as originally hypothesised, a large proportion of the DSI and DCQ items were relevant included alongside the items developed following the interview study with bus and coach drivers.
The final items were piloted on a representative sample of bus and coach drivers from the UK. The same drivers also completed a face validity questionnaire in order to gain feedback and ensure that the items were acceptable and relevant. Factor analysis revealed seven behavioural risk factors, Fatigue Proneness, Hazard Monitoring, Relaxed Driving, Anxious Driving, Thrill Seeking and Incident Inevitability. Factor analysis of coping risk items revealed five factors, Evaluative Coping, Emotion Focus Coping, Risky Coping, Antagonistic Coping and Avoidance. Item analysis was also conducted in order to ensure that the items within each factor were all contributing to and measuring the same construct (Garwood and Dorn, 2003).
Test-retest reliability analysis was conducted on a representative sample and the results indicate that the Bus Driver Risk Index™ is measuring aspects of bus driving that remain stable over a period of time and not aspects which change depending on the situation, time of day or mood of the driver (Dorn et al, 2010).
Face validity, content validity, criterion related validity and construct related validity were all addressed as part of the research programme. Results indicate that the Bus Driver Risk Index™ is a valid measure of bus driver behaviour with obvious relationships with other similar measures and with accident involvement, driving performance absenteeism and turnover. (Dorn, Garwood and Muncie, 2004; Dorn et al, 2010).
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Dorn, L, Stephen, L., af Wåhlberg, A. E., & Gandolfi, J (2010). Developing and validating a self-report measure of bus driver behaviour. Ergonomics, 53(12), 1420–14 33.
Dorn, L. & Garwood, L. (2004). Development of a psychometric measure of bus driver behaviour. Behavioural Research in Road Safety: 13th Seminar, Department for Transport, HMSO.
Dorn, L. Garwood, L & Muncie, H. (2003). The accidents and behaviours of bus drivers. Behavioural Research in Road Safety: 12th Seminar, Department for Transport, Dublin, HMSO.
Garwood, L. & Dorn, L. (2003). Stress vulnerability and choice of coping strategies in UK bus drivers. In L. Dorn. (Ed). Driver Behaviour and Training. Ashgate: Aldershot.