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Evaluation projects
Within many areas of human endevour, evaluations are of prime importance, because it is not very evident that whatever kind of intervention is used actually works. Evaluation research also has its own methodological and practical problems. Although interventions and their evaluations are often experimental in nature, their setting is most often not a controlled laboratory setting, but real life, meaning that any number and type of error effects come into play.
Current state of the project
Since 2008, I have been running some evaluation projects in the UK, concerning the effects of online education on offending road users’ behavior (for young drivers, seatbelt and red light offenders). The questionnaires have yielded some very interesting results, where especially the between-situations social desirability effect has probably not been reported before. Some penalty points data has been extracted, and more is under way.
Papers
af Wåhlberg, A. E. (2010). Re-education of young driving offenders; effects on self-reports of driver behavior. Journal of Safety Research, 41, 331-338.
af Wåhlberg, A. E. (in press). Evaluation of an e-learning seatbelt wearing intervention. In L. Dorn (Ed.) Driver Behaviour and Training, Volume V, pp. . Fifth International Conference on Driver Behaviour and Training. Paris November, 2011. Aldershot: Ashgate.
af Wåhlberg, A. E. (submitted). Re-education of young driving offenders; effects on recorded offences and self-reported collisions. Download pdf
Traffic accidents and driver celeration behavior measures
How is driving style to be optimally conceptualized, measured and related to accidents? Here, it suggested that the concept of variability of driving speed, measured as celeration (changes in speed) behavior, holds the answer. The theory of celeration behavior makes a number of predictions, and those tested in the papers below have tended to confirm them, especially the strong predictive power versus accidents. In general, the problem of predicting collision involvement is solved, it only remain for companies and authorities to apply this concept.
Current state of the project
My celeration research is now on the back burner, as most of my time is spent on methodology issues. I have tested most of the predictions made from the celeration theory, and they have turned out well. This research therefore shows that celeration is an extremely powerful predictor of accident involvement, and as there are several acceleration-based measurement systems available, this kind of surveillance and feedback should be used more widely, especially by transportation and insurance companies.
Important notice: The terminology I used in early versions of this research turned out to be unfortunate. The term 'g-force' has therefore now been replaced by 'driver celeration behavior' and 'driver vehicle control behavior'. To me, they all have the same meaning (changes in speed of the vehicle (along the surface) due to actions by the driver). However, 'g-force' already had a physical meaning which led people knowledgeable in this field astray from the meaning intended. Unfortunately, this term had already been used in some paper titles, and you might therefore come across these two; The reliability of g-force, and a replication of its relation to bus accidents, as well as; g-force, driver behavior and accidents – an analysis. The correct titles can be seen below.
I now use the term 'celeration' to denote changes in speed (driver vehicle control behavior). This term too is already in use by other parties. However, no other meaning is intended than the one stated here.
Papers
af Wåhlberg, A. E. (2000). The relation of acceleration force to traffic accident frequency: A pilot study. Transportation Research Part F, 3, 29-38.
af Wåhlberg, A. E. (2003). Stability and correlates of driver acceleration behaviour. In L. Dorn (Ed.) Driver Behaviour and Training, pp. 45-54. First International Conference on Driver Behaviour and Training. Stratford-upon-Avon 11-12 November, 2003.
af Wåhlberg, A. E. (2004). The stability of driver acceleration behavior, and a replication of its relation to bus accidents. Accident Analysis and Prevention, 36, 83-92.
af Wåhlberg, A. E. (2006). Speed choice versus celeration behavior as traffic accident predictor. Journal of Safety Research, 37, 43-51.
af Wåhlberg, A. E. (2006). Driver celeration behavior and the prediction of traffic accidents. International Journal of Occupational Safety and Ergonomics,12, 281-296.
af Wåhlberg, A. E. (2007). Aggregation of driver celeration behavior data: Effects on stability and accident prediction. Safety Science, 45, 487-500.
af Wåhlberg, A. E. (2007). Effects of passengers on bus driver celeration behavior and incident prediction. Journal of Safety Research, 38, 9-15.
af Wåhlberg, A. E. (2007). Long-term prediction of traffic accident record from bus driver celeration behavior. International Journal of Occupational Safety and Ergonomics, 13, 159-171.
af Wåhlberg, A. E., & Melin, L. (2008). Driver celeration behavior in training and regular driving. In L. Dorn (Ed.) Driver Behaviour and Training, Volume III, pp. 189-199. Aldershot: Ashgate. Third International Conference on Driver Behaviour and Training. Dublin 12-13 November, 2007.
af Wåhlberg, A. E. (2008). The relation of non-culpable traffic incidents to bus drivers' celeration behavior. Journal of Safety Research, 39, 41-46.
af Wåhlberg, A. E. (2008). Driver celeration behavior and accidents – an analysis. Theoretical Issues in Ergonomics Science, 9, 383-403.,
Acknowledgements: The 2000 and 2004 empirical studies were funded by the Swedish Transport and Communications Research Board (now merged with other state bodies into Vinnova), research grants 1997-0287 and 1998-0526, while the first version of the theoretical analysis was written during a stay in the year 2000 at the Transport Research Institute, Napier University, Scotland, UK, under a scholarship from the Swedish Institute. The other studies used data from the fuel efficient driving project funded by the Swedish Road Administration, grant AL90AB 2001:7758, and Gamla Uppsalabuss.
Bus driver accidents; basic aspects
Accidents are in many ways the central problem of transports, and therefore of transport research. However, not much attention has been payed to bus accidents (probably because these are usually not as serious as other crashes). This is a mistake from a methodological point of view, as buses in many ways can be viewed as a natural laboratory with excellent possibilities for controlled studies. Also, the crash data available from bus companies (and other transport companies) are probably of much higher quality than those from any other source. Therefore, the bus accident database for Gamla Uppsalabuss accidents that was started in 1995 features as a basic part of much of the research activities described on these pages.
Current state of the project
The Gamla Uppsalabuss database is still updated on a yearly basis, but I have little time to spare for this type of research at the moment. Along with Lisa Dorn, I have access to a vast amount of British bus accident and driver data, but whether there will be enough time to analyse it is unknown at the moment.
Papers
af Wåhlberg, A. E. (2002). Characteristics of low speed accidents with buses in public transport. Accident Analysis and Prevention, 34, 637-647.
af Wåhlberg, A. E. (2004). Characteristics of low speed accidents with buses in public transport. Part II. Accident Analysis and Prevention, 36, 63-71.
af Wåhlberg, A. E. (2005). Differential accident involvement of bus drivers. In L. Dorn (Ed.) Driver Behaviour and Training, Volume II, pp. 383-391. Aldershot: Ashgate. Second International Conference on Driver Behaviour and Training. Edinburgh 15-17 November, 2005.
af Wåhlberg, A. E. (2008). If you can’t take the heat: Influences of temperature on bus accident rates. Safety Science, 46, 66-71.
Dorn, L., & af Wåhlberg, A. E. (2008). Work related road safety: An analysis based on UK bus driver performance. Risk Analysis: An International Journal, 28, 25-35.
af Wåhlberg, A. E., & Dorn, L. (2009). Bus driver accident record; the return of accident proneness. Theoretical Issues in Ergonomics Science, 10, 77-91.
af Wåhlberg, A. E. (2009). Hourly changes in accident risk for bus drivers. Journal of Risk Research, 12, 187-197.
af Wåhlberg, A. E., & Dorn, L. (2009). Absence behaviour as traffic crash predictor in bus drivers. Journal of Safety Research, 40, 197-201.
af Wåhlberg, A. E., & Dorn, L. (submitted). Bus driver accident record; stability over time, exposure and culpability.
Acknowledgements: The initial work on the Gamla Uppsalabuss bus drivers was funded by the Swedish Transport and Communications Research Board, grants 1997-0259 and 1998-0526, and the database has been continously updated under the fuel efficient driving project funded by the Swedish Road Administration, grant AL90AB 2001:7758, and Gamla Uppsalabuss.
Methodological problems in traffic research
Being a young science, the methods and findings of traffic research, especially psychology, are often of doubtful value. Different fashions come and go, without any real progress being visible. From accident proneness via system theory to social psychology, not much useful research has really surfaced, although the claims are often bold. As a reaction to this low quality, some papers have surfaced. More are likely to come when possibilities open up.
The use of self-reported data on traffic behavior is very common and seem to be a fairly accepted method. However, there seem to be precious little research on the actual validity of the responses. This is especially so for accidents, despite this being a crucial variable in traffic research. In this study, bus drivers have reported on their own crashes for the previous three years, and these responses have been compared to the accident data base for the same drivers. There was sizeable under-reporting as well as over-reporting, and the results are discouraging for the use of self-reported accident data.
The second look at methodology was a review, where more than a hundred papers on psychological predictors of traffic accidents were evaluated on three methodological criteria. Most were found to be wanting, and the conclusion was that we do not really know much about what individual variables will predict a person's traffic accident frequency.
Also, together with Lisa Dorn (Cranfield University), I have taken a look at the induced exposure method, much used by traffic engineers to calculate risk ratios. However, when non-culpable accidents are used as the exposure proxy, this can go seriously wrong, because who is culpable is a bit hard to decide upon objectively. In our data, we show some ways of testing whether the assumption of randomness of non-culpable accidents is accurate.
We have also had a go at the forever popular DBQ. The findings should be disturbing to most, as should our papers on socially desirable responding in questionnaires. All who use self-reported data to predict other self-reported data should take heed.
Current state of the project
Due to my collaboration with Lisa Dorn, this project has been very much revived. Several papers are under construction, and funding for more research of this type is being sought.
This book is a detailed critizism of the methodology in most papers published about individual differences in traffic safety. Basically, the majority of research in this area is useless.
af Wåhlberg, A. E. (2009). Driver Behaviour and Accident Research Methodology; Unresolved Problems. Aldershot: Ashgate. http://www.ashgate.com/isbn/9780754670766
Papers
af Wåhlberg, A. E. (2002). On the validity of self-reported traffic accident data. E140 Proceedings of Soric´02. Download pdf-file Note that the copyright of this paper is held by the Center for Transport and Road Studies, University of Bahrain, Kingdom of Bahrain. Used by permission.
af Wåhlberg, A. E. (2003). Some methodological deficiencies in studies on traffic accident predictors. Accident Analysis and Prevention, 35, 473-486.
af Wåhlberg, A. E., & Dorn, L. (2007). Culpable versus non-culpable traffic accidents; what is wrong with this picture? Journal of Safety Research, 38, 453-459.
af Wåhlberg, A. E., Dorn, L., & Kline, T. (2010). The effect of social desirability on self reported and recorded road traffic accidents. Transportation Research Part F, 13, 106-114.
af Wåhlberg, A. E. (2010). Social desirability effects in driver behavior inventories. Journal of Safety Research, 41, 99-106.
af Wåhlberg, A. E., Dorn, L., & Kline, T. (in press). The Manchester Driver Behaviour Questionnaire as predictor of road traffic accidents. Theoretical Issues in Ergonomics Science,
af Wåhlberg, A. E. (in press). A reporting guide for studies on individual differences in safety. Journal of Safety Research,
Acknowledgements: The data for the first paper was gathered in projects funded by the Swedish Transport and Communications Research Board, grants 1997-0259 and 1998-0526 (database phase), and the TEMA-funding (questionnaire phase) by the same body, while the second was mainly written during a stay at the Transport Research Institute of Napier University, Edinburgh, UK, under a scholarship from the Swedish Institute, in the year 2000. The papers on social desirability partly used data from the evaluation of the Young Driver Scheme in Thames Valley, UK.
