UK Hazard Perception Test

1.3.8 UK Hazard Perception Test

One factor that has emerged in driving research is the fact that young novice drivers are significantly more likely than older and more experienced drivers to be involved in road accidents and to die or be seriously injured on the roads. An OECD report (ECMT, 2006) revealed that globally, 16-24 year old drivers are significantly over-represented in crash and fatality statistics. Despite the age group representing only 10% of the populations of OECD countries, young drivers represent 27% of all drivers killed in OECD countries. The report also found that the death rate for 18-24 year olds is about double that of older drivers and that motor vehicle crashes are the single greatest killer of 15-24 year olds in OECD countries (ECMT, 2006). It is possible that one of the reasons for this is that the HP abilities of young and inexperienced drivers are inferior to those of older and more experienced drivers.

One of the reasons put forward to explain the high accident rates for young novice drivers is that they have underdeveloped HP abilities. As mentioned previously, research has indicated a link between slow HP reaction times and a higher likelihood of a driver being involved in crashes (McKenna and Horswill,

1999; Pelz and Krupat, 1974; Quimby and Watts, 1981; Quimby et al., 1986;).

Meanwhile a study by Drummond (2000) linked slow HP reactions times to an increased likelihood of being involved in a fatal crash within the first year of driving. Quimby et al. (1986) found that longer HP reactions times were associated with higher crash rates after controlling for age, driving experience and simple reaction times. Research has found that inexperienced and untrained drivers have slower HP reaction times (McKenna and Crick, 1994; McGowan and Banbury, 2004; Wallis and Horswill, 2007), while young drivers have slower HP reaction times than middle-aged drivers (Quimby and Watts, 1981).

As a result of findings such as these, as well as findings showing that HP is a trainable skill (McKenna and Crick, 1994; Mills et al. 1998), the UK Government decided to implement a HP test that all learner drivers would have to pass in order to gain a full UK driving licence (first implemented in 2002). The logic behind the implementation of the HP test was that learner drivers who fail to respond quickly enough to driving hazards in video clips might fail to respond quickly enough to on-road hazards. This could potentially lead to these drivers being involved in more crashes if given a full driving licence. The finding that HP performance can be improved through training indicated that a proper training and testing system could improve the HP of drivers. For example, HP training and testing could potentially lead to learner drivers and their instructors focusing more on HP while driving, which in turn could reduce accident rates in novice drivers.

Although the test was implemented in 2002, the history of the UK HP test goes back a few years before this.

The current UK HP test used by the Driver and Vehicle Standards Agency (DVSA) was designed and validated by Grayson and Sexton (final report published in 2002), with assistance from the DSA (Driving Standards Agency- now part of the DVSA) and the Transport Research Laboratory (TRL). The aim of the research project was to create a test that could reliably distinguish between the HP abilities of experienced and inexperienced drivers, in turn making sure that only people with sufficient HP abilities could pass the test and receive a driving licence (with the aim of improving road safety). The design was heavily influenced by the video-based HP methodology pioneered by McKenna and Crick (1994) and Grayson and Sexton defined hazards on the basis of McKenna and Crick's definition of a hazardous situation. On the basis of this definition of a

hazardous situation, they created 96 written scenarios (scripts) to guide the filming of HP clips. These scenarios were based on 6 environmental scenarios (rural lanes, suburban roads, urban roads, residential areas, single carriageways and dual carriageways) and 3 hazard categories (entry of another object into the path of the vehicle, unexpected actions of the vehicle in front and hazardous action of oncoming traffic). The scripts were then used to design and film the HP clips, which were filmed from the bonnet of a car driving on UK public roads. The clips were either staged or filmed on an opportunistic basis.

1057 inexperienced or experienced drivers took part in the validation test of the HP clips and testing procedure. Four tests were produced (each having a combination of different HP clips that were the best etc.). Participants were presented with the HP clips and had to respond to a hazard with a button press (some clips had more than one hazard). Responses to the hazards were scored on the basis of hazard windows. These hazard windows defined the time points at which making a button press would result in a score being given, with button presses outside of this window not be given a score. The start of the hazard window marked the onset of the hazard, the time at which the hazard became perceptible and started to develop. The end of the window marked the occurrence of the hazard, the point at which avoiding action would now need to be taken.

Grayson and Sexton (2002) reported that each of the four tests produced high levels of reliability (vital for psychometric testing), and that three were able to distinguish between experienced and inexperienced drivers. However, a number of studies (which used the HP clips designed by Grayson and Sexton) found that these tests were unable to demonstrate an association with accident liability.

Chapman and Underwood (1998) failed to find differences in the scores of novice and inexperienced drivers using the HP clips designed by Grayson and Sexton.

They went on to suggest that differences in hazard types were in fact more important than the experience levels of the drivers. Field, Groeger and Hammond (1997) reported no correlation between hazard scores and any measure of accident involvement. Grayson and Maycock (1997) also failed to find any association between hazard scores and involvement in accidents.

This led to a further program of work with the TRL, with the aim of producing HP tests that would correlate with accident liability and driver experience. The HP items that were better able to discriminate experience levels

were analysed in order to understand what properties of the items allowed for this discrimination. The 'best' clips required drivers to thoroughly scan the scene as well as anticipate potentially hazardous events (which is similar to the findings of other HP testing and research). These clips were capable of discriminating driver experience as well as having “some association with retrospective accident liability” (Grayson and Sexton (2002), p.20). This information was then used to create a 'blueprint' that defined the types of HP items that were required to develop successful HP clips.

From this blueprint, new HP clips were filmed and tested on drivers with varying levels of experience. Grayson and Sexton concluded that the HP items possessed sufficient reliability and validity to create a new set of HP tests. Finally, Grayson and Sexton tested whether or not the new HP training could improve scores on the HP test. The DSA created a training package that learner drivers, ready to take their theory test, were taught from. These learners then took the newly designed HP tests. The results revealed that the use of the training package led to learner drivers achieving similar HP average scores as those of experienced drivers. This HP trial was then developed and expanded into the full UK HP test as it is administered today. Only items that were able to discriminate between learners, inexperienced and experienced drivers were included.  

1.3.9 Effect of The UK HP Test  

Given the reasons for introducing the HP in the UK, the most important factor is whether or not the test has reduced accident rates among newly qualified drivers. Wells et al. (2008) evaluated the impact that the HP test had on driving in the UK. They carried out a longitudinal study on newly qualified drivers who had not taken the HP test and those who had taken the recently introduced HP test.

They used questionnaires to gather information on any accidents, driving offences etc. They found that the HP test only had benefits for specific driving situations.

They reported that the HP test was associated with reductions in subsequent accident liability in the first year of driving for some specific accidents, with the size if the effect dependent on the accident type. For reported non low-speed accidents on a public road where the driver accepted some blame, the accident liability of those who had taken the hazard perception test was significantly lower