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The Deterrent Effect of Enforcement in Road Safety - Research Findings

DescriptionThis report was commissioned to investigate the deterrent effect of enforcement in road safety. More specifically the research examined drivers' awareness of penalties.
ISBN0 7480 6206 8
Official Print Publication Date
Website Publication DateJanuary 27, 1999
Development Department Research Programme Research Findings No 34 (1997)
The Deterrent Effect of Enforcement in Road Safety
System Three
ISBN0-7480-6206-8Publisher The Scottish Office
Little is known about the role of legal enforcement and penalties in influencing driving behaviour and hence safety on the roads The Scottish Office commissioned System Three Scotland to investigate the deterrent effect of enforcement in road safety. More specifically the research examined drivers' awareness of penalties, the influence of a range of potential risks associated with offending and tested whether enforcement has a different deterrent effect on different types of driving offence.
Main findings
  • Awareness of the law relating to motoring offences was generally high, especially for speeding and drunk driving, although some areas of confusion exist eg. on the rationale for different speed limits, which can have negative consequences for road safety.
  • Enforcement has a different deterrent effect according to the type of offence; for drink driving and dangerous driving it has a very strong effect, but a far more limited effect on speeding.
  • Drivers regard speeding as having very little risk associated with it, either in terms of getting caught or being involved in an accident.
  • Drivers believe that moderate speeding is tolerated by enforcement agencies.
  • There was little support for increasing current penalties for speeding.
  • Drivers identified speed cameras, especially mobile cameras, as having a major impact on their behaviour, though the effects tended to be localised.
  • Other measures with potential for deterring drivers from offending included improved driving tests, better road signing, and road safety campaigns designed to increase awareness of the consequences of offending.
The Scottish Office and other bodies charged with promoting road safety have, for many years, been concerned with both raising awareness of road safety issues and actively enforcing the law as it relates to driving offences. However, little is known about the extent to which the existence and operation of penalties for driving offences directly influence driving behaviour.
System Three was commissioned by The Scottish Office to examine the deterrent effects of enforcement in comparison to other influences on individual drivers' behaviour in respect of a range of driving offences: speeding, careless/dangerous driving and drunk driving. Specifically the research was designed:
  • to ascertain from the groups sampled, their awareness of the existing traffic laws and the extent to which this knowledge influences their driving behaviour;
  • to ascertain from drivers what deters them from infringing traffic laws i.e. fear of being caught and a penalty enforced, concern with being involved in an accident, awareness of the consequences of their actions or some other external influence;
  • to estimate the impact of enforcement measures on the driving behaviour of the two separate groups of offenders and non-offenders, and whether this changes according to the existence of penalty points on their driving licence;
  • to test whether enforcement has a different deterrent effect on different types of driving offence (speeding, drunk driving, careless/dangerous driving).
The study consisted of both quantitative and qualitative research -
1) a screening survey carried out amongst 1,250 drivers in households selected from 50 sampling points in mainland Scotland. Drivers were categorised according to their current driving behaviour and previous penalties for offences.
  • those who tend not to speed and who have never been penalised
  • those who currently tend to speed but who have never been penalised
  • those who currently tend to speed and who have been penalised in the past
  • those who tend not to speed and have been penalised in the past
These groups formed the basis for structuring the qualitative element of the research.
2) focus group discussions with 8 groups of drivers reflecting the range of offenders and nonoffenders. Eighteen drivers who had been charged with serious offences were interviewed individually.
Results Awareness of traffic laws
In both the screening survey and in the qualitative research, respondents were generally aware of the types of driving offence and the broad range of penalties which applied, and people's perceptions of penalties were generally realistic in terms of the most commonly imposed sentences. For example, 72 per cent of respondents in the screening survey thought that driving at 45 mph in a 30 mph area would attract a fixed penalty fine and 3 penalty points.
A number of areas of confusion and uncertainty did, however, emerge which have the potential to cause drivers to unwittingly offend or to undermine the road safety messages currently being promoted. The most significant of these were:
  • a lack of clarity over how and why speed limits are set at particular levels, with particular confusion over the National Speed Limit sign in different types of area.
  • a belief that the official speed limit would not be enforced until it had been exceeded to a significant extent, with some drivers adapting their behaviour to the unofficial limit.
  • uncertainty over the rate at which penalty points accumulate, their duration and their effect on insurance and other aspects of motoring.
  • confusion over the permissible level of blood alcohol in terms of standard measures of alcoholic drinks. In this case, the uncertainty has a positive effect on road safety since the overwhelming view expressed by drivers was that it was best to simply avoid drinking at all or to only have one or two drinks over the course of an evening.
  • uncertainty over the meaning of 'careless' or 'dangerous' driving. As a result of this uncertainty, drivers tend to rely on everyday definitions of 'careless' and 'dangerous' which leaves scope for a wide range of driver errors, inattentiveness and aggression to be routinely ignored or put down to bad habits, with no acknowledgement that they may cause, or contribute to, accidents.
These gaps in drivers' knowledge tend, on the whole. to have potentially negative consequences for road safety. With the exception of drinking and driving, there is no evidence that those drivers who are unclear tend to err on the side of caution.
Other factors influencing offending
Awareness of the law relating to driving is only one factor influencing drivers' behaviour. Other factors such as those listed below may also influence whether a driver will offend.
  • the likelihood of being caught
  • if caught, the likelihood of being penalised and the type of penalty
  • the degree of social stigma attached to the offence
  • the risk of personal injury attached to the offence
  • the risk of injury to others
  • gains in time/convenience
  • enjoyment or any pleasure derived from offending behaviour
  • the likelihood of damage to the driver's own, or another's, vehicle or property
  • other, non-judicial financial costs e.g. higher insurance premiums associated with offending or accidents resulting from the offence
  • the likelihood of gaining peer approval either through offending or being caught.
For the majority of motorists there is no systematic cost-benefit" analysis when deciding to offend. Different factors assumed different relative importance according to each offence and also according to the type of driver. In order to show the differences between the perceptions of each offence, the various influences were condensed into three categories reflecting (a) the likelihood of offending being detected and punished; (b) the likelihood of injury or damage to the driver or others or their property; and, (c) the extent to which the offence attracts social disapproval. This is shown in table 1 below.
Table I The likelihood of various potential outcomes of offending

Detection & punishment

Injury or damage

Social disapproval

Moderate speedLowLowLow
Excessive speedingMediumMediumMedium
Careless drivingLowHighMedium
Dangerous drivingLowMediumHigh
Drunk drivingMediumHighHigh
The research concluded that, overall, moderate speeding was relatively common because all the possible risks associated with it were perceived to be low. The principal difference between those who would speed excessively and other drivers was the point at which risks were perceived to become too great. There is a marked contrast between perceptions of the risks associated with speeding and with drunk driving. Regardless of the reality of the consequences of drunk driving, the perception is that drunk driving is a high-risk activity without any gains associated with it. This is particularly true in relation to being detected and punished which was itself seen as a medium risk but which brought with it severe criminal penalties and a range of personal and social penalties.
The impact of deterrence and punishment
The research examined those measures which have been used as part of a conscious effort to encourage drivers to comply with the law, particularly with regard to speeding and drunk driving. It also examined the effect of punishment on those drivers who had been caught.
These two aspects of enforcement are, of course, related. This is particularly the case with antispeeding measures where speed cameras, for example, are intended to act as both a deterrent and a mechanism for detection and punishment.
Deterrence mechanisms
Mechanisms for encouraging compliance with the law and promoting the role of the individual driver in ensuring road safety fall into 4 categories.
(1) those which educate drivers ie. the driving test.
In discussing how to improve road safety many respondents cited what they perceived as the inadequacy of the driving test in training drivers to cope with the 'real world'; in particular failing to teach cognitive skills such as observation and anticipation, and for neglecting aspects such as motorway driving, night driving and skid control.
(2) those which increase awareness of particular road safety issues ie. campaigns.
Many respondents were able to recall key road safety messages or spontaneously used information from advertisements and road safety campaigns to illustrate the possible consequences of offending. Two
messages in particular appear to have made a considerable impact: the general message of not drinking and driving and the potential impact of collisions, at various speeds, on children.
The general publicity on drinking and driving would appear to have had a significant effect although this is closely related to the simultaneous toughening of sentences. The various messages relating to speeding however do not appear to have had an impact outwith the vicinity of schools and housing areas.
(3) those which alert drivers to dangers and remind them of appropriate driving behaviour ie. road geometry and warning signs. A number of respondents suggested that more signs should be posted to remind them of the speed limit, though it is difficult to assess the extent to which these would be effective in moderating speeds.
(4) those which explicitly deter drivers from offending by threat of punishment eg. speed cameras and traffic patrols.
Speed cameras are a major deterrence mechanism and appear to be effective to the extent that they result in reduced speeds in the immediate vicinity of the camera and, perhaps, in neighbouring areas. However, this effect appears to be area specific without any general reduction in speeds and may modify behaviour only to the extent that it does not cause the camera to trigger. Mobile speed cameras, as well as the use of other, similar detection methods appear to have a greater deterrent effect because their use is unpredictable.
In the screening survey, 12 per cent of respondents had been penalised for speeding in the five years prior to the survey. Based on current driving behaviour it was concluded that those who had been penalised were as likely as not to re-offend. The group discussions and interviews revealed that some drivers had been penalised repeatedly.
There was little support in the survey for more severe punishments for speeding and yet the research concludes that the current system involving fines and points is relatively ineffective. The penalties are not a major factor deterring drivers who tend not to speed
anyway; nor do they appear to be a major concern of those engaged in moderate or excessive speeding (although they do appear to limit the extent of excessive speeding); and they do not prevent a significant proportion of those penalised from reoffending.
This is not surprising given the combination of a general perception that speeding is common-place and, to an extent, tolerated; the belief that being caught once is unlikely and that repeated detection is even less so; and that even if a person is caught, the belief is that penalties do not result in any real loss other than a modest fine.
The main effect of penalties on speeding is to make drivers more conscientious about staying within the 'unofficial' limit, particularly around speed cameras. However, for those drivers who speed habitually and excessively, getting caught is regarded as an 'occupational hazard' and something that is bound to happen from time to time. It is not seen as having any implications for their future driving and, since they enjoy driving fast and share the perception that detection is unlikely, being caught and penalised is unlikely to alter their behaviour.
This can be contrasted with the perception of offences such as dangerous and drunk driving and the effectiveness of the punishments in deterring reoffending. These offences are strongly perceived as serious crimes and respondents views tended to be very punitive, with a large minority considering current penalties too lenient.
Thus penalties for these offences have a specific deterrent effect for the individuals concerned and a strong deterrent effect on drivers in general. Unlike penalties for speeding, disqualification for drunk driving has both immediate and longer term effects.
The research has found that the influences on drivers' compliance with traffic law are many and complex. The deterrent effect of enforcement depends on the type of driving offence and the public's attitude towards the severity of that offence.
There is a belief that moderate speeding is tolerated by enforcement agencies, and that speeding in general has an associated low risk, either of getting caught or being involved in an accident. This finding points to the need to increase both the perception of risk by the driver and awareness of the real risks associated with speeding.
In terms of the other, non-speeding, offences considered in the research strong deterrent effects were identified with the penalties for drunk driving. Regardless of whether respondents had been penalised for drunk driving in the past, none considered drunk driving something they would do. The motivation for avoiding drunk driving varied, with previous offenders wishing to avoid the physical and social isolation associated with losing their licence, while non-offenders are more strongly motivated by the messages of risk -both of prosecution and accidents - promoted by mass, media campaigns. Both sets of respondents' views were also strongly punitive, regarding the current penalties as inadequate.
More generally, the research has tended to reaffirm the findings of previous research - the extent to which offending (particularly excessive speeding) is most common amongst identifiable sections of the driving population; is the outcome of a consideration of the cost and benefits of complying with the law; and is justified by a belief in the driver's ability to anticipate and control dangerous situations.
Respondents in general supported a range of complimentary measures designed to promote road safety, in particular campaigns to increase road safety awareness and the consequences of offending, and measures to remind drivers of speed limits.
"The Deterrent Effect of Enforcement in Road Safety ", the research report summarised in this Research Findings, may be purchased (price £5 per copy).
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