Speed cameras

The effects of speed cameras: How drivers respond

Claire Corbett and Frances Simon
Centre for Criminal Justice Research
Department of Law
Brunel University
February 1999


This study set out to examine the effects and effectiveness of various strategies related to the deployment of speed cameras, and to explore how different types of driver responded to cameras and perceived their operation. Recommendations for best deployment were to be considered. It was carried out between 1993 and 1996 after the Road Traffic Act 1991 authorised the use of automatic speed devices for the detection of offences. A series of 12 surveys arranged in five sets and having some cross-sectional and some longitudinal elements was undertaken together with some depth interviews, and self-report measures predominated. Five police forces helped to set up the research. In total 6879 drivers took part. The particular interventions focused upon comprised camera signing alone; two kinds of publicity campaign linked with speed camera deployment; prosecution following detection by speed camera; and the effects of cameras when first installed and over time.

Earlier research by one of the authors had indicated that drivers' initial reactions to the installation of cameras (Corbett 1995) had largely been one of four types. Drivers reported either that they had normally complied with speed limits on the survey road and so cameras would make no difference to them (these we termed 'conformers'); or that they had reduced their speed on the survey road to avoid detection (the 'deterred'); or that they slowed down on approach to cameras and accelerated away downstream ('manipulators'); or that they carried on as before driving well above the speed limit ('defiers'). As the ideal aim of speed cameras is to enlarge the proportion of deterred drivers, to maintain the number of those who have 'always complied' and to reduce the ranks of the defiers and manipulators, this study aimed to find out more about the two latter types of driver. To give an overall picture based on larger numbers, four samples, totalling 3440 cases, were added together. The general picture conjured up of manipulators was that they were the most calculating and sophisticated in their reactions to cameras. They approved of them less than other types but were familiar with them, they thought they knew where they were, how they operated and how to drive past them without getting caught. In our surveys they tended to be the youngest and had the second highest offending and speeding scores and the highest accident rate. Defiers were like manipulators in being most likely to drive company or high performance cars and they were most likely to deny a general link between speed and accident risk. Not unexpectedly they had the highest speeding and offending scores, and reported the highest speeds on the survey road after cameras or signs were installed. Such speed preferences could arise from defiers being the type most likely to discount the risk of detection (if driving above 45 mph on the survey road), least likely to think the police would take action against them if they were photographed, and most likely to expect leniency if police action followed. Conformers on the other hand presented a picture of generally law-abiding, cautious drivers who approved of cameras. They were the oldest and most experienced with the lowest speeding and offending scores and were least likely to have had an accident in the previous three years. The deterred tended to fall between conformers on the one hand and manipulators and defiers on the other, but on many variables they were much like conformers implying that it was the cameras that had made them so.

Despite its apparent crudeness, our four-class typology was found to distinguish ably between the types of drivers we had earlier identified on background characteristics, general driving style and perceptions of cameras. Moreover, results between surveys were consistent and stable, and the bulk of conformers and deterred on the survey road behaved similarly on other roads. More lability was indicated in the case of manipulators and defiers, suggesting that on less familiar roads a minority behaved as deterred, which raises questions about these defiers' true nature as people who apparently are uncaring about the threat of detection. Yet the impression from all our data was that everyone has a price and provided the threat of cameras remains a potent one, the proportion who ignore them will reduce sooner rather than later.

a) Camera signing alone
Three surveys were conducted in Eastleigh, Hampshire, the first before signs were erected, the second two months after and the third six months after. Overall it appeared there was a substantial reduction in speed and most of it lasted six months. At that point, of those respondents with scope to slow down over half were going more slowly, and 90% of those who before the signs had been keeping to the limits were still doing so. Although there were other enforcement signs and red light camera housings in a nearby city (Southampton), it seems that speed camera warning signs represented a real objective threat (correlating with the high subjective threat noted). So while the results must be considered in context, they were overall encouraging.
b) Two local publicity campaigns relating to the deployment of speed cameras
A longitudinal 'before' and 'after' design was used for both pairs of surveys in Northumbria and West Midlands, the second one taking place one to two months after each campaign had been mounted. The campaign in Northumbria aimed to enhance the perceived efficacy of existing fixed-site cameras by announcing that they would be supplemented by mobile ones, so undermining drivers' reliance on knowing where cameras were sited. That in West Midlands intended to suggest that the prosecution threshold (trigger) speed of existing speed cameras had been lowered, increasing the risk of detection. Together, the results suggested that local publicity campaigns may help reinforce perceptions of the potency of cameras and perhaps of the dangers of speed, even if at less than a conscious level for many, although among those at greater risk of losing their licence awareness may have been more conscious.
c) Payment of a fixed penalty after detection by speed camera
One survey was carried out of a sample of drivers detected on a road in the Thames Valley police force area, all of whom had paid a fine. At face value, many of the results indicated that the impact of prosecution was in the desired direction. So, for instance, while 26% said that before prosecution they normally kept below 31 mph on the survey road, this proportion rose to 87% afterwards. However, the inadvertent speeding of the majority, some of which was apparently due to believing the speed limit was higher, meant that for an unknown proportion (but less than 54%) the deterrent effects of prosecution may have been more apparent than real. Some information was also gathered from four other samples on the impact on their driving style of having penalty points. Together the results suggested that penalty points may have a restraining influence on a substantial proportion of drivers' speeds. d) Effects of speed cameras when first installed and over time A series of four surveys was specifically set up for the purpose of assessing initial reactions to cameras and drivers behavioural and perceptual responses over time. These were carried out in Surrey in hitherto 'virgin' territory, and data from two other surveys also supplemented the findings. The first Surrey survey was conducted before cameras were installed; the rest took place at two, six and eight months after commencing operation. The impact of the camera was greatest when first installed, with speed choice markedly reducing and the perceived risk of detection substantially increasing. These effects were largely maintained at least until the eight months point, although other perceptions and beliefs remained more or less static between the first and last Surrey surveys. It would be unrealistic to attribute all the encouraging results in the Surrey surveys to the operation of just one camera and it is likely that other peripheral factors were influential. Eight surveys addressed the issue of whether camera-induced speed behaviour generalises to other roads which have no indications of cameras. This is of importance because the use of speed cameras is restricted, being considered only when other potential solutions to speed-accident problems have been rejected. Altogether the results from the self-report data lent strong support to the notion that the deterrent effects of cameras spread to unsigned roads.

In sum, a main finding from our research was that, according to self-report measures, camera deployment can reduce drivers speeds markedly. Our results suggest that any of the measures investigated can be useful in helping to lower drivers' speeds, and most of the effects of installing cameras or signs lasted for several months. Moreover, some speed reduction was reported among all types of driver, not just the deterred, in regard to all deployment strategies. Overall, and for all types of driver except defiers, prosecution appeared to have the strongest deterrent effect, but results are site specific. The installation of cameras also had a pronounced effect, with a majority in our samples describing themselves as deterred after the erection of warning signs and cameras. Camera warning signs alone were moderately productive, and the effects were still largely present some months later. Local publicity campaigns seemingly influenced fewer than half of the speeders, especially manipulators, to slow down but as part of the effort to raise driver awareness of the risks of speeding they probably have merit. Defiers were the most intractable group, the majority remaining uninfluenced by any of the measures.
5. PERCEPTIONS, BELIEFS AND ATTITUDES TO CAMERAS Estimates of threshold speed above which cameras are activated varied little between survey sites (which all had 30 mph limits) or across time, the modal estimate being 35 mph and the next most frequent being 40 mph. In ten surveys the big majority thought the risk of detection for doing more than 45 mph on the survey road over the next three months was high. In the five surveys which questioned drivers a second time up to a third of respondents believed the risk of being caught for exceeding a speed limit on other main roads in the county had increased since they were first surveyed. The big majority of respondents believed that some police action would follow if they were detected by camera, and this perception varied little over time though it did vary somewhat by area. Around three quarters expected that the most likely penalty for doing 45 mph on the survey road would be a fixed one (a speeding ticket). Altogether it appeared that respondents collectively had a realistic idea of the likely consequences of detection for speeding. Most drivers in each survey were favourable to cameras, although those who had been caught approved less. Where measured, the proportions holding positive attitudes increased over time. Among those not previously caught by speed camera the bulk of manipulators and defiers also expressed views in favour of cameras, which is interesting since their behaviour in response to cameras would suggest otherwise. While overall the results on perceptions, beliefs and attitudes towards cameras were promising, there may nonetheless be an element of 'preaching to the converted'. The drivers most in favour of cameras, and most fearful and respectful of them, were those who are probably least likely to fall foul of them, i.e. conformers. At the other extreme, those who present the main problem to road safety planners - defiers and manipulators - seem the least respectful and fearful of cameras and least attitudinally influenced by them.

The conclusions of our research lead us to recommend that:
a) local publicity campaigns concerning the operation and existence of speed cameras continue to be mounted even if direct local benefits are not readily apparent. It appears that local campaigns can help keep the risks of speeding and the existence of cameras on the public agenda, and in cumulation with each and in combination with national efforts they may produce speed reductions.
b) a way be found to remind all drivers of current speed limit conventions and signing rules and to check more frequently their speedometers to help prevent inadvertent speeding. Some of those caught speeding unintentionally exceeded the limit through lack of attention and some through believing they were complying at the time of detection but were mistaken about the speed limit.
(c) a sustained and uniform policy of reducing camera threshold speeds is proceeded with as originally envisaged. In addition, it is suggested that future local publicity campaigns might usefully focus on advising drivers directly of reduced prosecution threshold ( trigger ) speeds in the area. Prosecution seemed especially salutary among intentional speeders, and most of those caught held positive attitudes to cameras (although only a minority of manipulators who had been caught were supportive). Based on our findings, reducing threshold speeds as originally planned is likely to lead to more speed reductions and only some slight loss of approval. Moreover, such a policy should help change perceptions among some that driving up to 10 mph above the speed limit is complying with the law.
(d) current resourcing arrangements be reviewed. In order to bolster the subjective risk of detection and increase the deterrent capability of speed cameras the objective risk must be maintained and preferably enhanced.
(e) insurance policies against disqualification for speeding be proscribed. Some drivers, especially defiers, may be tempted to ignore cameras safe in the knowledge that satisfactory alternative arrangements will be made for them in the event of their disqualification for speeding.
(f) a policy of reducing the visibility of roadside camera installations be introduced, and linking with (b) above, a policy of combined speed limit and camera warning signs in the target area is recommended. Undermining drivers confidence in knowing the location of fixed-site cameras may reduce manipulating and encourage more uniform lower speeds, as indicated by manipulators and defiers reports of driving on other (perhaps less familiar) signed roads. Signs are considerably cheaper than camera installations, and provided there is some genuine objective risk of detection our study suggests that subjective risk will follow.
(g) mobile cameras should have a continuing place in enforcing speed limits even if resource constraints mean that police do not actually use as many of them as their publicity campaigns might suggest. While mobile cameras may raise uncertainty as to the risk of detection provided drivers are aware of their existence, unless they are used in unattended mode their operation rather defeats a key purpose of cameras to free-up police time and they are costly in terms of limited police resources.
(h) wide use be made of powers to impose graduated fines based on declared net weekly income on speeding drivers who come before the courts (in accordance with revised guidelines for Magistrates Courts (Magistrates Association 1997)). While most drivers expected a fixed penalty if caught, our earlier and present research suggests that at current levels these are unlikely to deter the fastest ones unless they already have six or more penalty points. However, more points combined with heavier fines may have more effect.
(i) camera installation be restricted to sites which have previously experienced a speed-related accident problem or where the potential for accidents is higher than average, such as at roadworks. This is to prevent speculation that cameras are a good money-earner for police or the state and to raise the likelihood that cameras will cut accidents at a particular site.
(j) future media campaigns should point out that most drivers think they are better and safer than others which is illogical, and that the message of the danger of speed is directed at all drivers and does not exclude those who believe they are better. Some paradoxical findings highlighted the challenge ahead, such as manipulators and defiers holding mainly positive attitudes to cameras but attempting to subvert their purpose nonetheless.

Implicit throughout the report and underpinning much of our earlier research is that the ethos of speed not only permeates discourse on driving, but has infiltrated all aspects of modern life. So tackling the problem of speed on our roads runs counter to the general trend in society where speed is desired, valued and attractive. In this broader picture, attempts to modify drivers' speed by means of enforcement is unlikely ever to be enough (unless top speeds are restricted by technology), and a fundamental attitude change to speed on the roads is required. Individual inclinations to speed at a particular time and place are motivated by a range of factors, but the most important in our view is that drivers do not see occasions when they exceed limits as dangerous otherwise they would not do it. When they speed they feel they are in control and that little harm will befall them, and these perceptions are strengthened by the fact that negative reinforcement occurs only rarely. But this perception of control is to some extent illusory since, for instance, most drivers think they are more skilful than the average (e.g. Svenson 1981), most believe accidents are more likely to happen to them as passengers than as drivers (Horswill and McKenna 1997), and most think the roads would be safer if everyone drove like themselves (Corbett and Simon 1992). In addition, individual instances of speeding are carried out against a social backcloth in which several factors interlink. Most drivers speed, so it is a consensual activity and a social norm legitimated by other speeders, and in combination with the feeling of being in control leads to few drivers perceiving speeding as serious, harmful, criminal or immoral (Corbett and Simon 1992). Since there are difficulties in achieving widespread enforcement, the message picked up by drivers from this could be that some speeding is condoned, especially given the latitude in camera thresholds. And when drivers are detected, unless disqualification is imposed outright or under the 'totting' rules, fixed penalties are not perceived as particularly onerous (Corbett, Simon and O'Connell 1998). This is all set against a backdrop where motor vehicle manufacture is encouraged and is indeed a measure of the country's economic health, and where the demand for production of high performance vehicles is not discouraged by the state. So although we conclude that the proliferation of speed cameras is an important means by which to raise drivers' awareness of the dangers of speed and of inadvertent speeding, ultimately more than this and other forms of speed limit enforcement will be required in order to modify drivers' views on speed. Attention will need to be given to factors associated with overconfidence in being in control and with the broader social climate in which our car culture is embedded.

Corbett C and Simon F (1992). Unlawful Driving Behaviour: A Criminological Perspective. Contractor Report 310. TRL: Crowthorne.
Corbett C (1995). Road traffic offending and the introduction of speed cameras in England: the first self-report survey. Accident Analysis and Prevention, 27, 345-354.
Corbett C, Simon F and O'Connell M (1998). The Deterrence of High Speed Driving: A Criminological Perspective. Contractor Report 296, TRL: Crowthorne.
Horswill M and McKenna F (1997). The effect of perceived control on risk-taking. Journal of Applied Social Psychology (in press).
Svenson O (1981). Are we all less risky and more skilful than our fellow drivers? Acta Psychologica, 47, 143-148.

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