Do Speed Cameras Improve Road Safety?

S. Kidd

13 April 2003

Speed cameras improve road safety, but some speed cameras improve road safety more than others. In addition, there may be other measures which are more effective, either divorced from any aspects of speed camera operation, or in conjunction with them.

Do drivers 'speed' and is this speed detrimental to road safety? To a degree it is obvious that speed of vehicles poses considerable dangers but, less intuitively, the fact is that this risk increases exponentially with velocity. As a response to these two questions it is established that:

To place this in a more vivid context, according to RoSPA (2003), the chances of dying on a 40 mph road are approximately 16 times greater than on the same road with the same traffic at 10 mph or, according to the Department of Transport (1992) most pedestrians hit at 20mph walk away but at 40mph they die. A similar increase in risk applies to occupants of motor vehicles as well as their external victims.

There is no question that some speed reduction is a desirable aim and it is beyond conjecture that many people speed. It is important to understand the history to date of the UK government's policy on implementation of speed reduction through cameras.

The Great Britain Road Traffic Act (1991) instructed courts to accept evidence of speeding from approved cameras. There appears to have been an effort by the governments to address objections raised by some lobby groups through a stringent set of guidelines governing camera use. These constraints as highlighted by RoSPA (2003) until recently included:

Any transgression of guidelines was to result in the relevant authority being stripped of its power to use cameras, although a recent court case brought by Transport 2000 (2003) and the Slower Speeds Initiative has established that partnerships can now apply to conceal static cameras.

Several systems have been tested, incorporating both fixed and mobile cameras, but the crux of all is observation, recording and automatic penalising of transgressing vehicles. Digital cameras can now be placed some distance apart to record average speed rather than site specific instances.

A series of measures other than speed cameras might reduce speeds. Either taken individually or in combination, they may complement speed camera function or replicate it. Before exploring the detail of speed camera effectivity, it is important to understand the relative benefits of other strategies. Although all broadly successful, their advantages and disadvantages relative to speed cameras include and incorporate:

It is an eclectic combination of measures which probably realise optimum choices, therefore speed cameras should be considered.

The historical context of effectiveness of speed reduction techniques are summed up by Transafety (1997) stating, "Traditional speed management techniques are inefficient and have failed to lower highway driving speeds effectively... For speed management systems to be effective, enforcement must have a greater priority."

While agreeing that education and warning systems may serve a purpose, to achieve speed reductions a robust system of detection and punishment has to be utilised. This is in keeping with the current advice from Parliamentary Advisory Committee on Transport Safety (PACTS) (2003) that states the factors which determine whether a driver will offend include primarily:

and emphasises "Aspects which influence road users' perceptions of risk of detection are particularly relevant."

Traditional methods of enforcement (i.e. police patrols) are not working. Transsafety (1997) state "Such methods are labour-intensive and produce only temporary changes in driving behaviour"

Although insurance might be considered were there an accurate method of measuring the cost of damage, injury and life, the optimal speed reduction strategy involves making it difficult or impossible to exceed limits. Of the measures discussed only speed cameras and EVSA fulfil this brief and, as EVSA will not be available for several years, only speed cameras remain.

As regards funding, speed cameras have a major advantage over the systems outlined, as the cost of them can be borne directly by the offender. Although insurance premiums can go some way to targeting the offender, there is considerable room for error. By internalising costs, decisions are more efficient. It is simply not fair that the courteous fair and safe driver has to move an iota off the most efficient line to negotiate a road hump, yet it is logically equable that the cost of crime should be borne by the criminal.

Whilst conceding the potential advantages of AC-ASSIST (An Anti Collision and Autonomous support and safety intervention system), a capability of harmonising speeds along with the potential for a variety of other 'smart' applications, in an EVSA system, and accepting that traffic calming and education are instrumental in priming drivers, ultimately it is speed cameras which have the advantages of focus, availability and democracy, without the disadvantage of inefficient impedance of movement through physical obstruction.

Enforcement is the most vital component of any strategy to tackle crime, and given the automation of speed camera operation their deployment has distinct advantages over other methods. A report for the home office by Hooke et al (2003) on the speed camera trials in the UK tells us.

"The 5.3 million investment made to install speed cameras generated a return of five times this amount after one year and more than 25 times the amount after five years. All areas achieved a positive return after one year and in nine out of ten forces fine incomes covered the 'cost' of operations."

We are also given an injury accident reduction rate encountered in areas of visible speed cameras of 28%. According to Carsten et al, the best estimates of ISA indicate a 36% accident reduction.

At 5,600 per annum, as given Hooke et al (2003), the maintenance costs of speed cameras are high and, though return might be made on many, it would be prohibitively expensive to maintain blanket coverage across the country. It should be borne in mind that this is not imperative as it is sufficient that only the offender's perceptions of chances of detection rise close to 100%. Covert, dynamic location and stringent punishment (perhaps incorporating confiscation of vehicles for non payment of fines) would all encourage adherence of the law. The best evidence is that gained first hand, an example of which is the effectiveness of traffic signal cameras, in many ways serving a similar function to speed cameras. In 1997 the author was photographed transgressing a red light in Wakefield. There is little doubt that the author will not go past a red light again anywhere in the United Kingdom, let alone at the location.

Evidence for a 'ripple effect' of robust enforcement through speed cameras is given by the DfT (2001 3.2) who state:

"It was not expected that a crackdown on speeding at certain casualty black spots would have an immediate effect on casualties in the partnership area as a whole (as opposed to specific camera sites). However, taken together, the pilot areas demonstrate a decline in both casualties and collisions. Not all of this should be claimed as a direct result of the additional camera enforcement ... However, at least some of the decrease is likely to be attributable to cameras and associated publicity"

Economies of scale have the potential to bring the costs of speed cameras down and bearing in mind the PACTS (2003) advice above, more stringent enforcement and punishment would raise their effectiveness further.

There are more contentious aspects of speed cameras in the UK, i.e. that of concealment and degree of hypothecation. It is obvious that if camera locations are known then non-surveyed locations are equally well known. It is also plain, as shown by Keenan (2001) that many drivers decelerate approaching cameras and some accelerate away. This behaviour raises the chances of accidents through disharmonising road speeds between vehicles. Studies in New Zealand by have shown that concealed cameras at undisclosed locations have a far greater net benefit in accident reduction (17% in the test area), positive behavioural modification and revenue increase (4 times as many drivers were caught and fined). This is borne out by the personal experience illustrated previously and the studies of DeWaard and Roojers, who show that the average speeds of drivers who had been fined were less than a similar group who went unpunished.

Despite this overwhelming evidence that speed cameras work, along with research by, for example Chinn (1999), The DETR (1999) and Keenan (2002), we still have disincentives to their installation in this country, in that, as mentioned, no 'profit' is allowed. This means that the margins have to be calculated precisely and that all costs are not recovered at a local level. This brings about the interesting but rarely discussed speculation of privatising speed enforcement. Filming a speeding motorist, given modern video and camera technology is now a relatively simple process. If recording speeders could be opened to private administration the benefits of speed reduction might be enjoyed without the initial high public investment. Private CCTV coverage is often used in the prosecution of other criminals so, quite simply, why not car drivers?

Political acceptability should not be the main justification for statement. Society's attitude to speeding is tolerant compared to other activities such as drug taking, prostitution and blasphemy, yet none of these latter three actually involve killing people. Slavery, child labour and drink driving have all been perfectly acceptable to the public in general, but the ubiquity of speeding and the perceived remoteness of the danger it imposes have served to retain this crime's general acceptance. It is suggested that political will must drive opinion with the ultimate goal of equity and efficiency. Speed cameras are an example of failure to utilise an instrument thereby employing sub-optimal methods of operation.

Speed cameras do improve road safety in the United Kingdom but have, as yet, not been used to their full potential in reducing accidents.

References: All electronic sources are as of April 2003 unless stated

Australian Academy of Science, Fatal impact - the physics of speeding cars;

Carsten, O., Tate, F. (2000) External vehicle Speed Control, Deliverable D 17, Final report: Integration;

Cook, P. Traffic Calming and Speed Management, TMS Consultancy;

Chin, H.C. (1999). An Investigation into the Effectiveness of the Speed Camera. Article in The Proceedings of the Institution of Civil Engineers. Vol. 135. Issue No.2. pp.93-101.

DETR. (1999). Road Safety Research Report No.11: The Effects of Speed Cameras - How Drivers Respond. London, HMSO Stationary Office.

DfT (2002) Transport Statistics Great Britain London, HMSO Stationary Office.

DfT (2001) Cost recovery system for traffic Safety Cameras First Year Report;

Department of Transport (DoT) (1992) Killing Speed, Saving Lives

Great Britain (1991) Road Traffic Act (c. 40). London, HMSO Stationary Office

Hooke, A. et al (2003) Cost Benefit Analysis of Traffic Light and Speed Cameras. Home Office Police Research group;

Keenan, D. (2001). Measuring the effect of Speed Enforcement Cameras on Traffic Speed Violations. MSc (Eng.) dissertation. ITS, University of Leeds

Keenan, D. (2002). Speed Cameras - The True Effect on Behaviour. Traffic Engineering & Control magazine April 2002. pp.352-357.

New Zealand National Road Safety Committee (July 1999) Hidden speed camera trial evaluation report.

Parliamentary Advisory committee on Transport Safety (PACTS) (2003), Speeding: The Continuing Challenge;

RoSPA The Royal Society for the prevention of accidents (2003) Road Safety Information;

Transport 2000 (March 2003) Transport Retort Issue 26/1 ed Steve Hounsham, p.4

Transsafety 1997US Roads Road Management Journal;