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Risk Compensation

Risky business: safety regulations, riskcompensation, and individual behavior

James Hedlund

Government regulations and industry practices constrain our behavior in many ways in an attempt to reduce injuries. Safety features are designed into products we use: cars now have airbags; medicine bottles have “childproof” caps. Laws require us to act in a safe manner: we must wear seat belts while driving and hard hats in construction areas. But do these measures influence our behavior in other ways? Risk compensation theory hypothesizes that they do, that we “use up” the additional safety though more risky actions. This paper surveys risk compensation by reviewing its history, discussing its theoretical foundations, outlining evidence for and against its claims, and providing the author’s own views. It concludes by discussing the relevance of risk compensation for injury prevention workers who seek to reduce unintentional injuries.

Hedlund, J. (2000) Risky business: safety regulations, risk compensation, and individual behavior. Injury Prevention 6, 82-90.


(Full text)

Bicycle helmets: Should cyclists wear them?

Jake Olivier

School of Mathematics and Statistics, University of New South Wales, Sydney, Australia

A Systematic Review - Conclusions

  • Bicycle helmet use was associated with reduced odds of head injury, serious head injury, facial injury and fatal head injury. The reduction was greater for serious or fatal head injury. Neck injury was rare and not associated with helmet use. These results support the use of strategies to increase the uptake of bicycle helmets as part of a comprehensive cycling safety plan.

  • The effects of (possible) risk compensation has not been adequately researched, and there is evidence estimates of helmet effectiveness are not influenced by other risk factors.

  • Motor vehicles do not give more/less overtaking distance for helmeted or unhelmeted cyclists.

  • Mandatory bicycle helmet legislation is associated with large increases in helmet wearing.

  • Bicycle helmet legislation is also associated with reductions in cycling fatalities, head injuries and traumatic brain injury.

Full presentation

Journal article (Abstract   Full text)

SudhaJayaraman,  DineshSethi, Roger Wong

Injury is one of the top ten causes of death and disability worldwide. It results in an early loss of life for many young people and ongoing high medical care costs among survivors. Advanced life support (ALS) training for ambulance crews with emphasis on trauma is believed to have contributed to a reduction in the number of deaths from injury in predominantly high‐income countries where this service is available. ALS services are also being adapted for low‐ and middle‐income countries. This review of trials found there is no evidence to suggest that ALS training for ambulance personnel improves the outcomes for injured people.  (Full text)

Advanced training in trauma life support for ambulance crews

Alcohol and drug screening of occupational drivers for preventing injury

Clodagh M Cashman, Jani H Ruotsalainen, Birgit A Greiner, Paul V Beirne, Jos H Verbeek

Alcohol and drug abuse are serious public health problems worldwide. Workplace alcohol and drug testing is a common intervention, especially in developed nations, but it is costly and its use is controversial. This systematic review aimed to assess the effects of alcohol and drug screening among occupational drivers for preventing injury. 


We conducted a systematic search of the literature on the effects of alcohol and drug screening among occupational drivers for preventing injury. We then appraised the quality of the studies found and assessed their results. We found two time‐series studies conducted in the USA. One was conducted in five large transportation companies, and it examined the effects of two interventions of interest: implementation of legislation for mandatory random drug testing and mandatory random and for‐cause alcohol testing. The other study was conducted using national injury data.

There is limited evidence that in the long term mandatory drug‐testing interventions can be more effective than no intervention in reducing injuries in occupational drivers. For mandatory alcohol testing there was evidence of an immediate effect only.

Given the widespread practice of alcohol and drug testing and the paucity of evaluation studies found, more evaluation studies are needed. Interrupted time‐series is a feasible study design for evaluating interventions that aim at preventing alcohol and drug related injuries. However, time‐series studies of higher quality and of long duration are needed to increase the level of evidence. A cluster‐randomised trial would be the ideal study design to evaluate the effects of interventions for injury prevention in this occupational setting. (Full text)

Alcohol ignition interlock programmes for reducing drink driving recidivism

Charlene Willis, Sean Lybrand, Nicholas Bellamy

Convicted drink drivers are sometimes offered the choice of a standard punishment, or for an alcohol ignition interlock to be fitted to their car for a fixed period. To operate a vehicle equipped with an interlock, the driver must first give a breath specimen. If the breath alcohol concentration of the specimen is too high, the vehicle will not start. A number of studies have been conducted to see whether the interlock stops drink drivers from offending again. Most of these studies have not been of high quality. The interlock seems to reduce re‐offending as long as it is still fitted to the vehicle, but there is no long‐term benefit after it has been removed. However, more studies of good quality are needed to confirm these findings. The low percentage of offenders who choose to have an interlock fitted also makes it difficult to reach firm conclusions about their effectiveness. (Full text)

Area‐wide traffic calming for preventing traffic related injuries

Frances Bunn, Timothy Collier, Chris Frost, Katharine Ker, Rebecca Steinbach, Ian Roberts, Reinhard Wentz

Road traffic crashes are a major problem worldwide. In high‐income countries, traffic calming schemes aim to make the roads safer (particularly for vulnerable road users such as pedestrians and cyclists) in areas that are particular 'hot spots'. Strategies include slowing down traffic (eg road/speed humps, mini‐roundabouts, reduced speed limit zones), visual changes (road surface treatment, changes to road lighting), redistributing traffic (blocking roads, creating one‐way streets), and/or changes to road environments (such as trees). This review found that area‐wide traffic calming may have the potential to reduce death and injuries, but more research is needed particularly in low and middle income countries. (Full text)

Bicycle helmet legislation for the uptake of helmet use
and prevention of head injuries

Alison Macpherson, Anneliese Spinks

Cycling is a popular past‐time among children and adults and is highly beneficial as a means of transport and obtaining exercise. However, cycling related injuries are common and can be severe, particularly injuries to the head.

Bicycle helmets have been advocated as a means of reducing the severity of head injuries, however voluntary use of helmets is low among the general population. Bicycle helmet laws mandating their use have thus been implemented in a number of jurisdictions word‐wide in order to increase helmet use. These laws have proved to be controversial with opponents arguing that the laws may dissuade people from cycling or may result in greater injury rates among cyclists due to risk compensation. This review searched for the best evidence to investigate what effect bicycle helmet laws have had. There were no randomised controlled trials found, however five studies with a contemporary control were located that looked at bicycle related head injury or bicycle helmet use. The results of these studies indicated a positive effect of bicycle helmet laws for increasing helmet use and reducing head injuries in the target population compared to controls (either jurisdictions without helmet laws or non‐target populations). None of the included studies measured actual bicycle use so it was not possible to evaluate the claim that fewer individuals were cycling due to the implementation of the helmet laws. Although the results of the review support bicycle helmet legislation for reducing head injuries, the evidence is currently insufficient to either support or negate the claims of bicycle helmet opponents that helmet laws may discourage cycling.
 (Full text)

Cycling infrastructure  for reducing cycling injuries in cyclists

Caroline A Mulvaney, Sherie Smith, Michael C Watson, John Parkin, Carol Coupland, Philip Miller,Denise Kendrick, Hugh McClintock


Review question

This review aimed to answer the question "what effect do different types of cycling infrastructure have on cycling injuries and collisions?". Cycling infrastructure involves changes which are made to the road design or management of the road for cyclists. We aimed to include studies which looked at the effects of three types of cycling infrastructure:


  1. That which aims to manage the shared use of the road space for both motor vehicles and cyclists, for example, cycle lanes and shared use of a bus lane;

  2. That which separates cycle traffic from motorised traffic and may include special routes just for cycle traffic, for example, cycle tracks and cycle paths. These may be shared with pedestrians;

  3. Management of the roads to include separation of motor vehicle and cycle traffic (for example, traffic rules that ban certain types of traffic from making particular turns) and cycle turns at traffic signals.

    Comparisons were made with either routes or crossings that either did not have cycling infrastructure in place or had a different type of infrastructure. We were interested in studies with both adults and children. The primary outcome of interest was cycling injuries suffered as a result of a cycling collision. Secondary outcomes were collision rates for cyclists; and cycle counts, that is the number of cyclists using the infrastructure.


Cycling infrastructure involves making changes to the road environment to provide special facilities for cyclists. These may include putting in cycle lanes or giving cyclists right of way at junctions, or separating cyclists from fast‐moving or high‐volume traffic. Speed limits may be introduced which means cyclists share the road with vehicles moving more slowly. This review is important because if we want to get more people cycling, we need to know whether cycling infrastructure helps to keep cyclists safe.

Search date

We searched world‐wide research literature up to March 2015.

Study characteristics

The types of studies that could be included in this review are randomised controlled trials, cluster randomised controlled trials, controlled before‐after studies, and interrupted times series studies. We found 21 studies looking at the effects of 11 different types of cycling infrastructure. No studies reported self‐reported injuries or medically attended injuries. Fourteen studies reported police‐reported ‘cycle crashes’ or ‘accidents’ or ‘injury crashes’ and the other studies reported outcomes such as number of “cycle accidents” or “crashes involving cyclists”. Nine studies reported collisions by severity; seven studies reported on age of casualty; and two studies reported on sex. One study reported on the level of social deprivation. Cycle flow was collected in 14 studies.

Key results

Generally we found a lack of evidence that the types of cycling infrastructure we looked at affects injuries or collisions in cyclists. Cycle routes and networks do not seem to reduce the risk of collision. Speed limits of 20 mph, changing parts of the road network to some designs of roundabouts and changing busy parts of a cycle route may reduce the risk of collision. In terms of severity of injury, sex, age and level of social deprivation of the area, there is a lack of evidence to draw any conclusions concerning the effect of cycling infrastructure on cycling collisions.


Quality of the evidence

We carried out a thorough search for relevant papers. The quality of the evidence was low with 20 of the included 21 studies using a controlled before‐after study design. Few studies considered how factors such as weather and volume of traffic may affect collision rates. Few studies considered how changes in cycle rates seen as a result of installing infrastructure may affect changes in collision rates. (Full text)

Graduated driver licensing for reducing motor vehicle crashes among young drivers

Kelly F Russell, Ben Vandermeer, Lisa Hartling


Young drivers are at high risk of involvement in motor vehicle crashes. Graduated driver licensing (GDL) has been proposed as a means of reducing crash rates among novice drivers by gradually introducing them to higher risk driving situations. This review found 34 studies that have evaluated various types of GDL programs. All of the studies reported positive findings, with reductions for all types of crashes among all teenage drivers. However, the size of the reductions varied and, based on the included studies it is not possible to say which aspects of GDL programs have the biggest effect. Future research on GDL should evaluate the relative impact of different program components. (Full text)

Helicopter emergency medical services for adults with major trauma

Samuel M Galvagno Jr, Robert Sikorski, Jon M Hirshon, Douglas Floccare, Christopher Stephens, Deirdre Beecher, Stephen Thomas



Trauma is a leading cause of death and disability worldwide and, since the 1970s, helicopters have been used to transport people with injuries to hospitals that specialize in trauma care. Helicopters offer several potential advantages, including faster transport, and care from medical staff who are specifically trained in the management of major injuries.

Study characteristics

We searched the medical literature for clinical studies comparing the transport of adults who had major injuries by helicopter ambulance (HEMS) or ground ambulance (GEMS). The evidence is current to April 2015.


Key results

We found 38 studies which included people from 12 countries around the world. Researchers wanted to find out if using a helicopter ambulance was any better than a ground ambulance for improving an injured person's chance of survival, or reducing the severity of long‐term disability. Some of these studies indicated some benefit of HEMS for survival after major trauma, but other studies did not. The studies were of varying sizes and used different methods to determine if more people survived when transported by HEMS versus GEMS. Some studies included helicopter teams that had specialized physicians on board whereas other helicopter crews were staffed by paramedics and nurses. Furthermore, people transported by HEMS or GEMS had varying numbers and types of procedures during travel to the trauma center. The use of some of these procedures, such as the placement of a breathing tube, may have helped improve survival in some of the studies. However, these medical procedures can also be provided during ground ambulance transport. Data regarding safety were not available in any of the included studies. Road traffic and helicopter crashes are adverse effects which can occur with either method of transport.

Quality of the evidence

Overall, the quality of the included studies was low. It is possible that HEMS may be better than GEMS for people with certain characteristics. There are various reasons why HEMS may be better, such as staff having more specialty training in managing major injuries. But more research is required to determine what elements of helicopter transport improve survival. Some studies did not describe the care available to people in the GEMS group. Due to this poor reporting it is impossible to compare the treatments people received.


Based on the current evidence, the added benefits of HEMS compared with GEMS are unclear. The results from future research might help in better allocation of HEMS within a healthcare system, with increased safety and decreased costs.(Full text)

Helmets for preventing head and facial injuries in bicyclists

Diane C Thompson, Fred Rivara, Robert Thompson


Cycling is a healthy and popular activity for people of all ages. Crashes involving bicyclists are, however, common and often involve motor vehicles. Head injuries are responsible for around three‐quarters of deaths among bicyclists involved in crashes. Facial injuries are also common. The review found that wearing a helmet reduced the risk of head or brain injury by approximately two‐thirds or more, regardless of whether the crash involved a motor vehicle. Injuries to the mid and upper face were also markedly reduced, although helmets did not prevent lower facial injuries. (Full text)

Helmets for preventing injury in motorcycle riders

Bette C Liu, Rebecca Ivers, Robyn Norton, SoufianeBoufous, Stephanie Blows, Sing Kai Lo

Motorcyclists are at high risk in traffic crashes, particularly for head injury. A review of studies concluded that helmets reduce the risk of head injury by around 69% and death by around 42%. There is, so far, insufficient evidence to compare the effectiveness of different types of helmet. Some studies have suggested that helmets may protect against facial injury and that they have no effect on neck injury, but more research is required for a conclusive answer. The review supports the view that helmet use should be actively encouraged worldwide for rider safety. (Full text)

Interventions for increasing pedestrian and cyclist visibility for the prevention of death and injuries

Irene Kwan, James Mapstone

Pedestrians and cyclists are often killed or seriously injured in traffic crashes, especially in developing countries where walking and bicycling are essential modes of transportation. In the UK, one in three road traffic fatalities is a pedestrian or cyclist. Usually, in these crashes drivers fail to see the pedestrian or cyclist until it is too late. In recent years reflective garments, flashing lights, and other visibility aids have been used to try to prevent crashes.


The authors of this Cochrane review looked for studies which showed how effective visibility aids are for protecting pedestrians and cyclists. They focused their search on a type of study called a randomised controlled trial, which compares two similar groups of people who only differ on the issue being studied, for instance, the rate of crashes in communities with and without introduction of visibility aids. The authors found no studies that compared number of crashes but to date they have found 42 studies which compare driver detection of people with or without visibility aids. These studies showed that fluorescent materials in yellow, red and orange improved driver detection during the day; while lamps, flashing lights and retroreflective materials in red and yellow, particularly those with a 'biomotion' configuration (taking advantage of the motion from a pedestrian's limbs), improved pedestrian recognition at night. Although these visibility measures help drivers see pedestrians and cyclists, more research should be done to determine whether the increased visibility actually does prevent deaths and serious injuries. (Full text)

Interventions for promoting booster seat use in four to eight year olds travelling in motor vehicles

John E Ehiri, Henry OD Ejere, Lesley Magnussen, Donath Emusu, William King, Scott J Osberg

Booster seats are designed for use by children aged four to eight years, while travelling in motor vehicles. They aim to raise the child off the vehicle seat so that the adult seat belt fits correctly and the child can travel in greater comfort and safety. Public health and traffic safety agencies recommend the use of booster seats in children until the vehicle seatbelt fits properly; typically when the child is at least 58 inches tall, has a sitting height of 29 inches and weighs about 80 pounds.

In children aged four to seven years, booster seats are estimated to reduce the odds of sustaining clinically significant injuries during a crash by 59%, when compared to using ordinary vehicle seatbelts. Despite the evidence of effectiveness, many children are not restrained in age‐appropriate booster seats.

In light of the strong evidence for the safety benefits of booster seats, interventions specifically aimed at promoting their use have been implemented. To evaluate the effectiveness of such interventions, the authors of this systematic review examined all high quality trials investigating their effect on acquisition and use of booster seats.


The authors found five studies involving a total of 3,070 participants. All interventions investigated by the studies were found to increase the use of booster seats, compared to the group receiving no intervention. The distribution of free booster seats combined with education on their use, had a marked beneficial effect, as did incentives (for example, booster seat discount coupons or gift certificates) combined with education. Education‐only interventions also produced beneficial outcomes. One of the studies evaluated the effectiveness of the enforcement of a booster seat law, but did not detect an effect on usage.

The authors concluded that the current evidence suggests that several types of interventions aimed at increasing the use of booster seats among children aged four to eight years, are effective. However, there is still a need for further high quality trials, especially those conducted outside of the USA and Australia, where current research dominates. (Full text)

Interventions in the alcohol server setting for preventing injuries

Katharine Ker, Paul Chinnock

Injuries are a significant public health burden and alcohol intoxication (i.e. drunkenness) is recognised as a risk factor for injuries; indeed the effects of alcohol lead to a considerable proportion of all injuries. Alcohol‐associated injuries are a problem in both high‐ and low‐income countries.

Many interventions to reduce alcohol‐related injuries have a demand‐side focus and aim to reduce individuals' demand and consequently consumption of alcohol. However, there is increasing attention on supply‐side interventions, which attempt to alter the environment and context within which alcohol is supplied and consumed; the aim being to modify the drinking and/or the drinking environment so that potential harm is minimised.

This systematic review was conducted to examine the evidence for the effectiveness of interventions implemented in the alcohol server setting for reducing injuries. The authors of this systematic review examined all studies that compared server settings which received an intervention aimed at facilitating sensible alcohol consumption and/or preventing injuries, to server settings which did not receive such an intervention.

The authors found 23 studies; only five of these measured the effect on injury, the remaining 18 measured the effect on behaviour (by the patrons and/or the servers of the alcohol within the premises). The studies investigated a range of interventions involving server training, health promotion initiatives, a drink driving service, a policy intervention and interventions that targeted the server setting environment.

The authors concluded that there is insufficient high quality evidence that interventions in the alcohol server setting are effective in preventing injuries. The evidence for the effectiveness of the interventions on patron alcohol consumption was found to be inconclusive. There is conflicting evidence as to whether server behaviour is improved and it is difficult to predict what effect this might have on actual injury risk.

Lack of compliance with interventions seems to be a particular problem; hence mandated interventions or those with associated incentives for compliance, may be more likely to show an effect. The methodology of future evaluations needs to be improved. The focus of research should be broadened to investigate the effectiveness of interventions other than server training, where previous research dominates. When the collection of injury outcome data is not feasible, research is needed to identify the most useful proxy indicators. (Full text)

Motorcycle rider training for the prevention of road traffic crashes

Katina Kardamanidis, Alexandra Martiniuk, Rebecca Q Ivers, Mark R Stevenson, Katrina Thistlethwaite

Riders of motorcycles (a two‐wheeled vehicle that is powered by a motor and has no pedals ‐ Oxford English Dictionary Online), especially novice riders, have an increased risk of being involved in fatal crashes compared to other road users. Motorcycle rider training could be an important way of reducing the number of crashes and the severity of injuries.

The authors of this review examined all research studies that report an evaluation of the effectiveness of motorcycle rider courses in reducing the number of traffic offences, motorcycle rider crashes, injuries and deaths. This review included 23 research studies, including three randomised trials, two non‐randomised trials, 14 cohort studies and four case‐control studies. The types of rider training that were evaluated varied in content and duration. The findings suggest that mandatory pre‐licence training may present a barrier to completing a motorcycle licensing process, thus possibly indirectly reducing crash, injury, death and offence rates through a reduction in exposure to riding a motorcycle. However, on the basis of the existing evidence, it is not clear if (or what type of) training reduces the risk of crashes, injuries, deaths or offences in motorcyclists and the selection of the best rider training practice can therefore not be recommended.

It is likely that some type of rider training is necessary to teach motorcyclists basic motorcycle handling techniques and to ride a motorcycle safely. It is therefore important that further research work be conducted to rigorously evaluate motorcycle rider training courses, particularly in low income countries where the main burden of motorcycle injuries and deaths occur. (Full text)

Non‐legislative interventions for the promotion of cycle helmet wearing by children

Rachel Owen, Denise Kendrick, Caroline Mulvaney, Tim Coleman, Simon Royal

Many children suffer head injuries while riding a bike. This review focused on encouraging children to wear helmets, as distinct from compelling them to do so through laws. The authors wanted to find out which sort of helmet programmes work best, particularly with children from poor families who are less likely to own helmets. They found 29 helmet promotion programmes that had been studied. The programmes varied widely with regard to where they were carried out, age of the children, programme methods, etc. The results were also very varied but overall 11 studies found that after a helmet programme children were more likely to be observed wearing helmets than other children. More research is still needed but it seems likely that the best schemes are based in the community and involve both education and providing free helmets. Promotion of helmets in schools also seems to be effective. Promoting helmets appears to be more effective for younger children (aged 12 years and under) than for older children and young people. The studies reviewed did not look at the impact of helmet programmes on injury rates, or assess whether programmes had any negative effects such as reducing cycling. Most of the studies were undertaken in higher‐income countries and the additional effect of helmet promotion above existing legislation was not explored. More research is needed to understand more about whether providing subsidised helmets is as effective as providing free helmets and whether programmes in healthcare settings are as effective as those in schools or communities. Other types of helmet programmes (e.g. those including peer educators, those developing skills such as decision making and resisting peer pressure, or improving self esteem or self efficacy) need developing and testing, particularly for 11 to 18 year olds. The effect of helmet programmes in countries with existing cycle helmet legislation and in low and middle‐income countries also requires investigation. (Full text)

Post‐licence driver education for the prevention of road traffic crashes

Katharine Ker, Ian G Roberts, Timothy Collier, Fiona R Beyer, Frances Bunn, Chris Frost

Road traffic crashes are a major cause of death and injury worldwide. As drivers' errors are a factor often contributing to traffic crashes, driver education is often used in the belief that this makes drivers safer. Driver education for licensed drivers can be remedial programmes for those with poor driving records, or advanced courses for drivers generally. They can be offered by correspondence, in groups or with individualised training. The review of trials found strong evidence that no type of driver education for licensed drivers leads to a reduction in traffic crashes or injuries.(Full text)

Red‐light cameras for the prevention of road traffic crashes

Amy Aeron‐Thomas, Stephane Hesst

Road crashes are a leading cause of death and injury. One common place for these to happen is at junctions (intersections) controlled by traffic signals. 'Red‐light cameras' are now widely used to identify drivers that jump ('run') red lights, who can then be prosecuted. This review looked for studies of their effectiveness in reducing the number of times that drivers drive through red lights and the number of crashes. Very little research has been done and much of it has not allowed for the statistical problems that occur when recording this kind of information. However, five studies in Australia, Singapore and the USA all found that use of red‐light cameras cut the number of crashes in which there were injuries. In the best conducted of these studies, the reduction was nearly 30%. More research is needed to determine best practice for red‐light camera programmes, including how camera sites are selected, signing policies, publicity programmes and penalties. (Full text)

Safety education of pedestrians for injury prevention

Olivier Duperrex, Ian Roberts, Frances Bunn

A major proportion of the people killed or seriously injured in road traffic crashes are pedestrians, and children are particularly vulnerable. Education programmes try to teach people how to cope with the road environment. Parents are sometimes used as educators. The review of trials (mostly in children) found that pedestrian safety education can improve children's road safety knowledge and their observed road crossing behaviour. Education may need to be repeated at regular intervals, as the effect can decline with time. However, whether these changes to knowledge or behaviour can be linked to a reduction in pedestrian deaths and injuries is unknown. (Full text)

School‐based driver education for the prevention of traffic crashes

Ian G Roberts, Irene Kwan

Teenagers have a higher risk of road death and serious injury than any other group. School based driver education has been promoted as a strategy to reduce the number of road crashes involving teenagers. The results of this systematic review show that driver education in schools leads to early licensing. They provide no evidence that driver education reduces road crash involvement, and suggest that it may lead to a modest but potentially important increase in the proportion of teenagers involved in traffic crashes. (Full text)

Speed cameras for the prevention of road traffic injuries and deaths

Cecilia Wilson, Charlene Willis, Joan K Hendrikz, Robyne Le Brocque, Nicholas Bellamy

Road traffic crashes are a major cause of death and disability. The speed at which a vehicle travels is an important determinant of injury; the faster the vehicle is travelling, the greater the energy inflicted on the occupants during a crash, and the greater the injury.


Excessive speed (driving faster than the posted limit or too fast for the prevailing conditions) has been found to contribute to a substantial number of crashes. It is predicted that, if the number of speeding drivers is reduced, both the likelihood and severity of a crash will be lowered. Therefore, interventions aimed at reducing traffic speed are considered essential to preventing road injuries and deaths. The enforcement of safe speeds with speed cameras and associated automated devices is one such measure.

To evaluate the effectiveness of speed cameras, the authors examined all eligible studies, that is, studies that met pre‐set standard criteria. We analysed the effect of speed cameras on speeding, road traffic crashes, injuries and deaths by comparing what was happening in road areas before the introduction of speed cameras and after their introduction, and also by analysing what was happening in comparable road areas where no speed cameras were introduced during the study period.

The authors accepted a total of 35 studies for review which met the pre‐set criteria. All studies reporting speed outcomes reported a reduction in average speeds post intervention with speed cameras. Speed was also reported as either reductions in the percentage of speeding vehicles (drivers), as percentage speeding reductions over various speed limits, or as reductions in percentages of top end speeders. A reduction in the proportion of speeding vehicles (drivers) over the accepted posted speed limit, ranged from 8% to 70% with most countries reporting reductions in the 10 to 35% range.


Twenty eight studies measured the effect on crashes. All 28 studies found a lower number of crashes in the speed camera areas after implementation of the program. In the vicinity of camera sites, the reductions ranged from 8% to 49% for all crashes, with reductions for most studies in the 14% to 25% range. For injury crashes the decrease ranged between 8% to 50% and for crashes resulting in fatalities or serious injuries the reductions were in the range of 11% to 44%. Effects over wider areas showed reductions for all crashes ranging from 9% to 35%, with most studies reporting reductions in the 11% to to 27% range. For crashes resulting in death or serious injury reductions ranged from 17% to 58%, with most studies reporting this result in the 30% to 40% reduction range. The studies of longer duration showed that these positive trends were either maintained or improved with time.


The quality of the included studies in this review was judged as being of overall moderate quality at best, however, the consistency of reported positive reductions in speed and crash results across all studies show that speed cameras are a worthwhile intervention for reducing the number of road traffic injuries and deaths. To affirm this finding, higher quality studies, using well designed controlled trials where possible, and studies conducted over adequate length of time (including lengthy follow‐up periods) with sufficient data collection points, both before and after the implementation of speed cameras, are needed. As none of the studies were conducted in low‐income countries, research in such settings is also required. There is a greater need for consistency in methods, such as international standards for the collection and reporting of speed and crash data and agreed methods for controlling bias in studies. This would allow more reliable study comparisons across countries, and therefore greater ability to provide stronger scientific evidence for the beneficial effects of speed cameras. (Full text)

Street lighting for preventing road traffic injuries

Fiona R Beyer, Katharine Ker

Road traffic crashes are a major cause of death and injury, especially in low and middle‐income countries. Worldwide, each year over a million people are killed and some ten million people are permanently disabled in road traffic crashes. Furthermore, it is estimated that road traffic injuries will have risen from ninth to third in world disease burden rankings by 2020, and will account for 2.3 million deaths each year globally.

Street lighting has been suggested as a relatively low‐cost intervention with the potential to prevent traffic crashes. Street lighting may improve a driver's visual capabilities and ability to detect roadway hazards. However, it is also argued that street lighting could have an adverse effect on road safety; drivers may 'feel' safer because lighting gives them improved visibility which could result in them increasing speed and reducing concentration.

This systematic review was conducted to assess how street lighting affects the occurrence of road traffic crashes and associated injuries. The authors searched for all controlled trials comparing the effects of new street lighting with unlit roads, or improved street lighting with the pre‐existing lighting level. They found 17 controlled before‐after studies, all of which were conducted in high‐income countries. Twelve studies investigated the effects of newly installed street lighting, four the effects of improved lighting and one investigated both new and improved lighting. Five of the studies compared the effects of street lighting with a separate area control, while the remaining 12 used data from a day‐time control. The authors were able to pool crash or injury data from 15 of the studies. The risk of bias in these studies was judged to be high.

The results indicate that street lighting can prevent road traffic crashes, injuries and fatalities. This finding might be of particular interest to low and middle‐income countries where the policy on street lighting is less developed and the installation of suitable lighting systems is less common than in high‐income countries. However, further well designed studies are needed to determine the effectiveness of street lighting in middle and low‐income countries. (Full text)

Topical application of tranexamic acid for the reduction of bleeding

Katharine Ker, Deirdre Beecher, Ian Roberts

We will present the main results of the review in a ‘Summary of findings’ table.  We will include the following outcomes:

  • Blood loss;

  • Death;

  • Myocardial infarction;

  • Stroke;

  • Deep vein thrombosis;

  • Pulmonary embolism;

  • Receipt of blood transfusion.;

We will use GRADE pro software to prepare the summary of findings table. We will judge the overall quality of the evidence for each outcome as ‘high’, ‘moderate’, ‘low’ or ‘very low’ according to the GRADE approach (Schünemann 2011). We will consider the following:

  • Impact of risk of bias of individual trials;

  • Precision of pooled estimate;

  • Inconsistency or heterogeneity (clinical, methodological and statistical);

  • Indirectness of evidence;

  • Impact of selective reporting and publication bias on effect estimate.

(Full text)

Tranexamic acid for reducing mortality in emergency and urgent surgery

Pablo Perel, Katharine Ker, Carlos Hernando Morales Uribe, Ian Roberts

Emergency or urgent surgery, which can be defined as surgery which must be done promptly to save life, limb, or functional capacity, is associated with a high risk of bleeding and death. Antifibrinolytic drugs, such as tranexamic acid, promote blood clotting by preventing blood clots from breaking down. Previous studies have shown that this drug reduces the need for blood transfusion in patients undergoing elective surgery. The authors of this review searched for randomised controlled trials assessing the effects of tranexamic acid in patients undergoing urgent or emergency surgery.​

The results of this review show that tranexamic acid reduces the probability that a patient will receive a blood transfusion by around 30%. The effect of tranexamic acid on other important outcomes, such as death, remains uncertain. The authors conclude that larger studies should be done to assess the effects of tranexamic acid on relevant outcomes such as death in patients undergoing all types of emergency and urgent surgery. (Full text)

Vision screening of older drivers for preventing road traffic injuries and fatalities

EdiriweeraDesapriya, RahanaHarjee, Jeffrey Brubacher, Herbert Chan, D SesathHewapathirane, Sayed Subzwari, Ian Pike

Good vision is critical for safe driving performance. Because vision declines with age, and the percentage of older adults in the population is increasing, it has become more important to consider the vision screening requirements for older adults when designing evidence‐based traffic safety policy. Mandatory vision screening for the issue or renewal of a driver's licence helps to ensure that older drivers are fit to safely operate vehicles.To date, there has been no trial to demonstrate the impact of vision screening on the prevention of older driver‐related crashes. However, given the importance of good vision for safe driving, vision testing remains a relevant issue for all licensed drivers. (Full text)

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