Working Group 1: In-depth Accident Observations and Injury Statistics

Article Index


According to the recent survey by Working Group 1, most bicyclists in Europe recognise the increased safety of wearing a helmet. However, they provide an extensive list of reasons why they still do not do so, including thermal discomfort. Working Group 2 found similar results in their survey.
In addition, the lack of sufficient and consistent data about cycling accidents in different European countries makes it difficult to pinpoint exactly how beneficial bicycle helmets are, or how effective they are in preventing serious injury. In an attempt to collect and expand Europe-wide research on this topic, and provide recommendations for further improvements, Working Group 1 examined injury data from 20 European countries, conducted accident research and performed field studies of cyclists’ attitudes and behaviours regarding helmet usage. The primary goal was to offer advice and insight into improvements still yet to be made on a European level to make cycling even safer.

Starting with publications from the International Traffic Safety Data and Analysis Group (IRTAD), the Citizens Consular Assistance Regulation in Europe (CARE) and the European Road Safety Observatory (ERSO), Working Group 1 assembled as much data as was available. In particular, ERSO’s annual statistics reports, DaCoTa, provided data up to and including 2010. The largest German In-depth Accident Study Report (GIDAS) was also analysed, as it provided information on helmet efficacy in regard to head injury. Further research and field studies were then conducted to provide insight and information that could propel helmet safety standards to higher levels, and encourage helmet usage among cyclists.

Working Group Focus

In relation to COST Action TU1101, the primary focus of Working Group 1 was to:

  • Provide a report on Europe-wide bicyclist injuries in traffic accidents, with a focus on helmet usage;
  • Conduct an in-depth analysis of head injuries, and the effectiveness of bicycle helmets in real accident situations;
  • Examine the habits of cyclists in regard to helmet usage, with a particular focus on comfort, temperature and adjustments for climate;
  • Identify the influences of seating geometry, posture and helmet position on bicycle safety.

Overall Result

The primary conclusion of this Working Group is that the full potential of bicycle helmets has not yet been fully exhausted. In fact, helmets could even provide additional benefits, when protection is extended further on the lateral side. This extension to helmet protection has shown to be useful in preventing or reducing severe head injury.

Working Group 1 is confident in its recommendation that increased usage of bicycle helmets can reduce the number and severity of head injuries. In addition, the Working Group recommends the optimisation of helmet design as a means of providing more head protection upon bicycle accident impact. Furthermore, additional design modifications, based upon real accident data, can help improve overall protection factors. While literature varies on the overall effectiveness of bicycle helmets, the inconsistent usage and lack of data mean that absolute conclusions cannot yet be drawn about the overall impact of bicycle helmets on safety.

In addition, Working Group 1’s output indicates that design improvements and regulatory changes that focus on specific bicycle types (city bikes, racing bikes, mountain bike, e-bikes, etc.) can positively influence accident outcomes. Safety factors can also be increased when the helmet is properly positioned on the head, and when helmets are customised to fit the specific needs of different cyclists. Depending upon the type of bicycle used, the cyclists’ upper body is in a more upright or forward-leaning position. If the cyclist adjusts the position of the helmet to accommodate these different positions, he can strongly improve his visual acuity. Improvements here can also contribute to an optimised helmet position in the event of impact with the road or a vehicle.

Implications for Industry

Helmet design can have a tremendous impact on the prevention of bicyclist injuries or the reduction of their severity. In particular, the optimisation of helmet design on the lateral part of the helmet, and modification of the helmet standards set forth in CEN EN 1078 guidelines can improve protection zone and impact conditions, based on data gathered from actual accidents.

Furthermore, both helmet design and usage guidelines should be adjusted according to the types of bicycles (city bikes, mountain bikes, racing bikes, touring bikes, e-bikes, etc.), and clarity about the best helmet position and cyclist posture can also have a positive affect on overall bicyclist safety. This can lead to improved helmet usage amongst cyclists with these specific types of bicycles.

Implications for Legislators

One of the key implications for legislators in regard to Working Group 1’s investigations was the call for a more centralised, accurate and comprehensive reporting structure for bicycle-related accidents and injuries. Each country examined had different levels of reporting available (some none at all) and data was retrieved from a variety of sources. A more effective reporting structure for bicycle and helmet use, and the monitoring of data from hospitals, government and infrastructure, as well as the standardisation of injury severity measurements, would provide a better overall view of the European challenges and opportunities for cyclists. Moreover, statistical reliability and consistency could be greatly improved if police reports at the scene of bicycle accidents also included accurate injury data.

In addition, as the output of the investigation clearly indicates that the number and severity of head injuries are reduced by helmet usage, legislators should take this all-important factor into consideration in any discussion of helmet legislation.

Report on Europe-wide Bicyclist Injuries in Traffic Accidents, with a Focus on Helmet Usage

Although the amount and quality of bicycle-related accident data varies greatly per country, Working Group 1 was able to draw a number of important conclusions. Using DaCoTa Fact Sheets to assemble data up to and including 2012, it appears that cyclists represent about 5% of all fatalities in IRTAD countries, and the trend has been increasing since 2010. In the 20 EU countries covered by the data, bicycle fatalities made up about 6.8% of the total road accident fatalities reported.

In general, cyclist fatalities decreased between 2001 and 2010, but statistics vary greatly from country to country. For example, the fatality rate for cyclists in Ireland is about one per every one million inhabitants, while in the Netherlands, Romania and Hungary, about eight out of every one million inhabitants dies in a bicycle accident. In Denmark, an estimated 75% of cyclist fatalities occur in urban areas, while in Spain, only 26% of fatalities take place in urban settings. Obviously, exposure (time spent bicycling or distance covered by the bicycle) plays a key role in this. Working Group 2 quantified these factors for the first time for many countries.

The severity of non-fatal injuries is also difficult to pinpoint, as different countries have different definitions of what constitutes a ‘slight’ or ‘severe’ injury. In addition, the usage of helmets also varies greatly per country, with 3% of cyclists using them in Italy, as compared to more than 50% in Norway. The highest helmet usage rates can typically be found amongst children, as several countries have mandatory helmet usage laws in place for young bicyclists. However, other countries have stated that they do not intend to enact helmet mandates, because doing so might lead to a reduction in cycling activities.

Bicycling and alcohol consumption

An in-depth study in Germany measured the effect that alcohol consumption can have on both the perception and outcome of bicycle accidents. Alcohol has been tied directly to both an increase in cyclists’ fault for traffic accidents, and the decrease in helmet usage rates. Cyclists who had consumed alcohol were less likely to wear a helmet. Cyclists who were not deemed responsible for an accident were also less likely to have consumed alcohol than those who were held partially responsible for accidents. Overall, the greatest risk of head injury did not occur in collisions with other vehicles, but rather in accidents related to falls.

Accidents among e-bikers in Switzerland

Accident investigation of the users of electronic bicycles (e-bikes) in Switzerland shows that e-bikers who were involved in accidents tended to be older than most bicyclists involved in accidents. The investigation also indicates that e-bikers tended to be involved in accidents that did not involve collision with another vehicle. It was also concluded that both bicyclists and riders of e-bikes over the age of 40 are at a higher risks of sustaining severe injuries in an accident than bicyclists and e-bikers aged 39 and younger.

In-depth Analysis of Head Injuries, and the Effectiveness of Bicycle Helmets in Real Accident Situations

WG1 figure 17

Percentage distribution of the collision partners of injured cyclists with and without helmet.

In Germany, a database of head injuries sustained in accidents, the German In-depth Accident Study (GIDAS), revealed that overall, helmet usage rates are increasing in Germany. However, the number of cyclists who currently wear a helmet is about 10% - still extremely low.
However, the GIDAS study also shows a strong tie between helmet usage and the reduction in both the frequency and severity of head injuries. Helmets provide a significant protection against skull fractures, severe brain injuries, and skull base fractures alike. About 40% of cyclists who did not wear a helmet suffered head injuries as the result of accidents. In 13% of those cases, the head was the only body part to be injured, and in 23% of cases, the head was the most severe of injuries sustained to multiple body parts.

Bicycle helmets can also be considered to be particularly effective for older adults, especially those over 50 years of age. In this age group, a significant increase in severe head injuries could be observed, attributed to the much lower biomechanical load limits for older persons.

Helmets and facial injuries

Since the lower parts of the face are not included as part of the helmet protection area of the head, the use of helmets had virtually no influence on facial fracture statistics. Scientific literature also does not indicate a reduction in facial injury through the use of helmets. However, the use of helmets did show protective effects for the upper and middle parts of the face, due to the protruding frontal part of the helmet structure. And of course, helmets are already very beneficial for protection of the head itself.

Optimisation of helmet design based on accident observations

Working Group 1’s investigations showed that optimising helmet design, particularly on the sides and edges of the helmet, could have a positive effect on the reduction of severe injury. In terms of shock absorption, extending the protection zone currently identified in the existing standard CEN EN 1078 would be appropriate. Impacts on the side of the helmet appear to result in greater injury severity than impacts at the top of the helmet. Enlarging the protection zone and optimising helmet design would result in further optimisation of shock absorption capabilities and overall protection, both during impact with flat surfaces, and impact with edgy surfaces, such as collisions with the edgy parts of cars and trucks. However, extending the surface covered by a helmet may also increase (thermal) discomfort. Future efforts should continue the multidisciplinary approach initiated in the present network.

 The Habits of Cyclists in Regard to Helmet Usage

To analyse helmet usage and practices in Europe, Working Group 1 developed a questionnaire to collect relevant information by means of a field study carried out from 2010 to 2014.

Despite some limitations and boundary conditions, the results of the survey did indicate that helmet usage varies, depending upon the country and the type of bicycle. Cyclists in Finland tend to wear helmets more often than in other countries, for example. And those who ride racing bikes are more likely to wear helmets than riders of other types of bikes.

The survey also provided insight into cyclists’ perceived safety. In general, those interviewed thought that riding a bicycle was more dangerous than walking or driving a car, whether cyclists wore a helmet or not.

Cyclists seem to be aware of the dangers of biking in general, and most believe that helmets increase cycling safety even more, and also increase the cyclists’ overall feeling of safety. However, a litany of reasons was given for why bikers nevertheless choose not to wear them. From carelessness to short biking distances, from warm temperatures to inconvenience, bikers tend to go without protective headgear. Even a lack of a place to put the helmet when arriving at their destination was a reason given for not wearing one. Physical complaints like excessive sweating, headaches, or a narrow field of vision were also among the reasons.

Most remarkable from the survey was that 48% of the respondents indicated that they had been involved in a serious fall from a bike, and 26% reported a collision with a car while cycling. Collisions were rarely reported to the police, and primary impact zones were given as the sides and front of the head/helmet. In this way, the survey substantiates the conclusions drawn from earlier research, and supports the recommendation to modify helmet designs to further protect these impact areas.

 The Influences of Seating Geometry, Posture and Helmet Position on Bicycle Safety

In another field study, Working Group 1 took pictures of bicyclists in all age ranges and bicycle types, in order to evaluate posture, head position and helmet position. From these pictures, different angles were identified in order to assess helmet position and body posture while cycling. The incline of the line between the handlebars and the seat can indicate the degree to which the handlebars are raised above the seat. Combining these measurements with an approximation of the cyclist’s age provided data about posture and head positioning.

WG1 figure 36

Establishment of angels relevant for seating geometry and vision limits

Of course, the type of bike had a major influence on handlebar positioning. Racing bikes often have handlebars that rest below the level of the seat, while mountain bikes and city bikes do not. Helmeted riders held their heads slightly lower than those who did not wear a helmet. The limitation of vision, mostly due to the helmets sun shade, varied from 0 degrees (horizontal line from the eye to the sun shade) to 75 degrees upwards. Age appeared to have no impact on posture or head positioning. However, older riders who wore helmets tended to wear them lower on their faces, which could possibly affect vertical vision limitations.

 Further Research

Overall, the studies begun by Working Group 1 in some European countries could be carried out for all of Europe. The primary area in need of further investigation is in the development of a Europe-wide system through which European cycling data, accident information and data about helmet usage could be continuously collected. Such data can be more uniformly, accurately, comprehensively and effectively collected, shared and distributed. Only then can we analyse and interpret Europe-wide data in order to evaluate the true influence of helmets on increasing bicycle safety.

In addition, improvements to helmet design and helmet usage standards, customised for each type of bicycle, can increase helmet effectiveness and the likelihood that cyclists will actually wear protective headgear. Further research can support the need for improved protection zones and side-impact panels.


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