As is the case for car and truck drivers, accidents involving motorized and non-motorized two-wheeled vehicles are caused to a large extent by a lack of risk awareness, disregard for traffic rules, excessive speed, driving under the influence of alcohol, distraction and a lack of consideration for other road users. This should not be the case. Responsible behavior, interaction and communication with other road users, as well as the correct assessment of one's own abilities and appropriate training, are effective ways of counteracting this risk.

The facts and figures mentioned in the chapter "Accidents" have already made it clear that human error in road traffic is a major risk factor, especially for motorized and non-motorized two-wheeled vehicles. For example, in Germany in 2018, according to the Federal Statistical Office, "incorrect road use" among cyclists led to almost 12.500 accidents with personal injury, motorcyclists and users of motorcycles with insurance license plates (mopeds, pedelecs, and three- and light four-wheeled vehicles) were dominated by "inappropriate speed" (around 6,700 accidents with personal injury).600 and just under 1.700 accidents with personal injury). Other common types of misconduct include driving under the influence of alcohol, disregarding the right of way/priority, insufficient distance, risky overtaking maneuvers, and errors when turning, turning, reversing, or driving in and out of traffic.
In this context, it is also interesting to note a calculation by the Allianz Center for Technology on the main causes of accidents with personal injury by type of road user in Germany from 1991 to 2018. This shows that the number of cyclists as the main cause of accidents has gone up by just under 30 percent in the aforementioned period – from just under 33.000 in 1991 to around 42.550 in 2018. Since 2013 in particular, the percentage has risen constantly and in some cases sharply – although it must be taken into account that the absolute number of people who cycle and also the total mileage have also increased continuously over the years. In the case of car drivers as the main cause of accidents with personal injury, there has been a decline of almost 25 percent in the period mentioned – from around 273.500 to circa 206.000.
INTERACTION INCREASES SAFETY.
CAR DRIVERS AND CYCLISTS – TWO DIFFERENT SPECIES?
Whether motorcycle, bicycle or pedelec riders or users of e-scooters and pedal scooters: For each of these rider groups, interaction and communication with other road users are key safety factors, sometimes even vital for survival. This is especially true for the understanding between two-wheeled and car drivers. Research findings on this point to diverse communication patterns that on the one hand increase road safety, but on the other hand can also have an escalating effect. The latter often occurs when emotional components such as anger and rage come to the forefront.
The fact is: With increasing acceptance and spread of bicycles as an everyday means of transport, people who previously preferred cars are also switching to bicycles more frequently. The type of traffic participation often depends on the situation; for example, the length and quality of the route or the current traffic situation play a role here. When changing the means of transport, there is inevitably also a change in the perception and evaluation of traffic situations. This individual change of perspective can support the learning of safe interaction patterns between car drivers and cyclists.
CHANGING THE MODE OF TRANSPORT MEANS AT THE SAME TIME CHANGING THE PERCEPTION AND EVALUATION OF TRAFFIC SITUATIONS.
In this context, the result of a study commissioned by Ford as part of its 2018 "Share the Road" campaign is exciting: The study found that the use of different modes of transportation influences perception. Round 2.000 people from Germany, France, Italy, Spain and Great Britain were asked to recognize and differentiate between images under laboratory conditions. The results showed that car drivers who also ride bicycles have a better situational awareness. In 100 percent of the scenarios shown, they were faster at identifying the images and also detecting changes between two images.
According to a study by Rowden, P. et. al. (2016), it can be assumed in principle that many drivers behave in a more rule-abiding manner when they are traveling by car than by bicycle. This may be due to the fact that cyclists consider themselves to be less dangerous than car drivers and therefore do not perceive their own violations of the rules to be as serious. To compare the natural riding behavior of drivers of different bicycle classes (bicycles and pedelecs), von Schleinitz, K. et al. (2016) collected data from real-life situations for a study. The participants used their own bicycles, which were equipped with measuring devices and cameras. The report analyzes, among other things, rule violations by cyclists such as disobeying red lights.
BY CAR, MANY DRIVERS BEHAVE IN A MORE RULE-ABIDING MANNER THAN BY BICYCLE.
The study showed that in order to avoid stopping at red lights, violations were committed in more than 20 percent of the situations, with no significant differences in terms of bicycle type. Frequently observed, for example, was a direct crossing of the red light without stopping, or a brief stop in order to cross the intersection at the red light after all. Especially when turning right, an above-average number of cyclists failed to observe the red light. Red light violations were observed especially at so-called T-intersections, which indicates that violations occur preferentially in easily manageable situations. The reasons given for breaking the rules were, in particular, the desire to maintain speed, but also to shorten the route.
In addition to red light violations, there was also an increase in violations related to the use of infrastructure. Bicycle and pedelec riders often used footpaths in violation of the rules. Due to the high number of violations, it seems reasonable to strive for stronger monitoring and punishment of cyclists overall, which should include follow-up training among other things. In any case, the punishment of a behavior-related offense should always include a check of the vehicle for compliance and road safety.
COMMUNICATION CONFLICTS JEOPARDIZE ROAD SAFETY
A particular threat to road safety is developing communication conflicts between cyclists and motorists. They mainly result from behavior that is experienced as inappropriate or even judged as aggressive by the respective other road user group. For example, aggressive behavior among cyclists is often observed as a reaction to motor vehicle driving maneuvers perceived as risky. The same applies vice versa. Parking in bike lanes, overtaking too closely or carelessly opening car doors are also often seen by cyclists as deliberate provocation.
In general, bicyclists are viewed by many motorists as "outgroup" (Walker et al. (2007)) perceived not to be riding on the street. Rejection or even aggressiveness here is the result of the perception of the bicyclist as an "intruder" and the resulting emotional stress. This perception is more common in countries with a lower proportion of cyclists and poorly developed bicycle infrastructure. Bicyclists and motorists show different reactions to stressful situations, with bicyclists tending to avoid overt conflict and motorists being more confrontational. This can also be interpreted as a consequence of the different perceived levels of subjective safety.
A study by Heesch, K. C. (2011) addresses bicyclists' experiences of harassment or coercion by motorists. Responding to an online survey conducted by Bicycle Queensland, an organization that promotes bicycle use, 1.830 participants. Overall, 76 percent of men and 72 percent of women reported harassment or coercion, respectively, by drivers on the road in the previous 12 months. The most frequently cited forms included: tailgating (66 percent), insults (63 percent), and sexual harassment (45 percent). The likelihood of being exposed to such behaviors depends on factors such as age, body weight, bicycling experience/frequency, and location of travel. Young to middle-aged riders with more riding experience seem to be more affected by this than older riders. The same is true, according to the aforementioned survey, for cyclists riding on the road in competitive mode or purely for fun, as well as for cyclists riding in more affluent neighborhoods.
The fear of such harassment is a barrier for people who would like to ride a bike, but do not yet implement it. A starting point to counteract this would be campaigns that should draw attention to appropriate riding behavior and also point out which traffic rules exist and, above all, emphasize the rights of bicyclists on the road. Another approach would be to use driver education to raise awareness among motorists about the diversity of road users and particular aspects of danger and safety needs.
INTERACTION IS THE BE-ALL AND END-ALL FOR FEWER ACCIDENTS
A study by Walker, I. et al. (2007) found that when drivers come into contact with cyclists, they focus their gaze primarily on their faces. Although they also use gestures of the cyclist, such as extending the arm to indicate the desire to turn, to decipher the intention and further course of cyclists, the cyclist's face is fixed first and for the longest time. This tendency was evident regardless of the subject's gender and experience, and was further exacerbated when the bicyclist appeared to be looking at the subject. Results indicate that social cognitions are addressed in interactions with bicyclists. The tendency to fixate the face during a social interaction can be explained in evolutionary psychological terms by the fact that a person's appearance and facial expressions can provide his or her counterpart with a great deal of information about the person's intentions and characteristics. However, the presence of cues by line of sight and face often had a confusing effect on motorists and lengthened their reaction time when interacting with bicyclists and other vulnerable road users. However, since facial fixation is not triggered as a reflex, there is an opportunity to mitigate this tendency through training or education efforts.
When clear formal information such as hand signals was absent, greater attention was directed to the bicycle itself. Previous studies have shown that motorists are also quite good at inferring the intentions of bicyclists from their position on the road. Because many of the communication channels used by bicyclists are informal and thus ambiguous, information about potential communication leaks – such as the fact that motorists often fail to recognize their signs or anticipate their actions – should be increased, especially among young bicyclists. Public information campaigns tailored to safety education of all groups of drivers and their interaction should emphasize communal and social behavior on the road and convey that all road users are equally legitimized to use the public space.
THE PUBLIC STREET SPACE IS THERE FOR EVERYONE.
Walker and his research colleagues also pointed out the effect of several other factors on road user behavior. The study shows that riding position, helmet use, bicycle type, and the gender of bicyclists have an impact on how they pass motorists, as different characteristics are attributed to bicyclists based on these characteristics. The farther from the curb a bicyclist rides, the less space he or she is given by motorists. In summary, motorists were found to give cyclists less space when they were wearing helmets, riding further down the center of the road, were male, and when the person overtaking was a bus/truck driver. This indicates that these drivers usually follow a certain path when overtaking, which is hardly influenced by the cyclist's position. However, it is not necessarily safer for cyclists to ride closer to the edge of the road, where other factors such as drainage grates or parked vehicles can be risk factors. In particular, it is more unsafe for cyclists to ride close to the edge of the road in intersections, as drivers of motorized vehicles largely focus on the area around the center of the road when observing traffic and thus easily overlook cyclists.
The finding that bicyclists wearing helmets are given less space suggests that they are perceived as safer and more protected from serious crash damage. This leads to the fact that car drivers do not consider a closer overtaking as risky as when a cyclist is not wearing a helmet. Greater passing distances were evident when a bicyclist was perceived to be female, possibly because female bicyclists are perceived to be more unpredictable or more easily vulnerable. While each of the studies highlights a specific region, riding behavior depends on many factors, including factors that vary by region. Nevertheless, these points make it clear that drivers of motorized vehicles adapt their overtaking behavior to the perceived characteristics of bicyclists and do not have an independent overtaking scheme for bicyclists as a group.
INTERACTION OF DRIVING BEHAVIOR WITH TECHNOLOGY AND INFRASTRUCTURE
In addition to the characteristics of cyclists, the type of vehicle used by those overtaking also played a role. Here, buses and heavy-duty trucks were the vehicles that overtook significantly closer. This can probably be attributed to the fact that these vehicles, due to their dimensions and slow acceleration, take longer to complete the overtaking process, as well as would have to swerve more strongly into the other lane than smaller vehicles. Since long gaps in oncoming traffic are rarer, overtaking is done closer to the cyclist. In addition, a potential hazard arises from the fact that bicyclists are not visible to drivers of large vehicles throughout the overtaking process, which results in a greater tendency to revert to the original lane position even though the bicyclist is still next to the vehicle. This example makes it particularly clear that the construction of separate bike lanes is essential for increasing the safety of cyclists.
Horswill, M. S. et al. (2015) go into more detail about the interaction of driving behavior with technology and infrastructure in their study. In general, an expansion of the bicycle network leads to a reduction in mileage-related accidents. If the bicycle infrastructure enables a safe separation of cyclists from fast motorized traffic, this increases the safety of cyclists. This effect can be observed particularly strongly at intersections, where, on the other hand, infrastructural separation proves to be especially difficult. Increased security leads then again to a higher number of wheel users. In addition to changes in bicycle infrastructure, measures that improve the clarity of road traffic are also useful, so that vulnerable road users such as pedestrians and cyclists are not so easily overlooked. Supportive of this can also be driver assistance features in the motorized vehicle that help notice bicyclists and pedestrians. Even though cyclists, at least in Germany, are generally not allowed to ride on the sidewalk: Measures such as restricting or prohibiting parking on sidewalks and imposing stronger sanctions for non-compliance with this prohibition would also be effective in increasing the visibility of two-wheeled cyclists.
Hamilton-Baillie, B. et al (2008) have also looked at communication behavior between different groups of road users and present the concept of "Shared Space". This is about integrating road users in one place without sacrificing safety, mobility or accessibility. In particular, an increase in traffic safety is to be achieved through mutual consideration, with communication between each other playing the central and overriding role, since all road users have equal rights. The design features include the mixing principle of all road users and thus also an extensive renunciation of signage and demarcations, since all road users follow implicit rules. The principle is not new at all, but is practiced in different cities since several decades. Positive examples of the application of the concept are, for example, the Laweiplein intersection in Drachten (Netherlands) or Blackett Street in Newcastle (England).
Typical design approaches for Shared Spaces include creating levelness so that pedestrians and users of motorized and non-motorized transportation interact on one level and the traffic space appears cohesive and coherent, and subtle markings that indicate where the respective separations are located. Removing most of the signage and traffic lights encourages organic communication and reduces speeds. Usually, shared space represents a successful restructuring of road traffic: There is less congestion and, due to lower speeds, fewer accidents as well as less serious consequences of accidents. It can also be shown that the satisfaction of all road users increases. Before establishing shared space, however, transportation planners should always carefully consider whether it actually makes sense in the desired location.