Bicycle helmets – A case of risk compensation?

Several studies have shown that bicycle helmets have the potential of reducing injuries from accidents. Yet, no studies have found good evidence of an injury reducing effect in countries that have introduced bicycle helmet legislation. Two of the most promising explanations for why helmet laws do not work as intended are risk compensation and shifts in the cycle population as a response to the law.The present article investigates whether the lack of effect of helmet wearing laws is due to risk compensation mechanisms or population shifts (i.e. discouraging cyclists with the lowest accident risk, and thereby increasing the overall average risk per cyclist). A random sample of 1504 bicycle owners in Norway responded to a questionnaire on among other things helmet use, bicycle equipment use, accident involvement, cycling behaviour and risk perception. Data were analysed by using structural equation model (SEM). The results show that the cyclist population in Norway can be divided into two sub-populations: one speed-happy group that cycle fast and have lots of cycle equipment including helmets, and one traditional kind of cyclist without much equipment, cycling slowly. With all the limitations that have to be placed on a cross sectional study such as this, the results indicate that at least part of the reason why helmet laws do not appear to be beneficial is that they disproportionately discourage the safest cyclists.     

Cycling strategies of young and older cyclists

This study concentrates on the cycling strategies of older cyclists (54–62 year olds) in comparison to young cyclists (20–30 year olds). While cycling in a safe laboratory set-up, controlled lateral perturbations are applied to the rear of the bicycle. Three possible strategies to keep balance are analysed for a young and older aged group: steering, lateral trunk movement and outward knee movement. Older subjects appear to rely more on knee movement as a control mechanism than young subjects. Furthermore, the frequency domain analysis revealed that the older adults need more effort to counteract high frequency perturbations. Increased inter-individual variation for the older adults subject group suggests that this group can be seen as a transition group in terms of physical fitness. This explains their increased risk in single-sided bicycle accidents (i.e. accidents involving the cyclist only). Therefore, older cyclists could benefit from improving the stability of cycling at lower speeds.     

The perception of bicycle crashes with and without motor vehicles: Which crash types do older and middle-aged cyclists fear most?

Several studies have focused on the perceived risk of bicycle crashes (irrespective of crash types) and concluded that cycling near high volumes of motor vehicles deters people from cycling. The perceived risk of bicycle crash types (with or without motor vehicles) has not yet been studied. Cyclists, both in countries with low and high levels of cycling participation, are substantially more likely to sustain severe injuries in single-bicycle crashes than in bicycle-motor vehicle crashes. This questionnaire study sets out to compare which bicycle crash types are perceived to cause most hospitalizations among cyclists. The study comprised cyclists over 55 years in the Netherlands, and over 40 years in the Belgian regions of Flanders (a region with high cycling participation), Brussels and Wallonia (regions with low cycling participation). The majority of cyclists (60%) perceive bicycle-motor vehicle crashes cause most hospitalizations among cyclists. This percentage is greatest in the areas of Brussels and Wallonia and lowest in the Netherlands. Cyclists who were involved in a bicycle-motor vehicle crash themselves are more likely to regard this crash type as the most common cause of hospitalizations among cyclists, while cyclists over 60 years who were involved in a crash without a motor vehicle are more likely to perceive that crash type as the most common cause. The smaller perception bias in the study areas with higher cycling participation – particularly the Netherlands and to a somewhat lesser degree Flanders – is probably due to bicycle infrastructure being more separated from high-speed motor traffic, leaving cyclists less exposed. The outcomes show that cyclists underestimate the likelihood of severe injuries due to single-bicycle crashes. New interventions should raise the awareness of the risk of single-bicycle crashes and provide solutions to avoid such crashes.     

Cyclist strategies and behaviour at intersections. Conscious and un-conscious strategies regarding positioning

Severe and even fatal accidents between cyclists and motor vehicles commonly occur at intersections. Many of these accidents occur with right-turning vehicles, with drivers not observing an adjacent cyclist. Few structured investigations exist regarding the interaction between cyclist and motor vehicle, and factors in need of study are how infrastructure and vehicle properties affect human decision-making and cycling behaviour. Therefore, a bicycle simulator study was performed, where vehicle type, presence of lane markings and lane width were systematically varied in a scenario with a cyclist approaching a vehicle from behind, at a signalized city intersection. 33 participants cycled through 8 intersection variants each. Data on cycling trajectories, stopping points and speed was coupled with survey data from the participants, and semantically categorized verbal responses to questions regarding strategy for choice of stopping point. Results show that all three factors (vehicle type, lane markings and available vehicle-adjacent space) significantly affects cyclists’ behaviour and conscious strategies. Participants were more cautious in the presence of a truck than a car, reflected in choice of position when cycling and stopping, and in explicit verbalisations regarding perilous aspects of the situation and their conscious and strategic choice of positioning. Available lateral space also affected stop positions and feeling of safety (expressed verbally). Presence of bicycle lane markings made the cyclists inclined to continue into the space to the right of the vehicle. This was revealed by their positioning and speed, and also apparent in the verbal expressions, especially the positive remarks on the situation and conditions. However, the perceived comfort with lane markings present was actually lower than when they were missing. Cyclist type (slow, moderate, or fast) matters with the self-reported faster cyclists being more prone to stop to the right than the slower one.     

Investigating cycling kinematics and braking maneuvers in the real world: e-bikes make cyclists move faster,brake harder,and experience new conflicts

Pedelecs (e-bikes), which facilitate higher speeds with less effort in comparison to traditional bicycles (t-bikes), have grown considerably in popularity in recent years. Despite the large expansion of this new transportation mode, little is known about the behavior of e-cyclists, or whether cycling an e-bike increases crash risk and the likelihood of conflicts with other road users, compared to cycling on t-bikes. In order to support the design of safety measures and to maximize the benefits of e-bike use, it is critical to investigate the real-world behavior of riders as a result of switching from t-bikes to e-bikes.Naturalistic studies provide an unequaled method for investigating rider cycling behavior and bicycle kinematics in the real world in which the cyclist regularly experiences traffic conflicts and may need to perform avoidance maneuvers, such as hard braking, to avoid crashing. In this paper we investigate cycling kinematics and braking events from naturalistic data to determine the extent to which cyclist behavior changes as a result of transferring from t-bikes to e-bikes, and whether such change influences cycling safety.Data from the BikeSAFE and E-bikeSAFE naturalistic studies were used in this investigation to evaluate possible changes in the behavior of six cyclists riding t-bikes in the first study and e-bikes in the second one. Individual cyclists’ kinematics were compared between bicycle types. In addition, a total of 5092 braking events were automatically extracted after identification of dynamic triggers. The 286 harshest braking events (136 cases for t-bike and 150 for e-bike) were then validated and coded via video inspection.Results revealed that each of the cyclists rode faster on the e-bike than on the t-bike, increasing his/her average speed by 2.9–5.0 km/h. Riding an e-bike also increased the probability to unexpectedly have to brake hard (odds ratio = 1.72). In addition, the risk of confronting abrupt braking and sharp deceleration were higher when riding an e-bike than when riding a t-bike.Our findings provide evidence that cyclists’ behavior and the way cyclists interact with other road users change when cyclists switch from t-bikes to e-bikes. Because of the higher velocity, when on e-bikes, cyclists appear to have harder time predicting movements within the traffic environment and, as a result, they need to brake abruptly more often to avoid collisions, compared with cycling on t-bikes. This study provides new insights into the potential impact on safety that a cycling society moving to e-bikes may have, indicating that e-cycling requires more reactive maneuvers than does cycling traditional bicycles and suggesting that any distractive activity may be more critical when riding e-bikes compared to traditional bikes.     

Analysis of heart rate variability amongst cyclists under perceived variations of risk exposure

Cycling as a mode of travel provides an opportunity for many people to increase their levels of regular physical activity and contribute to their mental and physical health. Heart rate is often used as a means of measuring the intensity and energy expenditure of physical activity. However, heart rate is also linked to emotional factors such as anxiety and fear. Perceptions of risk due to external factors such as other road users and infrastructure may arouse such emotions in urban cyclists. The present study set out to investigate whether or not perceptions of risk among urban cyclists may lead to increased heart rates. Cyclists completed a test route in normal traffic conditions in Cork, Ireland and heart rates and self-reported risk ratings were recorded in real time. Evidence was found of a link between perceptions of risk and heart rates. This raises questions regarding the use of heart rate to estimate exercise intensity and energy expenditure during urban cycling. The perceptions of cyclists of their safety in relation to various road elements on familiar routes were also assessed, as well as specific events which they perceive to be high in risk. The results indicate that incidents involving car traffic and busy roads which offer no protection from interaction with car traffic are associated with greatest perceptions of risk.     

How visually impaired cyclists ride regular and pedal electric bicycles

The present study investigates whether visually impaired cyclists compensate for their vision limitations by maintaining a lower speed or a larger distance to the kerb than normally sighted cyclists when riding a regular bicycle or pedal electric bicycle (pedelec). A normally sighted control group (n = 10), a peripheral visual field loss group (n = 9), and a low visual acuity group (n = 12) rode a fixed route (7.5 km) in the Netherlands on a regular bicycle and on a pedelec. Speed and lateral position were measured when participants cycled a (I) one-way cycle path, (II) two-way cycle path, (III) residential area, and (IV) shared space zone. With regard to both the regular bicycle and the pedelec, no significant speed or lateral position differences were found between the three groups. In conclusion, for some people with severe and permanent visual impairments, and under certain circumstances, regular bicycle and pedelec riding may be possible without noticeable speed reduction or adapted lane position to compensate for their functional impairment. The present findings may further optimise the cycling advice provided by mobility trainers of vision rehabilitation centres and the independent mobility of visually impaired people.     

Evaluating bicyclists’ risk perception using video clips: Comparison of frequent and infrequent city cyclists

Hazard and risk perception has been studied extensively among car drivers, and their link to crash involvement is established. Bicyclists, in particular, are vulnerable road users. Better understanding of their risk and hazard perception could help to improve their traffic safety.In this study, we investigated the risk perception of bicyclists in a city environment. Two groups of bicyclists were compared: 19 frequent and 19 infrequent bicyclists. Participants were shown video clips taken with a camera attached to the handlebar of a bicycle, and they were asked to continuously indicate with a slider how much caution the situation needed.The frequent cyclists had more frequent rises in the caution estimate, which suggest that they anticipated or detected more hazards than infrequent cyclists. This is in line with the classical hazard perception results, which link the car driving experience to faster and more accurate hazard perception. The overall level or caution was not directly related to the rise event rate or bicycling frequency. Those cyclists who reported typically cycling faster than others showed elevated overall level of caution on sidewalks compared with others, but there was no difference on bike paths.     

Modeling the impact of traffic conditions and bicycle facilities on cyclists’ on-road stress levels

Past research efforts have shown that cyclists’ safety, stress, and comfort levels greatly affect the routes chosen by cyclists and cycling frequency. Some researchers have tried to categorize cyclists’ levels of traffic stress utilizing data that can be directly measured in the field, such as the number of motorized travel lanes, motorized vehicle travel speeds, and type of bicycle infrastructure. This research effort presents a novel approach: real-world, on-road measurements of physiological stress as cyclists travel across different types of bicycle facilities at peak and off-peak traffic times. By matching videos with stressful events, it was possible to observe the circumstances of those stressful events. The stress data was normalized, and the method was carefully validated by a detailed analysis of the stress measurements. Novel statistical results from a multi-subject study quantifies the impact of traffic conditions, intersections, and bicycle facilities on average stress levels.     

“Put the blame on…others!”: The battle of cyclists against pedestrians and car drivers at the urban environment. A cyclists’ perception study

The main hypothesis of the paper is that cyclists tend to blame primarily car drivers, for the conflict events they have experienced with cars, but they do not have the same intention for the conflict events with pedestrians. For this purpose, 306 cyclists were interviewed through a revealed questionnaire survey and 64% revealed that they had experienced a conflict with a pedestrian whereas 55% revealed that they had experienced a conflict with a car. From the responses, two linear regression models were developed, with the perceived responsibility considered as the dependent variable.The cycling–pedestrian model indicated that cyclists who also have car accessibility, tend to blame primarily the pedestrians for the incidents, compared to cyclists who do not possess a car. Further, cyclists tend to give less responsibility to pedestrians for incidents occurred at sidewalks, crosswalks, etc. compare to incidents occurred at shared use paths. In addition, cyclists do not blame pedestrians for conflicts occurred primarily at sidewalks and crosswalks; places were pedestrians are considered to have the priority. Finally, cyclists aged between 55 and 64 years old, are giving less responsibility to pedestrians for the incident, compare to cyclists aged between 25 and 39 years old.On the other hand, the cycling–car model showed that an illegal cyclist’s movement at a road segment can reduce by half the responsibility the cyclists give to the car drivers, compare to the responsibility they give when the latter have an aggressive driving behavior. It was also found that cyclists, who tend to cycle less than 1 h, do not blame so much the car drivers for the incident, compared to cyclists that cycle for longer. Finally, cyclists who prefer the bicycle lane to be located along the road instead at the sidewalk, tend to accuse less the drivers for the incident.     

Who,where, when: the demographic and geographic distribution of bicycle crashes in West Yorkshire

Factors associated with cycle safety, including international differences in injury and mortality rates, protective equipment and bicycle training, have been subject to increasing academic interest. Environmental variables associated with cycle safety have also been scrutinised, but few studies have focussed on geographical factors at the local level. This paper addresses this research gap by analysing a geo-referenced dataset of road traffic incidents, taken from the UK’s STATS19 dataset (2005–2012). We investigate incidents involving cyclists within West Yorkshire. This is an interesting case study area as it has an historically low cycling rate but very ambitions cycling plans following investment from the Department of Transport. West Yorkshire is found to be an unusually risky area for cyclists, with an estimated 53 deaths and 1372 serious injuries per billion kilometres cycled, based on census commuting statistics. This is roughly double the national average. This riskiness varies spatially and temporally, broadly in line with expectations from the previous literature. An unexpected result was that cycling seems to be disproportionately risky for young people in West Yorkshire compared with young people nationally. The case study raises the issue of potential negative health impacts of promoting cycling amongst vulnerable groups in dangerous areas. We conclude by highlighting opportunities for increasing cycling uptake via measures designed primarily to improve safety. The analysis underlying this research is reproducible, based on code stored at github.com/Robinlovelace/bikeR.     

Differences in cycling performance of Dutch and non-Dutch students in the Netherlands

Thirty-seven young adult participants completed a bicycle ride through the city of Groningen. Behaviour of Dutch and non-Dutch cyclists was compared in three conditions: on a control track (i.e. a one-way bicycle path), on a complex intersection, and on a roundabout. Basic bicycle control of the two groups did not differ, neither did reported invested mental effort. However, non-Dutch participants made more serious errors in the experiment and reported to have had more crashes previous to the experiment. It is concluded that the performance of non-Dutch cyclists who continue cycling upon arrival in a new country, does not differ on the control level, but at the higher manoeuvre level more performance errors were observed in the non-Dutch group.     

Risk compensation theory and bicycle helmets – Results from an experiment of cycling speed and short-term effects of habituation

It has been suggested that the safety benefits of bicycle helmets are limited by risk compensation. The current study contributes to explaining whether the potential safety effects of bicycle helmets are reduced by cyclists’ tendency to cycle faster when wearing them (as a result of risk compensation), and if this potential reduction can be associated with a change in perceived risk. A previous study (Fyhri & Phillips, 2013) showed that non-routine helmet users did not increase their speed immediately after being given a helmet to wear, while routine helmet users cycled more slowly. The current study tests whether the previously found reduction in speed in response to helmet removal – as an indirect indicator of risk compensation – could be established in non-routine helmet users, after a period of habituation while cycling with a helmet.We did this by conducting a randomized crossover trial, in which we used GPS-derived speed calculations and self-reported risk perception. To test the effect of habituation, we used a design where each participant took part in two rounds with a break between and each round having two trips. We collected the data in June 2015. Non-routine helmet users (N = 31) were recruited in the field (along cycle routes in Oslo), and through a sample drawn from the Falck National register of bicycle owners. In the first phase of the study, all participants were asked to complete a test route (2.4 km downhill) with and without a helmet. In the second phase of the experiment, conducted after 1.5–2 h, the same participants again completed the test route with and without a helmet. In the time between the first and second phases of the experiment, all participants were given helmets, and told to use them on a predefined bicycle route.Habituation to the helmet between the first and second phases of the experiment did not produce any decrease (with helmet removal) in speed, on top of the habituation that occurred while cycling down the hill (the order effect). Mean speed difference for cycling with/without a helmet before the break was −0.76 km/h, after the break this difference was 0.32 km/h; 95% CIs [−0.5, 2.9] and [−0.9, 1.5]. We argue that risk compensation is an unlikely effect of using a bicycle helmet, and probably cannot explain any adverse effects related to helmet legislation.     

Group cycling safety behaviours: A systematic review

BackgroundThe popularity of cycling in a group is longstanding and increasing. Compared to riding as an individual, many cyclists feel safer when riding in a group as they have better personal security, potential support in case of mishaps, safer wayfinding and are more visible to other road users. However, further to the safety challenges shared with individual cyclists, group cyclist safety is impacted by rider proximity, the larger space taken up on roadways, potentially higher speeds, and social norms that could increase risky behaviours. Despite these unique safety considerations, the practice of cycling in groups has received little academic attention and group cyclist safety behaviours have not been analysed by road safety researchers.ObjectiveTo identify, describe, categorise and conceptualise within a teamwork framework, safety related behaviours of groups of cyclists as mentioned in academic literature.MethodsThree academic databases (Google Scholar, Proquest, and Scopus) were searched for peer reviewed literature that mentioned safe or risky behaviours of groups of cyclists. A total of 32 papers met the inclusion criteria. Relevant group cyclist behaviours were described and categorised using a conceptual teamwork framework.ResultsGroup cyclists’ safety behaviours are governed by a comprehensive but informal and adaptable set of rules. These rules are safety critical and are often strictly controlled within groups. Many groups of cyclists may ride in a safer manner than individual cyclists due to teamwork factors, particularly shared mental models, team orientation, and adaptability.ConclusionGroup cyclists take safety seriously. Teamwork factors may make behavioural interventions to decrease risky behaviours easier to implement with group cyclists compared to individual cyclists. Investigation of group cycling safety behaviours may inform safe system interventions to increase road safety.     

Factors associated with cyclists’ self-reported choice of lane position

Riders cycling on roads without bicycle lanes are generally advised to ride in the centre of their lane (primary position), and to move toward the left of the lane (in left-hand traffic; secondary position) only to let faster traffic pass and when it is safe. The present research investigated which situational and personal characteristics were associated with choice of lane position, and whether choice of lane position is associated with on-road crash involvement. A large cohort of bicycle riders from New South Wales Australia reported on their cycling patterns and crashes in 6 reporting weeks over a 1-year period using on-line surveys. During one reporting week 1525 participants identified their preferred choice of lane position in each of 6 visually-depicted scenarios that were designed to investigate the influence of number of lanes (in the cyclists’ direction of travel), parked cars, and bus lanes. A majority of respondents preferred the secondary position in scenarios with a clear kerbside lane. Respondents were significantly more likely to choose the primary position in multiple-lane situations compared to single-lane situations, if there were parked cars in the kerbside lane, and if they were female, younger, experienced riders, transport riders, or high intensity riders. Controlling for personal characteristics, choosing the primary position in a single clear traffic lane scenario was associated with a higher on-road crash rate, while choosing the primary position in a traffic lane with parked cars scenario was associated with a lower on-road crash rate. Results suggested that when riding on-road the bicycle riders in this Australian cohort prefer to keep their distance from motorised traffic, allowing traffic to pass safely when space allows. Nonetheless, results suggested that choice of lane position is highly dependent on the local road and traffic environment. Further research is needed to support advice to cyclists.     

Patterns in perceived crash risk among male and female drivers with and without substantial cycling experience

Perceived risk of crashes is generally higher in female than in male cyclists. No study has assessed whether these gender differences only apply to riding bicycles. Using an online risk assessment task and survey, this study (a) tested the hypothesis that compared to men, women perceive higher risks, irrespective of traffic mode and (b) explored gender differences in the predictors of perceived risk. Data were analysed from 595 driver licence holders in Australia: 444 who cycled regularly, termed ‘cyclists’ from here on (31% women) and 151 regular drivers who did not (63% women), who are referred to as ‘drivers’. Cyclists in their role as cyclists and drivers in their role as drivers (traffic role) were instructed to imagine being in a specified traffic scenario and to assess crash likelihood. Each of 6 traffic scenarios was presented twice but differing in configuration: a violating car and a violating bicycle. A mixed ANOVA, with rated probability of a crash as the dependent variable, gender and traffic role as grouping factors, and configuration as the repeated measure, resulted in a main effect of configuration, showing that both drivers and cyclists perceived higher levels of risk of violating cars than of violating bicycles (η_p2 = 0.34). The interaction of traffic role and configuration showed this difference to be smaller for drivers than for cyclists (η_p2 = 0.18). This suggests that drivers are aware of the car’s high injury potential in crashes with cyclists. The main effect of gender showed that irrespective of traffic role, women perceived higher risk than men, which supported the hypothesis that gender differences are not limited to cycling (η_p2 = 0.03). The main effect of traffic role was not significant.For the predictors of perceived risk, ANOVA showed main effects for traffic role and gender, with small effect sizes (from η_p2 = 0.02 to η_p2 = 0.03). Cyclists were more confident, less inattentive and more in favour of stricter laws. Women felt less skilled and were more concerned about risks. None of the interactions between gender and traffic role were significant, which lent further support to the hypothesis that gender differences were a general rather than a cycling specific characteristic. Thus, perceived risk does not differ between women who regularly cycle and those who do not. These findings may inform interventions about the role of perceived risk in the uptake of cycling.     

Safety equipment use and crash involvement among cyclists – Behavioral adaptation,precaution or learning?

The present study has investigated relationships between cyclists’ safety equipment use, crash involvement, and other safety relevant behavior. The main focus is on relationships that indicate either behavioral adaptation (safety equipment use leads to riskier behavior) or precautionary behavior (safety equipment is used for cycling in risky situations). Three consecutive surveys were conducted in 2015, 2016, and 2017 years among 650 Norwegian cyclists. Most items were dichotomized and analyzed with logistic regression models. In contrast to the behavioral adaptation hypothesis, regular use of safety equipment (bicycle lights, high-visibility clothing, and helmets) was found to be negatively related to some types of high-risk behavior (listening to music and taking chances while cycling). Regular use of bicycle lights and high-visibility clothing is also negatively related to collision involvement. Safety equipment use was found to be positively related to regular winter cycling and cycling in mixed traffic (not on sidewalks), and it is most likely used as a precautionary measure in such situations. Some cyclists learn from crash involvement by starting to use safety equipment after a crash, but the results do not indicate that crash involvement deters from cycling. The main conclusion from the study is that recommending, promoting or even mandating safety equipment for cyclists can be expected to improve safety and that behavioral adaptation is not likely to occur, at least not to an extent that will outweigh the positive safety effects. The results do not support reservations against the use of “sporty” (well-equipped) models in campaigns for promoting cycling.     

Relationships amongst psychological determinants,risk behaviour,and road crashes of young adolescent pedestrians and cyclists: Implications for road safety education programmes

Road safety education (RSE) assumes that psychological determinants predict risk behaviour, and subsequently that risky road behaviour predicts crash involvement. This study examined the validity of this assumption, by analysing these relationships in two age groups of teen cyclists and pedestrians: a younger age group (12 and 13 years old: n = 1372) and an older age group (14–16 years old: n = 938). A questionnaire was administered at school during regular class consisting of items on demographics, on risk behaviour based on the Generic Error Model System (GEMS), on psychological determinants targeted in RSE programmes, and on crash involvement and near crashes. For the younger age group, the results indicated that the risk behaviours ‘errors’, ‘dangerous play’, and ‘lack of protective behaviour’ predicted self-reported crashes; for the older age group only ‘errors’ were found to be predictive of self-reported crashes and near crashes. Path analyses confirmed that risk behaviour could be predicted from the psychological determinants, sharing respectively 44% of the variance in the younger age group and 34% in the older group. In conclusion, these results confirm the RSE assumption that psychological determinants are associated with a higher frequency of risk behaviours and that the latter are again associated with higher crash frequencies. Just as in earlier studies on adolescent risk behaviour, the GEMS based distinction between errors and violations was not confirmed, suggesting that this distinction – derived from studies on adult car drivers – may not apply to young adolescent cyclists and pedestrians.     

Influences on anger in German urban cyclists

Previous research shows that anger and aggression among road users lead to maladjusted driving and a higher risk of accidents. Especially cyclists as vulnerable road users have a high risk of being injured if they are involved in accidents. This paper examines reasons for cycling anger in two studies. The first study aimed at identifying anger provoking events. Seventy-three cyclists were invited to discuss anger provoking events in a focus group setting. These events were rated regarding their anger intensity, clustered within focus groups, and aggregated across all groups. The first study revealed 208 unique cycling anger provoking events of varying anger intensity that were summarized in six clusters. The second study aimed at validating these anger provoking events, the ratings, and the clusters. Here, 129 participants were asked to complete a four-time point diary study (over the course of ten days), in which they registered all anger provoking events that they experienced while cycling. The results of this study validated most of the anger provoking events of the first study. Both studies show that most anger provoking events are related to conflicts between cyclists with other road users like car drivers and pedestrians. Moreover, conflicts with car drivers seem to cause stronger anger among cyclists than conflicts with other cyclists or pedestrians. Implications for further research and the planning of road infrastructure are discussed.     

The impact of a child bike seat and trailer on the objective overtaking behaviour of motorized vehicles passing cyclists

IntroductionThe lateral clearance distance of a motorized vehicle while overtaking a cyclist is a key indicator of safety. This lateral clearance distance has never been measured for cyclists transporting a child. Therefore the aim of this study was to investigate the behaviour of motorized vehicles in overtaking cyclists with and without a child on the same bicycle.MethodsThe lateral clearance distance of the overtaking manoeuvres of motorized vehicles was measured using an instrumented bicycle when performing 19 cycling trips on one single road with two different types of cycling infrastructure (a bike lane and shared lane marking) in the Brussels Capital Region (Belgium). Mixed effect regression was used to examine the effect of cycling condition (cyclist without a child [control], cyclist with a child bike seat and cyclist with a child bike trailer) and secondary independent variables (i.e. cycling infrastructure, peak traffic hours and traffic density) on the lateral clearance distance.ResultsThe mean lateral clearance distance in ‘cyclists without child’ was significantly smaller (117.3 cm) than in ‘cyclists with child’ (128.8 cm) (95%CI [7.2;15.9]). Looking at ‘morning peak traffic hours’ (i.e. 7:00 to 9:00 a.m.) a cyclist with child bike seat was overtaken at greater lateral clearance distances than a cyclist with a child bike trailer or a cyclist without child (p=0.041). Furthermore, the percentage of passing manoeuvres under 100 cm was significantly higher in ‘cyclist without child’ (35.3%) in comparison to ‘cyclist with child bike seat’ (21.8%) and ‘cyclist with child bike trailer’ (21.8%) (Chi2=29.19, p<0.001). No significant differences were found between a shared lane marking and bike lane.ConclusionDrivers of motorized vehicles do adapt their overtaking manoeuvre when they overtake cyclists transporting a child, keeping greater and therefore safer lateral clearance distances. In morning peak traffic hours and/or crowded circumstances the child bike seat can be considered as the safest way to transport a child in terms of lateral clearance distance. In general, with 25.3% overtaking manoeuvres under 100cm, police should monitor compliance with the traffic rules with regard to cyclists, and motorists should be more aware of the overtaking traffic rules.