Unsafe bicyclist overtaking behavior in a simulated driving task: The role of implicit and explicit attitudes

Drivers passing cyclists: How does sight distance affect safety? Results from a naturalistic study

INTRODUCTION

Cycling is popular for its ecological, economic, and health benefits. However, especially in rural areas, cyclists may need to share the road with motorized traffic, which is often perceived as a threat. Overtaking a cyclist is a particularly critical maneuver for drivers as they need to control their lateral clearance and speed when passing the cyclist, possibly in the presence of oncoming vehicles or view-obstructing curves. An overtaking vehicle can destabilize the cyclist when passing with low clearance and high speed. At the same time, the cyclist may get scared and eventually stop cycling. In this work, we investigated how visibility regarding available sight distance-an important factor for infrastructure design and regulation-affects drivers' behavior when overtaking cyclists.

METHOD

Using four roadside-based traffic sensors, we collected naturalistic data that contained kinematics of drivers overtaking cyclists on a rural road in Sweden. We modeled lateral clearance and speed at the passing moment in response to variables such as sight distance and oncoming traffic with a Bayesian multivariate approach.

RESULTS

Fitted on 81 maneuvers, the model revealed that drivers reduced lateral clearance under reduced sight distance. Speed was similarly reduced, however, not as clearly. When an oncoming vehicle was present, it had a similar-yet stronger-effect than sight distance. While we found an overall correlation between clearance and speed, some maneuvers were recorded at critically low clearance.

CONCLUSIONS

Cyclists' safety is endangered when passed by drivers under reduced visibility or close to oncoming traffic.

PRACTICAL APPLICATIONS

Decision-making for infrastructure and policymaking should aim at prohibiting overtaking in areas with reduced visibility or close oncoming traffic. The model developed in this study may serve as a reference to vehicle active-safety systems and automated driving. The collected and processed data may support evaluating driver models fitted on less ecologically valid data and simulated active-safety systems.

Improving attitudes towards vulnerable road users

Some car drivers pass vulnerable road users (VRUs) at too high a speed and leave too little gap. Research suggests that out-group bias and a lack of empathy may relate to these dangerous incidents. To address this problem, four road safety videos were created with the aim of increasing car drivers' empathy toward Vulnerable Road Users (VRUs). Each video focused on the back-story of a VRU (two horse riders and two cyclists), with a predominantly persuasive approach to inducing empathy and reducing out-group bias. The effectiveness of the videos on car drivers' immediate implicit and explicit attitudes, and on their future intended behaviour around these VRUs, was assessed by comparing intervention participants' responses with those of control participants, both before and after the intervention. Explicit attitudes towards horse riders improved following the intervention for drivers who saw the horse rider videos compared to a control group. The horse rider videos did not however improve explicit attitudes toward cyclists. Similarly, those participants who saw the cyclist videos showed improved attitudes towards cyclists but not horse riders. An Implicit Attitude Test (IAT) found no implicit biases for or against horse riders or cyclists, either before or after the intervention. Intended future passing behaviour was affected by the intervention however, with car drivers reporting greater intended passing distances and lower passing speeds compared to the control group. The results suggest that safety campaigns that adopt this approach can change attitudes and intended behaviours towards VRUs.

Why Not Pedal for the Planet? The Role of Perceived Norms for Driver Aggression as a Deterrent to Cycling

Cycling has many benefits for humans and the planet. This research investigates perceived norms and driver behavior toward cyclists as issues that may be useful for addressing reluctance to cycle. It connects perceived norms observed in the road context regarding aggressive driver behavior towards cyclists, and norms observed in workplaces regarding sustainability (perceived green psychological workplace climate) with driver aggressive behavior toward cyclists. Self-reported online survey responses from N = 426 Australian drivers were collected. Perceived norms regarding aggressive driver behavior toward cyclists were linked to drivers engaging more frequently in such behavior, but no such link was found for perceived green psychological workplace climate. However, perceived green psychological workplace climate moderated the link between perceived norms regarding aggressive driver behavior toward cyclists and drivers engaging in such behavior. When drivers perceived aggression toward cyclists to be common on the road, perceived green psychological workplace climate weakened the link between perceived norms regarding aggressive driver behavior towards cyclists and drivers engaging in such behavior. Findings reinforce the role of perceived road context norms regarding aggressive driver behavior toward cyclists for drivers engaging in such behavior. They illustrate that, while not directly linked, sustainability norms perceived in other contexts have a role in shaping car driver behavior towards cyclists. The study's findings suggest that interventions targeted at aggressive behavior toward cyclists in road contexts can focus on driver behavior norms and can be complemented by normative interventions in other settings to shape a key deterrent to cycling.

The good and the bad: Are some attribute words better than others in the Implicit Association Test?

The Implicit Association Test (IAT) is one of the most popular measures in psychological research. A lack of standardization across IATs has resulted in significant variability among stimuli used by researchers, including the positive and negative words used in evaluative IATs. Does the variability in attribute words in evaluative IATs produce unwanted variability in measurement quality across studies? The present work investigated the effect of evaluative stimuli across three studies using 13 IATs and over 60,000 participants. The 64 positive and negative words that we tested provided similar measurement quality. Further, measurement was satisfactory even in IATs that used only category labels as stimuli. These results suggest that common sense is probably a sufficient method for selection of evaluative stimuli in the IAT. For reasonable measurement quality, we recommend that researchers using evaluative IATs in English select words randomly from the set we tested in the present research.

Bicyclist-evoked arousal and greater attention to bicyclists independently promote safer driving

While attention has consistently been shown to be biased toward threatening objects in experimental settings, our understanding of how attention is modulated when the observer is in an anxious or aroused state and how this ultimately affects behavior is limited. In real-world environments, automobile drivers can sometimes carry negative perceptions toward bicyclists that share the road. It is unclear whether bicyclist encounters on a roadway lead to physiological changes and attentional biases that ultimately influence driving behavior. Here, we examined whether participants in a high-fidelity driving simulator exhibited an arousal response in the presence of a bicyclist and how this modulated eye movements and driving behavior. We hypothesized that bicyclists would evoke a robust arousal and orienting response, the strength of which would be associated with safer driving behavior. The results revealed that encountering a bicyclist evoked negative arousal by both self-report and physiological measures. Physiological and eye-tracking measures were themselves unrelated, however, being independently associated with safer driving behavior. Our findings offer a real-world demonstration of how arousal and attentional prioritization can lead to adaptive behavior.