When measuring how drivers overtake cyclists, one of the underlying problems is extracting the overtaking event from a time series of lateral distance readings. This note aims to describe a simple approach that seems effective in applications like ours. It consists of carefully transforming our problem into a network problem, then leveraging a community detection algorithm to extract subsequence candidates. Lastly, we choose the anomalous subsequence from the set of returned subsequences. To the best of our knowledge, this approach to anomaly detection does not appear in the literature even though it is intuitive, offers a fair amount of control, and is not computationally expensive. Our goal is to present the crux of the method with clarity and identify where more effort could improve it. We demonstrate our approach with modularity-based community detection and point out a shared nature of our approach with density-based cluster detection methods. 

Right-hook crashes in right-hand traffic where cyclists going straight are struck by right-turning vehicles pose a major safety concern. This study aims to establish to which extent such conflicts may stem from non-driving-related tasks (NDRT), low saliency of cyclists (covertness), or drivers’ insufficient knowledge of applicable rules.

Forty-four drivers participated in a fixed-base driving simulator study using an extended reality (XR) setup with integrated eye tracking. Participants were stratified by urban cycling experience (cyclist-drivers vs. drivers) and self-reported driving style (cautious vs. assertive). Each drove an urban route including 12 right-turn-on-yield scenarios, with and without NDRT. Observed visual sampling was combined with a questionnaire-based rule knowledge assessment to examine whether scanning failures were due to workload or lack of rule knowledge.

NDRT engagement primarily reduced default glances while glances to relevant areas (Left, Right, Over Shoulder) were preserved. Over-the-shoulder checks were rare overall. In 85 % of right-turns, no such glance occurred before turning, regardless of NDRT status. Rule knowledge mirrored these patterns, with drivers being more likely to correctly indicate the requirement to yield to salient crossing traffic streams of cars (96 % correct) or cyclists and pedestrians (81 % correct) than non-salient crossing bicycle or pedestrian traffic (46 % correct). Drivers with cycling experience scored slightly better overall but still missed nearly half of the non-salient yielding requirements.

The findings indicate that gaps in rule knowledge contribute to failures to check for cyclists. Countermeasures should prioritise systemic interventions, complemented by education, rather than solely relying on behaviour-focused measures.

Nuvarande regel om “betryggande avstånd” vid omkörning är otydlig och svår att tillämpa. Minskat omkörningsavstånd ökar kollisionsrisken och otryggheten. Forskningen visar samtidigt att nära omkörningar är vanligt förekommande. Ett införande av en fast avståndsregel (t.ex. 1,5 meter) riskerar att bli svårt att efterleva och kontrollera. Denna policy brief föreslår i stället en tydligare och mer tillämpbar princip: att cyklister inte ska köras om av motorfordon inom samma körfält. Förslaget bedöms ha goda förutsättningar att för bättra trafiksäkerheten och öka tryggheten, samtidigt som det är enklare att kommunicera, följa upp och efterleva.

Många förare har ett avsökningsbeteende som systematiskt missar vissa potentiella konflikter, vilket indikerar att deras mentala modeller är felaktiga. Exempelvis förekommer att förare inte tittar efter cyklister som kommer bakifrån innan de svänger höger. Vi undersöker därför hur avsökningsbeteende och anpassning till situationen varierar med omgivande trafik, körriktning, trafikregler och icke-körrelaterade uppgifter, för att förbättra förståelsen av varför förare gör systematiska fel då de söker av omgivningen.

En körsimulatorstudie i stadsmiljö med 40 förare har genomförts. Förarna valdes baserat på självskattad körstil (offensiv/defensiv) samt vana av att cykla i stadsmiljö (erfaren/oerfaren cyklist). Deltagarna exponerades flertalet gånger för tre situationer: sväng i korsning med interagerande cyklist, övergångställe med fotgängare, samt interaktion med andra motorfordon. Under försöket har data om hur förarna kör i förhållande till omgivningen och andra trafikanter, förarnas blickbeteende, förarnas arbetsbelastning, samt hur förarna interagerar med en icke-körrelaterad uppgift samlats in. Analyserna pågår i skrivande stund. Resultaten är därför avgränsade till situationen "korsning med interagerande cyklist".

Förarna stannade eller krypkörde innan de körde ut i korsningen i 254 av de 348 passagerna med högersväng och i 331 av 348 passager med vänstersväng. I många fall sökte försökspersonerna efter informationen för tidigt, t ex tittade försökspersonerna höger/vänster i korsningen när sikten fortfarande blockerades av kringliggande byggnader i 20% av passagerna. Beroende på kategori tittar mellan 50–80% av förarna i speglarna och/eller över axeln efter cyklister innan de svänger ut i korsningen. Den kategori som tittar oftast är de defensiva förarna som även är vana cyklister.

Högersvängsolyckor är ett vanligt scenario där cyklister blir påkörda. En trolig orsak är att förare inte söker av sina döda vinklar. Frågan är varför förare glömmer, eller inte ens känner till, att de behöver titta efter cyklister som kommer bakifrån. Våra preliminära resultat ger inga tydliga svar, mer än att bilister som även har erfarenhet av att cykla i stadstrafik är bättre på att samspela med cyklister.

Previous research has shown that drivers often fail to yield to cyclists who have the right of way, particularly when turning right. This finding was confirmed in a driving simulator study. To determine whether this is a systematic issue related to the type of attention required by road users, a systematic investigation was conducted.

When travelling through an intersection, different trajectories intersect. Various rules determine who has priority, resulting in different attention targets that road users must monitor to proceed safely and in accordance with the rules. For example, when going straight on a main road, the only attentional requirements on the driver are to monitor to the left and right for pedestrians who might want to cross on the zebra crossing. On a subordinate road in the same situation, the driver also needs to check for cross traffic from the left and from the right.  

The attention targets at intersections can be classified as either ‘overt’ (visible via signs, road markings, etc.) or ‘covert’ (unmarked and have to be remembered, e.g., the need to check ‘over the right shoulder’ for cyclists and pedestrians when a driver is turning right from a main road). Additionally, they can be categorised as ‘same-mass’ (for partners in an encounter) or ‘lower-mass’ (as in the turning-right example where the cyclist has lower mass), and as ‘required’ (when one must yield to superior traffic streams) or ‘not required’ (when one has priority).   

Målet för denna studie är att undersöka vad olika cyklister anser som en ”betryggande omkörning”. Datainsamlingen genomfördes i VTI:s cykelsimulator med mixed reality. Tre grupper av cyklister (transportcykling, träningscykling, ingen cykling på landsväg) upplevde sammanlagt sex olika svenska vägtyper: allt från en smal landsväg utan mittlinje till en 2+1-väg. Deltagaren placerade sig i sidled om hen hade gjort i verklig trafik och blev omkörd två gånger av en personbil. Deltagaren kommenterade landsvägen och omkörningen med avseende på hur trygg man kände sig och ombads vid “otrygg” känsla förklara om och på vilket sätt omkörningen skulle kunna bli betryggande. Dessa önskemål implementerades och omkörningen upprepades. När deltagaren var nöjd testades och bedömdes omkörning med lastbil på samma sätt. 

Preliminära resultat visar att vägtyp och fordonens hastighet spelar roll för hur trygga omkörningar upplevs, men även att detta skiljer sig åt mellan cyklistgrupper. Vägar med högre hastighetsgräns och mycket smala vägar upplevs som mindre attraktiva. Vid omkörning önskades i många fall ett helt filbyte av fordonet. Generellt kräver man större omkörningsmarginal för lastbil än personbil, där luftdraget och obehaget som relaterar till fordonets storlek och massa nämndes som orsaker. Träningscyklisterna nöjde sig med mindre marginaler än de andra två grupperna. I alla grupper ökade trygghetsgraden betydligt om omkörningarna skedde enligt de egna önskemålen. 

Resultaten tyder på att landsvägar kan göras mer tillgängliga för fler människor genom att förbättra omkörningsbeteendet. Detta kan ske genom lagkrav, fordonsteknologi, kampanjer och infrastrukturutformning. På så sätt skulle vägnätet kunna bli mer tillgängligt även för den som vill resa aktivt.

Conflicts arise when motor vehicles cross cycle paths during turns, often due to drivers neglecting over-the-shoulder glances. This paper examines the visual attention of car drivers at urban unsignalized intersections, considering turning direction, cross traffic, and cyclist approaching from behind.

A study with 44 participants was conducted using a fixed-base driving simulator equipped with an eXtended Reality (XR)-based visual system, which provided 360° immersion and enabled eye tracking for head movements and over-the-shoulder glances. Drivers were recruited based on urban cycling experience (inexperienced/experienced) and driving style (cautious/assertive). 

Results showed that in 47.8 % of intersection approaches, participants failed to adequately check for cyclists from behind. Driver characteristics did not consistently reveal traits associated with this neglect. Although cautious drivers with urban cycling experience made fewer mistakes, all groups were generally poor at checking for cyclists from behind. Post-drive questionnaire results on rule knowledge showed that, across participants, only half of the requirements to check for cyclists approaching from behind were indicated correctly. 

Drivers are more consistent in checking for cross-traffic, suggesting the neglect to check for cyclists is systemic rather than individual. The lack of awareness among drivers about their obligation to check for cyclists can be attributed to the less obvious nature of this traffic stream, as it comes from behind and lacks signs or warnings. Checking over the shoulder is physically more effortful, and cyclists may often pre-empt collisions, reinforcing drivers’ mental models to turn without checking. To improve safety, changes counteracting systemic biases against cyclists are needed.  

Since December 2023, so-called High-Capacity Transport vehicles (up to 34.5 m length) are allowed on parts of the Swedish network of primarily divided roads. Investigations are ongoing under which premises longer HCT vehicles can be allowed on undivided rural roads, where cyclists and other active travellers may be present. On rural roads, overtaking manoeuvres are a frequently occurring encounter between cyclists and motorists. The fear related to dangerous overtakes is a major deterrent to rural cycling, and the aerodynamic load generated especially by large vehicles may pose a danger in that it could affect cyclist stability. To systematically investigate the effects of lateral distance, overtaking vehicle speed and truck length on cyclists stability and perception of discomfort, a controlled study was conducted in a laboratory setting. In a 700 m long tent, 23 experienced road cyclists rode on free rollers while being overtaken by a 16.5 m and a 32.5 m long truck combination at 50 and 80 km/h, with lateral distances of 1 m, 1.5 m and 2 m. Additionally, a reference overtake was run, reflecting a full lane change at reduced speed (16.5 m truck, 50 km/h, 3.5 m). Lateral distance had the largest impact on aerodynamic load and discomfort ratings, followed by speed. The length of the truck only had a minor effect. The cyclists’ lateral position on the rollers was not affected by any of the three factors, but increased slightly from before to during to after the overtaking manoeuvre, regardless of the condition. Based on these findings, a full lane change is recommended when overtaking cyclists. To which extent a speed adaptation is appropriate as compensatory measure needs to be investigated further.

Currently, the development of high-fidelity cycling simulators lags behind that of driving simulators. This limits the potential for controlled studies in cycling research. This paper presents the VTI Cycling Simulator ”How We Roll” (HWR), a novel, roller-based system designed to provide a realistic cycling experience while maintaining experimental adaptability. The simulator enables riders to use their own bicycles, preserving natural lean and steer dynamics without complex modelling and simulation. Visual immersion is achieved through XR integration with an Unreal Engine-based environment, enhancing realism in simulated traffic scenarios. Initial studies using HWR demonstrate its effectiveness in replicating real-world conditions, including overtaking events and infrastructure variations. First results show high participant acceptance and realistic behavioural responses, and strong alignment with real-world settings revealing strong alignment. Key challenges include braking fidelity, cornering dynamics, and torque refinement. Nonetheless, the simulator’s flexibility and immersive design position it as a powerful tool for investigating cyclist behaviour. The paper concludes with future directions aimed at expanding simulator capabilities and integrating co-simulation approaches for multi-modal traffic safety research.

Increased cycling, also in rural areas, is important for transitioning to a more sustainable transport system. Also, long combination vehicles (LCVs), in Sweden labelled high-capacity transport (HCT; up to 34.5 m, the previous limit was 25.25 m) can contribute to this goal. If granted access to a larger share of the road network, those trucks can be used more effectively. However, cycling and other active transport on those roads may be negatively impacted. To investigate direct and indirect effects on cyclists when LCVs are using the same road, a study was conducted in real traffic. Nineteen experienced road cyclists rode on a 5 km long rural road segment. Three trucks of different lengths were driven along the same route, instructed to overtake the cyclists where possible and with a full lane change. This generated 175 overtakes by the trucks and 607 overtakes by other traffic. The cyclists reported the overtakes with the trucks to feel safe and found the length of the truck not to be relevant if a full lane change was made while overtaking. The trucks needed more time to overtake than other traffic, and they also waited longer for an overtaking opportunity. In a car-following situation, the clearance of the following vehicles was influenced by the lead vehicle, making it especially important for heavy vehicles to give cyclists a wide berth. Pending further investigations, the conclusion is that for cyclists to feel safe, a full lane change when overtaking should be standard procedure not only for LCVs, but for motorised traffic in general.