Motor vehicle passing speed and lateral clearance jointly determine both bicyclist injury risk and perceived safety during overtaking events. Most prior studies have examined these factors separately and/or in limited settings. Real-world evidence describing how passing speed and clearance interact across heterogeneous roadway contexts remains limited. This study evaluates high-resolution naturalistic overtaking data within a kinetic-energy injury framework to evaluate whether roadway context and bicycle infrastructure modify both passing speed and lateral clearance, and whether spatial compensation meaningfully offsets energetic exposure.
Methods
Following institutional review board approval, naturalistic cycling data were collected from six commuter cyclists riding as normal using a sensor suite including cameras, lidar, rear-facing radar, GPS, and inertial measurement unit. Approximately 9,900 km of riding were recorded over four months. Overtaking events were detected and characterized using time-synchronized radar and lidar data, yielding 8,753 passes with reliable vehicle speed estimates after quality filtering. Overtaking events were map-matched to OpenStreetMap roadway attributes and supplemented with image-based manual coding to classify functional class, posted speed limit, lane count, centerline configuration, and bicycle infrastructure type. Ordinary least-squares regression models with participant-clustered standard errors were applied to evaluate infrastructure effects and speed-distance relationships, including interactions with driver speeding behavior.
Results
Passing speed varied substantially across roadway contexts, increasing with functional class and posted speed limit. Mean passing speed ranged from approximately 10 m/s (residential roads) to nearly 15 m/s (primary and four-lane facilities). In contrast, lateral clearance varied modestly across contexts, with mean values generally between 2.2 and 3.0 m and substantial overlap among categories. After adjustment for roadway characteristics, standard painted bicycle lanes were associated with reduced passing distance (β = -0.31 m) and higher passing speed (β = +1.36 m/s) relative to roads without bicycle accommodation. Shoulders were associated with the highest passing speeds and no meaningful increase in clearance. The overall compensation slope, defined as the increase in lateral clearance with increasing speed, was small: 0.016 m per 1 m/s (∼2.8 inches per 10 mph). Modest but statistically significant compensation was observed among drivers exceeding the speed limit and on higher-speed, higher-capacity roadways.
Conclusions
Roadway context strongly influenced passing speed, whereas lateral clearance adjustments were comparatively small and inconsistent. Across various naturalistic environments, lateral clearance did not increase proportionally at higher speeds. On-road bicycle infrastructure without accompanying speed management did not reliably reduce high-speed passing and, in some contexts, was associated with closer overtaking. These findings demonstrate the need for vehicle speed reduction and improved separation of bicycles from motor vehicle traffic to reduce crash injury risk.
OBJECTIVE
Overtaking maneuvers between motor vehicles and bicycles (OVB) represent a critical hazard for cyclists due to required lateral clearances and vehicle speeds. This study aims to evaluate the OVB process in urban environments, focusing on the main geometric and operational attributes that influence cyclists' objective road safety indicators.
METHODS
A quasi-naturalistic observational study was conducted on urban roads in Fortaleza, Brazil, using an instrumented bicycle. Data on vehicle speed, lateral passing distance, lane configuration, vehicle type, and the presence of adjacent traffic were collected across 1,075 overtaking maneuvers. Statistical analyses were performed to assess the impact of these attributes on safety indicators.
RESULTS
Analysis revealed that 76% of observed passing maneuvers violated the Brazilian national recommendation of maintaining a minimum lateral distance of 1.50 m. The presence of cycling infrastructure and the absence of traffic in adjacent lanes were significantly associated with greater passing distances. Furthermore, a behavioral compensatory threshold was identified at a 0.85-meter lateral distance: drivers modulated speed as a risk-mitigation mechanism only during critical clearances, whereas no speed adjustments were observed at the 1.50-meter legal threshold.
CONCLUSIONS
A vast majority of drivers fail to comply with recommended passing distances, highlighting the need for targeted infrastructure and operational interventions. The existence of dedicated cycling facilities effectively improves lateral separation. Moreover, drivers adapt speed only under extreme proximity (under 0.85 m), demonstrating that legal limits alone do not induce safer driver behavior without structural or physical support.
Ellen Pinto, C. Torres, F. Cunto· Traffic Injury Prevention· 0 citations
Motorcycles are Indonesia’s predominant mode of transportation and contribute to a substantial share of road traffic accidents. The research aims to identify key behavioural factors contributing to motorcycle-related conflict risks at intersections and to propose evidence-based safety interventions. This study analyzed speed characteristics with varying degrees of disruption that motorists would experience at the intersection. These disruptions were categorized into high, low, no disruption, and left-turn movements. High disruption was defined as vehicles stopping in the middle of the intersection as motorcyclists approached, while low disruption was defined as vehicles preparing to enter the intersection from minor roads. In addition to speed characteristics, this study also observed lane-changing behavior when disruptions occurred at the intersection. To obtain detailed data, drone-based cameras were used for observations, and the results were validated against radar speed measurements. The results show that 67.94% of riders exceed the 60 km/h speed limit during the morning period, while 33.27% exceed it in the afternoon, indicating clear temporal differences in operating speeds. Approximately 85 per cent of lane-changing manoeuvres occur within 20 metres of the conflict point, reflecting short decision distances that increase collision risk. Riders also exhibit assertive gap-acceptance behaviour, often requiring main-road vehicles to adjust their speed. Statistical validation confirms that there is no significant difference between drone-derived and radar-based speed measurements, demonstrating the reliability of the drone-based methodology. Based on these findings, the study recommends targeted speed management measures, including automated enforcement and the use of traffic-calming devices; improved lane discipline through more precise road markings and selective physical separation; and junction design enhancements, such as motorcycle waiting areas and advanced stop lines. These measures can improve motorcycle safety at priority junctions and support more efficient and predictable urban traffic operations.
Benidiktus Susanto, Siti Malkhamah, Latif Budi Suparma et al.· Journal of the Civil Enginee...· 0 citations
OBJECTIVE
Professional delivery riders in China have experienced a sharp increase in traffic crashes, injuries, and fatality rates over recent years. This observational study sought to identify and analyze risk factors influencing riding behavior among electric bicycle delivery riders compared to other electric bicycle riders during potential conflicts at unsignalized intersections.
METHODS
Two typical unsignalized intersections in Nantong City with mixed traffic (pedestrians, motorized and non-motorized vehicles) were selected for observation. Through systematic video coding and analysis of 637 min of continuous video observations, we extracted a total of 1,558 potential conflict events, including interactions between electric bicycle riders and pedestrians, motorized vehicles, or non-motorized vehicles. Among these events, 394 occurred under congested traffic and 1,164 under free-flowing traffic. Data were analyzed via descriptive statistics, non-parametric chi-square tests and logistic regression.
RESULTS
(1) Under congested traffic conditions, delivery riders generally exhibited more pronounced hazardous riding behaviors than other riders, and such differences were more obvious among male and young delivery riders; (2) Regardless of road user type, delivery riders exhibited a high proportion (about 20%) of hazardous riding behaviors under both traffic conditions; (3) During potential conflicts with motor vehicles in congested traffic, delivery riders engaged in more hazardous riding than other riders; (4) Professional delivery riders engaged in risky behavior at a rate 1.88 times that of other riders.
CONCLUSIONS
For delivery riders at unsignalized intersections, hazardous riding behaviors are influenced by the combined effects of traffic conditions, rider demographic characteristics, and potential conflict objects. Professional delivery riders exhibit the highest risk levels under congested traffic conditions, particularly during potential conflicts with motor vehicles. Findings reflect the influence of occupational demands, such as tight delivery schedules, on delivery riders' riding strategies in various contexts.
Yunxin Chang, Jinnuo Li, Huarong Wang et al.· Traffic Injury Prevention· 0 citations
Expressways are designed to facilitate uninterrupted traffic flow; however, localized roadside features such as bus laybys disrupt vehicle dynamics and reduce operational capacity. While classical speed–density models provide theoretical foundations for freeway analysis, localized disturbances are frequently omitted from conventional modeling. This study evaluates the speed–density relationship of passenger cars on a basic expressway segment adjacent to a bus layby along the Federal Highway (KM 17) in Selangor, Malaysia. Traffic data were collected across peak and off-peak periods using elevated video recordings and analyzed via Tracker motion-analysis software across 36 five-minute intervals. Comparative evaluation against classical single-regime models demonstrated that the linear Greenshields model ($V_s = 116.97 - 1.381k$) provided the most robust fit, explaining 75.05% of the variation in passenger car speed ($R^2 = 75.05\%$, $F = 102.27$, $p < 0.001$). The empirical findings indicate that each 10-unit increase in density ($pcu/km$) induces an approximate 14 $km/h$ reduction in speed, largely driven by lane-changing turbulence and deceleration near the layby weave zone. These results underscore the need for infrastructure authorities to incorporate localized disturbance factors into expressway capacity planning and offer actionable insights for optimizing bus layby geometry and setback distances to preserve highway efficiency.
Ifham Fathi Sayuti, T. Besar, Noorazlan Hasnim et al.· International journal of res...· 0 citations
This study develops and validates a smartphone-based framework for automatically detecting emergency maneuvers, strong jolts, and crashes involving electric scooters and electric bicycles. Detection criteria were established through controlled track experiments and subsequently evaluated using data collected during a naturalistic riding study involving 119 participants and more than 26,000 km and 1,600 h of riding, combining accelerometer, gyroscope, GPS, and video recordings. Threshold-based detection criteria were defined using variables selected for their physical relevance and ability to discriminate between target and non-target situations. Hard braking, sharp turns, strong jolts, and crash-related events were identified using combinations of acceleration, jerk, rotational dynamics, and post-event vehicle motion. Video review showed that 74% of hard-braking detections corresponded to harsh-braking maneuvers, 64% of sharp-turn detections reflected genuine avoidance maneuvers, and 91% of strong-jolt detections were associated with infrastructure features. Video verification of collision candidates confirmed several reported and previously unreported impacts, including collisions with other road users and single-vehicle falls. Application of the framework to the naturalistic dataset revealed marked differences between vehicle types. E-scooter users experienced higher rates of hard braking and strong jolts than e-bicycle users, reflecting behavioral differences and vehicle characteristics. Illustrative mapping examples showed that detected events and rider-reported hazardous situations could occur in close proximity, suggesting opportunities for future spatial analyses of micromobility safety. Although additional validation on larger crash datasets is required, the results demonstrate that threshold-based approaches can provide meaningful indicators of rider safety, support large-scale monitoring of micromobility risks, and contribute to infrastructure and transport-safety assessment.
C. Naude, Ebrahim Riahi, Bastien Canu et al.· Accident Analysis and Preven...· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
