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Speeding increases the likelihood and severity of road traffic crashes, but many riders do not consider speeding as a serious safety issue. By using belief-based variables derived from the Theory of Planned Behaviour (i.e. behavioural beliefs, normative beliefs, and control beliefs), this study investigated the socio-cognitive determinants of speeding intentions among Vietnamese adolescents operating motorized/electrified two-wheelers. 189 adolescent powered two-wheeled riders in Ho Chi Minh City participated in a cross-sectional survey. The results lend clear support to the Expectancy-Value approach since belief-based product factors (e.g. outcome beliefs x outcome evaluations) significantly and independently contributed to the prediction of speeding intentions. Speeding intentions were mostly influenced by behavioural beliefs, followed by normative beliefs and control beliefs, respectively. This study not only proves the Expectancy-Value approach as an appropriate framework for the investigation of speeding intentions but also supports authorities in the formulation and execution of more effective interventions for reducing speeding among adolescent powered two-wheeled riders in Vietnam. Instead of motivation-oriented methods, there is a need for strategies that stimulate the translation of good intentions into the desirable behaviour, and encourage adolescents not to relapse in case they are exposed to risk facilitating circumstances. Yet, besides focussing on person-specific dispositions towards speeding, policy makers are advised to adopt a more broadly encompassing systemic approach with inclusion of safe roads, safe vehicles, improved post-crash care, and shared stakeholder responsibilities. [ABSTRACT FROM AUTHOR]

• Motorcyclists' responses to occluded-surprise and expected conflicts was studied. • Most riders preferred braking over swerving at the beginning of the interaction. • Linear relationship existed between the deceleration rates and time-to-collisions. • Linear relationship existed between the jerk values and time-to-collisions. • There was no significant effect of scenario type on the jerk behavior. Evasive action performance of motorcycle riders plays a vital role in the prevention of road crashes. In possible conflicting scenarios, motorcycle riders need to respond quickly and perform evasive actions successfully to prevent collisions with other vulnerable road users such as crossing pedestrians. To study the motorcycle rider behavior in conflicts with occluded and visible pedestrians, we designed four mock-up pedestrian scenarios, which includes, two surprise scenarios, one stationary scenario, and one expected scenario. Riders' responses to the conflicts were measured using instrumented vehicle's trajectory. Most riders preferred deceleration over swerving at the beginning of the interaction, followed by swerving at manageable speeds. Further, the analysis of riders' deceleration rates revealed that a linear relationship existed between the deceleration rates and time to collisions (TTC). The study also analyzed the riders' responses using repeated-measures analysis of variance (RM-ANOVA) to check for the effect of scenario type on deceleration rates. Results indicated that scenario type significantly affected the mean deceleration rates. Further, RM-ANOVA analysis carried out on the jerk behavior of motorcycle riders indicated that there was a significant effect of scenario type on the jerk behavior. Motorcycle riders' jerks varied linearly with TTC and motorcyclists employ relatively higher decelerations and jerks when faced with pedestrians emerging suddenly from occluded locations such as from the blind spots formed due to parked vehicles. This study helps in understanding motorcycle rider behavior in critical situations and shows the need for assistive evasive systems for motorcycle riders to mitigate collisions with other vulnerable road users. [ABSTRACT FROM AUTHOR]

This article reports a systematic investigation carried out to model the lateral movement decisions of Powered-Two-Wheelers (PTWs) in disordered heterogeneous traffic conditions. The lateral maneuvering decisions of PTWs were framed as a typical multiclass classification problem, and significant factors governing such decisions were identified. Four machine learning models, along with the statistical model, were built to achieve this objective. The comparative analysis regarding the predictive performance of these models shown that the random forest model outperforms the rest of the considered models in terms of its classification power. To this end, the results from this investigation revealed that the lateral movement pattern of PTWs could be predicted using speed and spatial information of its surrounding vehicles. Interestingly, this information can be seamlessly collected with some sensors presently deployed in the advanced vehicles. Thus, the developed models would help in the design of active safety and driving assistance systems for such vehicles. [ABSTRACT FROM AUTHOR]

In many countries, urbanization has seen a rapid increase in demand for mobility in cities. Much of this demand is met by private vehicles, of which conventionally powered two-wheelers significantly contribute to air pollution. The consumer adoption of alternative fuel powered two-wheelers has not been the subject of as much study as passenger cars. In particular, studies of consumer adoption of electric motorcycles, which are a rapidly emerging and an environmentally more sustainable alternative to conventional powered two-wheelers, are few. This study explores the extent of this research gap. The development of motorcycles is analyzed with a focus on Asia, which accounts for 80% of the global fleet. Powered two-wheelers are categorized in terms of regulatory, fuel and technical aspects. Studies of the adoption of electric motorcycles are reviewed. Operational models and deployment in ownership-based or access-based economical models are discussed. An overview of the research methods that are used in existing studies of electric motorcycles is given and the results and their implications are discussed. These findings provide a useful insight for future research, for transportation managers and for policymakers. [ABSTRACT FROM AUTHOR]

• Response patterns of PTW riders vary depending on the type of traffic conflict. • Intense steering plays major role in evading PTW conflicts than hard braking. • Right turning PTW crossing through moving vehicles experience higher crash risk. • Combined steering and braking is the most frequent evasive action for PTW riders. • Through moving PTW crossing through moving vehicles commit driver/rider error. The study investigates the braking and steering evasions of powered two-wheelers (PTWs) during severe conflicts observed at an unsignalized intersection. Traffic conflicts were detected using a surrogate safety indicator called anticipated collision time (ACT). Then the peak-over-threshold approach was used to identify the severe conflicts and the evasive actions. Conflicts between right-turning PTWs and through-moving vehicles, through-moving PTWs crossing through-moving vehicles, and merging/diverging PTWs were analyzed using the minimum ACT (ACT min), maximum deceleration rate (DR max), maximum yaw rate (YR max), and time of evasive action (TEA). The evasive actions were classified into five categories: driver/rider error, no-evasion, braking-only, steering-only, and both braking and steering. Analysis reveals that right-turning PTWs experience higher crash risk (0.7 %) than the other movements. PTW riders primarily employ extreme steering maneuvers (greater than 13 degrees/s) to evade conflicts, whereas braking rates lie in the normal ranges (less than 1.5 m/s2). The time of evasive action varies between 2.04 and 2.44 s, with the right-turning PTW riders responding early. Through-moving riders commit errors while evading severe conflicts and perform fewer evasive actions than right-turning and merging/diverging riders. Right-turning riders perform more steering-only evasions than braking-only, whereas the riders involved in the other two conflicts execute more braking-only evasions. These findings suggest that conflict type influences riders' braking and steering responses. Hence, future applications in advanced driver/rider assistance systems and training programs should consider appropriate evasive action strategies for different conflict types. [ABSTRACT FROM AUTHOR]

A difference between Powered Two Wheelers (PTW) drivers’ behavior and other drivers’ behavior in urban arterials is the frequency of overtaking. The present paper focuses on PTW overtaking and models the specific behavior using concepts of Game Theory. Both the PTW driver and the lead vehicle’s driver are assumed rational decision-makers that develop strategies, trying to maximize their payoffs. These strategies may be cooperative or not with respect to the distances and safety gaps and other behavioral aspects. The payoff function is formulated based on a novel latent statistically determined driving indicator, which quantifies both the driving risk and comfort. The proposed model is evaluated using trajectory data from video recordings on an urban arterial. Results show that both drivers have maximized gains by following a cooperative strategy. Findings also reveal that the successful overtaking rate is higher, when the PTW driver is non-cooperative, whereas lower overtaking rates occur, when the driver of the lead vehicle is non-cooperative. Finally, the concepts of Dominant Strategies, bounded rationality and the construction of the optimum payoff function are further discussed.

Highlights • Data from 428 in-depth powered two-wheeler crashes were clustered. • This analysis identified the main factors that contribute to crash occurrence. • The latent class clustering and test of independence resulted in seven clusters. • Different mechanisms for riders and other road users were indicated. • Results provided detail on how factors interact in different crash types. Abstract Powered two wheeler (PTW) riders are a group of vulnerable road users that are overrepresented compared to other road user groups with regards to crash injury outcomes. The understanding of the dynamics that occur before a crash benefits in providing suitable countermeasures for said crashes. A clearer interpretation of which factors interact to cause collisions allows an understanding of the mechanisms that produce higher risk in specific situations in the roadway. Real world in-depth crash data provides detailed data which includes human, vehicular and environmental factors collected on site for crash analysis purposes. This study used macroscopic on-scene crash data collected in the UK between the years 2000–2010 as part of the "Road Accident In-depth Study" to analyse the factors that were prevalent in 428 powered two-wheeler crashes. A descriptive analysis and latent class cluster analysis was performed to identify the interaction between different crash factors and develop PTW scenarios based on this analysis. The PTW rider was identified as the prime contributor in 36% of the multiple vehicle crashes. Results identified seven specific scenarios, the main types of which identified two particular 'looked but failed to see' crashes and two types of single vehicle PTW crashes. In cases where the PTW lost control diagnosis failures were more common, for road users other than the PTW rider detection issues were of particular relevance. [ABSTRACT FROM AUTHOR]

Driving errors are considered to be the greatest contributory cause in all road accidents and an important contributory cause of most fatal accidents. This is particularly the case for the users of powered two-wheeled vehicles (PTWs), perhaps because PTW riders play a greater role in the control of their vehicles’ stability than four-wheeled vehicle drivers. Thus, observing and analyzing the evolution of riders’ behavior in a real-life context is an important step in the identification of the road environment characteristics that constitute a risk factor for PTW riders. A relevant research issue in naturalistic studies is related to the detection and identification of critical riding events from among the vast amount of data recorded during the experiment. In this paper, two approaches were used to automatically detect such critical riding events. First, we formalized this problem in terms of detecting changes in the mean and variance of the signals generated by the acceleration and angular velocity sensors. For this purpose, two steps were performed: 1) a data segmentation and feature extraction step in which the multidimensional time series of accelerometer and angular velocity data were segmented and modeled using a Gaussian mixture model with quadratic logistic proportions; and 2) a classification step in which each detected segment was assigned to the appropriate riding sequence, whether “naturalistic” or “critical” (i.e., fall or near fall), using the k-nearest neighbor algorithm. The second approach was based on online fall detection. This methodology used control charts (a multivariate cumulative sum), an approach that has been traditionally employed for sequential detection. These two algorithms were applied to a database composed of data from a real-life driving experiment. The obtained results show the effectiveness of both methodologies. [ABSTRACT FROM AUTHOR]

• Motorcycles exhibit a significantly higher incidence of severe traffic conflicts at intersections than other motorized vehicles. • Intersections with traffic flows and poor visibility to the left are identified as high-risk areas for motorcyclists. • Motorcycle taxi drivers are the user group with the highest frequency and exposure involved in traffic conflicts. • Motorcyclists who engage in risky behaviors and fail to follow road safety regulations increase the potential for traffic conflicts. The global motorcycle market has grown significantly, with over 770 million vehicles estimated to be in use worldwide. Motorcycle-related road traffic deaths in low and middle-income countries (LMICs) like Colombia are concerning, comprising 30% of all reported fatalities. Cartagena has an average of 70 motorcycle-related deaths annually between 2019 and 2022, making it a high-risk area for motorcyclists. The study aimed to identify factors associated with motorcyclist safety at unsignalized three-legged and four-legged intersections in Cartagena by observing the behavior of the motorcyclists and the analysis of the potential traffic conflicts. The observational analysis focused on the access of motorcyclists from a secondary road to a main road since it is the behavior offered by the most significant road interaction and the potential risk of traffic conflicts due to crossing. The observational process was consolidated at ten three-legged intersections and seven four-legged intersections. Thirty-six hours of videos were collected considering different time slots and weekdays randomly distributed during September 2019 and March 2020. The selection of the intersections included different vehicular flows and road safety conditions. The variables considered in the study were: interaction with other road users, motorcyclist behavior, vehicle handling, potential distractors, and safety elements. The study used the Swedish Traffic Conflict Technique to analyze conflict analysis, incorporating the Post Encroachment Time (PET) measurement. The analysis was developed with descriptive and inferential statistical techniques. The collected variables were analyzed individually (frequency analysis), and contrasts were conducted with the PET values. The study evaluated associations between motorcycles and other motorized road actors at intersections about behaviors and crossroads. In the Records, 10,281 motorcycle accesses at three and four-Legged Intersections were interactions with other road users, where 2417 and 1903 resulted in potential traffic conflicts, respectively. Average potential conflicts per hour were 115 and 127 at three and four-legged intersections. At the two intersections, the average PET values in motorcycles were between 2.09 and 2.10 s, while in the other motorized road users, it averaged around 2.67 to 2.71 s. In the road conditions, it was identified that intersections with a traffic flow of<10,000 vehicles/day and poor visibility to the left of the intersection lead to more unsafe conditions for motorcyclists. Motorcycle taxi drivers were the user group most frequently involved in traffic conflicts. Actions on the part of motorcyclists, such as risky behaviors, not using helmets, not using turn signals, and not waiting patiently for access, showed a relationship with the potential for traffic conflicts. Finally, turns to the left, particularly the indirect turn to the left on the opposite road, showed a greater risk of traffic conflicts. The study found that motorcycles exhibit more severe traffic conflicts than motorized vehicles at intersections. Infrastructure conditions significantly impact the risk of intersection conflicts. Individual behaviors such as not stopping at intersections and driving recklessly increased the risk of traffic conflicts. The study recommends improving infrastructure such as visibility and signaling and implementing separators to reduce travel speed and traffic conflicts for motorcycles. [ABSTRACT FROM AUTHOR]

Currently studies exploring the effect of real-time traffic and weather characteristics on crash severity are relatively limited, and studies focusing on powered two-wheelers (PTWs) are even fewer. The objective of this paper is to add to current knowledge through the investigation of PTW occupant injury severity on the urban motorway Attica Tollway in Athens, Greece. For that purpose, 163 crashes (23 severe/fatal and 140 slight) that occurred between 2006 and 2011 were analyzed by considering real-time traffic and weather parameters. The required crash data was extracted from the Greek crash database of the National Technical University of Athens and also Attica Tollway. Traffic data were extracted from the Traffic Management Center of Attica Tollway, and weather data were extracted from the Hydrological Observatory of Athens (HOA). To reduce data dimensionality and to overcome multicollinearity between variables, a two-step approach was followed. First, principal component analysis and random forests were used as preliminary analyses. To account for the low number of and proportion of killed and severely injured (KSI) occupants, a Firth logistic regression was then applied. Results showed that in general, traffic and speed variations caused more severe injuries whereas weather parameters seemed to have no effect. It was also found that mean speeds and variations in volumes of trucks increased the crash injury severity of PTW crashes, but it was interesting that an increased proportion of trucks led to slighter injuries. The findings of this paper are considered promising and will contribute to better understanding of occupant injury severity on urban motorways by focusing on PTWs. [ABSTRACT FROM AUTHOR]

Objective: The ISO13232 standard provides guidelines and methodologies for research on the effectiveness of protective devices fitted to motorcycles. The accident database used to develop the standard was composed of 2 data sets from Hannover and Los Angeles, dating from 1996. This study aims to apply the methodology outlined in the standard to a more recent European accident database to determine whether the set of the 7 most relevant impact configurations identified in the ISO13232 are representative of the European context.Methods: The ISO13232 database was rebuilt from the data tables attached to the standard and processed according to the procedure described in ISO13232-Part 2, to ensure reproducibility of the results. The comparison data set was extracted from the Motorcycle Accidents In-Depth Study (MAIDS) database. Data were then coded, processed, and analyzed using the ISO13232 methodology. To eliminate any subjectivity in the selection process of the configurations, a new ranking criterion (configuration risk index, CRI) was implemented. The CRI combined the evaluation of an accident configuration's frequency of occurrence and its harmfulness.Results: Comparison of the frequency ranking of the impact configurations from the 2 databases revealed some notable differences. Five of the 10 most important configurations were common to both databases, although ranking order differed. CRI-based selection led to differences in ranking orders. The CRI allowed better identification of the most important configurations and it was employed to define the proposed new set of configurations.Conclusion: A new set of 7 accident configurations was defined by applying the ISO13232 procedure to the MAIDS data and ranking the results with a newly proposed method. The final set had only one configuration in common with those defined in the ISO13232, testifying to the importance of defining an updated and more representative set of configurations for the European context. [ABSTRACT FROM AUTHOR]

The scientific literature indicates that solid particle number (SPN) emissions of motorcycles are usually higher than that of passenger cars. The L-category (e.g., mopeds, motorcycles) Euro 4 and 5 environmental steps were designed to reduce the emissions of particulate matter and ozone precursors such as nitrogen oxides and hydrocarbons. In this study the SPN emissions of one moped and eight motorcycles, all fulfilling the Euro 4 standards, were measured with a SPN measurement system employing a catalytic stripper to minimize volatile artefacts. Although the particulate matter mass emissions were 11 particles/km with sizes larger than 23 nm) and four motorcycles exceeded the limit by a factor of up to four. The measurement repeatability was satisfactory (deviation from the mean 10%) and concentration differences between tailpipe and dilution tunnel were small, indicating that performing robust SPN measurements for regulatory control purposes is feasible. However, steady state tests with the moped showed major differences between the tailpipe and the dilution tunnel sampling points for sub-23 nm particles. Thus, the measurement procedures of particles for small displacement engine mopeds and motorcycles need to be better defined for a possible future introduction in regulations.

Objective: The objective of this study is to estimate the crash risk per kilometer traveled by powered two-wheeler (PTW) riders filtering through traffic on urban roads. Methods: Using the traffic injury crashes recorded by the police over a period of 3 years on 14 sections of urban roads in the city of Marseille, France, and a campaign of observations of PTWs, the crash risk per kilometer traveled by PTWs filtering was estimated and compared to the risk of PTWs that did not filter. Results: The results show that the risk of PTW riders being involved in injury crashes while filtering is significantly higher than the risk for riders who do not filter. For the 14 sections studied, it is 3.94 times greater (95% confidence interval [CI], 2.63, 5.89). This excess risk occurred for all PTW categories. Furthermore, no space appears to be safer than the others for filtering. Riders filtering forward along the axis of the carriageway, along bus lanes, or between traffic lanes (lane-splitting) all have a crash risk greater than the risk of those who do not filter. Conclusions: All measures limiting the practice of filtering by PTWs on urban roads would probably contribute to improving the safety of their users. [ABSTRACT FROM AUTHOR]

• Powered two wheelers evade sideswipe conflict by extreme steering instead hard brakes. • On six-lane highways sideswipe crash risk is higher for powered two wheelers. • Non-stationary extreme value models outperform stationary ones. • Sideswipe crash risk increases with the increase in maximum yaw rate, deceleration. Evaluating the impact of evasive actions such as braking and steering on the crash risk assessment of vehicles is a scarce endeavor due to the lack of relevant data. This study uses Extreme Value Theory to investigate and model the effect of evasive actions on the sideswipe crash risk of powered two-wheelers (PTWs) moving on multilane rural highways. The crash risk was projected from the observed sideswipe conflicts that were quantified using a surrogate safety indicator called anticipated collision time (ACT). The vehicle trajectory data extracted from traffic videos, collected using an unmanned aerial vehicle, was used as the input for the analysis. The data was denoised using a state-of-the-art trajectory reconstruction method called recursively ensembled low pass filtering. Once the conflicts were identified from the trajectory data, the crash risk models were developed considering five covariates: maximum deceleration rate, maximum yaw rate, and the times spent in decelerating, accelerating, and steering during a sideswipe conflict. These covariates were used to capture the non-stationarity in the traffic conflict extremes. The best performing non-stationary model was selected by comparing the negative log-likelihood values with the stationary-one. The findings suggest that the PTWs experience significant sideswipe crash risk on four-lane (crash risk 0.09%) and six-lane (crash risk 0.17%) highways. The sideswipe crash risk of PTWs increases with the increase in the intensity of braking and steering actions measured in terms of maximum deceleration and yaw rates. Further, this study emphasizes that incorporating the effects of evasive actions in the crash risk estimation and developing non-stationary models could significantly improve the precision of crash frequency estimates. Based on the findings it can be concluded that for the safety improvement of PTWs on multilane highways, lane-restriction should be imposed which can increase the safety margin during sideswipe conflicts. [ABSTRACT FROM AUTHOR]

The present paper employs advanced statistical modeling in order to assess the spatial factors that may influence the maneuverability of Powered Two-Wheelers (PTW) in urban corridors during overtaking. Using trajectory data from video recordings, two types of maneuvers are examined: those that occur with a lane change and those conducted without speed change and/or lane change (on the fly). The modeling approach has two parts: First, the probability to conduct an overtake is statistically modeled. Second, a Multiple Indicators-Multiple Causes (MIMIC) latent variable model is developed to assess the microscopic traffic characteristics and other critical factors that may affect the maneuverability of PTW. Results show that during overtaking, speed difference from the preceding vehicle is the most significant factor. Further results from the MIMIC model indicate that the PTW maneuverability is related to the type of overtake, the distance between the PTW and the vehicle being overtaken, as well as speeds. [ABSTRACT FROM PUBLISHER]

Motorcyclists have a relative high risk of crash involvement. As a consequence there is an on-going search for safety measures to improve road safety for motorcyclists. One popular measure is motorcycle training. Although intuitively sound, there are only few thorough studies on rider training courses and they do not always show a positive safety effect. The aim of this study was to assess the effects of the advanced rider training course ‘Risk’. Through random assignment motorcyclists ( N = 222) were assigned to an experimental and control condition. At pre- and post-test, participants completed a questionnaire and their riding behaviour was assessed in an on-road ride. Furthermore, a selection of participants took a hazard perception test at post-test. Participants in the experimental condition ( n = 137) followed the advanced training course ‘Risk’ between pre- and post-test. Result s indicated that trained participants were rated higher on safe riding than the control group. A positive effect was also found for riding behaviour, i.e., speed and position on the road if it needed to be adapted to increase visibility and in reaction to potential hazard. The training did not affect riders’ assessment of their own riding behaviour. Overall the trained riders performed better on the hazard perception test. This study is a step forward to demonstrate that motorcyclists’ traffic behaviour can be positively influenced by the right training course. Crucial for this training course is that it did not lead to overconfidence, while it quantifiably improved traffic behaviour. [ABSTRACT FROM AUTHOR]

Introduction The risk of collision between pedestrians and powered two-wheelers is poorly understood today. The objective of this research is to determine the risk for powered two-wheeler drivers of hitting and injuring a pedestrian per kilometer driven in towns and to compare this risk with that run by four-wheeled vehicle drivers. Method Using the bodily injury accidents recorded by the police on nine roads in the city of Marseille in 2011 and a campaign of observations of powered two-wheeler traffic, we estimated the risk per kilometer driven by powered two-wheeler drivers of hitting a pedestrian and compared it with the risk run by four-wheeled vehicle drivers. Results The results show that the risk for powered two-wheeler drivers of hitting and injuring a pedestrian is significantly higher than the risk run by four-wheeled vehicle drivers. On the nine roads studied, it is on average 3.33 times higher (95% CI: 1.63; 6.78). Taking four more years into account made it possible to consolidate these results and to tighten the confidence interval. Conclusion There does indeed seem to be problems in the interactions between pedestrians and powered two-wheeler users in urban traffic. These interaction problems lead to a higher risk of hitting and injuring a pedestrian for powered two-wheeler drivers than for four-wheeled vehicle drivers. The analysis of the police reports suggests that part of this increased risk comes from filtering maneuvers by powered two-wheelers. Practical applications Possible countermeasures deal with the urban street layout. Measures consisting in reducing the width and the number of traffic lanes to a strict minimum and installing medians or pedestrian islands could be an effective way for the prevention of urban accidents between pedestrians and powered two-wheelers. [ABSTRACT FROM AUTHOR]

Regulated and unregulated emissions from a 2-stroke and a 4-stroke scooter were characterized during a legislative driving cycle in a certified laboratory. Scooter exhaust was analyzed at the tailpipe, in a dilution tunnel, and partly collected in a mobile smog chamber for photochemical ageing. We present evidence that the photochemically aged exhaust from a 2-stroke and a 4-stroke scooter produces considerable amounts of secondary organic aerosol: from 1.5 to 22.0 mg/km, and from 5.5 to 6.6 mg/km, respectively. Tests were repeated after replacing the standard petrol and synthetic lube oil with an alkylate fuel (with low content of aromatic compounds) and ultra-clean lube oil (low ash forming potential). We observed emission reduction (with some exceptions) for several gaseous and particulate phase species, in particular for carbon monoxide (from 8% up to 38% and from 31% to 50%, for the 2-stroke and the 4-stroke scooters, respectively), particulate mass (from 32% up to 75% for the 2-stroke scooter), aromatic compounds (89% and 97% for the 2-stroke and the 4-stroke scooter, respectively), and secondary organic aerosol (from 87% to 100% and 99% for the 2-stroke and the 4-stroke scooters, respectively). We attribute the organic aerosol reduction to the low content of aromatics in the alkylate fuel. [ABSTRACT FROM AUTHOR]

Abstract: For a few years, the use of powered two-wheelers has taken off in Paris. It then became critical for the City of Paris to understand both the mechanisms leading to traffic accidents involving at least one powered two-wheelers user and the perception of their risk when riding in dense urban areas. In so doing, two studies were carried out along similar lines so that their results could be compared. The first study focused on the perception of situations where accidents are most likely to occur. The second one was an analysis of police reports of accidents involving at least one powered two-wheelers and the drawing-up of prototypical accident scenarios. Comparing the results of the two studies revealed a gap between perceived and objective risks of these users. In fact, they rather fear the situations during which a car driver is changing lanes, while accidents involving them occur more often when a car driver turns (right, left or U). Knowledge of this dissonance in terms of awareness of road risks for powered two-wheelers and equally, other road users, will give the City of Paris food for thought. The promising results of this study have encouraged the City of Paris to extend it to other types of users, such as cyclists or elderly pedestrians. [Copyright &y& Elsevier]

Abstract: Aim of the study was the analysis of powered two-wheeler (PTW) crashes in Italy in order to detect interdependence as well as dissimilarities among crash characteristics and provide insights for the development of safety improvement strategies focused on PTWs. At this aim, data mining techniques were used to analyze the data relative to the 254,575 crashes involving PTWs occurred in Italy in the period 2006–2008. Classification trees analysis and rules discovery were performed. Tree-based methods are non-linear and non-parametric data mining tools for supervised classification and regression problems. They do not require a priori probabilistic knowledge about the phenomena under studying and consider conditional interactions among input data. Rules discovery is the identification of sets of items (i.e., crash patterns) that occur together in a given event (i.e., a crash in our study) more often than they would if they were independent of each other. Thus, the method can detect interdependence among crash characteristics. Due to the large number of patterns considered, both methods suffer from an extreme risk of finding patterns that appear due to chance alone. To overcome this problem, in our study we randomly split the sample data in two data sets and used well-established statistical practices to evaluate the statistical significance of the results. Both the classification trees and the rules discovery were effective in providing meaningful insights about PTW crash characteristics and their interdependencies. Even though in several cases different crash characteristics were highlighted, the results of the two the analysis methods were never contradictory. Furthermore, most of the findings of this study were consistent with the results of previous studies which used different analytical techniques, such as probabilistic models of crash injury severity. Basing on the analysis results, engineering countermeasures and policy initiatives to reduce PTW injuries and fatalities were singled out. The simultaneous use of classification trees and association discovery must not, however, be seen as an attempt to supplant other techniques, but as a complementary method which can be integrated into other safety analyses. [Copyright &y& Elsevier]

Abstract: Powered two wheelers (PTWs) come in diverse forms and are used for a range of purposes in very different parts of the world. In many parts of the world, the forms and uses of PTWs are changing, influenced by social, economic and demographic changes. Most of the challenges associated with PTWs relate to safety, while the majority of the opportunities relate to mobility. The challenges for improving safety relate to the PTW user, other road users, the road environment, the vehicle, data and research, and socio-political dimensions. The relative importance of particular challenges varies between developed and developing countries, and among developing countries according to whether PTWs are largely used for recreation or for transport. PTWs present a range of psychological, transport, economic and environmental opportunities to individuals and societies. The fun and excitement of riding PTWs is a major motivator for their purchase and use for recreational purposes, both off-road and on-road. The transport and economic advantages to the individual also need to be considered. At a societal level, research has examined the potential for increasing PTW volumes to reduce fossil fuel use and traffic congestion in busy cities. The future of PTWs may differ greatly between countries and environmental and technological changes are leading to an evolution in the form of PTWs to encompass new modes of personal transportation. [Copyright &y& Elsevier]

Air pollution remains a serious concern for European citizens. The relative contribution of mopeds and motorcycles to air pollution started to increase as the levels from other vehicles started to decrease. The information on emission levels of Euro 4 motorcycles is limited because they were only recently introduced into the market (2016). In this study, the emissions of a 1 L Euro 4 motorcycle were determined with two drivers and two different sampling configurations (i.e., open or closed transfer tube to the dilution tunnel; both allowed in the current regulation). The motorcycle respected the current Euro 4 limits and even the future Euro 5 limits for most pollutants (CO 600 mg/km, NOx 48 mg/km, total hydrocarbons 60 mg/km). The particulate emissions, which are not regulated for this category of vehicles, were also very low and fulfilled the current limits of passenger cars (particulate mass < 0.5 mg/km, particle number 3 × 1011 p/km). The total particle emissions (i.e., including volatiles) were also low with the open configuration (6 × 1011 p/km). They increased more than one order of magnitude with the closed configuration due to desorption of deposited material from the transfer tube. For the gaseous pollutants, there was no significant difference between open or closed configuration (CO2 within 0.3%, rest pollutants 10%), but they were different between the two drivers (CO2 1.3%, rest pollutants 25%–50%). The main message from this work is that open and closed configurations are equivalent for gaseous pollutants but the open should be used when particles are measured. [ABSTRACT FROM AUTHOR]

• This study investigated PTW crashes occurred in Spain in the period 2011–2013. • The study used different data mining techniques: classification trees and rules discovery. • Crash types associated with high severity are run-off-the-road (ROR) and head-on (HO) crashes. • Crash patterns associated with high severity and with ROR and HO crashes have been singled out. • Countermeasures to mitigate PTW severe injuries and fatalities are suggested. Powered two-wheelers (PTWs) are growing globally each year as they are considered an attractive alternative to cars (flexible, small, affordable, fast and easy to park), especially on congested traffic situations. However, PTWs represent an important challenge for road safety. In fact, in 2016, Spain ranked fifth in terms of PTW fatalities among EU 28. For this reason, this paper aims to investigate which are the patterns among crash characteristics contributing to PTW crashes in Spain. Data from 78,611 crashes involving PTWs occurred in Spain in the period 2011–2013 were analyzed. The analysis was performed by using classification trees and rules discovery which are suitable models aimed at extracting knowledge and identifying valid and understandable patterns from large amounts of data previously unknown and indistinguishable. The response variables assessed in this study were severity and crash type. As a result, several combinations of road, environmental and drivers' characteristics associated with severity and typology of PTW crashes in Spain were identified. Based on the analysis results, several countermeasures to solve or mitigate the safety issues identified in the study were proposed. From the methodological point of view, study results show that both the classification trees and the a priori algorithm were effective in providing non-trivial and unsuspected relations in the data. Classification trees structure allowed a simpler understanding of the phenomenon under study while association discovery provided new information which was previously hidden in the data. Given that the results of the two different techniques were never contradictory, we recommend using classification trees and association discovery as complementary approaches since their combination is effective in exploring data providing meaningful insights about PTW crash characteristics and their interdependencies. [ABSTRACT FROM AUTHOR]

The scientific literature indicates that solid particle number (SPN) emissions of motorcycles are usually higher than that of passenger cars. The L-category (e.g., mopeds, motorcycles) Euro 4 and 5 environmental steps were designed to reduce the emissions of particulate matter and ozone precursors such as nitrogen oxides and hydrocarbons. In this study the SPN emissions of one moped and eight motorcycles, all fulfilling the Euro 4 standards, were measured with a SPN measurement system employing a catalytic stripper to minimize volatile artefacts. Although the particulate matter mass emissions were <1.5 mg/km for all vehicles tested, two motorcycles and the moped were close to the SPN limit for passenger cars (6 × 1011 particles/km with sizes larger than 23 nm) and four motorcycles exceeded the limit by a factor of up to four. The measurement repeatability was satisfactory (deviation from the mean 10%) and concentration differences between tailpipe and dilution tunnel were small, indicating that performing robust SPN measurements for regulatory control purposes is feasible. However, steady state tests with the moped showed major differences between the tailpipe and the dilution tunnel sampling points for sub-23 nm particles. Thus, the measurement procedures of particles for small displacement engine mopeds and motorcycles need to be better defined for a possible future introduction in regulations. [ABSTRACT FROM AUTHOR]