A different perspective on conspicuity related motorcycle crashes

The most common type of conflict in which a motorcyclist is injured or killed is a collision between a motorcycle and a car, often in priority situations. Many studies on motorcycle safety focus on the question why car drivers fail to give priority and on the poor conspicuity of motorcycles. The concept of ‘looked-but-failed-to-see’ crashes is a recurring item. On the other hand, it is not entirely unexpected that motorcycles have many conflicts with cars; there simply are so many cars on the road. This paper tries to unravel whether – acknowledging the differences in exposure – car drivers indeed fail to yield for motorcycles more often than for other cars. For this purpose we compared the causes of crashes on intersections (e.g. failing to give priority, speeding, etc.) between different crash types (car–motorcycle or car–car). In addition, we compared the crash causes of dual drivers (i.e. car drivers who also have their motorcycle licence) with regular car drivers. Our crash analysis suggests that car drivers do not fail to give priority to motorcycles relatively more often than to another car when this car/motorcycle approaches from a perpendicular angle. There is only one priority situation where motorcycles seem to be at a disadvantage compared to cars. This is when a car makes a left turn, and fails to give priority to an oncoming motorcycle. This specific crash scenario occurs more often when the oncoming vehicle is a motorcycle than when it is a car. We did not find a significant difference between dual drivers and regular car drivers in how often they give priority to motorcycles compared to cars.     

Issues in motorcycle sensory and cognitive conspicuity: The impact of motorcycle low-beam headlights and riding experience on drivers’ decisions to turn across the path of a motorcycle

Background

Crashes involving a passenger car and a motorcycle, where the car is turning across the path of the motorcycle, are a major crash type of motorcycle riders. It has been proposed that the incidence of such crashes could be reduced through improvements in motorcycle conspicuity. Operation of low-beam headlights on motorcycles has been discussed as one approach for improving the “sensory conspicuity” of motorcycles during daylight hours, whilst previous experience as a rider may serve to heighten “cognitive conspicuity” through raised awareness of motorcyclists on our roads.

Method

Twenty-three experienced car drivers with no riding experience (“drivers”) and 20 experienced car drivers who were also motorcycle riders (“driver–riders”) completed a series of trials in a driving simulator where their task in each trial was to turn ahead of an oncoming vehicle if they felt that they had sufficient room to do so safely. A key manipulation across trials was whether the oncoming vehicle was a motorcycle with headlights on, or a motorcycle with headlights off. Time gap (short, medium, long) was also manipulated.

Results

Results indicate that, at time gaps defined in the current study as short, low-beam headlights may confer some benefit in gap acceptance by encouraging drivers to accept fewer gaps ahead of a motorcycle with headlights on than ahead of a motorcycle with headlights off. No statistically significant differences in gap acceptance between the headlight conditions were found at either the medium or long time gaps. Irrespective of time gap, driver–riders were found to adopt a more efficient turn strategy than drivers with no direct riding experience.

Conclusions

Overall, the present research provides support for the use of low-beam headlights and riding experience as tools through which to augment the sensory and cognitive conspicuity of motorcycles, respectively. It is proposed that further research aim to explore directly the precise mechanisms underlying the observed effects.     

Driver workload during differing driving maneuvers

Motorcycle-automobile accidents occur predominantly when the car driver turns left across the motorcyclist's right-of-way. Efforts to decrease this specific collision configuration, through an increase in motorcycle conspicuity, have concentrated on the physical characteristics of the motorcycle and its rider. The work reported here examines the behavior of car drivers during different driving sequences, in particular during left-turn maneuvers. An experiment is reported that used simultaneous video-taping of the driver and the forward-looking scene. Subjects followed a preset on-road course and were observed for head movements to determine the possibility of structural interference eye-blink frequency, probe-response time, and probe response error, as measures of cognitive or mental workload. In addition, the subjects completed two major subjective workload evaluations as reflections of effort directed to different components of the driving task. Results indicated that there were significant increases in head movements and mental workload during turn sequences compared to straight driving. This result of higher driver workload may be responsible for increasing the potential for detection failure. Such a propensity is also fostered by the higher structural interference that may be expected during turns. Failures to observe during turning sequences have differing outcomes depending on the presence of opposing traffic, as during the left turn, compared with the absence of such opposition, as occurs in the right turn. Also, the less conspicuous the oncoming vehicle in the left turn scenario, the higher the probability of detection failure. At the present time the least conspicuous powered vehicle is the motorcycle.     

Effects of oncoming vehicle size on overtaking judgments

During overtaking maneuvers on two-way highways drivers must temporarily cross into the opposite lane of traffic, and may face oncoming vehicles. To judge when it is safe to overtake, drivers must estimate the time-to-contact (TTC) of the oncoming vehicle. Information about an oncoming vehicle’s TTC is available in the optical expansion pattern, but it is below threshold during high-speed overtaking maneuvers, which require a large passing distance. Consequently, we hypothesized that drivers would rely on perceived distance and velocity, and that their overtaking judgments would be influenced by oncoming vehicle size. A driving simulator was used to examine whether overtaking judgments are influenced by the size of an oncoming vehicle, and by whether a driver actively conducts the overtaking maneuver or passively judges whether it is safe to overtake. Oncoming motorcycles resulted in more accepted gaps and false alarms than larger cars or trucks. Results were due to vehicle size independently of vehicle type, and reflected shifts in response bias rather than sensitivity. Drivers may misjudge the distances of motorcycles due to their relatively small sizes, contributing to accidents due to right-of-way violations. Results have implications for traffic safety and the potential role of driver-assistance technologies.     

Motorcyclists violating hook-turn area at intersections in Taiwan: An observational study

Research has suggested that the most typical and catastrophic automobile–motorcycle crash takes place when an automobile manoeuvres into the path of an oncoming motorcycle at intersection, which involves a motorist infringing upon the motorcycle's right of way (ROW). In Taiwan, motorcycles, on the other hand, are the one that has been observed to violate the ROW of approaching automobiles at intersections. Such a ROW-violation by left-turn motorcyclists in front of approaching traffic is a safety problem in terms of its frequency and accident consequence. Using high-definition video cameras to capture motorcycles’ behaviours, the present study empirically analyses the determinants of motorcyclists violating the hook-turn area (HTA) that has been implemented in Taiwan to deter motorcyclists from violating the ROW of approaching vehicles. Mixed (random parameters) logit models are found to be superior in fitting the data to traditional binary logit models. Main findings include that there was an increased likelihood of HTA-violation at T/Y intersections, in rural areas, during non rush hours, when the riders were females, younger, when riders were travelling on mopeds or heavier motorcycles, when traffic volume was less, and when riders were with half-style helmets. Implications of the research findings, the concluding remarks, and recommendations for future research are finally provided.     

A simulator study investigating how motorcyclists approach side-road hazards

The most common form of motorcycle collision in the UK occurs when another road user fails to give way and pulls out from a side road in front of an oncoming motorcyclist. While research has considered these collisions from the car driver's perspective, no research to date has addressed how motorcyclists approach these potential hazards. This study conducted a detailed analysis of motorcyclist speed and road position on approach to side-roads in a simulated suburban setting. Novice, Experienced and Advanced riders rode two laps of a simulated route, encountering five side-roads on each lap. On the second lap, a car emerged from the first side-road in a typical ‘looked but failed to see’ accident scenario. Three Experienced riders and one Novice rider collided with the hazard. The Advanced rider group adopted the safest strategy when approaching side-roads, with a lane position closer to the centre of the road and slower speeds. In contrast, Experienced riders chose faster speeds, often over the speed limit, especially when approaching junctions with good visibility. Rider behaviour at non-hazard junctions was compared between laps, to investigate if riders modified their behaviour after experiencing the hazard. Whilst all riders were generally more cautious after the hazard, the Advanced riders modified their behaviour more than the other groups after the hazard vehicle had pulled out. The results suggest that advanced training can lead to safer riding styles that are not acquired by experience alone.     

Augmented reality cues to assist older drivers with gap estimation for left-turns

The objective of this study was to assess the effects of augmented reality (AR) cues designed to assist middle-aged and older drivers with a range of UFOV impairments, judging when to make left-turns across oncoming traffic. Previous studies have shown that AR cues can help middle-aged and older drivers respond to potential roadside hazards by increasing hazard detection without interfering with other driving tasks. Intersections pose a critical challenge for cognitively impaired drivers, prone to misjudge time-to-contact with oncoming traffic. We investigated whether AR cues improve or interfere with hazard perception in left-turns across oncoming traffic for drivers with age-related cognitive decline. Sixty-four middle-aged and older drivers with a range of UFOV impairment judged when it would be safe to turn left across oncoming traffic approaching the driver from the opposite direction in a rural stop-sign controlled intersection scenario implemented in a static base driving simulator. Outcome measures used to evaluate the effectiveness of AR cueing included: Time-to-Contact (TTC), Gap Time Variation (GTV), Response Rate, and Gap Response Variation (GRV). All drivers estimated TTCs were shorter in cued than in uncued conditions. In addition, drivers responded more often in cued conditions than in uncued conditions and GRV decreased for all drivers in scenarios that contained AR cues. For both TTC and response rate, drivers also appeared to adjust their behavior to be consistent with the cues, especially drivers with the poorest UFOV scores (matching their behavior to be close to middle-aged drivers). Driver ratings indicated that cueing was not considered to be distracting. Further, various conditions of reliability (e.g., 15% miss rate) did not appear to affect performance or driver ratings.     

Estimating the subjective risks of driving simulator accidents

We examine the subjective risks of driving behavior using a controlled virtual reality experiment. Use of a driving simulator allows us to observe choices over risky alternatives that are presented to the individual in a naturalistic manner, with many of the cues one would find in the field. However, the use of a simulator allows us the type of controls one expects from a laboratory environment. The subject was tasked with making a left-hand turn into incoming traffic, and the experimenter controlled the headways of oncoming traffic. Subjects were rewarded for making a successful turn, and lost income if they crashed. The experimental design provided opportunities for subjects to develop subjective beliefs about when it would be safe to turn, and it also elicited their attitudes towards risk. A simple structural model explains behavior, and showed evidence of heterogeneity in both the subjective beliefs that subjects formed and their risk attitudes. We find that subjective beliefs change with experience in the task and the driver's skill. A significant difference was observed in the perceived probability to successfully turn among the inexperienced drivers who did and did not crash even though there was no significant difference in drivers’ risk attitudes among the two groups. We use experimental economics to design controlled, incentive compatible tasks that provide an opportunity to evaluate the impact on driver safety of subject's subjective beliefs about when it would be safe to turn as well as their attitudes towards risk. This method could be used to help insurance companies determine risk premia associated with risk attitudes or beliefs of crashing, to better incentivize safe driving.     

Infield logistics planning for crop-harvesting operations

Crop-harvesting operations are typically carried out with combine harvesters. The harvested product is transferred to one or more tractors every time the combine harvester's storage capacity is reached. The efficiency of the process can be significantly improved by computing optimal routes and interactions for the harvest vehicles in the field. Furthermore, an automated method for generating itineraries for the harvest vehicles facilitates the planning for autonomous agricultural vehicles. The infield logistics problem is formulated as an integer linear programming vehicle routing problem with additional turn penalty constraints, but, because of the high number of decision variables, it is not possible to solve cases of realistic field size. The solution time of the infield logistics problem is considerably reduced by reformulating it as a modified minimum-cost network flow problem. This specific structure allows the exact solution of intermediate-size planning problems in a much shorter time period. The result of solving the infield logistics problem with the proposed modelling approaches is a set of itineraries (‘tours’), covering the entire field. Each ‘tour’ is characterized by the combine harvester's start and end points and the positions where the combine harvester needs to be unloaded. The planning models minimize non-productivity (i.e. the time when a combine harvester travels in a field without harvesting). The results indicate that coordination between combine harvesters and tractors is also improved.     

Crossing roads safely: an experimental study of age differences in gap selection by pedestrians

The over-representation of older pedestrians in serious injury and fatal crashes compared to younger adults may be due, in part, to age-related diminished ability to select gaps in oncoming traffic for safe road-crossing. Two experiments are described that examine age differences in gap selection decisions in a simulated road-crossing environment. Three groups of participants were tested, younger (30-45 years), young-old (60-69 years) and old-old (>75 years). The results showed that, for all age groups, gap selection was primarily based on vehicle distance and less so on time-of-arrival. Despite the apparent ability to process the distance and speed of oncoming traffic when given enough time to do so, many of the old-old adults appeared to select insufficiently large gaps. These results are discussed in terms of age-related physical, perceptual and cognitive limitations and the ability to compensate for these limitations. Practical implications for road safety countermeasures are also highlighted, particularly the provision of safe road environments and development of behavioural and training packages.     

Analysis of fatal motorcycle crashes: crash typing

There were 2074 crashes fatal to a motorcycle driver in the United States during 1992. A computer program was developed to convert Fatal Accident Reporting System (FARS) data for these crashes into standard format English language “crash reports.” The computer generated reports were analyzed and crash type categories were defined. Five defined crash type categories accounted for 1785 (86%) of the 2074 crash events: Ran off-road (41%); ran traffic control (18%); oncoming or head-on (11%); left-turn oncoming (8%); and motorcyclist down (7%). Alcohol and excessive speed were common factors associated with motorcyclist crash involvement. Left turns and failure to yield were common factors associated with the involvement of other motorists. Suggested countermeasures include helmet use and enforcement of speed and impaired driving laws.     

Relations between temperamental fear and risky pedestrian behavior

Objective

Child pedestrian injury poses a significant global public health challenge. This study examines relations between temperamental fear and children’s risky pedestrian behavior, utilizing mediation analytic strategies to study underlying mechanisms of the hypothesized relation.

Methods

As part of a larger study, 240 seven- and eight-year-old children completed 30 crossings in a virtual reality (VR) pedestrian environment. Three pedestrian behaviors were considered: start gap (lag after a traffic gap appears before child initiates crossing into the gap), time to contact (TTC; gap between avatar and the lead oncoming vehicle), and hits (collisions with vehicles in simulated crossings). Temperamental fear was measured by parent report.

Results

Fearful children were more likely to be struck by virtual vehicles, and the relation between fear and risky pedestrian behaviors was mediated by start gap and TTC. Specifically, children who were temperamentally more fearful were more likely to hesitate before initiating crossing, which led to shorter gaps between themselves and the oncoming vehicle, hence causing them to be more likely to be hit by virtual vehicles. Gender interacted with fear, such that fearful girls were most likely to be hit.

Conclusions

Both temperamental fear and gender influenced the risk of child pedestrian injuries. Delayed entry into traffic and shorter gaps between children and oncoming vehicles may underlie this relation. Future research should explore how these factors might influence the effectiveness of prevention programs.     

Validation of the motorcycle operator skill test

This study's aim was to determine what demographic and experiential factors are related to scores on the Motorcycle Operator Skill Test. It was expected that the greater the riding experience and training, the higher would be the skill scores. Applicants for a motorcycle operator's licence were administered a questionnaire and the Skill Test prior to taking the licensing test. The questionnaire and skill data for those applicants passing the licensing test were analyzed and it was found that skill was greater among the more experienced riders (i.e. miles ridden motorcycle) but unexpectedly it was lower among training course graduates. Also, males performed better than females and younger motorcyclists performed better than older motorcyclists. Further analyses revealed that course graduates had less skill than untrained riders even when experience differences were controlled. The implications of the present data for the effectiveness of motorcycle training courses are discussed.     

军用运输机驾驶装置使用需求调查

目的 了解军用运输机飞行员对中央杆、侧杆和驾驶盘的评价和使用偏好.方法 以自编的调查问卷对飞行员进行问卷调查.结果 飞行员最为关注的驾驶装置特性依次是“在载荷、振动条件下保持稳定、柔和操纵”、“提高飞机操纵品质”、“保持最佳眼位,达到最佳舱外视野”.结论 驾驶装置的研制需依次侧重稳定性、操纵品质、最佳视野等方面.     

Mind the gap: training road users to use speed and distance when making gap-acceptance decisions

Accurate gap-acceptance decisions require individuals to take into account both the distance to and the speed of an oncoming vehicle. The aim of the present studies was to develop an intervention that could successfully teach road users to focus on speed as well as distance. Across three studies, participants judged whether it was safe to cross the road or not when an oncoming vehicle was approaching from different distances and at different speeds. Study 1 trialed two techniques (“standard feedback” versus “three-look”) aimed at improving gap judgments. Standard feedback involved telling participants what the actual speed of a car was after they had made an estimate, whereas the three-look technique required participants to make timed and controlled head movements when scanning the road environment. Only standard feedback increased the participants’ mean gap-acceptance accuracy (assessed using both verbal and behavioral response measures). Study 2 also trialed two techniques, the standard feedback intervention used in Study 1, and a “two-response” intervention in which participants judged whether the oncoming vehicle was traveling at an atypical or normal speed. Study 2 found the two-response intervention to be more promising than the standard feedback procedure. Finally, Study 3 used video footage of oncoming vehicles to train younger (18–27 years) and older (60–80 years) adults and found the two-response intervention to be successful at improving gap-acceptance accuracies for both age groups. However, the intervention also resulted in more conservative gap judgments from participants in the older population independent of improvements in accuracy.     

Plasticity in small-sized metallic systems: Intrinsic versus extrinsic size effect

A material strength depends on its microstructure, which in turn, is controlled by an engineering process. Strengthening mechanisms like work hardening, precipitate, and grain boundary strengthening can alter the strength of a material in a predictive, quantitative manner and are readily linked to the deformation mechanism. This quantification strongly depends on the characteristic length scale of a particular microstructure, thereby dictating bulk material’s strength as a function of, for example, grain or precipitate size, twin boundary spacing, or dislocation density. This microstructural, or intrinsic, size governs the mechanical properties and post-elastic material deformation at all sample dimensions, as the classical definition of “ultimate tensile strength” deems it to be “an intensive property, therefore its value does not depend on the size of the test specimen.” Yet in the last 5 years, the vast majority of uniaxial deformation experiments and computations on small-scale metallic structures unambiguously demonstrated that at the micron and sub-micron scales, this definition no longer holds true. In fact, it has been shown that in single crystals the ultimate tensile strength and the yield strength scale with external sample size in a power law fashion, sometimes attaining a significant fraction of material’s theoretical strength, and exhibiting the now-commonly-known phenomenon “smaller is stronger.” Understanding of this “extrinsic size effect” at small scales is not yet mature and is currently a topic of rigorous investigations. As both the intrinsic (i.e. microstructural) and extrinsic (i.e. sample size) dimensions play a non-trivial role in the mechanical properties and material deformation mechanisms, it is critical to develop an understanding of their interplay and mutual effects on the mechanical properties and material deformation, especially in small-scale structures. This review focuses on providing an overview of metal-based material classes whose properties as a function of external size have been investigated and provides a critical discussion on the combined effects of intrinsic and extrinsic sizes on the material deformation behavior.     

The effects of changes in the traffic scene during overtaking

Overtaking maneuvers were studied in real traffic, by comparing cases where a change in the opposite traffic occurred during the overtaking maneuver i.e., appearance of an oncoming car, with cases where no change occurred during the maneuver i.e., either an already apparent oncoming car or no oncoming car. In total 45 naturally occurring cases of overtaking were analysed. By examining the time headways (TH) between the overtaking car and the other cars involved, at the end of the maneuver, a significant correlation was found between the TH to opposite traffic and the TH rear to the overtaken car. In cases where a change in the opposite traffic occurred and the proximity to opposite traffic was below a critical TH (<4 s) the appearance of a new-oncoming car caused the overtakers to actively press, both longitudinally and laterally, close to the overtaken car. In cases of overtaking where no change in the opposite traffic occurred, the TH rear to the overtaking vehicle was unaffected by the TH to the opposite traffic. Interestingly, in comparing cases where an oncoming car appeared during overtaking with cases where an oncoming car was apparent from the start of the maneuver both the TH to the opposite traffic and the duration of the maneuver were not found to be significantly different. It is suggested that drivers were probably expecting to be confronted with an oncoming car during the overtaking. However, the decreased available time to disambiguate this situation leads the overtaking driver to limit the rear safety margin of the vehicle being overtaken. The appropriateness of this practice, in terms of safety, remains questionable.     

The intention and willingness to pay moving violation citations among Taiwan motorcyclists

This study uses three-level scenario design and Spike model constructs to investigate the risk premium Taiwan motorcycle operators are willing to pay for moving violations. The primary focus of the investigation is on four types of moving violations including speeding, running red lights, right turn on red violations, and drunk driving. In the model, these four types of violations influence the willingness to pay a risk premium. The results show that, in addition to increasing enforcement, raising the level of fines is one of the most effective methods to influence levels of compliance. Estimated results through the Spike model show that speeders will accept a risk premium of NT$740 (US$1 = NT$30), while motorcycle operators who run red lights will accept a risk premium of NT$1100, motorcycle operators who turn right on red will accept a risk premium of NT$367, and motorcyclists who drive drunk will accept a risk premium of NT$18,540. This indicates that current fines in Taiwan could be raised.     

Structural optimization of a motorcycle chassis by pattern search algorithm

Changes to the technical regulations of the motorcycle racing world classes introduced the new Moto2 category. The vehicles are prototypes that use single-brand tyres and engines derived from series production, supplied by a single manufacturer. The stability and handling of the vehicle are highly dependent on the geometric properties of the chassis. The performance of a racing motorcycle chassis can be primarily evaluated in terms of weight and stiffness. The aim of this work is to maximize the performance of a tubular frame designed for a motorcycle racing in the Moto2 category. The goal is the implementation of an optimization algorithm that acts on the dimensions of the single pipes of the frame and involves the design of an objective function to minimize the weight of the frame by controlling its stiffnesses.     

Influence of road markings,lane widths and driver behaviour on proximity and speed of vehicles overtaking cyclists

The proximity and speed of motor traffic passing cyclists in non-separated conditions may be so close and so great as to cause discomfort. A variety of road design and driver behaviour factors may affect overtaking speeds and distances. The investigation presented in this paper builds on previous research and fills gaps in that research by considering the presence of cycle lanes on 20 mph and 30 mph roads, different lane widths, different lane markings, vehicle type, vehicle platooning and oncoming traffic. Data were collected from a bicycle ridden a distance of one metre from the kerb fitted with an ultrasonic distance detector and forward and sideways facing cameras.