Motorcycle active safety systems: Assessment of the function and applicability using a population-based crash data set

Classifying safe following distance for motorcycles to prevent rear-end collisions

This study aims to classify motorcycle (MC) following distance based on trajectory traffic data and identify the risks associated with MC following distances to prevent rear-end collisions. A total of 8,223 events of a MC following a vehicle were investigated in Pathum Thani, Thailand, and 41 cases of MC rear-end crashes were analyzed between 2017 and 2021. Time headway (TH), safe stopping distance (SSD) and time to collision (TTC) were applied to the proposed concept to determine safe following distance (SFD). Speed and following distance for actual rear-end crashes were applied to validate SFD. Results showed that the proposed SFD model identified the causes of MC rear-end collision events as mostly due to longitudinal critical area (38 cases, 92.68%), implying insufficient MC rider reaction and decision time for evasive action. The longitudinal warning area had relatively few chances for rear-end collisions to occur, with only 3 cases recorded. VDO clip extracts from MC rear-end crashes illustrated 11 cases (26.83%) of rider fatality. The study findings revealed that the SFD concept can help to prevent MC rear-end collision events by developing reminder systems when the rider reached the following distances of both warning and critical areas.

Motorcycle emergency steering assistance: A systematic approach from system definition to benefit estimation and exploratory field testing

Braking assistance systems are already contributing to improving motorcyclists' safety, however, research on emergency systems acting on the steering is lacking. These systems, already available for passenger cars, could prevent or mitigate motorcycle crashes in which safety functions based only on braking are ineffective. The first research question was to quantify the safety impact of diverse emergency assistance systems acting on the steering of a motorcycle. For the most promising system, the second research question was to assess the feasibility of its intervention using a real motorcycle. Three emergency steering assistance systems were defined in terms of Functionality, Purpose, and Applicability: Motorcycle Curve Assist (MCA), Motorcycle Stabilisation (MS), and Motorcycle Autonomous Emergency Steering (MAES). Experts evaluated each system's applicability and effectiveness based on the specific crash configuration (using Definitions for Classifying Accidents - DCA), the Knowledge-Based system of Motorcycle Safety (KBMS), and the In-Depth Crash Reconstruction (IDCR). An experimental campaign was conducted with an instrumented motorcycle to assess the rider's reaction to external steering input. A surrogate method for an active steering assistance system imparted external steering torques in correspondence with a lane change to analyse the effect of the steering inputs on motorcycle dynamics and rider controllability. MAES globally got the best score for each assessment method. MS received better evaluations than MCA in two out of three methods. The union of the three systems covered a sizeable fraction of the crashes considered (maximum score in 22.8% of the cases). An estimation of the injury potential mitigation, based on injury risk functions for motorcyclists, was made for the most promising system (MAES). The field test data and video footage showed no instability or loss of control, despite the high intensity (>20Nm) of the external steering input. The rider interviews confirmed that the external action was intense but manageable. For the first time, this study presents an exploratory assessment of the applicability, benefits, and feasibility of motorcycle safety functions acting on the steering. MAES, in particular, was found applicable to a relevant share of crashes involving motorcycles. Remarkably, applying an external action to produce a lateral avoidance manoeuvre proved feasible in a real-world test setting.

The Role of Bidirectional VLC Systems in Low-Latency 6G Vehicular Networks and Comparison with IEEE802.11p and LTE/5G C-V2X

In this paper, we present very recent results regarding the latency characterization of a novel bidirectional visible light communication (VLC) system for vehicular applications, which could be relevant in intelligent transportation system (ITS) safety applications, such as the assisted and automated braking of cars and motorbikes in critical situations. The VLC system has been implemented using real motorbike head- and tail-lights with distances up to 27 m in a realistic outdoor scenario. We performed a detailed statistical analysis of the observed error distribution in the communication process, assessing the most probable statistical values of expected latency depending on the observed packet error rate (PER). A minimum attainable observed round-trip latency of 2.5 ms was measured. Using our dataset, we have also estimated the probability to receive correctly a message with a specific average latency for a target PER, and we compare it to the ultra-reliable low-latency (URLL) 5G communications service. In addition, a mobility model is implemented to compare the VLC and radio frequency (RF) technologies (IEEE802.11p, LTE, 5G) to support an automated braking systems for vehicles in urban platooning.

Motorcycle curve assist: A novel approach based on active speed control for crash injury reduction

OBJECTIVE

Safely negotiating curves with a powered-two-wheeler (PTW) requires a high level of skill, and a significant proportion of PTW crashes have a curve involvement. This study aimed to estimate the applicability, potential benefits and feasibility of novel Motorcycle Curve Assist (MCA). The system is designed to operate an emergency control of the speed of a motorcycle approaching a bend at an inappropriate speed.

METHODS

First, the MCA system intervention was defined. Second, the applicability of the system and an estimate of its potential benefits was performed based on a PTW crash database. Motorcyclists' injury risk estimates, MCA working parameters and timing of intervention were employed to estimate the potential injury reduction of applicable crash types. Third, a field test campaign involving 29 common riders as participants was conducted to investigate the real-world applicability and acceptability among end-users of the system deployment in one relevant riding condition adopting a range of parameters of intervention.

RESULTS

In the crash database, 23% of cases had curve involvement and after detailed analysis, 14% resulted to be suitable for MCA (60% of cases with curve involvement). The potential relative injury risk reduction considering only the benefits due to crash speed reduction ranged from 3-9% for MAIS2+ to 9-27% for MAIS3+ injuries. Field tests were performed in corners approached at an average speed of 28.7 km/h and an average lean angle of 20°. The system provided a mean deceleration of 0.33 g reached with a fade-in jerk of 1.73 g/s, for an average total duration of 0.59 s. For the field test component, participants reported good controllability of the system, with no incipient loss of control recorded nor reported by participants.

CONCLUSIONS

The proposed approach for MCA implementation showed considerable potential benefits in terms of injury reduction. The intervention with the defined working parameters was considered feasible by a sample of end-users. When integrated with an intervention logic capable of predicting emergency situations while approaching curves, MCA will be a technology capable of assisting PTW riders in conditions where other available active safety systems do not.

Applicability Assessment of Active Safety Systems for Motorcycles Using Population-Based Crash Data: Cross-Country Comparison among Australia, Italy, and USA

The role of powered two-wheeler (PTW) transport from the perspective of a more sustainable mobility system is undermined by the associated high injury risk due to crashes. Motorcycle-based active safety systems promise to avoid or mitigate many of these crashes suffered by PTW riders. Despite this, most systems are still only in the prototype phase and understanding which systems have the greatest chance of reducing crashes is an important step in prioritizing their development. Earlier studies have examined the applicability of these systems to individual crash configurations, e.g., rear-end vs. intersection crashes. However, there may be large regional differences in the distribution of PTW crash configurations, motorcycle types, and road systems, and hence in the priority for the development of systems. The study objective is to compare the applicability of five active safety systems for PTWs in Australia, Italy, and the US using real-world crash data from each region. The analysis found stark differences in the expected applicability of the systems across the three regions. ABS generally resulted in the most applicable system, with estimated applicability in 45–60% of all crashes. In contrast, in 20–30% of the crashes in each country, none of the safety systems analyzed were found to be applicable. This has important implications for manufacturers and researchers, but also for regulators, which may demand country-specific minimum performance requirements for PTW active safety countermeasures.

Motorcycle Autonomous Emergency Braking (MAEB) employed as enhanced braking: Estimating the potential for injury reduction using real-world crash modeling

OBJECTIVE

Recent field-tests on Motorcycle Autonomous Emergency Braking system (MAEB) showed that higher levels of deceleration to improve its effectiveness were feasible. However, the potential of MAEB in mitigating rider injuries is not well understood, particularly in scenarios where the efficacy of standard MAEB is limited because the rider is manually braking. The purpose of this study was first, to assess the injury mitigation potential of MAEB and second, to test MAEB as an enhanced braking system applied in circumstances where the rider is braking before a crash.

METHODS

Data from previously investigated motorcycle injury crashes that occurred on public roads in Victoria, Australia were reconstructed using a 2D model. The intervention of MAEB was applied in the simulations to test both MAEB standard and MAEB working as enhanced braking system. The effects of MAEB in mitigating crashes were separated by crash configuration and evaluated based on the modeled reductions in impact speed and injury risk, employing injury risk functions available in the literature.

RESULTS

After modeling was applied, MAEB was found to be applicable in 30 cases (91% of those in which was estimated as "possibly applicable"). The modeled Impact Speed Reduction (ISR) among the 30 cases averaged 5.0 km/h. In the cases without manual braking, the mean ISR due to standard MAEB was 7.1 km/h, whereas the relative injury risk reduction ranged from 10% for MAIS2+ to 22% for fatal injuries. In the 14 cases with manual braking, the modeled application of MAEB as enhanced braking led to an average ISR ranging from 5.3 km/h to 7.3 km/h. This resulted in an injury risk reduction ranging from 9% to 12% for MAIS2+ and from 16% to 21% for fatal injuries, depending on the different modes of MAEB.

CONCLUSIONS

This study modeled the potential benefits of the highest levels of intervention for MAEB field-tested to date. The findings estimate the degree to which MAEB could mitigate motorcycle crashes and reduce injury risks for motorcyclists. New strategies for MAEB intervention as enhanced braking were modeled through crash simulations, and suggest improvements in the benefits of MAEB when riders are braking before the crash. This highlighted the requirement to perform new field-based tests to assess the feasibility of MAEB deployed as enhanced braking system.

Visual Feedback Effectiveness in Reducing Over Speeding of Moped-Riders

The use of assistance systems aimed at reducing road fatalities is spreading, especially for car drivers, but less effort has been devoted to developing and testing similar systems for powered two-wheelers (PTWs). Considering that over speeding represents one of the main causal factors in road crashes and that riders are more vulnerable than drivers, in the present study we investigated the effectiveness of an assistance system which signaled speed limit violations during a simulated moped-driving task, in optimal and poor visibility conditions. Participants performed four conditions of simulated riding: one baseline condition without Feedback, one Fog condition in which visual feedback was provided so as to indicate to the participants when a speed limit (lower than that indicated by the traffic signals) was exceeded, and two post-Feedback conditions with and without Fog, respectively, in which no feedback was delivered. Results showed that participants make fewer speeding violations when the feedback is not provided, after 1 month, and regardless of the visibility condition. Finally, the feedback has been proven effective in reducing speed violations in participants with an aggressive riding style, as measured in the baseline session.