INTRODUCTION:Automated lane change systems allow drivers to receive support for maneuver execution and sometimes initiation. Research suggests that delegating action selection to automation can impair awareness and reduce readiness to intervene if automation fails. The current study was designed to compare manual lane changes with two automated variants: driver-initiated but system-executed, and system-initiated and -executed after driver confirmation. METHOD:Fourteen drivers were provided with instrumented Tesla Model 3s for a 4-week study period, during which video of the driver, the cabin, and the forward roadway, as well as data on vehicle speed and position were recorded. Automated lane changes were compared with manual lane changes, with each automated event matched to a similar manual one through stratified random sampling. Self-report questionnaires were administered at the conclusion of the study to examine drivers' subjective experiences. RESULTS:Drivers undergoing both variants of automated lane changes appeared to use the information displayed on the vehicle's center stack as a replacement for directly observing the forward roadway. The system-initiated automated lane changes were unique, however, in that drivers exhibited even shorter glances to the side mirrors and more frequent cell phone use compared with the other control modes, as well as reduced on-road glance duration over the second half of the study period. We also found that driver mistrust increased the most when the vehicle canceled an automated lane change, with system cancellations predicting lower future system use and less positive subjective perceptions of the system overall. CONCLUSION:Findings clarify differences between automation that supports the execution of a maneuver compared with one that supports both initiation and execution. The latter may risk driver disengagement and insufficient automation verification behavior. PRACTICAL APPLICATIONS:Automakers and system designers should be cautious about implementing automated support for action selection without ensuring that drivers engage in sufficient oversight.

Pedestrian automatic emergency braking systems (P-AEB) have recently been introduced in the vehicle fleet to reduce vehicle-to-pedestrian collisions. However, studies on the real-world efficacy of these systems have yielded mixed results. To better understand the factors that influence P-AEB performance, previous simulation and counterfactual studies have evaluated the effects of different P-AEB characteristics on collision avoidance. Previous studies have focused on using a hypothetical P-AEB response model to either estimate the potential benefit of P-AEB or evaluate system configuration performance to optimize P-AEB design. This study aimed to understand the shortcomings of current production P-AEB systems for consumer testing organizations to use for encouraging the continuous improvement of those systems. The present study re-simulated 64 vehicle-to-pedestrian collision cases included in the in-depth Vulnerable Road Users Injury Prevention Alliance database to evaluate the stochastic response of rating-specific P-AEB systems and identify the most challenging pedestrian scenarios and the factors limiting P-AEB performance. Our P-AEB models represented the test responses of systems rated as superior, advanced, or basic by the Insurance Institute for Highway Safety (IIHS). We explored the effects of detection range, detection angle, and the lateral distance threshold for system activation. Results indicated a clear correlation between collision avoidance and the IIHS P-AEB rating. The study also identified three challenging scenarios: (1) highly obstructed cases, (2) high-speed vehicle cases, and (3) cases with high pedestrian crossing speed. None of the explored system designs were able to eliminate collisions in highly obstructed cases due to the late appearance of the pedestrian. In high-speed vehicle cases and in those with high pedestrian crossing speeds, P-AEB performance was limited by the detection range and the lateral distance threshold, respectively. Consumer testing organizations can use these findings to revise existing test programs, improve program relevance for vehicle-to-pedestrian crashes, and incentivize improvements to P-AEB systems.

OBJECTIVE:Bicycle-detecting automatic emergency braking (B-AEB) systems have the potential to prevent and mitigate many vehicle-bicycle crashes. Vehicle deceleration from B-AEB could result in a potential disbenefit scenario by changing the impact configuration from the bicycle striking the vehicle side to the bicycle being struck by the vehicle front. The purpose of this research was to use simulation to investigate the potential disbenefit of B-AEB in straight crossing path scenarios. METHODS:This study used an analytical set of equations to determine the collision configuration between a small car and bicycle based on speed and the time-to-intersect (TTI) of the straight crossing paths. The vehicle speed was varied from 3.6 to 130 km/h, and the bicycle speed was varied from 3.6 to 28.8 km/h. Starting positions were varied from 0.1 to 3.2 s before the vehicle and bicycle paths intersected. B-AEB deceleration magnitudes from 0 g to 0.9 g were simulated. In total, this study simulated over 127 million scenarios. The potential disbenefit scenario in simulation was compared with real-world bicycle crash data. RESULTS:The configuration in which the bicycle struck the vehicle side occurred in a larger proportion of crash scenarios at lower vehicle speeds. For example, a bicycle traveling 15 km/h struck a vehicle traveling 40 km/h in 31.2% of crash scenarios but only struck a vehicle traveling 80 km/h in 18.2% of crash scenarios. At the same time, B-AEB systems avoided more crashes when the vehicle was going slower. At a vehicle speed of 40 km/h, B-AEB systems that activated at least 0.75 s TTI with over 0.7 g of deceleration were able to completely avoid the potential disbenefit scenario. Simulation results indicated that two existing B-AEB systems, one that braked at 1.05 s TTI at 0.9 g and the other at 1.2 s TTI at 0.7 g in controlled testing, would avoid these disbenefit collisions up to vehicle speeds of 60 km/h. At vehicle speeds over 60 km/h and activations over 0.75 s TTI, B-AEB could change the configuration but the impact speed would be reduced to below 37 km/h, which is associated with a less than 5% risk of serious injury for the bicyclist. CONCLUSIONS:This study considered all straight crossing path crashes between a small car and a bicycle and considered the circumstances under which B-AEB could lead to a change in crash configuration resulting in a potentially worse outcome. Among the crash scenarios with a potential for disbenefit with B-AEB activation, current B-AEB systems are activating early enough and braking hard enough to simply avoid the collision at speeds up to 60 km/h and mitigate the probability of serious injury at higher speeds.

OBJECTIVE:In the U.S., bicyclist fatalities have risen 47.5% over the last decade. On some of their latest vehicles, automakers have introduced bicycle-detecting automatic emergency braking (AEB) systems that automatically apply the brakes to avoid or mitigate collisions with bicyclists. These systems are not evaluated in the U.S. market, although similar tests are conducted elsewhere. The purpose of this study was to use simulation to understand the AEB system characteristics that might perform well in potential testing protocols. METHODS:Using openPASS, a bicycle and passenger vehicle were simulated traversing through a four-way intersection of two- lane roadways. Both a straight crossing path and a parallel path scenario were simulated with the subject vehicle traveling between 20 and 80 km/h and the bicycle traveling between 5 and 20 km/h. The subject vehicle's sensor field of view (30, 60, 90, 120, 150, 180 degrees) and range (10, 20, 30, 40, 50, 60 m) were varied, and the AEB response was designed to match the braking characteristics observed in pedestrian crash-avoidance testing. In total, 30 hypothetical AEB systems were tested in 20 unique straight crossing path scenarios and 18 hypothetical AEB systems were tested in 24 unique parallel path scenarios. RESULTS:In the straight crossing path scenario, when evaluating based on avoidance, the simulations where the subject vehicle and bicycle were moving at similar speeds differentiated systems by the sensor field of view. In both straight crossing path and parallel path scenarios, collision avoidance at higher relative speeds was differentiated by the sensor range. CONCLUSIONS:A straight crossing path protocol with the subject vehicle and bicycle moving at similar, low speeds could lead to bicycle-detecting AEB implementations with a wider field of view. The test speed in both scenarios primarily influenced the sensor range. This research provides testing agencies with information about how testing protocol decisions could influence AEB system design. In addition, this study demonstrates the feasibility of using simulation tools to develop relevant crash avoidance testing protocols. Future simulations could predict the performance in real-world bicycle crashes of systems that would also perform well in the potential testing protocols.

OBJECTIVE:In 2022, 1,105 bicyclists were killed and 46,195 were injured in motor vehicle crashes in the U.S. Automatic emergency braking (AEB) systems that automatically apply the vehicle brakes can avoid or mitigate bicyclist crashes, but the feature is not evaluated or required in the U.S. This study characterized police-reported vehicle-to-bicycle crashes and assessed speed reductions by two AEB systems in controlled tests replicating common crash vehicle-bicycle scenarios. METHODS:From 2018 to 2022, a total of 159,474 police-reported and 3,305 fatal crashes involving one passenger vehicle and one bicyclist were extracted from the Crash Report Sampling System and Fatality Analysis Reporting System. Crash configuration and pre-impact movement were coded using the Crash Type variable descriptions. Estimated speeds from 93 crashes were extracted from the Vulnerable Road User Injury Prevention Alliance (VIPA) database. AEB system performance in the 2023 Toyota RAV4 and 2023 Subaru Forester was evaluated when approaching a 15 km/h crossing bicycle target at 40, 50, and 60 km/h during the day and when approaching a slower-moving bicycle target ahead at 50, 60, and 70 km/h during the day and night. RESULTS:Crossing path crashes accounted for 56% of police-reported vehicle-to-bicycle crashes. The estimated travel speed in VIPA crossing path crashes was most frequently 0-20 km/h for the vehicle and 0-17 km/h for the bicycle. Parallel path crashes accounted for 57% of fatal vehicle-to-bicycle crashes. The estimated speed in VIPA parallel path crashes most frequently was 65 km/h or higher for the vehicle and 0-17 km/h for the bicycle. In controlled evaluations, the AEB systems completely or nearly avoided the bicycle target in the crossing path scenarios during daytime and in parallel path scenarios during daytime and at night with high beams. However, the AEB systems only marginally reduced vehicle speed in the parallel path scenarios at night with low beams. CONCLUSIONS:Current AEB systems mitigated crossing and parallel path bicycle crashes during the day but not when approaching a bicycle from behind at night with low beams. AEB systems that perform well in every crossing path and parallel path scenario could address 28,600 police-reported and 600 fatal bicycle crashes each year.

OBJECTIVE:The public, regulators, and domain experts alike seek to understand the effect of deployed SAE level 4 automated driving system (ADS) technologies on safety. The recent expansion of ADS technology deployments is paving the way for early stage safety impact evaluations, whereby the observational data from both an ADS and a representative benchmark fleet are compared to quantify safety performance. METHODS:In January 2024; a working group of experts across academia, insurance, and industry came together in Washington, DC to discuss the current and future challenges in performing such evaluations. A subset of this working group then met, virtually, on multiple occasions to produce this paper. RESULTS:This paper presents the RAVE (Retrospective Automated Vehicle Evaluation) checklist, a set of fifteen recommendations for performing and evaluating retrospective ADS performance comparisons. The recommendations are centered around the concepts of (1) quality and validity, (2) transparency, and (3) interpretation. CONCLUSION:Over time, it is anticipated there will be a large and varied body of work evaluating the observed performance of these ADS fleets. Establishing and promoting good scientific practices benefits the work of stakeholders, many of whom may not be subject matter experts. This working group's intentions are to: i) strengthen individual research studies and ii) make the at-large community more informed on how to evaluate this collective body of work.

OBJECTIVE:Seat belts reduce the risk of crash-related injury and fatality and are important for pregnant occupants. Previous research is mixed on whether belt use increases during pregnancy, but has consistently found that pregnant occupants misposition their belts. This study examined reported seat belt use and positioning among pregnant and nonpregnant people in the U.S. to examine whether there are changes in use during pregnancy and rates of correct positioning. METHODS:An online survey was administered to a nationally representative sample of U.S. men and women who were at least 21 years old and drove or rode in a vehicle at least once per week and a comparison sample of pregnant people. Respondents were asked about the frequency of belt use, reasons for nonuse, belt positioning, and information received about belt use during pregnancy. The final sample included 1,187 nonpregnant respondents and 824 pregnant respondents. RESULTS:Overall, 90% of nonpregnant respondents and 87% of pregnant respondents reported they always used a belt; this difference was not statistically significant. However, the odds that pregnant respondents "always" used a belt during pregnancy was twice that of "always" using a belt before pregnancy. Discomfort, forgetting, and traveling a short distance were common reasons why nonpregnant respondents did not use a belt. Discomfort, forgetting, and the baby's safety were common reasons for pregnant respondents. Pregnant respondents reported significantly more discomfort from the belt than nonpregnant respondents. Only 21% of pregnant respondents positioned the lap and shoulder belt correctly compared with 39% of nonpregnant respondents. CONCLUSIONS:Reported seat belt use among pregnant people before pregnancy increased during pregnancy, but use during pregnancy did not differ from the nonpregnant sample. Most pregnant respondents reported always using a belt, but only a small proportion positioned it correctly. Discomfort is a key barrier to positioning a seat belt correctly, whether an occupant is pregnant or not. Restraint system design should be improved to accommodate larger abdomens and other physical changes associated with pregnancy. Educational campaigns should target nonpregnant and pregnant people with information about correct belt positioning and address misconceptions that belt use compromises fetal safety.

BACKGROUND:Correct seatbelt use during pregnancy is critical for ensuring maternal and fetal safety during a motor vehicle crash. This study aimed to investigate seatbelt use among pregnant vehicle drivers in Australia, focusing on correct seatbelt positioning and the potential influence of comfort and the receipt of seatbelt information. METHOD:An online survey was completed by 1,491 participants (M = 33.2 years, SD = 4.1, Range = 18.0 - 50.0 years). RESULTS:While nearly all participants (99.1%) reported 'always' wearing their seatbelt while driving a vehicle, only 41.4% met the correct seatbelt positioning criteria, defined as positioning the lap belt under the belly and low over the upper thighs and the shoulder belt between the breasts. Despite increased discomfort with seatbelt use as pregnancy advanced, discomfort was not significantly associated with correct seatbelt positioning. Additionally, while most participants had not received information about seatbelt use during pregnancy (87.7%), those who did had better knowledge (96.2% vs. 90.5%, χ2(1) = 7.16, p < 0.05), and were more likely to meet all three criteria for correct seatbelt positioning during pregnancy (56.8% vs. 39.3%, χ2(1) = 20.26, p < 0.001), than participants who had not received information (90.5%). However, receiving information did not necessarily increase confidence in correct seatbelt use, as participants who had received information were actually less likely to be confident in their ability to use the seatbelt correctly (3.3% vs. 6.6%, χ2(2) = 8.24, p < 0.05). CONCLUSIONS:These findings highlight a significant gap in correct seatbelt positioning among pregnant occupants and the scope for substantial improvement in correct positioning by providing specific information on seatbelt use during pregnancy. PRACTICAL APPLICATIONS:To improve correct seatbelt use among pregnant individuals, public health messaging should be enhanced, and obstetrician-gynaecologists, nurses and other healthcare professionals should provide clear guidance on correct seatbelt positioning throughout the pregnancy. Future research should focus on developing effective educational strategies, assessing vehicle design improvements for comfort and safety, and exploring other factors influencing correct seatbelt use during pregnancy.

OBJECTIVE:In 2021; half of crash fatalities occurred at night when some road users, like pedestrians, are particularly vulnerable. Automatic emergency braking (AEB) systems can avoid or mitigate collisions by automatically applying the brakes, but their performance may be hindered in low lighting. The purpose of this study was to estimate the proportion of real-world crashes where headlights could provide enough visibility for the driver or AEB system to detect and avoid the collision. METHODS:This study used IIHS headlight testing data and Crash Report Sampling System crash data from 2016 to 2021. The median 5-lux visibility distance was calculated for each IIHS headlight rating: good, acceptable, marginal, and poor. For three response profiles, a typical human driver, a fast human driver, and a camera-based AEB system, the maximum travel speed in which a vehicle could come to a complete stop within the 5-lux distance was computed. The real-world crash coverage of each headlight system and response profile was defined as the proportion of crashes that occurred on dark, unlit roads with a speed limit below the estimated maximum travel speed, where the vehicle could stop within the visibility distance. RESULTS:The median low-beam visibility distance for poor-rated headlights was 68.2 m and for good-rated headlights was 103.1 m on the right side of straight roads. The typical human driver could have enough time to detect and avoid 46.2% of nighttime pedestrian crashes with poor-rated headlights and 70.1% with good-rated headlights. The visibility distance greatly increases with high beams and would allow the typical human driver to detect and avoid over 90% of nighttime crashes. Good-rated and acceptable-rated headlights allow AEB systems to theoretically have enough visibility distance to avoid nearly every nighttime crash. CONCLUSIONS:Vehicles with good- or acceptable-rated headlights and active high beams are theoretically capable of providing sufficient light for speeds up to 165.8 km/h (103 mph), even covering most speeding vehicles. Future simulations of AEB systems on vehicles equipped with good- or acceptable-rated headlights and automatic high beams may not need to consider headlight visibility.

ObjectiveAutomatic emergency braking (AEB) and forward collision warning (FCW) are effective at preventing rear-end crashes, but they may perform better in some rear-end crash scenarios than others. The goal of this study was to estimate the effects of front crash prevention systems equipped to passenger vehicles in crashes where another passenger vehicle, a medium/heavy truck, or a motorcycle is struck and compare effectiveness by struck vehicle type.MethodsMore than 160,000 two-vehicle rear-end crashes were identified where a passenger vehicle with or without FCW and AEB was the striking vehicle and another passenger vehicle, medium/heavy truck, or motorcycle was the struck vehicle. Poisson regression was used to estimate the effect of front crash prevention by struck vehicle type on rear-end crash rates per registered vehicle year, accounting for the state and year of the crash and the make, model year, class, and engine type of the striking vehicle.ResultsFront crash prevention was associated with a 53% reduction in rear-end crash rates when striking another passenger vehicle, which was significantly larger than the reductions of 38% when striking a medium/heavy truck and 41% when striking a motorcycle. Reductions in rear-end injury crash rates when striking a passenger vehicle also were larger than when striking a medium/heavy truck and when striking a motorcycle.DiscussionIf all passenger vehicles were equipped with FCW and AEB that were as effective in crashes striking a truck or motorcycle as they are in crashes with another passenger vehicle, over 5,500 additional crashes with medium/heavy trucks and 500 with motorcycles could potentially be prevented annually in the United States above what would be expected from current front crash prevention systems. Extending front crash prevention testing in consumer information programs to include motorcycle and truck targets could encourage auto manufacturers to improve performance in these crash scenarios.

OBJECTIVE:Automatic emergency braking systems with pedestrian detection (PAEB) are effective at preventing pedestrian crashes, but the safety benefits are not observed at night. This study used the Insurance Institute for Highway Safety (IIHS) PAEB test data to characterize PAEB responses in different lighting conditions and for different rated systems. METHODS:Data from 6,919 IIHS PAEB tests were retrieved from IIHS databases. Invalid trials, trials without AEB, and trials with outliers were removed leaving 5,894 trials from 212 model year 2018 to 2023 vehicles for analysis. PAEB responses were characterized by computing the time-to-collision (TTC) of forward collision warning (FCW) and AEB; brake threat number (BTN); mean deceleration; maximum deceleration; and maximum jerk. A linear mixed-effects model was used to predict each dependent measure with scenario (crossing adult, stationary adult), speed, rating (superior, basic/advanced), lighting (day, night with high beams, night with low beams), and their interactions. Vehicle was included as a random effect. A Bonferroni correction was applied to maintain a family-wise type-1 error rate of 0.05 across 138 total hypothesis tests. RESULTS:PAEB system warnings were later and automatic braking occurred later as speed increased at night with low beams but changed little at night with high beams and during the day (p < 0.0004). BTN increased more rapidly as speed increased at night with low beams compared with high beams and during the day (p < 0.0004). Based on the BTN model, on average, PAEB systems can brake to avoid the adult mannequin (BTN < 1) when closing speed is less than 67 km/h during the day and at night with high beams but only when closing speed is less than 49 km/h at night with low beams. Superior-rated PAEB systems warned and braked earlier compared with basic/advanced-rated systems (p < 0.0004). CONCLUSIONS:Increased lighting from high beams made nighttime performance resemble daytime performance in controlled testing. Increasing output from vehicle low beams, increasing the use of high beams, and enhancing overhead lighting around crosswalks and pedestrian areas are all methods for increasing lighting, improving pedestrian conspicuity, and enhancing PAEB performance to prevent pedestrian crashes.

Objectives: Automatic emergency braking systems with pedestrian detection (PAEB) reduce the rate of police-reported pedestrian crashes during the day but not at night (Cicchino 2022). This study evaluated how increasing pedestrian conspicuity using clothing or by increasing roadway lighting affected PAEB performance. Methods: The PAEB system in a 2023 Mazda CX-5, 2023 Honda CR-V, and a 2023 Subaru Forester were evaluated when an adult-sized mannequin crossed the road as each vehicle approached at 40 km/h. The mannequin was dressed in black, black with a retroreflective jacket, black with retroreflective strips in a biological motion configuration, or white. Light towers provided 0, 10, or 20 lux of average illumination in the crosswalk. The vehicle low beams were used in every combination of clothing and roadway lighting and high beams were used when the mannequin was in black without roadway lighting. Percent speed reduction was computed to compare PAEB performance between vehicles. Results: A collision occurred in 84% of trials with the CR-V, 88% of trials with the CX-5, and 2% of trials with the Forester. The Honda PAEB system reduced speed by 40% when the pedestrian was in black and high beams were used but did not reduce speed with low beams without roadway lighting. The system reduced speed somewhat with 10 and 20 lux of roadway lighting with the pedestrian in black or white clothing. The CX-5 PAEB system reduced speed by 68% when the pedestrian was wearing black and high beams were used but only by 30% with low beams without any roadway lighting. The CX-5's PAEB system performance improved with increased roadway lighting when the pedestrian was wearing black. The CR-V and CX-5 PAEB systems did not reduce speed when the pedestrian was wearing retroreflective strips. The Subaru PAEB system reduced speed by 100% in all but one trial. Conclusions: Additional vehicle lighting enhanced PAEB system performance, but PAEB system performance with additional roadway lighting or more conspicuous clothing was inconsistent. Existing PAEB system hardware may be insufficient, or detection algorithms too brittle to cope with variations in the appearance of pedestrians at night.

Researchers can estimate the potential safety benefits of front crash prevention (FCP) systems by simulating system performance in rear-end crash scenarios reported to police or captured during naturalistic driving. Data to support assumptions about FCP systems in production vehicles, particularly automatic emergency braking (AEB), are limited. This study used detailed information from the Insurance Institute for Highway Safety’s (IIHS's) FCP evaluation to characterize interventions in vehicles that performed well (superior-rated vehicles) and those that did not perform as well (basic/advanced-rated vehicles) when approaching a stationary surrogate vehicle on a test track at 20 and 40 km/h, and estimated performance in similar conditions at higher speeds. Vehicle and video data from 3,231 IIHS FCP tests conducted at 20 and 40 km/h and 51 IIHS FCP research tests conducted at 50, 60, and 70 km/h with AEB responses were analyzed. Forward collision warning (FCW) and AEB time-to-collision (TTC), mean deceleration, maximum deceleration, and maximum jerk from the beginning of automatic braking to the end of braking or impact were computed for each test. Each dependent measure was modeled with test speed (20 km/h, 40 km/h), IIHS FCP test rating (superior, basic/advanced), and the interaction between test speed and rating. The models were used to estimate each dependent measure at 50, 60, and 70 km/h, and model predictions were compared with the observed performance of six vehicles in IIHS research test data. Vehicles with superior-rated systems warned and began braking earlier, had a greater average rate of deceleration, reached a higher peak deceleration, and had greater jerk than vehicles with basic/advanced-rated systems, on average. The interaction between test speed and vehicle rating was significant in each linear mixed-effects model, indicating that these differences changed with test speed. FCW and AEB in superior-rated vehicles occurred 0.05 and 0.10 s earlier, respectively, per 10-km/h increase in test speed compared with basic/advanced-rated vehicles. Mean deceleration and maximum deceleration for FCP systems in superior-rated vehicles increased 0.65 m/s2 and 0.60 m/s2 more, respectively, per 10-km/h increase in test speed than for systems in basic/advanced-rated vehicles. Maximum jerk increased 2.78 m/s3 per 10-km/h increase in test speed for basic/advanced-rated vehicles but decreased 0.25 m/s3 for systems in superior-rated vehicles. The root mean square error between the observed performance and estimated values at 50, 60, and 70 km/h indicated that the linear mixed-effects model had reasonable prediction accuracy for every measure except jerk at these out-of-sample data points. The findings from this study provide insight into the characteristics that make FCP effective for preventing crashes. Based on performance in the IIHS FCP test, vehicles with superior-rated FCP systems had earlier TTC thresholds and braked with greater deceleration that increased with speed compared with basic/advanced-rated systems. The linear mixed-effects models that were developed can guide assumptions about AEB response characteristics for superior-rated FCP systems in future simulation studies.

Objective Federal Motor Vehicle Safety Standard (FMVSS) 208 requires every passenger vehicle to provide an auditory signal lasting 4 to 8 seconds and a visual display lasting 60 seconds when the driver is unbelted at ignition. This requirement does not increase seat belt use. This paper summarizes the latest research on using vehicle technology to increase seat belt use and existing safety standards worldwide to support the strengthening of FMVSS 208. Method Studies of seat belt reminders and interlocks published in peer-reviewed journals, conference proceedings, or as technical reports were identified in online databases and reviewed along with current requirements worldwide. Results from past research were used to estimate the front- and rear-seat daytime belt use rate and the annual number of lives that could be saved by a persistent audible reminder at each seating position. Results Most motor vehicle occupants routinely buckle up. Those that do not typically forget, are going a short distance, or find belts uncomfortable. Seat belt reminders can remind or motivate occupants to buckle up. Enhanced reminders that exceed FMVSS 208 increase belt use by 6 percentage points. Reminders also can increase rear belt use, and although required throughout the world, are not required by FMVSS 208. More persistent reminders, like those required around the world, with a continuous, long-lasting audible signal increase belt use by 30% among drivers who do not routinely buckle up. If every vehicle in the U.S. had such a reminder at each seating position, then it was estimated that the daytime belt use rate in the U.S. would increase about 3 percentage points from 90.3% to 93.2% in the front row and by about 6 percentage points from 80% to 85.9% in the rear row. It was estimated that the increase in belt use from a continuous, long-lasting audible reminder could potentially save about 1,600 lives each year. Seat belt interlocks can increase belt use, but acceptance is a stumbling block. Public outcry ensued after interlocks were required in 1973, and public sentiment remains negative. Opinions toward front and rear reminders are more favorable. Furthermore, past research suggests interlocks may be no more effective for increasing seat belt use than persistent audible reminders. The effect of interlocks on rear belt use have not been explored. Conclusion Persistent seat belt reminder systems that last at least 90 seconds can potentially save hundreds of U.S. motorists each year. Robust empirical evidence, successful exemplars from organizations throughout the world, and a clear public health benefit exists for strengthening FMVSS 208 to require more persistent audible reminders at every seating position.

Government and consumer-information organizations can motivate automakers to address additional crash types through front crash prevention (FCP) testing programs. This study examined the current state of crashes potentially relevant to current and future FCP systems to provide a roadmap for the next crash types that vehicle testing programs in the United States should evaluate. Crash records from 2016 to 2020 were extracted from the Crash Report Sampling System (CRSS) and the Fatality Analysis Reporting System (FARS). Crashes were restricted to ones involving no more than two vehicles where the striking or path-intruding vehicle was a passenger vehicle and a vehicle defect was not coded. Percentages of police-reported crashes, nonfatal-injury crashes, and fatal crashes were computed for different crash types and circumstances. Rear-end and pedestrian crashes evaluated in existing FCP testing programs accounted for 27% of all police-reported crashes, 19% of nonfatal-injury crashes, and 18% of fatal crashes. The remaining crash types relevant to FCP accounted for 25% of police-reported crashes, 31% of nonfatal-injury crashes, and 23% of fatal crashes. A turning passenger vehicle crossing the path of an oncoming vehicle accounted for the largest proportion of the remaining police-reported (8%) and nonfatal-injury crashes (13%). Head-on crashes accounted for the largest proportion of remaining fatal crashes (9%). Most FCP-relevant police-reported crashes occurred on roads with a posted speed limit between 30 and 50 mph. Medium/heavy trucks were the crash partner in a disproportionate number of fatal head-on and rear-end crashes and motorcycles in a disproportionate number of fatal rear-end and turning crossing-path crashes. Fatal bicyclist and pedestrian crashes were overrepresented at night. The findings from this study indicate that testing organizations should evaluate FCP performance at higher speeds; with non-passenger vehicles and vulnerable road users; during the night; and in more complex head-on and turning crash scenarios to reduce crashes of all severities. Some of these conditions are currently assessed by other testing organizations and can be readily adopted by U.S. programs or possibly addressed with new approaches like virtual testing.

Objective: A recent study by Kidd (2022) recommended that organizations evaluating front crash prevention (FCP) systems like automatic emergency braking and forward collision warning increase speed differentials in existing test scenarios from 25 mph to 45 mph to make the tests more representative of police-reported rear-end crashes. Kidd used the posted speed limit as a proxy for the striking vehicle's travel speed prior to the crash. The current study used velocity data from event data recorders (EDRs) in rear-end crashes to evaluate this assumption. These same data were used to replicate another study (Farmer 2003) that showed the speed limit was a poor surrogate for delta-V in rear-end crashes. Method: A total of 11,199 crash records during 2017-2020 were extracted from the Crash Investigation Sampling System database. The analysis was restricted to 436 of these records that involved two vehicles with a front-to-rear manner of collision or rear-end crash configuration with EDR data from the striking vehicle. The relationships between the posted speed limit and striking-vehicle travel speed and between the speed limit and delta-V were modeled using regression. Results: On average, the speed limit overestimated striking-vehicle travel speed by 2 mph, but the relationship between the speed limit and travel speed was not linear. The speed limit reasonably approximated travel speed on roads with speed limits of 30 and S0 mph or higher. It slightly overestimated travel speed on roads with 40-45 mph speed limits and underestimated it on roads with limits of 25mph or less. The probability that the striking vehicle's travel speed was 25mph or less on any road was 0.09. In contrast, the probability of the striking vehicle's travel speed being 45mph or less was 0.54 overall and 0.75 or higher for roads with a speed limit between 25 and 45mph. As found in prior research, there was no significant relationship between the speed limit and delta-V. Conclusion: The posted speed limit was a reasonable surrogate for the striking vehicle's travel speed prior to police-reported rear-end crashes on roads with a speed limit above 25 mph. It was not a reasonable surrogate for delta-V. Travel speeds on roads with speed limits of 25 mph or less were much higher than the speed limit, which suggests that existing scenarios used to evaluate FCP system performance represent travel speeds in fewer police-reported rear-end crashes than previously thought. Increasing speed differentials in existing FCP test scenarios to 45 mph would reflect the striking vehicle's travel speed in three quarters of rear-end crashes on roads with a speed limit of 45mph or less.

Objective Forward collision warning and automatic emergency braking (AEB) systems help prevent rear-end crashes where a vehicle strikes the rear of another. However, the benefits may be limited if the systems are stymied by common crash circumstances or only target scenarios evaluated in vehicle testing programs. This study examined the prevalence of characteristics that may limit AEB system performance in police-reported rear-end crashes and the relevance of scenarios used to evaluate these systems. Methods Police-reported rear-end crashes (n = 6,731,215, Crash Report Sampling System) and fatal rear-end crashes (n = 4,285, Fatality Analysis Reporting System) with a fatality in the striking or struck vehicle during 2016-2019 were analyzed. Percentages of police-reported rear-end crashes, nonfatal-injury rear-end crashes, and fatal rear-end crashes were computed to identify common crash characteristics. Roadway speed limit was used as a proxy for striking vehicle speed. Results A straight-moving vehicle striking a stopped or decelerating vehicle on roads with a speed limit of 40 km/h (25 mph) or less only accounted for 3% of all rear-end crashes, 3% of nonfatal-injury rear-end crashes, and 1% of fatal rear-end crashes. In contrast, 36% of all rear-end crashes, 36% of nonfatal-injury rear-end crashes, and 11% of fatal rear-end crashes involved a straight-moving vehicle striking a stopped or decelerating vehicle on roads with a speed limit between 56 and 72 km/h (35 and 45 mph). A medium or heavy truck was the struck vehicle in 32% of fatal rear-end crashes, and a motorcycle was the struck vehicle in 11% of fatal rear-end crashes. At least one of the following characteristics that may degrade AEB system performance was present in 14% of the rear-end crashes studied: striking vehicle turning; a struck vehicle turning or changing lanes; a struck vehicle that is not a passenger vehicle; wintery weather; wet or icy roads; or a speed limit of 113 km/h (70 mph) or higher. Conclusion Circumstances shown to diminish AEB effectiveness accounted for 14% of rear-end crashes, and scenarios currently used to evaluate AEB systems accounted for 3%. Evaluating AEB systems at speeds up to 72 km/h (45 mph) and incorporating a motorcycle or medium/heavy truck target will make AEB evaluations more representative of police-reported rear-end crashes.

Driving automation systems are being introduced into mass-market vehicles, but little is known about whether drivers will trust driving automation systems and use the technology. In this study, volunteer drivers operated five vehicles equipped with automated longitudinal and lateral control and completed surveys about their experience. A subset of drivers also documented uncomfortable experiences as they used the automation while driving. Driver agreement that the automation improved the overall driving experience was significantly higher for Vehicle A than the systems implemented in the other four vehicles. Drivers reported significantly higher trust in adaptive cruise control than in lane centering in every vehicle but Vehicle B. Increased agreement that the automation consistently detected lane lines; detected moving vehicles ahead; and made smooth, gentle steering inputs was associated with significant increases in agreement that the automation improved the overall driving experience. Situations where drivers reported feeling uncomfortable with the automation during their drive were dominated by instances where lane centering struggled with common roadway features such as hills and intersections. (C) 2019 Elsevier Ltd. All rights reserved.

Seat belt interlock systems that restrict the use of the vehicle or a vehicle feature when an occupant is unbelted are effective for increasing seat belt use but might be unacceptable to consumers. This study collected driver opinions about whether 3 seat belt reminder systems and 3 interlock systems, two that restricted speed and one that prevented shifting into gear, would increase belt use and were acceptable. Twenty-eight volunteers, 22 who routinely did use a belt and 6 who routinely did, drove 6 vehicles with these technologies on a closed course while unbelted or completing tasks that led to unbelted driving. Participants indicated their level of agreement from 1 (strongly disagree) to 5 (strongly agree) with 5 statements after driving each vehicle. Participants reported stronger levels of agreement that each interlock system would make them buckle up more frequently than 2 of the 3 reminder systems. Agreement about finding the various technologies acceptable, requiring them in a vehicle, avoiding purchasing a vehicle with them, or circumventing them was not significantly different among technologies. When asked to circumvent each interlock system, participants most commonly sat on a buckled belt, routed the belt behind their back, or buckled and unbuckled in various manners. Most participants raised safety concerns in a post-study interview about the interlock systems, particularly those that restricted speed. Hence, although interlocks were perceived as more effective for increasing belt use and no more or less acceptable than reminders following a brief hands-on experience, interlocks created safety concerns that may impede acceptance.

Introduction: Vehicle technologies that increase seat belt use can save thousands of lives each year. Kidd, Singer, Huey, and Kerfoot (2018) found that a gearshift interlock was more effective for increasing seat belt use than an intermittent audible reminder, but interlocks may not be more effective than persistent audible reminders lasting at least 90 seconds. Method: Forty-nine part-time belt users with a recent seat belt citation who self-reported not always using a seat belt drove two vehicles for 1 week each. Thirty-three drove a Chevrolet with an intermittent audible reminder followed by either a BMW with a persistent 90-second audible reminder (n = 17) or a Subaru with an incessant audible reminder (n = 16). The other 16 participants experienced the BMW persistent reminder followed by an interlock that limited speed to 15 mph during unbelted driving. These data were combined with data from 32 part-time belt users in Kidd et al. (2018) who experienced the intermittent reminder for 2 weeks or the intermittent reminder for 1 week and a gearshift interlock the next. Results: Relative to the intermittent reminder, seat belt use was significantly increased an estimated 30% by the BMW persistent reminder, 34% by the Subaru incessant reminder, and 33% by the speed-limiting interlock. Belt use was increased an estimated 16% by the gearshift interlock, but this change was not significant. More participants circumvented the speed-limiting interlock to drive unbelted than the audible reminders. Responses to a poststudy survey indicated that interlocks were less acceptable than reminders. Conclusions: Audible reminders lasting at least 90 seconds and a speed-limiting interlock were more effective for increasing seat belt use than an intermittent audible reminder, but reminders were found more acceptable. Practical applications: Strengthening existing U.S. safety standards to require audible reminders lasting at least 90 seconds for front-row occupants could save up to 1,489 lives annually. (C) 2019 National Safety Council and Elsevier Ltd. All rights reserved.