National Highway Traffic Safety Administration Research Articles

Effect of vehicle speed on injury of child passenger in frontal crashes

Speed is major cause of death to vehicle occupants especially children. Studying effect of speed on child injury severity is crucial to establishing safety regulations. This work investigates the effect of vehicle speed on the severity of injury sustained by three-year-old (3YO) children. Restrained 3YO child dummy Finite Element (FE) model was used to conduct crash simulation at impact speed of 40km/h, 46 km/h and 48 km/h in Ford Taurus FE model using LS DYNA code. Vehicle deceleration was found to increase with increase in speed. Head Injury Criteria (HIC36), HIC15, chest acceleration (CA), chest severity index (CSI), chest deflection (CD) and neck moment (NM) were evaluated and compared with National Highway Traffic Safety Administration (NHTSA) threshold. It was found that the injury parameters sustained by 3YO child increased with increase in speed. HIC36 was found to be above threshold for 48km/h and 46km/h. Speed of 40 km/h had all the injury values below the threshold. Chest deflection was lower than the threshold for all the three speeds. Chest acceleration and neck moment were also presented and their values also increase with speed, though, NHTSA doesn’t capture their threshold. The study disseminates information on the effect of speeding on child injuries in frontal crashes for road safety agents and vehicle designers and users. Limiting vehicle speed is therefore crucial to child occupant protection.

Investigation of THOR-AV 5F Biofidelity in Sled Test Conditions with a Semi-Rigid Seat

<div class="section abstract"><div class="htmlview paragraph">THOR-AV 5F, a modified THOR-5F dummy, was designed to represent both upright and reclined occupants in vehicle crashworthiness studies. The dummy was evaluated in four test conditions: a) 25° seatback, 15 km/h, b) 25° seatback, 32 km/h, c) 45° seatback, 15 km/h, d) 45° seatback, 32 km/h. The dummy’s biomechanical responses were compared against those of postmortem human subjects (PMHS) tested in the same test conditions. The latest National Highway Traffic Safety Administration (NHTSA) BioRank method was used to provide a biofidelity ranking score (BRS) for each data channel in the tests to assess the dummy’s biofidelity objectively. The evaluation was categorized into two groups: restraint system and dummy. In the four test conditions, the restraint system showed good biofidelity with BRS scores of 1.49, 1.47, 1.15, and 1.79, respectively. The THOR-AV 5F demonstrated excellent biofidelity in three test conditions: 25° seatback, 15 km/h (BRS = 0.76); 25° seatback, 32 km/h (BRS = 0.89); and 45° seatback, 32 km/h (BRS = 0.93). In the fourth test condition, 45° seatback, 15 km/h, the dummy demonstrated good biofidelity with a BRS score of 1.06. The dummy demonstrated good durability. No damage was identified with a full inspection conducted after the tests.</div></div>

Evaluation of DAMAGE Algorithm in Frontal Crashes

<div class="section abstract"><div class="htmlview paragraph">With the current trend of including the evaluation of the risk of brain injuries in vehicle crashes due to rotational kinematics of the head, two injury criteria have been introduced since 2013 – BrIC and DAMAGE. BrIC was developed by NHTSA in 2013 and was suggested for inclusion in the US NCAP for frontal and side crashes. DAMAGE has been developed by UVa under the sponsorship of JAMA and JARI and has been accepted tentatively by the EuroNCAP. Although BrIC in US crash testing is known and reported, DAMAGE in tests of the US fleet is relatively unknown. The current paper will report on DAMAGE in NCAP-like tests and potential future frontal crash tests involving substantial rotation about the three axes of occupant heads. Distribution of DAMAGE of three-point belted occupants without airbags will also be discussed. Prediction of brain injury risks from the tests have been compared to the risks in the real world. Although DAMAGE correlates well with MPS in the human brain model across several test scenarios, the predicted risk of AIS2+ brain injuries are too high compared to real-world experience. The prediction of AIS4+ brain injury risk in lower velocity crashes is good, but too high in NCAP-like and high speed angular frontal crashes.</div></div>

Injury and fatality risks for child pedestrians and cyclists on public roads

BackgroundPedestrians and cyclists are often referred to as “vulnerable road users,” yet most research is focused on fatal crashes. We used fatal and nonfatal crash data to examine risk factors (i.e., relationship to an intersection, urbanicity, crash circumstances, and vehicle type) for police-reported pedestrian and cyclist injuries on public roads among children aged 0–9 and aged 10–19. We also compared risk factors among these two age groups with adults aged 20–29 and aged 30–39.MethodsCrash data were obtained for 2016–2020 from the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System for fatal crash injuries and Crash Report Sampling System for nonfatal crash injuries. We collected data on victim demographics, roadway, and vehicle- and driver-related factors. Descriptive analyses were conducted between and within pedestrian and cyclist victims.ResultsWe analyzed 206,429 pedestrian injuries (36% in children aged 0–19) and 148,828 cyclist injuries (41% in children aged 0–19) from 2016 to 2020. Overall, child pedestrians had lower injury rates than adults, but children aged 10–19 had greater cycling crash rates than adults. Almost half of the pedestrian injuries in children aged 0–9 were “dart-out” injuries (43%). In the majority of the cyclist injuries, children in both age groups failed to yield to vehicles (aged 0–9 = 40% and aged 10–19 = 24%). For children and all ages included in the study, the fatality risk ratio was highest when pedestrians and cyclists were struck by larger vehicles, such as trucks and buses. Further exploration of roadway factors is presented across ages and transportation mode.ConclusionOur findings on child, driver, vehicle, and roadway factors related to fatal and nonfatal pedestrian and cyclist injuries may help to tailor prevention efforts for younger and older children.

Comparison of frontal crash compatibility metrics between battery-electric and internal-combustion-engine passenger vehicles

Objective The objective of this study was to determine if there are any emerging issues related to battery-electric vehicles’ (BEVs’) geometry, force distribution, and extra weight that may make them more aggressive partners in front-to-front crashes through comparisons of stiffness metrics derived from crash tests. Methods We examined load cell wall data from the National Highway Traffic Safety Administration’s (NHTSA’s) New Car Assessment Program full-width frontal crash test at 56 km/h. Fourteen BEVs, ranging in class from small cars to large SUVs, were compared with 92 internal-combustion-engine (ICE) vehicles, ranging in class from small cars to midsize pickups. We selected vehicles based on the test results available in the NHTSA Vehicle Crash Test Database, and there were no tests of battery-electric (BE) pickups. Data included load-cell-wall force-time histories and longitudinal vehicle acceleration from the body structure. We constructed force-displacement diagrams and calculated static, dynamic, energy-equivalent, and initial front-end-stiffness metrics from load cell wall forces, vehicle acceleration, and static front-end crush measurements for each vehicle. Linear regression models were applied to the metrics for comparison between powertrains. Results BE cars and BE SUVs weighed more than their ICE counterparts, on average 369 kg and 286 kg more, respectively. Initial (200 mm and 400 mm), energy-equivalent and dynamic front-end-stiffness metrics, average height of force, and individual maximum forces, when compared with vehicle shadow, were not statistically different between powertrains. Static stiffness (p = 0.04) and initial stiffness (300 mm; p = 0.05) decreased for BEVs with greater shadow and increased with greater shadow for ICE vehicles. When controlling for vehicle shadow, dynamic crush was greater (p = 0.01), the percentage of center force was lower (p < 0.001), and maximum peak force was higher (p = 0.01) for BEVs compared with ICE vehicles. For the Kia Niro BEV and ICE pair, the 329 kg heavier BEV had a 165 mm longer crush distance, which resulted in lower forces and stiffness metrics compared with the traditional ICE counterpart. Conclusion Overall, this study indicates that current BEVs are not excessively aggressive in terms of stiffness metrics for frontal crash compatibility compared with ICE vehicles.

ACCIDENT AVOIDANCE DUE TO TIRE INFLATION

Maintaining optimal tire pressure is a crucial aspectthat allows for greater vehicle control and, as a result, increases vehicle and human safety. This study seeks to identify remedies in the event of anomalous tire pressure, thereby ensuring the vehicle's safety. According to the National Highway Traffic Safety Administration (NHTSA), abnormal tire pressure- related collisions result in 660 fatalities and 33,000 injuries each year. The pressure of the tire is checked and monitored to assure its safety, and thus the vehicle's safety. In this project, the pressure and wear and tear on the vehicle's tire are both monitored and quantified. Key Words: Tire and Wheel, air compressor, motor, pressuresensor, microcontroller, alerting

Alcohol Exclusion Laws and Its Drawbacks

Photo ID 143764115 © Chris Dorney | Dreamstime.com INTRODUCTION Since the repeal of the 18th Amendment in 1933, alcohol consumption has become prevalent among many Americans. Alcohol intoxication is an increasing contributor to emergency room visits wherein individuals present to the emergency department (ED) in an inebriated state,  often with secondary injuries or severe medical co-morbidities related to alcohol poisoning. The ED is a stressful environment with providers working under taxing conditions while triaging difficult cases. Alcohol related visits contribute to this added stress for staff given that intoxicated individuals increase wait times for the ED, use up valuable resources, and have the capacity to act violently towards providers. As one nurse puts it, some intoxicated individuals  present with “an aggressive state, perhaps have been in a fight, blood everywhere, careening  around the place – it can make things very difficult.”[1] To combat these circumstances, thirty-four States including the District of Columbia have implemented a countermeasure recognized as Alcohol Exclusion Laws (AELs).  AELs reduce or cut insurance coverage of certain visits to the ED if the cause of the visit is due to alcohol intoxication.[2] The vast implementation of this law is derived from the idea of individual decision making, that it is an individual’s choice to consume alcohol, and therefore they hold a personal responsibility for their intoxication. By using insurance coverage as a leverage, the law aims at reducing the number of ED visits relating to alcohol intoxication, saving resources, and deterring irresponsible drinking. While the intention behind AELs aims for positive change, it is unethical to use AELs, a form of financial leverage, to address certain problems within emergency medicine.  ANALYSIS Stigma is prominent in almost all substance abuse cases including those seen with alcohol intoxication. Many patients feel embarrassment or shame when seeking medical attention for a condition that was brought on by alcohol misuse. A personal account by Jonathan Hunt Glassman, a former alcoholic and NBC contributor, emphasizes on this negative bias. He knows firsthand how unsettling an ED visit can be. He felt demoralized from a superficial prognosis  made by a nurse on his complex alcohol abuse condition, in which the nurse said, “You need to  stop drinking.”[3] Whether it be from shame or insecurities about an individual’s condition, the stigma behind substance abuse cases in the emergency department and the daunting task of asking for help can turn a lot of patients away from seeking and receiving medical treatment. The implementation of Alcohol Exclusion Laws can amplify this already present stigma. A study conducted by the National Institute of Health (NIH) analyzed States that implemented and continued to enforce Alcohol Exclusion Laws and the stigma in those states surrounding alcohol-related ED visits. The result from the study showed that AELs correlated with an increase in stigmatization regarding medical attention for alcohol-related incidents, and that AELs “negatively impact people’s willingness to seek medical care after alcohol-related injuries or  illnesses.”[4] Both the NIH study and the personal account by Hunt-Glassman go on to show that  AELs have the adverse effect of reinforcing the stigma surrounding alcohol cases in the ED.  While the idea behind AELs is in good faith, it contributes to the stigma. This contribution ethically challenges the idea that the emergency room is a space where the treatment of injuries is carried out without biases infringing on such medical care. The mission of EDs is to provide medical care to anyone in need. AELs have the effect of discouraging these patients from seeking help with the unintended consequence of doing them harm.  A point of argument for the implementation of AELs is that it is the individual’s choice to be intoxicated and therefore justifiable that an individual receives less insurance coverage for medical expenses from a preventable intoxication. The idea of it being an individual choice to become intoxicated is one of the strongest supports for these exclusion laws. However, it is unjust to assume that all alcohol intoxications come by choice. Instances that disprove this assumption include both the college party scene and bar scene. Spiked drinks significantly increase alcohol concentration and can cause any responsible drinker to become intoxicated without intention or against their will. Additionally, alcoholic beverages served in various social gatherings like those in or around college campuses may not have a clear percentage of alcohol determination. Liquor containing high percentages of alcohol, such as Everclear which contains up to 190 proofs, are often masked by sweeteners and flavorings. Cocktails like these can cause a person to become dangerously intoxicated without their realization or intention. Some may argue that consuming an alcoholic beverage still holds accountability, that the person should be aware of the potential for a tampered drink, and therefore AELs should remain in use to deter this. However, like any law, AELs needs to have defined restrictions and/or exemptions. If the individual choice argument is used in favor for AELs, then how far reaching can the laws be applied? An attorney who specializes in these exclusion laws believes that AELs often offer more ambiguity than clarification when it comes to insurance policy, which leads to further ways insurance claims can be denied.[5] CONCLUSION In summary, the idea behind the use of Alcohol Exclusion Laws aims to reduce intoxication cases in the ED, however, there are drawbacks and aspects of this law that challenge the ethics of seeking medical care from the emergency department. The present stigma surrounding going to the ED for alcohol-related emergencies is already prevalent in hospitals across the country. When applying AELs, the present stigma may be magnified and further push the idea that seeking help for alcohol-related emergencies is shameful and embarrassing for patients, and therefore should be punished via financial means. Secondly, one of the main justifications for AELs is the idea that it is a deliberate intention to become intoxicated. It isn’t always the intention of individuals to get drunk when they choose to consume alcohol. There are additional factors that may play a part to exonerate a person’s accountability. It is difficult for people to recall the specifics of a situation when they become intoxicated; in some cases, accountability cannot be determined and the used of AELs can become unjustified. Overall, Alcohol Exclusion  Laws try to solve the issue of alcohol incidents in a way that produces more detriment than progress. A method to combat the issue of irresponsible drinking and intoxication in the emergency room within the US should not use AELs and financial leverage as one of its forefronts. In fact, a study that based its findings obtained from the Behavioral Risk Factor  Surveillance System nationwide survey that spanned twenty-four years from 1993-2017,  showed no real impact on binge drinking or increased alcohol consumption.[6] Given the downsides to AELs and its proven non-significant effects, several States have already repealed their AELs. For all these reasons, it would be beneficial to find an alternate method to address alcohol related issues within healthcare. - [1] Gregory, A. (16 Jun 2014). Nurses say drunk patients should be banned from A&amp;E as ‘waste of resources’ UK:  Mirror. https://www.mirror.co.uk/news/uk-news/nurses-say-drunk-patients-should-3706280 2(Jan 2008). [2] Alcohol Exclusion Laws. National Highway Traffic Safety Administration. https://www.nhtsa.gov/sites/nhtsa.gov/files/810885.pdf. [3] Glassman, J.H. (28 Apr 2022). Why don’t alcoholics get prescribed the medication they need?. NBC.  https://www.nbcnews.com/think/opinion/alcohol-related-deaths-er-visits-rose-covid-solution-use- rcna26425. [4] Azagba, S., Ebling, T., Hall, M., (2023). Health claims denial for alcohol intoxication: State laws and structural stigma. Wiley Online Library. https://onlinelibrary.wiley.com/doi/10.1111/acer.15153.  [5] (7 Sep 2021). The Alcohol Exclusion Chart Denied Life Insurance Claim. https://www.lifeinsuranceattorney.com/blog/2021/september/the-alcohol-exclusion-state-chart-denied-life-in/. [6] Azagba, S., Shan, L., Ebling, T., Wolfson, M., Hall, M., Chaloupka, F., (26 Nov 2022). Does state repeal of alcohol  exclusion laws increase problem drinking? National Institutes of Health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10099925/.

The influence of roadway characteristics and built environment on the extent of over-speeding: An exploration using mobile automated traffic camera data

Over-speeding is a pivotal factor in fatal traffic crashes globally, necessitating robust speed management strategies to augment road safety. In 2021, the National Highway Traffic Safety Administration reported over 12,000 speed-related fatalities in the United States alone. Previous studies aggregated over-speeding tendency; however, the extent of over-speeding has a significant implication on the crash outcome. This study delves into the prevalence and magnitude of over-speeding in various scenarios, utilizing data from traffic cameras in Edmonton, Canada, and employing a negative binomial statistical model for analysis. The model elucidates the significance and likelihood of over-speeding tendencies by incorporating temporal and built environment variables—year, month, number of lanes, dwelling unit types, school-related, and open green space. Study results indicated that the aggregation of the over-speeding data tends to underestimate the influence of various factors. Notably, the estimated impact of the posted speed limit is up to over two times for the disaggregated models compared to the aggregated model. Further, the summer months exhibit a roughly 25% uptick in speed limit violations for aggregated models compared to about 40% for disaggregated approaches. Conversely, a discernible decline in over-speeding tendencies is observed with camera enforcement, showcasing a 25% reduction over four years. Built environment variables presented mixed results, with one-unit dwellings associated with a 12% increase in over-speeding, while proximity to schools indicated a 10% decrease. These pivotal findings provide policymakers and practitioners with valuable insights to formulate targeted interventions and countermeasures to curtail speed limit violations and bolster overall road safety conditions.

History of NHTSA’s upgrade of FMVSS 208 addressing airbag induced fatalities and serious injuries

Objective The objective of this paper is to provide a history of the National Highway Traffic Safety Administration’s (NHTSA’s) extensive efforts of incorporating advanced airbag technology capability beyond that available in first-generation airbag systems into FMVSS No. 208. Methods In the paper, NHTSA’s actions and their collaborative efforts with automakers, automaker suppliers, insurance industry, academia, and other Federal agencies were reviewed, and the key efforts have been highlighted. Through their efforts, NHTSA developed its strategy by first undertaking near term actions and then undertaking the strategy for longer term actions. Rulemaking was undertaken in three steps. Then, as sufficient data became available, NHTSA documented the effectiveness of the rulemakings. Results The approach taken by NHTSA with the goal of preserving the safety benefits of the first-generation of frontal airbags while minimizing their danger to children and at-risk adults paved the way for the advanced airbags final rule and an interim final rule issued on May 12, 2000 (see Federal Register Notice 65 FR 30680). A follow-up final rule was issued on August 31, 2006, to change the test speed of the belted 5th percentile female dummy from 48 km/h to 56 km/h (30 mph to 35 mph). The final rule was updated on November 2, 2007, to permit manufacturers to earn advance credits for vehicles that are certified in compliance with the new higher speed requirement one year in advance of the regulatory requirements. Conclusion NHTSA engagement in efforts with multiple partners toward identifying the safety issues, was an integral part of NHTSA’s strategy in addressing the problem, arriving at immediate actions that NHTSA took, and detailing a comprehensive look at the longer-term approach required to resolve the safety issues. The approach taken by NHTSA paved the way for the advanced airbags final rule and an interim final rule issued on May 12, 2000 (Federal Register Notice 65 FR 30680). NHTSA had undertaken a successful collaboration of the Federal Government, the automobile industry, equipment suppliers, insurance companies, traffic safety advocates, law enforcement agencies from across the country, and the media to solve the airbag related safety issue.

Crossing the line: access to trauma care across state borders

ObjectiveThis study investigates the challenge posed by state borders by identifying the population, injury, and geographic scope of areas of the country where the closest trauma center is out-of-state, and...

Designing Audible Safety with Acoustic Vehicle Alerting System for Commercial Vehicles

Abstract: Electric and hybrid vehicles, known for their environmental benefits, also present a unique challenge because of their quiet operation. In urban settings, this lack of noise increases the potential for accidents with pedestrians who rely heavily on auditory cues. In response to this concern, Acoustic Vehicle Alerting Systems (AVAS) have been introduced and many countries, including the US and EU, have mandated the installation of Acoustic Vehicle Alerting Systems. These systems produce sounds to alert pedestrians of an approaching vehicle by increasing the audibility of electric and hybrid vehicles to ensure pedestrian safety [1]. In this paper, we dive deep into designing an effective AVAS for commercial vehicles, such as trucks and buses. Any AVAS must conform the international regulations such as the ECE-R138 regulation by the United Nations Economic Commission for Europe (UNECE) and FMVSS 141 by the National Highway Traffic Safety Administration (NHTSA), so our design adheres to guidelines set by key global bodies. This endeavour was supported by The Scientific and Technological Research Council of Türkiye. Our AVAS not only offers a variety of sound options but also includes self-diagnostic features to ensure its consistent performance. An integral part of our study was the utilization of an ASIL-B functional safety-compliant embedded MCU system to generate and manipulate psychoacoustic sounds. The regulations regarding the acoustic characteristics of AVAS sounds, such as minimum sound level, frequency spectrum, and frequency shift, have been instrumental in improving awareness of the AVAS sounds of quiet vehicles[2]. The ultimate aim is to showcase a versatile, compliant, and efficient AVAS, beneficial for the future landscape of electric and hybrid commercial vehicles

The typical AV accident scenarios in the urban area obtained by clustering and association rule mining of real-world accident reports

Automated Vehicles (AVs) based on a collection of advanced technologies such as big data and artificial intelligence have opened an opportunity to reduce traffic accidents caused by human drivers. Nevertheless, traffic accidents of AVs continue to occur, which raises safety and reliability concerns about AVs. AVs are particularly vulnerable to accidents on urban roads than on highways due to various dynamic objects and more complex infrastructure. Several studies proposed a scenario-based approach of experimenting with the response of AVs to specific situations as a way to test their safety. Reliable and concrete scenarios are necessary to test AV safety under critical conditions accurately. This study aims to derive a typical accident scenario for evaluating the safety of AVs, specifically in urban areas, by analysing collisions reported by the DMV of California, USA. We applied a hierarchical clustering method to find groups of similar reports and then executed association rule mining on each cluster to correlate between accident factors and collision types. We combined statistically significant association rules to constitute a total of 14 scenarios that are described according to an adapted PEGASUS framework. The newly obtained scenarios exhibit significantly different accident patterns than the typical Human-driven Vehicles (HVs) in urban areas reported by National Highway Traffic Safety Administration. Our discovery urges AV safety to be tested reliably under scenarios more relevant than the existing HV accident scenarios.

Pyramid Scene Parsing Network for Driver Distraction Classification

In recent years, there has been a persistent increase in the number of road accidents worldwide. The US National Highway Traffic Safety Administration reports that distracted driving is responsible for approximately 45 percent of road accidents. In this study, we tackle the challenge of automating the detection and classification of driver distraction, along with the monitoring of risky driving behavior. Our proposed solution is based on the Pyramid Scene Parsing Network (PSPNet), which is a semantic segmentation model equipped with a pyramid parsing module. This module leverages global context information through context aggregation from different regions. We introduce a lightweight model for driver distraction classification, where the final predictions benefit from the combination of both local and global cues. For model training, we utilized the publicly available StateFarm Distracted Driver Detection Dataset. Additionally, we propose optimization techniques for classification to enhance the model’s performance.

Analysis of the mechanism of side impact of cars

Problem. Globally, car crashes are the major cause of death, killing 1.2 million people, and despite improvements in car safety, forecasts indicate that car crash deaths will increase significantly by 2030 due to the increase in the number of cars. Such a trend requires an increase in passive safety in the design of cars. It is also necessary to consider with these factors the most popular segments of SUV cars, which during an accident create more dangerous consequences in the event of a side impact, taking into account the mass and dimensions parameters. Goal. The aim is to conduct an analysis of the side collision mechanism of cars of different mass and dimensional parameters. Taking into account the trends in the sale of cars, identifying the most popular classes of cars in Ukraine both on the new car market and on the second-hand market, to further identify problems in testing cars according to various certification protocols. Methodology. The approaches to solving the tasks used in the work are based on the use of statistical data and comparative analysis of various methodologies and certification protocols. Results. Considering that scientific studies of frontal impact are presented by the scientific community in the broadest form, the study of the side impact of two cars is currently a relevant direction, taking into account the global trend towards the production of cars in the SUV segment, which exceed passenger cars in terms of mass and dimensions. In a road accident with a side impact of a passenger car and an off-road vehicle of the SUV segment, we will get a large difference in the height of the primary impact, which is 250 millimeters. That is, all the energy of the impact to the side of the passenger car falls not on the safety bar, but 250 millimeters higher, which will inevitably lead to fatal injuries to the driver and passenger. Unfortunately, the European NCAP and the US National Highway Traffic Safety Administration use moving barriers that are similar in terms of mass and dimensions to an average passenger car. Originality. The obtained results of the analysis of the mechanism of the car side collision make it possible to evaluate the current trend of the automobile market in terms of passive safety and, in particular, to conduct certification tests for side impact in a new way. Practical value. The obtained results can be recommended when studying the structural features of preparing and conducting crash tests.

Characteristics of Rear-End Collisions: A Comparison between Automated Driving System-Involved Crashes and Advanced Driving Assistance System-Involved Crashes

With the increasing number of vehicles equipped with automated driving systems (ADS) being tested on public roads and the expanding market share of vehicles equipped with advanced driving assistance systems (ADAS), the number of ADS- or ADAS-involved crashes increases. Thus, it is necessary to investigate the distribution of ADS- and ADAS-involved crashes and the factors leading to them. The rear-end collision has been found to dominate ADS-involved crashes. However, no research has explored the conditions when ADS-involved rear-end collisions are more likely to happen and no research has investigated ADAS-involved rear-end crashes. Based on 130 ADS-involved crashes and 84 ADAS-involved crashes extracted from a dataset collected by the National Highway Traffic Safety Administration (NHTSA) between July 2021 and May 2022, this study explored the crash patterns, especially rear-end crashes, of ADS- and ADAS-controlled vehicles. Results show that rear-end collisions dominate both ADS- and ADAS-involved crashes, especially ADAS-involved crashes. The type of both ADS-involved and ADAS-involved crashes was affected by the speed of the ego-vehicle relative to the posted speed limit. Further, the type of ADS-involved crash was affected by the pre-crash movement of the crash partner, while the type of ADAS-involved crash was further associated with the road type. The findings can provide insights into the design of ADAS and ADS control algorithms, the external human-machine interface design of the vehicles with ADS or ADAS, and the training program of human road users to improve traffic safety in mixed traffic.

The Relative Risk of Alcohol-Involved Crashes as a Function of Time of Day.

Epidemiological research has repeatedly found that alcohol-impaired driving is associated with elevated risk of crash involvement in a dose-response fashion. Although experimental studies show that alcohol impairment of cognitive and psychomotor driving skills is exacerbated by sleep deprivation, there is less evidence that the combination of drowsiness and alcohol predicts actual motor vehicle crashes. We explored this by reanalyzing data from the National Highway Traffic Safety Administration Drug and Alcohol Crash Risk Study, constructing separate risk curves for daytime and nighttime hours. Controlling for driver demographics and driving exposure, and excluding other impairing drugs, we observed significantly greater risk of crash during the night versus the day at blood alcohol concentrations (BACs) between approximately .04 and .12 g/dl. Based on fitted point estimates, at .08 g/dl, the risk of crash at night was three times the risk of crash during the day. The association between BACs and crash risk was markedly different during daytime versus nighttime hours. Increased daytime risk was not observed until BACs exceeded the .08 g/dl per se legal limit. Results are interpreted as emphasizing the sedating role of alcohol. Implications are discussed.

A comparison of patterns and contributing factors of ADAS and ADS involved crashes

Crashes involving Advanced Driver Assistance Systems (ADAS) and Automated Driving Systems (ADS) have been increasing in recent years. Understanding the characteristics of these crashes can guide the optimization of driving automation systems and the policies improving the safety of mixed traffic. However, due to the limited available data, the crashes of ADS- and ADAS-controlled vehicles are still under-investigated. Thus, utilizing the latest National Highway Traffic Safety Administration crash reports, our study explores the patterns and contributing factors of ADAS- and ADS-involved crashes. The sequences of events leading to crashes were extracted from the reports and then categorized into five clusters. Next, for incomplete records, a non-parametric imputation method was applied based on Random Forest. Finally, logistic regression models were built to explore the factors associated with the crashes. The results show that the automation level, speed limit, and vehicle speed are predictors of crash patterns. At the same time, the crash pattern, combined with incident time, roadway type, roadway surface, and vehicle model year are associated with crash outcomes (i.e. contact area and injury severity). The results indicate that further improvement of the ADS/ADAS control algorithms and driver education may be needed to improve the safety of mixed traffic.

The role of autonomous vehicles in transportation equity in Tempe, Arizona

In 2016, The National Highway Traffic Safety Administration reported that human error is involved in 94–96% of all motor vehicle crashes. Also in 2016, Bonnefon et al. predicted that autonomous vehicles could eliminate 90% of traffic collisions due to their elimination of human error. However, questions of safety, accessibility, and social equity have arisen after the first pedestrian death by an autonomous vehicle in its testing phase occurred in Tempe, AZ, in 2018. This project analyzes how social equity issues shape the discussion, creation, and implementation of governmental policies and regulations surrounding driverless automobiles in Tempe, using policy and text analysis as well as semi-structured interviews of government officials or residents of Tempe. Informed by the concept of the right to the city and critical legal studies, this research suggests that public policy around autonomous vehicles does create new and expand existing spaces for inequality in Tempe. This is exacerbated by increased awareness of inequality within Arizona’s autonomous vehicle regulation scheme and its entire transportation system after the first pedestrian death by autonomous vehicle.

Determination of functional scenarios for intersection collisions

IntroductionThe National Highway Traffic Safety Administration (NHTSA) estimated that in 2019, intersection crashes accounted for $179 billion of economic damages and $639 billion in societal damages. Intersection advanced driver assist systems (I-ADASs) and automated driving systems (ADS) are designed and have been actively deployed to avoid or mitigate these intersection crash scenarios. Given the indeterminate parameter space for describing collision scenarios, evaluators, and designers are all challenged with condensing the possible intersection crash configurations into digestible, executable conditions for scenario-based simulation testing. The objective of this study is to identify functional intersection crash configurations for I-ADAS and ADS safety evaluation. MethodsReal-world intersection crash characteristics are important considerations for scenario testing as these features can directly correlate to or influence causality, controllability, and potential injury severity. To identify functional intersection crash types, similar crash scenarios were grouped together by identified critical features using an unsupervised decision tree model. A key advantage of this approach was that the implemented cluster crash scenarios would be understandable and interpretable by users. Unsupervised decision trees work by generating uniformly distributed synthetic data with features from real data and classifying all the data as real or synthetic. Long, non-diverging branches were manually pruned to reduce overfitting and improve model performance. Feature importance values were computed based on how effective a given variable grouped the crashes together. Data sourcesThis analysis selected intersection cases that only involved two vehicles from the Crash Investigation Sampling System (CISS) spanning 2017 to 2020. Crash features such as road geometry, intersection signal, and vehicle configuration were important to consider for scenario generation. CISS contained the traffic device, device functionality, vehicle intended pre-event movement, road alignment, road profile, trafficway flow, number of lanes, and crash type for each crash case. Intersection geometry, intersecting road angle, each vehicles’ legal moves, and the presence of a two-way-left-turn-lane (TWLTL), channelized roads, bike lanes, crosswalks, street parking, slip lanes, and visual obstructions were manually recorded from the scene diagram. ResultsThe tree identified 44 functional intersection crash configurations after pruning. These clusters have five main sections: Straight-crossing path (SCP) crashes at 4-legged intersections, Left-Turn-Across-Path/Opposite Direction (LTAP/OD) crashes at 4-legged intersections, other crash types at 4-legged intersections, roundabout and multileg intersections, and 3-legged intersection crashes. The features that best split the data were TWLTL, lane travel direction violation, and traffic control device functionality. The largest cluster was SCP crashes at 4-legged, undivided intersections where the traffic control device was working and both vehicles did not violate the direction of their lane of travel. This cluster was adjacent to 32 vehicles in similar SCP crashes except a vehicle performed an unexpected maneuver based on their lane position. ConclusionThese 44 identified crash configurations could be useful in bolstering the robustness of I-ADAS and ADS intersection scenario testing as they are a compact representation of all the police reported intersection crashes where a vehicle was towed. Future studies could generate logical scenarios with distributions of initial conditions and behaviors from these clusters that could be used to evaluate an I-ADAS or ADS.

Do Drivers Understand Cyclists’ Communication Cues?

To navigate safely in the traffic environment, drivers must correctly predict cyclists’ intentions. When drivers are unable to correctly predict cyclists' intentions collisions may occur. The current study aimed to determine what combinations of cues would allow drivers to correctly predict a cyclist's intentions. In particular, the study examined how drivers used lane position, hand signals, and head movements (i.e., looking over a shoulder) to make judgments about a cyclist’s intentions. A second aim was to examine drivers’ understanding of arm signals that are recommended by the National Highway Traffic Safety Administration. Our results revealed that only straight arm turn signals were correctly understood by all the drivers. Combining cues increased the number of drivers who correctly predicted the cyclist's intentions. To improve cyclists’ safety, transportation laws could be rewritten to include instructions on using lane position and head turns to communicate intentions more effectively.