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Studies of rollover accidents have reported crash attributes such as the number of rolls, rollout distance, initial over-the-ground speed, average roll rate, average over-the-ground deceleration, magnitude of roof deformation, cumulative damage, time and post-crash headroom. While these more general attributes are related to the repeated vehicle-to-ground impacts during a rollover, it has been previously shown [1] that a specific ground impact during a rollover and its consequences can be studied in more detail by using its acceleration time history (crash pulse or impulse) and energy loss. These two quantities are particularly meaningful to use when studying impact mechanics, however, they are limited to circumstances where the data exists, which means real-world on-road crashes cannot be used directly. Acceleration and energy data have been collected and previously published for three Subaru Forester dolly rollover tests, and have been studied in more detail in this writing.

There is a limited amount of data currently available on the acceleration and braking performances of school buses. This paper analyzes the braking performance of various Type A and Type C school buses with hydraulic and air brakes. The effect of ABS and Non-ABS systems as well as driver experience is discussed. A comparison with passenger car braking performance is presented. The acceleration of a school bus is also presented. Evaluations of “normal” and “rapid” accelerations are presented for Type A and Type B buses. A comparison with commonly used acceleration values for various vehicles is presented.

Unintended acceleration events due to pedal misapplication have been shown to occur more frequently in older vs. younger drivers. While such occurrences are well documented, the nature of these movement errors is not well-characterized in common pedal error scenarios: namely, on-road, non-emergency stopping or slowing maneuvers. It is commonly assumed that drivers move in a ballistic or “direct hit” trajectory from the accelerator to the brake pedal. However, recent simulator studies show that drivers do not always move directly between pedals, with older drivers displaying more variable foot trajectories than younger drivers. Our study investigated pedal movement trajectories in older drivers ages 67.9 ± 5.2 years (7 males, 8 females) during on-road driving in response to variable traffic light conditions. Three different sedans and a pick-up truck were utilized.

Because the great majority of All-Terrain Vehicles (ATVs) use a solid rear axle for improved off-road mobility, these vehicles typically transition from understeer to oversteer with increased cornering severity in tests customarily used by automobile manufacturers to measure steady-state vehicle handling properties. An oversteer handling response is contrary to the accepted norm for on-road passenger vehicles and, for this reason, has drawn scrutiny from numerous researchers. In this paper, an evaluation of ATV handling is presented in which 10 participants operated an ATV that was configured to have two different steady-state cornering characteristics. One configuration produced an approximately linear understeer response (labeled US) and the other configuration transitioned from understeer to oversteer (labeled US-OS) with increasing lateral acceleration in constant-radius turn tests conducted on a skid pad.

This paper explores tire placement with given tread depths on vehicles from two distinct perspectives. The first area explored is an analysis of crash data recently reported by the National Highway Traffic Safety Administration (NHTSA). In this report, thousands of tire-related crashes were investigated where the tread depth and inflation pressure were logged for each tire and assessments were made as to whether tire condition was a factor in the crash. The analysis of the data shows that in regards to accident causation, it is not statistically significant which axle has the deepest tread. What is significant is that a tread depth at or below 4/32″ anywhere on the vehicle leads to an increased rate of crashes. To understand the physics implied by the NHTSA data, a study was performed on how the placement of tires of various tread depths affects the steering, handling, and braking performance of a modern sport utility vehicle.

Blunt impacts to the back of the torso can occur in vehicle crashes due to interaction with unrestrained occupants, or cargo in frontal crashes, or intrusion in rear crashes, for example. Six pendulum tests were conducted on the back of an instrumented 50th percentile male Hybrid III ATD (Anthropomorphic Test Device) to determine kinematic and biomechanical responses. The impact locations were centered with the top of a 15-cm diameter impactor at the T1 or at T6 level of the thoracic spine. The impact speed varied from 16 to 24 km/h. Two 24 km/h tests were conducted at the T1 level and showed repeatability of setup and ATD responses. The 16 and 24 km/h tests at T1 and T6 were compared. Results indicated greater head rotation, neck extension moments and neck shear forces at T1 level impacts. For example, lower neck extension was 2.6 times and 3.8 times greater at T1 versus T6 impacts at 16 and 24 km/h, respectively.

The emergence of Plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs) as a viable means of transportation has been coincident with the development of lithium-ion (Li-ion) battery technology and electronics. These developments have enabled the storage and use of large amounts of energy that were previously only possible with internal combustion engines. However, the safety aspects of using these large energy storage battery packs are a significant challenge to address. In addition, the rapid advances in electrode and electrolyte materials for Li-Ion batteries have made comparisons and ranking of safety parameters difficult because of the substantial variations in cell designs. In this work, we outline a method for quantifying the thermal safety aspects of Li-ion battery technologies using a Cone Calorimeter.

As micromobility devices (i.e., e-bikes, scooters, skateboards, etc.) continue to increase in popularity, there is a growing need to test these devices for varying purposes such as performance assessment, crash reconstruction, and design of new products. Although tests have been conducted across the industry for electric scooters (e-scooters), this paper describes a novel method for crash testing e-scooters with anthropomorphic test devices (ATDs) “riding” them, providing new sources for data collection and research. A sled fixture was designed utilizing a pneumatic crash rail to propel the scooters with an overhead gantry used for stabilization of the ATD until release just prior to impact. The designed test series included impacts with a 5.5-inch curb at varying incidence angles, a stationary vehicle, or a standing pedestrian ATD. Test parameter permutations included changing e-scooter tire sizes, impact speeds, and rider safety equipment.

Advanced Driver Assistive System (ADAS) technologies have been introduced as the automotive industry moves towards autonomous driving. One ADAS technology with the potential for substantial safety benefits is forward collision warning and mitigation (FCWM), which is designed to warn drivers of imminent front-end collisions, potentiate driver braking responses, and apply the vehicle's brakes autonomously. Although the proliferation of FCWM technologies can, in many ways, mitigate the necessity of a timely braking response by a driver in an emergency situation, how these systems affect a driver's overall ability to safely, efficiently, and comfortably operate a motor vehicle remains unclear. Exponent conducted a closed-course evaluation of drivers' reactions to an imminent forward collision event while driving an FCWM-equipped vehicle, either with or without a secondary task administered through a hands-free cell phone.

Seat strength has increased over the past four decades which includes a transition to dual recliners. There are seat collision performance issues with stiff ABTS and very strong seats in rear impacts with different occupant sizes, seating positions and physical conditions. In this study, eight rear sled tests were conducted in four series: 1) ABTS in a 56 km/h (35 mph) test with a 50th Hybrid III ATD at MGA, 2) dual-recliner ABTS and F-150 in a 56 km/h (35 mph) test with a 5th female Hybrid III ATD at Ford, 3) dual-recliner ABTS in a 48 km/h (30 mph) test with a 95th Hybrid III ATD leaning inboard at CAPE and 4) dual-recliner ABTS and Escape in 40 km/h (25 mph) in-position and out-of-position tests with a 50th Hybrid III ATD at Ford. The sled tests showed that single-recliner ABTS seats twist in severe rear impacts with the pivot side deformed more rearward than the stanchion side.

The average body weight of the US population has increased over time. This study investigates the effect of increasing weight on seat and occupant responses in 15-18 km/h and 42 km/h rear sled tests. The effect of initial occupant posture is also discussed. Seven tests were conducted with lap-shoulder belted ATDs (anthropometric test device) placed on older and modern driver seats. Four tests were conducted with a 50th percentile male Hybrid III, two with 95th percentile male Hybrid III and one with a BioRID. The ATDs were ballasted to represent a Class I or II obese occupant in three tests. The tests were matched by seat model and sled velocity. The effect of occupant weight was assessed in three matches. The results indicated an increase in seatback deflection with increasing occupant weight.

There are established federal requirements and industry standards for frontal crash testing of motor vehicles. Consistently applied methods support reliability, repeatability, and comparability of performance metrics between tests and platforms. However, real world collisions are rarely identical to standard test protocols. This study examined the effects of occupant anthropometry and passive restraint deployment timing on occupant kinematics and biomechanical loading in a moderate-severity (approximately 30 kph delta-V) offset frontal crash scenario. An offset, front-to-rear vehicle-to-vehicle crash test was performed, and the dynamics of the vehicle experiencing the frontal collision were replicated in a series of three sled tests. Crash test and sled test vehicle kinematics were comparable. A standard or reduced-weight 50th percentile male Hybrid III ATD (H3-50M) or a standard 5th percentile female Hybrid III ATD (H3-5F) was belted in the driver’s seating position.

In recent years, the discussion around the advent of highly automated vehicles has shifted from “if” to “when.” Commercially available vehicles already incorporate automated vehicle (AV) technologies of varying capability, and the eventual transition to fully automated systems, at least within certain predefined Operational Design Domains, is largely considered inevitable. While the full ramifications of this shift and the eventual depreciation of human driver control are still under intense debate, there is broad agreement on one issue -the advent of driverless systems will remove several constraints on the design of vehicle interior spaces, creating the opportunity for innovation. Even at this early stage, ambitious design concepts of purpose specific vehicles - mobile gyms, offices, bedrooms - have been proposed. More grounded designs, such as rotating passenger seats, have also been put forward.

Electric vehicles (EVs) and the development around them has been rapid in recent years. As the battery is the most essential component of an electric vehicle, a lot of research and analysis has been focused on ensuring safe and reliable performance of batteries. Considering the location, size, and operating conditions for EV batteries, they must be designed with an in-built safety infrastructure keeping in mind certain realistic scenarios such as fire exposure, mechanical vibration, collisions, over-charging, single cell failures, and others. In this paper, we discuss an overview of various EV battery failure mechanisms, present current safety and abuse testing methods and standards associated with such mechanisms and discuss the need for the development and implementation of additional testing standards to better characterize the safety performance of EV battery packs.

As the automated vehicle (AV) industry continues to progress, it is important to establish the level of operational safety of these vehicles prior to and throughout their deployment on public roads. The Institute of Automated Mobility (IAM) has previously proposed a set of operational safety assessment (OSA) metrics which can be used to quantify the operational safety of vehicles. The OSA metrics provide a starting point to consistently quantify performance, but a framework to interpret the metrics measurements is needed to objectively quantify the overall operational safety for a vehicle in a given scenario. This work aims to present an approach to applying a calculation of the safety envelope component of the OSA metrics to rear-world collisions for use in such an assessment. In this paper, the OSA methodology concept is introduced as a means for quantifying the operational safety of a vehicle.

Three years of data from the Large Truck Crash Causation Study (LTCCS) were analyzed to identify accidents involving heavy trucks (GVWR >10,000 lbs.). Risk of rollover and ejection was determined as well as belt usage rates. Risk of ejection was also analyzed based on rollover status and belt use. The Abbreviated Injury Scale (AIS) was used as an injury rating system for the involved vehicle occupants. These data were further analyzed to determine injury distribution based on factors such as crash type, ejection, and restraint system use. The maximum AIS score (MAIS) was analyzed and each body region (head, face, spine, thorax, abdomen, upper extremity, and lower extremity) was considered for an AIS score of three or greater (AIS 3+). The majority of heavy truck occupants in this study were belted (71%), only 2.5% of occupants were completely or partially ejected, and 28% experienced a rollover event.

The operational safety of automated driving system (ADS)-equipped vehicles (AVs) must be quantified using well-defined metrics in order to gain an unambiguous understanding of the level of risk associated with AV deployment on public roads. In this research, efforts to evaluate the operational safety assessment (OSA) metrics introduced in prior work by the Institute of Automated Mobility (IAM) are described. An initial validation of the proposed set of OSA metrics involved using the open-source simulation software Car Learning to Act (CARLA) and Scenario Runner, which are used to place a subject vehicle in selected scenarios and obtain measurements for the various relevant OSA metrics. Car following scenarios were selected from the list of 37 pre-crash scenarios identified by the National Highway Traffic Safety Administration (NHTSA) as the most common driving situations that lead to crash events involving two light vehicles.

Field data was analyzed on second-row children in front, side and rear impacts to study fatality trends by model year (MY) and calendar year (CY) with 1980-2020 MY vehicles. The different MY and CY perspectives show changes in rates that are useful for setting priorities for second-row child safety in rear impacts. 1990 to 2019 FARS was queried to assess the number of fatally injured and non-ejected second-row children (0-15 years old) in crashes without fires. The children included outboard occupants seated behind an occupied front seat and center occupants. The data was analyzed for rear, front and side impacts to assess crash frequency. 1990-2015 POLK was queried to assess exposure of registered vehicles and estimate a fatality rate. The FARS and POLK data were sub-grouped by MY of the vehicle and CY of the crash. There were 2.8-times more fatally injured children in frontal crashes than in the rear crashes. The ratio of frontal and rear crashes varied with CY sub-groups.

Temperature measurements during a full-scale burn test of a 2001 full-size pickup truck showed that the fire progressed in distinct stages in both the engine and passenger compartments. Although the fire started in the engine compartment and had a relatively long growth period, when a localized area reached about 700°C, a distinct transition occurred where the rate of fire spread increased, leading to full involvement of all engine compartment combustibles. As the engine compartment became fully involved, a hot gas layer then accumulated at the ceiling of the passenger compartment, producing a strong vertical temperature gradient. When the temperature at the ceiling reached about 600°C, another distinct transition occurred where the rate of fire spread increased, leading to full involvement of the passenger compartment. The highest temperature during the test occurred within the engine compartment in an area that had the greatest fuel load, and not the area of origin.

Fires involving cars, trucks, and other highway vehicles are a common concern for emergency responders. In 2013 alone, there were approximately 188,000 highway vehicle fires. Fire Service personnel are accustomed to responding to conventional vehicle (i.e., internal combustion engine [ICE]) fires, and generally receive training on the hazards associated with those vehicles and their subsystems. However, in light of the recent proliferation of electric drive vehicles (EDVs), a key question for emergency responders is, “what is different with EDVs and what tactical adjustments are required when responding to EDV fires?” The overall goal of this research program was to develop the technical basis for best practices for emergency response procedures for EDV battery incidents, with consideration for suppression methods and agents, personal protective equipment (PPE), and clean-up/overhaul operations.