Vehicle Safety

Resources

The Office of Vehicle Safety Research and supports U.S. DOT’s and NHTSA’s safety goals by conducting research and safety testing of motor vehicles and motor vehicle equipment. 

NHTSA’s recently published vehicle safety reports are listed chronologically below.

25 Results
Revised THOR 50th Percentile Male Dummy Seating Procedure

NHTSA developed a seating procedure for the THOR 50th percentile male dummy (THOR-50M). The original was released with a December 2015 Request for Comments (RFC), and some updates were presented at a public meeting at VRTC in August 2016.  This report discusses the changes to the seating procedure since the original that were reflected updates to the THOR-50M, additional experience using the procedure, and comments received.  Some revisions were minor wording changes to better clarify the steps of the procedure. The more significant revisions to the procedure are discussed in this report and include heel point definitions for different accelerator pedal types, seat fore/aft position, H-point tolerances, and final head angle.

Indicators of Driver Adaption to Forward Collision Warnings: A Naturalistic Driving Evaluation

Studies have found that vehicles equipped with forward collision warning (FCW) systems can help drivers reduce the likelihood crashes, but to date the research has only addressed initial safety benefits on short-term exposure (up to one month), and not how those benefits may change over time with longer exposure. This study looks at performance, safety impact, and driver acceptance of FCW systems with automatic emergency braking (AEB) over time using a one-year naturalistic field test of 38 participants (20 to 29 years old) driving 2013 Cadillac SRXs equipped with FCW and AEB systems.  To assess safety, two areas were addressed:  overall driving behavior and rear-end near crash events. Overall, the accuracy and frequency of FCW alerts in the field test were very high, while the accuracy and frequency of AEB events was not. No changed were observed in driver’s speed maintenance, following headway, or alert rate.  Driver’s exposure to near-crash events showed a significant decrease in near-crash events per mile from a predicted 2.634 near-crashes per 1,000 vehicle miles traveled (VMT) during the first 1,000 miles to 0.615 conflicts per 1,000 VMT during the last 18,000 miles (a 76.6 percent decrease).  Drivers showed a significant decrease in the number of near-crash events per month, from a predicted rate of 2.377 conflicts during the first month to 0.815 conflicts during the fourteenth month (a 65.7 percent decrease).  These results suggest that the safety benefits of FCW systems are sustained over longer-term exposure.

Safety Performance of Rechargeable Energy Storage Systems

This report describes objective test procedures based on failure mode and effects analysis (FMEA) for meaningful, comparable, and quantitative evaluations of Li-ion-based rechargeable energy storage systems (RESSs) in electrically propelled platforms. These are applicable to all components of RESS and ancillary vehicle systems associated with electric propulsion; they can also serve as best practice guides for safety assessment of future designs. RESS safety performance is assessed with single and dual-point failure modes during all normal and abnormal operating conditions including charging, vehicle storage, operation, crash event, and post-crash state.

Human Factors for Connected Vehicles Transit Bus Research

This report describes the tasks and demands associated with driving a transit bus, and directly supports the development of design guidelines for future transit safety technologies. The frequency and costs of bus-pedestrian accidents have created considerable interest in technologies that detect pedestrian hazards and warn the bus operator in time to mitigate or prevent an accident. This project addressed a lack of data on bus operator task demands through a mix of surveys, literature reviews, ride-alongs, cognitive task analyses, prototyping activities, and focus groups. The project team was aided tremendously by the support and involvement of transit agencies and their drivers in Seattle, Washington, and Portland, Oregon (King County Metro & TriMet). Key findings from the task analyses illustrated the high demand and complicated nature of bus operator specific activities such as the management of passenger boarding/payment, the navigation of intersections, and the driving on roadways where there is the co-occurrence of visual demands in disparate portions of the roadway scene and bus interior. The project also identified: safety issues (e.g., the impact of current riders on hazard detection, possible conflict between drivers’ behaviors and local laws/policy, and impacts of new technologies on rider perceptions about driver behaviors) that are critical to the introduction of safety technologies for transit, additional research questions about bus operators’ tasks, and the implications of these tasks for the design of pedestrian detection and alerting systems.

Crashworthiness Models for Automotive Batteries

Safety is a key element of electrochemical batteries that convert chemical reactions to electrical energy, especially applied to large automotive batteries in electric vehicles. High energy stored in EV battery packs translates to higher probability of fire in case of crash impact. The mechanisms leading to internal short circuit due to deformation are not well understood. This report summarizes the effort to pinpoint the critical deformation necessary to trigger a short via experimental study on large format automotive Li-ion cells. Experiments were conducted on deformation of stacks of 10 pouch cells representing the half-modules in a Ford Focus EV battery pack.

Lower Leg Biofidelity Corridors for Heel Impact

The primary purpose of this report is to develop biofidelity corridors for the small female foot/leg in axial loading.  This effort built upon previous testing that was done with mid-sized male specimens.  For this project, small female specimens were tested, both with and without a shoe on.  The corridors developed are directly applicable to the THOR 5th female anthropomorphic test device, which is currently undergoing initial biofidelity evaluation. These biofidelity response corridors were based on anticipated measurement capabilities of typical ATDs, and include metrics such as internal tibia and fibula axial load, external footplate axial load, knee axial load, and footplate displacement. Overall, it was found that the shod corridors developed were narrower than either the combined dataset corridors or the barefoot corridors. Additionally, corridors developed with data scaled by leg-length were narrower than those developed using unscaled data. Shod, scaled corridors are recommended for use in 5thth female ATD biofidelity evaluations.

Advanced Automatic Collision Notification Research Report

This report describes NHTSA’s progress understanding the safety potential and technical considerations of post-crash automatic collision notification (ACN) and advanced automatic collision notification (AACN) technologies that send automatic notification of a crash that reached a minimum severity such as air bag deployment. Notification to a public safety answering point (PSAP, or 9-1-1 call center) or telematics service provider (TSP) occurs via cellular signal that allows the vehicle to place a call and transmit data. Research on target populations who may benefit from AACN, injury prediction, and estimates of costs and benefits/potential lives saved were included.

Functional Safety Assessment of a Generic Accelerator Control System With Electronic Throttle Control in Gasoline-Fueled Vehicles

This report describes research to derive safety requirements related to the failures and countermeasures of the accelerator control system with electronic faults such as electronic throttle control (ACS/ETC) signals, following an industry process standard specifically in vehicles with diesel engines. This study follows the Concept Phase process in ISO)26262 and applies hazard and operability study, functional FMEA, and STPA methods. It identifies five safety goals and 204 ACS/ETC system safety requirements as well as potential opportunities to improve the risk assessment approach in ISO 26262.

An Assessment Method for Automotive Intrusion Detection System Performance

In response to the increased attack surfaces on modern vehicles due to expanded use of software and the introduction of wireless interfaces, a new market has emerged for intrusion detection systems (IDSs), which can detect some types of attacks and are under development by several companies. NHTSA requested development and demonstration of a method for assessing the in-vehicle performance of anomaly-based IDSs for vehicle data buses, specifically buses using controller area network protocols. IDSs may (1) protect vehicles from direct malicious manipulation of the data bus traffic, or (2) detect symptoms of unfriendly modification of firmware on one of the dozens of electronic control units (ECUs) on a modern vehicle’s network. The methodology used provides a means to assess the performance of automotive IDS products, to provide quantitative and qualitative analysis of performance, and to offer insights on potential IDS options.

Relative Frequency of U.S. Pedestrian Injuries Associated With Risk Measured in Component-Level Pedestrian Tests

Injury data about U.S. pedestrians was analyzed to estimate frequencies of injuries associated with impacts to vehicle components that could be tested by available component-level pedestrian test equipment. The relative frequencies of injuries that could be affected by pedestrian headform tests, upper legform tests, and lower legform tests were compared. These injuries could be reduced or mitigated if vehicle performance were improved. To determine pedestrian body regions and impacting vehicle components the tests used the same test tools and procedures defined for European New Car Assessment Programme (Euro NCAP) pedestrian testing. Vehicle components in test procedures used test zones defined for Euro NCAP pedestrian test procedures. Therefore, the real-world injuries associated upper legform component tests in this study include all cases with hip, pelvis, or thigh injuries from impact to the hood leading edge or grille. Data on the frequency of injuries by body region was drawn from pedestrian cases in the National Trauma Data Bank (NTDB) from 2007 to 2014 and the Pedestrian Crash Data Study from 1994 to 1998. Injury severity was categorized using the Abbreviated Injury Score and the Maximum Abbreviated Injury Score (MAIS) for each pedestrian.