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  • DOT HS 812 207 Crash Warning Interface Metrics: Warning and Message Perception Under Ambient Noise Conditions Laboratory Experiments November 2015

    The Crash Warning Interface Metrics program addresses issues of the driver-vehicle interface for advanced crash warning systems. This report summarizes the methods and findings of three laboratory experiments that investigated acoustic signal detectability and perception under varied ambient noise conditions. These experiments replicated and expanded the findings of an on-road experiment that found that auditory signal detectability, perceived urgency, and perceived meaning can be substantially impaired under conditions of elevated ambient noise. As expected, increases in signal loudness led to higher ratings for noticeability, urgency, and annoyance. This effect was more pronounced in the louder ambient noise conditions than in the relatively quiet baseline condition, which suggests that higher loudness levels are particularly beneficial for maintaining the noticeability and perceived urgency of warnings in loud ambient noise conditions. This experiment found that noticeability, perceived urgency, and annoyance were highly intercorrelated.

  • DOT HS 812 208 Driver-Vehicle Interfaces for Advanced Crash Warning Systems: Research on Evaluation Methods and Warning Signals, November 2015

    The Crash Warning Interface Metrics (CWIM) program addresses driver-vehicle interface (DVI) for advanced crash warning systems. This report summarizes the methods and findings of 16 experiments grouped under three main research areas: (1) research on collision warning and lane departure warning protocol development; (2) research on variability among warning signals in three main topic areas; and (3) temporal aspects of interference from other in-vehicle messages, included two driving simulator experiments on effects of a non-urgent alerts occurring before urgent crash warnings on driver behavior. The experiments found that non-urgent messages that preceded warnings did not necessarily slow responding to the warning, though longer time gaps tended to result in faster reaction times than shorter time gaps. The experiments also provided some evidence that warning response is impaired when the early alert and warning share the same perceptual mode. Implications for DVI design were drawn from the findings of these experiments. Formal FCW and LDW evaluation protocols were developed as methods for assessing DVIs for production or near-production systems.

    DOT HS 812 208a Driver-Vehicle Interfaces for Advanced Crash Warning Systems: Research on Evaluation Methods and Warning Signals: Appendices A-F



  • DOT HS 812 209 Warning and Message Perception Under Ambient Noise Conditions: On-Road Experiment Report Under Crash Warning Interface Metrics 3 Program November 2015

    This report describes research on the effects of various vehicle interior ambient noise conditions on driver perception of warnings and messages as part of the Crash Warning Interface Metrics program. This study measures driver perception of warnings and alerts against ambient noise on actual roads. Compact, sedan, SUV vehicles with windows up, music off; windows down, music off; and windows up, music on were measured in 15 different tonal and voice messages. Background noise from music, and especially from open windows, interfered with the perception of auditory signals presented at 65 decibels. Sounds and voice messages of approximately equal loudness under relatively quiet listening conditions differed substantially in noticeability and urgency even under the baseline condition and even more under the music and open windows conditions. Some sounds suffered low detection rates under noise, particularly the windows down condition.


  • Characterization Test Procedures for Intersection Collision Avoidance Systems Based on Vehicle-to-Vehicle Communications, (DOT HS 812 223)  December 2015

    This report describes characterization test procedures developed to quantify the performance of intersection collision avoidance (ICA) systems based on vehicle-to-vehicle communications. These systems warn the driver of an imminent crossing-path collision at a road junction, and apply automatic braking if the driver does not respond in a timely manner.This report describes test procedures for most common crossing-path, pre-crash scenarios that involve light vehicles (passenger cars, vans, minivans, SUVs, or light pickup trucks with gross vehicle weight ratings less than 10,000 pounds). The test procedures include crash-imminent test scenarios to collect information on the ranges and time-to-collisions of crossing-path collision alerts and automatic braking onsets in prototype systems. In addition, the test procedures incorporate scenarios where countermeasures are not needed to assess the capability of ICA systems to distinguish between crash-imminent and benign driving scenarios.
  • Evaluation of Heavy-Vehicle Crash Warning Interfaces (DOT HS 812 191) September 2015

    This report evaluates heavy-vehicle collision warning interfaces as they pertain to auditory and visual components of forward collision warning systems. The results indicate that drivers receiving imminent collision warning alerts responded significantly quicker than drivers who did not receive alerts to potential rear-end events. Effects of muting other sources of in-cab audio were explored. Participants performed as well or even better when the other audio sources were not muted as long as the alerts were loud enough (15 dBA above in-cab noise level). If a visual component is part of the alert in the instrument panel, data suggests that it may be more effective if presented as an information component, not as the main alert component. This will assist drivers to look at the forward roadway as their first reactions instead of getting drawn to the visual component first. Data also suggests the auditory component should be the main alerting component in order to elicit the drivers looking to the forward roadway as their first reactions. This result was found to be true in both a truck-trailer combination units and motorcoaches. It should be noted that haptic alerts were not considered in this study.

  • Adaptive Driving Beam Headlighting System Glare Assessment(DOT HS 812 174) August 2015. This report summarizes NHTSA’s evaluation of existing adaptive driving beam headlight systems.  “Adaptive Driving Beam" (ADB) is a type of adaptive front-lighting system where the system automatically enables upper beam headlamps and adapts its beam pattern to the presence of oncoming and preceding vehicles in order to improve long-range visibility for the driver without causing discomfort, distraction, or glare to other road users.  The research informed NHTSA’s response to a Toyota petition asking that FMVSS No. 108 be modified to specifically allow adaptive driving beam (ADB) headlights.  Multiple other OEMs have expressed interest in offering this technology on US vehicles.

  • Human Factors Evaluation Of Level 2 and Level 3 Automated Driving Concepts (DOT HS 812 182) July 2015 This study investigated user interactions with partially automated vehicles where some of the driver’s role is turned over to the vehicle. It focused on how the driver makes those changes, and how this interaction is affected by the human-machine interface. It also shows that effective human interface elements can help drivers to resume control of the vehicle quickly.
  • NHTSA’s 2014 Automatic Emergency Braking Test Track Evaluations, (DOT HS 812 166)
  • NHTSA’s 2014 light vehicle automatic emergency braking (AEB) test program evaluated the ability of a 2014 Acura MDX, a 2014 BMW i3, a 2015 Hyundai Genesis, and a 2014 Jeep Grand Cherokee to be tested with the agency’s August 2014 draft crash-imminent braking (CIB) and dynamic brake support (DBS) test procedures. The maneuvers were successfully validated and the performance of the vehicles compared to a common set of draft assessment reference values (ARVs). None of the vehicles discussed in this report were able to satisfy all CIB ARVs if their performance was considered against a “seven of eight” evaluation criteria, and only the Jeep Grand Cherokee was able to satisfy the DBS ARVs during at least seven of eight trials for each test condition.
  • Review and Analysis of Potential Safety Impacts of and Regulatory Barriers to Fuel Efficiency Technologies and Alternative Fuels In Medium- and Heavy-Duty Vehicles (DOT HS 812 159)
  • The heavy-duty vehicle category, which spans from ¾-ton pickup trucks and vans up to the largest tractor-trailers, represents a major opportunity to cut transportation oil use and carbon pollution. This study assessed the safety of various engine and vehicle technologies that reduce fuel consumption and greenhouse gas (GHG) emissions, including alternative fuels such as natural gas, biodiesel, electricity, etc. The findings suggest that the potential safety hazards identified during operation, maintenance, and crash scenarios can be prevented or mitigated by complying with safety regulations, voluntary standards, and industry best practices.
  • Effects of Tire Rolling Resistance Levels on Class 8 Tractor Trailer Stopping Distance Performance (DOT HS 812 176)
  • The Federal Motor Carrier Safety Administration and National Highway Traffic Safety Administration commissioned a joint test program through to explore the effects of tire rolling resistance on Class 8 tractor-trailer stopping distance over a range of loading and surface conditions to determine whether there is a relationship between tire rolling resistance and stopping distance for vehicles of this type. The results suggest that tire rolling resistance is not a reliable indicator of Class 8 tractor-trailer stopping distance. Wet and dry stopping distance versus overall vehicle rolling resistance values did not meet the minimum threshold for any of the statistical significance test conditions. Tire rolling resistance and stopping distance were found to be negligible for the dry tests for both loading conditions. In terms of compliance with Federal safety standards, it was found that the stopping distance performance of the vehicle with the four tire sets studied in this research were well under the Federal Motor Vehicle Safety Standards No. 121 stopping distance requirements.
  • Measurement of School Bus Pedal Dimensions DOT HS 812 168, June 2015
  • The National Transportation Safety Board (NTSB) investigated four crashes of school buses and one of a fire truck that occurred from 2005-2009 and concluded that these accidents were consistent with pedal misapplication. Among the NTSB recommendations was that NHTSA analyze pedal configurations in heavy vehicles to determine the effect of pedal design on the driver’s task. This research was performed to provide an overview of the range of typical pedal dimensions in school buses.
  • Van Hool 2014 CX45 Motorcoach Lane Departure Warning System Evaluation  DOT HS 812 0130, March 2015

  • Driver Brake and Accelerator Controls and Pedal Misapplication Rates in North Carolina  DOT HS 812 058, May 2015


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