- Validations of Integrated DVI Configurations Final Research Report (DOT HS 812 310) September 2016This report documents the development and proof-of-concept of an integration architecture (IA) prototype managing V2Vs. Driver data created a user-modified configuration to demonstrate the need and impact of a defined IA in the V2V environment. This research supports NHTSA’s focus on V2V technologies that have the potential to significantly affect driving safety, mobility, and sustainability of the transportation system.
- Commercial Connected Vehicle Test Procedure Development and Test Results – Blind Spot Warning/Lane Change Warning, (DOT HS 812 317) November 2016
test procedures to evaluate the blind spot warning/lane change warning (BSW/LCW) safety application of commercial vehicles with vehicle-to-vehicle (V2V) equipment. The prototype V2V equipment was observed to be capable of tracking potential BSW/LCW threats, but occasionally the equipment would not recognize that a vehicle was in the V2V equipment determined blind spot warning zone due to the equipment’s error in estimating the lateral range between the vehicles. The V2V equipment determined blind zone was different for each side of the vehicle evaluated in this study (shorter on right side). When the turn signals were activated, the blind zone was extended by a time based on the closing speed of the approaching vehicle. The BSW/LCW test procedures are generally well developed but the blind zone definition for commercial vehicles/tractor-trailers combinations needs to be further refined.
Driver Acceptance of Collision Warning Applications Based on Heavy Truck V2V Technology (DOT HS 812 336)
This report describes an independent evaluation and analysis of methods and results of data gauging heavy-truck driver acceptance of collision warning based on V2V communication technology during driver acceptance clinics. V2V technology transmits vehicle information—location, size, and speed— to predict impending collisions and warn the driver. Results suggest V2V safety warnings have a high acceptance rate among heavy truck drivers. Results from the clinics will help shape future research into improved V2V safety applications for heavy vehicles.
In-Vehicle Voice Control Interface Performance Evaluation, Final Report (DOT HS 812 314),
This paper reports empirical research about voice control systems used by drivers and the measures that could be used for evaluating these possible distractions while driving. An on-road study identified drivers’ patterns of use and interaction errors encountered with VCS. Twenty-two themes characterized interactions with VCS. Results suggest an evaluation protocol based solely on error free trials would not be representative of many VCS interactions commonly experienced. Two other studies were conducted in controlled laboratory environments. Results indicated that both performance and eye glance measures may be appropriate for evaluation of VCS and that the computer-based protocol yielded similar results to the driving simulator protocol.
- Crash Avoidance Needs and Countermeasure Profiles for Safety Applications Based on Light Vehicle-to-Pedestrian Communications (DOT HS 812 312)
This study will help support the development of V2P based collision avoidance technologies and examined the GES and FARS crash databases in order to classify 21 pedestrian pre-crash scenarios based on different vehicle and pedestrian maneuvers. These scenarios were ranked based on associated costs and five priority scenarios were selected that represent 88 percent of pedestrian crash costs. For the priority scenarios crash contributing factors were examined and quantified to identify common occurrences in crashes, including physical settings, environmental conditions, and driver and pedestrian characteristics. Kinematic equations describing the crash scenarios were also derived and exercised to obtain estimates of the minimum stopping distances for various vehicle velocities and braking levels. The goal of this study was to develop an updated understanding of the pedestrian crash problem and the potential of V2P technology to address pedestrian crashes.
- Commercial Connected Vehicle Test Procedure Development and Test Results - Emergency Electronic Brake Light (DOT HS 812 327)
This report documents NHTSA’s test track research performed to support development of objective test procedures to evaluate the blind spot warning/lane change warning (BSW/LCW) safety application of commercial vehicles with vehicle-to-vehicle (V2V) equipment. The prototype V2V equipment was observed to be capable of tracking potential BSW/LCW threats, but occasionally the equipment would not recognize that a vehicle was in the V2V equipment determined blind spot warning zone due to the equipment’s error in estimating the lateral range between the vehicles. The V2V equipment determined blind zone was different for each side of the vehicle evaluated in this study (shorter on right side). When the turn signals were activated, the blind zone was extended by a time based on the closing speed of the approaching vehicle. The BSW/LCW test procedures are generally well developed but the blind zone definition for commercial vehicles/tractor-trailers combinations needs to be further refined.
- Commercial Connected Vehicle Test Procedure Development and Test Results – Forward Collision Warning (DOT HS 812 298) This report documents NHTSA’s test track research performed to support development of objective test procedures to evaluate the forward collision warning (FCW) safety application of commercial vehicles with vehicle-to-vehicle (V2V) equipment. The prototype V2V equipment was observed to be capable of tracking potential FCW threats, but had some issues when vehicles were in a curve or when switching lanes. For the curve tests, the V2V equipment had trouble determining the lateral distance between the host vehicle (HV – test subject) andthe remote vehicle (RV – collision threat) for certain scenarios. Future testing with commercial vehicles equipped with V2V technology will be required to fully develop some of the FCW objective test track procedures and performance metrics.
- DOT HS 812 300 Summary of NHTSA Heavy Vehicle Vehicle-to-Vehicle Safety Communications Research July 2016
This report summarizes NHTSA’s V2V research on heavy vehicles (trucks and buses over 10,000 pounds). Most of the research conducted under the light vehicle V2V research program is directly applicable to applications in heavy vehicles, including the foundational elements such as 5.9 GHz Dedicated Short Range Communications and the supporting security credential management system that enables trust for V2V Basic Safety Messages. Heavy-vehicle V2V systems have been prototyped and tested in controlled scenarios in track testing and driver clinics as well as in a real world environment in Ann Arbor, Michigan. Testing these heavy-vehicle V2V systems included class 8 tractors in an integrated configuration, retrofit safety devices designed to facilitate installation of V2V capability in existing trucks, and retrofitted local transit buses. Additional research is exploring V2V systems in single-unit trucks and areas such as cyber security.
- DOT HS 812 276 Commercial Connected Vehicle Test Procedure Development and Test Results – Intersection Movement Assist May 2016
This report documents NHTSA’s test track research performed to support development of objective test procedures to evaluate the intersection movement assist (IMA) safety application of commercial vehicles with vehicle-to-vehicle (V2V) equipment. The prototype V2V equipment was observed to track potential IMA threats, but the IMA warnings and alerts issued from the V2V equipment on the trucks occurred very early. Due to the early warnings it was not possible to fully evaluate some of the test procedures.
Future testing with commercial vehicles equipped with V2V technology will be required to fully develop the IMA objective test track procedures and performance metrics.
- DOT HS 812 285 Assessment of Safety Standards for Automotive Electronic Control Systems, June 2016
This report summarizes the results assessment and comparison of six industry and government safety standards relevant to the safety and reliability of automotive electronic control systemsThese standards are ISO 26262 (Road Vehicles - Functional Safety), MIL-STD-882E (Department of Defense Standard Practice, System Safety), DO-178C (Software Considerations in Airborne Systems and Equipment Certification), Federal Motor Vehicle Safety Standards, AUTOSAR (Automotive Open System Architecture), and MISRA C (Guidelines for the Use of the C Language in Critical Systems).. The assessment was carried out along the 11 dimensions: (1) type of standard, (2) definition of safety and hazard, (3) identification of safety requirements, (4) hazard and safety analysis methods, (5) management of safety requirements, (6) risk assessment approach, (7) design for safety approach, (8) software safety, (9) system lifecycle consideration, (10) human factors consideration, and (11) approach for review, audit, and certification.
- DOT HS 812 280 Field Study of Heavy-Vehicle Crash Avoidance Systems: Final Report June 2016
This study investigated the performance of collision avoidance systems (CASs) currently used in the trucking industry. A total of 169 drivers operating 151 tractor-trailers from 7 trucking companies were recruited to a 1-year field operational test. All vehicles were equipped with either the Meritor WABCO OnGuard or the Bendix Wingman Advanced CAS system. A new miniature data acquisition system (MiniDAS) was developed by the Virginia Tech Transportation Institute to collect continuous video of the forward roadway, video of the driver's face, CAS activations and alerts, and vehicle network data whenever the trucks were in motion. Six thousand CAS activations and lane departure warning alerts were sampled, including all automatic emergency braking events and impact alerts. In order to estimate system reliability, these were analyzed to determine whether a safety critical event (SCE) took place. An SCE could be a crash, a near crash, or a crash-relevant conflict, all of which require the driver to perform a rapid evasive maneuver. No rear-end collisions were reported by participating companies in the 3 million miles of driving data recorded in this study. The more severe alerts had increased activation likelihood when a driver response was required. This study did not find that drivers changed their driving performance over time; neither the alert activation rates changed, nor drivers' response to the alerts meaningfully changed over time at highway speeds.
- DOT HS 812 247 Large-Scale Field Test of Forward Collision Alert and Lane Departure Warning Systems February 2016
This report covers a field study of vehicle crash warning technologies using an innovative large-scale data collection technique
for gathering information about the crash avoidance systems and how drivers respond to them. Although the specific system studied was the General Motors camera-based forward collision alert and lane departure warning system, this technique could be applied to other emerging active safety crash avoidance systems.
The study team found that this data collection technique has several strengths including cost, sample size, and naturalistic testing by having drivers using their own vehicles where they can adjust system settings or even turn systems off. The technique allowed researchers to study possible long-term changes in how drivers adapt to such systems, and to acquire “rapid-turnaround” large-scale results in an efficient manner.
- DOT HS 812 224 Independent Evaluation of Heavy-Truck Safety Applications Based on Vehicle-to-Vehicle and Vehicle-to-Infrastructure Communications Used in the Safety Pilot Model Deployment January 2016
This report presents the methodology and results of an independent evaluation and analysis by the Volpe National Transportation Systems Center of heavy trucks participating in the Safety Pilot Model Deployment (SPMD), a field study vehicle-to-vehicle (V2V) communication technology, The heavy trucks in the -- part of U.S. DOT's Intelligent Transportation Systems research program. In 2012 the SPMD deployed in Ann Arbor, Michigan, approximately 2,800 vehicles equipped with designated short-range-communication-based V2V and vehicle-to-infrastructure (V2I) technology in real-world driving environments. The goals of the evaluation were to characterize capability, assess unintended consequences of the warnings, and gauge driver acceptance of V2V and V2I safety applications. The evaluation is based on naturalistic driving by 33 participants who drove heavy trucks equipped with V2V and retrofit safety devices. The results V2V safety applications work in real-world environments and issue useful alerts in driving conflicts. However, improvement in the accuracy of these warnings is needed.
- DOT HS 812 222 Independent Evaluation of Light-Vehicle Safety Applications Based on Vehicle-to-Vehicle Communications Used in the 2012-2013 Safety Pilot Model Deployment
This report describes the methodology and results of an evaluation of safety applications for passenger vehicles in the 2012-2013 Safety Pilot Model Deployment, part of U.S. DOT’s Intelligent Transportation Systems research program. In 2012, the pilot model deployed approximately 2,800 vehicles equipped with designated short-range, communication-based vehicle-to-vehicle (V2V) and vehicle-to-infrastructure technology in a real-world driving environment. The goals of the independent evaluation were to characterize the capability, assess unintended consequences, and gauge driver acceptance of the V2V safety applications. The evaluation is based on naturalistic driving by 127 participants who drove passenger vehicles with fully integrated V2V communication systems for 6 months each. Additionally, 293 participants drove passenger cars with aftermarket communication systems for 12 months each. The vehicles were equipped with a suite of V2V safety applications that issued alerts to participants in potential crash scenarios. The results of the analysis suggest that V2V safety applications work in a real-world environment and issue valid alerts in driving conflicts, but improvements in their ability to correctly differentiate imminent threats from various normal driving situations are needed so as to reduce nuisance warnings. Results from the model deployment will help shape future research direction.
- DOT HS 812 225 Acoustic Data for Hybrid and Electric Heavy-Duty Vehicles and Electric Motorcycles
The Pedestrian Safety Enhancement Act of 2010 requires NHTSA to establish a Federal Motor Vehicle Safety Standard requiring an alert sound for pedestrians to be emitted by all types of electric or hybrid-electric vehicles. NHTSA completed acoustic measurements for hybrid and electric heavy-duty vehicles (gross vehicle weight rating over 10,000 lb.) and for electric motorcycles. This acoustic data analysis was conducted to support activities related to the PSEA. Two electric motorcycles were tested and one electric vehicle delivery truck was tested. In addition, screening data for four hybrid and electric heavy-duty vehicles were collected to obtain raw descriptions of the sound characteristics for a subset of heavy-duty vehicles. The measurements protocol used for the screening tests follows general procedures in SAE J 2889/1, Measurement of Minimum Noise Emitted by Road Vehicles, but does not fulfill all its parameters. Several aspects are different, including the acoustic environment, operating conditions, test surface, number of microphones, and microphone position.
- DOT HS 812 172 Evaluation of Adaptive Cruise Control Interface Requirements On the National Advanced Driving Simulator August 2015
New advanced driver support systems are now being introduced into passenger vehicles. Key questions are how driving performance and behavior adapt over long-term use. Early adopters of new technologies provide a unique population from which early assessments of new technology safety impacts can be made. Of interest in this project were the safety implications of long-term use of adaptive cruise control (ACC). The goal of the study was to understand the relationship between experience with ACC and driving performance.
- DOT HS 812 173 Enhanced Seat Belt Reminder System Features for Teenagers August 2015
This report describes how teenagers and their parents reacted to “enhanced” seat belt reminders and alerts that are more assertive and persistent than what most cars have. Teens gave feedback regarding a set of these alerts in simulated drives. The main measures were the likelihood of buckling up and the strength and annoyance of the alerts. Effectiveness and annoyance were highly correlated, although no system or feature emerged as dramatically more effective than any other. Visual displays were less effective and less annoying than sound alerts. Parents of teens who experienced the new alerts participated in group discussions about their teens’ seat belt use and their preferences for alerts. Based on the findings, a set of recommendations for the design of seat belt reminders specifically for teenage drivers and their passengers was developed.
- 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
- Heavy-Vehicle Lane Departure Warning Test Development, DOT HS 812 078, November 2014
- Detection Response Task (DRT) Evaluation for Driver Distraction Measurement Application, DOT HS 812 077, November 2014
- Assessment of the Information Sharing and Analysis Center Model, DOT HS 812 076, October 2014
- A Summary of Cybersecurity Best Practices, DOT HS 812 075, October 2014
- Characterization of Potential Security Threats in Modern Automobiles: A Composite Modeling Approach, DOT HS 812 074, October 2014
- National Institute of Standards And Technology Cybersecurity Risk Management Framework Applied to Modern Vehicles, DOT HS 812 073, October 2014
- Human Factors for Connected Vehicles: Effective Warning Interface Research Findings, DOT HS 812 068, September 2014
- Vehicle-to-Vehicle Communications: Readiness of V2V Technology for Application, DOT HS 812 014, August 2014
- Human Factors Evaluation of Level 2 and Level 3 Automated Driving Concepts: Past Research, State of Automation Technology, and Emerging System Concepts, DOT HS 812 043, July 2014
- Human Factors Evaluation of Level 2 and Level 3 Automated Driving Concepts: Concepts of Operation, DOT HS 812 044, July 2014
- Blind Spot Monitoring in Light Vehicles - System Performance, DOT HS 812 045, July 2014
- Objective Tests for Forward Looking Pedestrian Crash Avoidance/Mitigation Systems, DOT HS 812 040, June 2014
- Heavy Truck Pre-Crash Scenarios For Safety Applications Based on Vehicle-to-Vehicle Communications DOT HS 812 023, June 2014
- Target Crashes and Safety Benefits Estimation Methodology For Pedestrian Crash Avoidance/Mitigation Systems, DOT HS 811 998, April 2014
- NHTSA Tire Aging Test Development Project Phase 2 - Evaluation of Laboratory Tire Aging Methods, DOT HS 811 885, February 2014
- Basis of Design for Advanced Crash-Avoidance Technology Test Course, DOT HS 811 988, March 2014
- Assessing the Feasibility of Vehicle-Based Sensors to Detect Drowsy Driving, DOT HS 811 886, February 2014
- Traffic Safety Facts: Advanced Countermeasures for Multiple Impairments, DOT HS 811 887, February 2014