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Human Factors

Human Factors Program Areas

Safety Problem Identification

Many higher-end vehicles are offered with technologies before they become common to all vehicles. To learn about how drivers interact with these technologies NHTSA conducts research on these “Early Adopters.”      

“100 Car” Study:
A key to the development of effective crash countermeasures is an understanding of pre-crash causal and contributing factors. This research effort was initiated to provide an unprecedented level of detail concerning driver performance, behavior, environment, driving context and other factors that were associated with critical incidents, near crashes and crashes for 100 drivers across a period of one year. A primary goal was to provide vital exposure and pre-crash data necessary for understanding causes of crashes, supporting the development and refinement of crash avoidance countermeasures, and estimating the potential of these countermeasures to reduce crashes and their consequences.

Databases from the 100-Car study are available for public use on the Virginia Tech Transportation Institute website:

To determine when and if a driver is performing safely an objective means to evaluate driver behavior (a metric) needs to be developed. NHTSA is engaged in efforts to be able to measure driver workload, performance and driver distraction. A better understanding of drivers’ capacities can lead to systems that are in line with their capabilities.

Driver Workload Metrics:
Today's drivers often deal with an onslaught of information that can divert their attention from their primary task of driving. Although some in-vehicle technologies are intended to improve safety, the use of multiple devices may distract the driver and actually jeopardize safety. When multi-tasking, drivers divert their attention from the road to glance at displays, operate controls, or listen and speak to a voice interface. These reports are the result of a cooperative study with industry to develop techniques to objectively evaluate the attentional demands of operating in-vehicle devices on various aspects of driver performance.

Crash Warning Interface Metrics:

Advanced Crash Warning Technologies (ACWT) have the potential to improve safety by preventing crashes and mitigating their impacts by warning drivers of the need for corrective action. However, the question remains as to whether ACWT will produce the anticipated significant safety improvements. If the system is not designed to be compatible with driver capabilities, drivers may not fully understand or react appropriately to the crash alerts. It is also possible that their use will introduce unforeseen or unintended consequences, particularly if drivers do not understand how the system works Therefore, it is important to develop a set of test protocols and metrics to evaluate the relation of ACWT design to driver performance and behavior. The goal of this project is to derive such metrics.

Visibility and Lighting

Enhanced Rear Lighting and Signaling:

Work on the Center High Mounted Stop Lamp:

Turn signal Color:

Forward Vision:

NHTSA is investigating the effects of A pillar designs on crash risk as well as the safety value of Night vision systems.

Night Vision
Lighting system improvements to increase driver vision at night are limited by the concurrent need to avoid blinding other drivers and reducing their ability to see the road. Therefore other methods of increasing driver night vision (NV) capability have been developed that do not affect the vision of other drivers at night. NV systems based on infrared (IR) technology have been developed by some manufacturers who have offered them as options on their production vehicles. NHTSA is currently preparing to conduct a simulator study on IR NV warning systems to investigate the effectiveness of a NV system with automatic warning in eliciting appropriate driver avoidance behaviors to detect pedestrians and road hazards.


Rear Vision:

NHTSA is conducting research to measure the direct visibility from vehicles as well as the capabilities of vehicle technologies aimed to augment rear visibility.

Driver Assistance

Forward Collision, Lane Departure, Intersection Violation

Crash Warning Interfaces:

Drowsy Driving:

Intersection Warning:

Forward Collision:

Lane Departure:

ACC, Parking Aids

Adaptive Cruise Control:

Parking Aids/Backover Prevention:

Congressional Reports:

Experimental Reports:

Survey Reports:

Estimates and Case Files:


Public meeting to identify human factors research to support guidelines and possible standardization of collision warnings

Reducing Unsafe Behaviors

In 2004, there were 16,694 alcohol-related fatalities reported, equal to one alcohol-related fatality every 31 minutes and representing 39% of the total traffic fatalities for the year. As of that same year, every State and the District of Columbia had created laws making it illegal to drive with a BAC of .08 g/dL or higher.

While traditional solutions to reduce the number of alcohol-related crashes have been effective, new approaches are needed to make additional reductions in this type of crash. These include various applications of vehicle-based technologies to prevent alcohol-impaired drivers from driving. Technologies that might be used in these applications include advanced, non-intrusive BAC detection and driving impairment detection.

Advanced Alcohol Detection Technology Study:
The goal of this multi-year study is to develop alcohol detection technologies that are less intrusive than existing ignition interlocks with the hope of greater public acceptance for installation in vehicles. Technologies that are integrated into vehicles and relatively transparent to drivers may hold the greatest promise for widespread deployment. Towards this goal, the study will support the development and testing of prototypes and subsequent hardware that may be installed in vehicles.

Using the National Advanced Driving Simulator to Identify Driver Performance Indicators of Impairment:
The goal of this study is to identify how impairment influences driving performance to identify reliable, feasible, and robust means of detecting impairment in real time by appropriate vehicle-based sensors, and to determine what is the reliability and accuracy of the measures.

Review of Alcohol Prevention Technologies:
This project reviewed technology alternatives to detect driver blood alcohol concentration and alcohol-impaired driving. The technologies included tissue spectroscopy, ethanol vapor detectors, and ocular measures. Taking an international perspective, the project report references relevant literature, incorporates input from stakeholders, and includes a concept of operations to describe how to implement technology-based countermeasures that addresses concerns such as privacy, public acceptance, and legal issues.

Related Reports:


Distraction is anything that diverts the driver’s attention from the primary tasks of navigating the vehicle and responding to critical events.  To put it another way, a distraction is anything that takes your eyes off the road (visual distraction), your mind off the road (cognitive distraction), or your hands off the wheel (manual distraction).  So when you think about tasks that can be a driving distraction, you can see that they often fit into more than one category: eating is visual and manual, whereas using a navigation system is all three.  

There are two basic components of the distraction safety problem: The attentional demands of the distracting task and the frequency with which drivers choose to multitask.  Task demands relate to the amount of resources (visual, cognitive, manual) required to perform the task.  The other issue is exposure, which is how often drivers engage in the task.  Putting those two concepts together, even an easy task can be a bigger safety problem if the person does the task 50% of their driving time. 

Current and previous NHTSA research investigates how distraction impacts driver performance, and develops and evaluated vehicle-based countermeasures to minimize the negative effects. 

Agency Plans

Research Reports

General Distraction Reports


Wireless Communication

Research Programs:

Public Forums / Presentations

Additional Information

Vehicle technologies to reduce teen’s unsafe behaviors:
This project will explore one promising approach to reduce novice teen driver crashes: using advanced in-vehicle technologies to monitor novice teen driver’s behavior. Such technologies can be integrated into a device to monitor and reduce unsafe behaviors through several interface approaches, including:

  • Vehicle Adaptations—Automatically prohibiting behaviors detected, e.g., safety belt interlocks;
  • In-Vehicle Feedback—Providing drivers with real time information, e.g., speeding in curves;
  • Reporting—Recording behaviors to transmit them at a later time to parents, insurance companies, driver educators, etc.

The goal is to provide a knowledge base about teen driver behaviors and support for the development of recommendations for the capabilities, operational concepts, and interfaces that would lead to effective, acceptable, and widely deployed technologies.

Related Reports:

Enhanced Seatbelt Reminder Systems:

With the goal of increasing safety belt use, automobile manufacturers have designed a variety of reminder systems to alert drivers and front seat passengers that their belt is not being worn.  These warning extend beyond the FMVSS 108 requirement and vary in implementation (e.g., presence and type of auditory or visual characteristics) and duration. 

The goal of the enhanced seat belt reminder system project is to investigate the effectiveness and acceptability of these systems on seat belt use.  The evaluation will look at the effectiveness and acceptability of these systems, including specific system characteristics.  The project will also include a separate evaluation of teen drivers and their acceptance of such systems


Related Reports:

Child Seat Use:

Child safety seats are a form of protection most effective for young children in motor vehicles. Common misuses such as loose harnesses, improper attachment, and incorrect recline angles contribute to the difficulty with installing child safety seats. An observational pilot study was conducted to examine child safety seat errors during novice installation.

Our current study focuses on novice installation in cars with the LATCH system. The purpose of this study is to evaluate the design of the CSS and how current vehicles and child seats could be enhanced to be even more effective. Identifying the common error points during child seat installation can lead us to understand the underlying factors that contribute to these errors


Traffic Safety Facts - Fuel Economy Driver Interfaces: Usability Study of Display Component Concepts DOT HS 811 320, May 2010  

Traffic Safety Facts - Fuel Economy Driver Interfaces: Driving Simulator Study of Component Concepts DOT HS 811 321, May 2010

Fuel Economy Driver Interfaces: Develop Interface Recommendations Report on Task 3 (Technical Report) DOT HS 811 319, May 2010

Fuel Economy Driver Interfaces: Design Range and Driver Opinions - Report on Task 1 and Task 2, DOT HS 811 092, August 2009