Human Factors & System Safety
Human performance and the systems that shape it.
Could It Have Been Avoided?
Human factors is the study of how people perceive and respond to their environment, and how the systems around them shape that performance. At the individual level, we determine what a person could see, whether they would recognize a hazard, and how quickly they could react. At the system level, we look at whether an organization relied on people to avoid hazards or built in controls to reduce risk at its source, because safety works best when systems are designed so ordinary people don’t have to be perfect. Our experts weigh both to establish whether an incident was avoidable, a question that often goes to the heart of liability. We provide objective analysis and expert testimony for attorneys and insurers on either side of a claim.
Perception-Response Time & Avoidability
Whether a person could detect and react to a hazard in time to prevent an incident. Includes perception-response time, accident avoidance, and the responses typically expected from drivers and pedestrians.
Visibility & Conspicuity
Whether an object or hazard was detectable and recognizable under the conditions present. Includes line-of-sight and obstruction analysis, contrast, and lighting in nighttime and low-light scenes, including correction for how photographs and video can misrepresent the actual conditions.
Driver & Pedestrian Behavior
How people behave and respond in specific conditions. Includes response to visual, auditory, and tactile cues, hazard recognition, distraction, and the effects of impairment.
Systems Safety & Organizational Factors
Why the conditions of a system or organization allowed an incident, complementing technical analyses of what happened and how. We assess how system design, operational conditions, and risk controls shaped human performance and decision-making, and we evaluate hazard recognition, risk management, safety culture, training, supervision, policies, procedures, corrective actions, and organizational decision-making.
Related practices: Human factors and systems-safety principles apply across engineering, workplace safety, premises liability, transportation, construction, and product cases. For the incident sequence, see Accident Reconstruction; for injury causation, see Biomechanics; for worksite and OSHA matters, see Workplace Safety.
Our Capabilities
Determination of whether a specific party could have avoided an accident, which is often central to liability. We weigh the available time, distance, and response options against typical driver and pedestrian capabilities.
Evaluation of whether known hazards, prior incidents, or warnings prompted timely and effective corrective action, including questions of foreseeability and notice.
Evaluation of how distraction, inattention, fatigue, and impairment affected a person’s ability to perceive and respond to a hazard.
Analysis of how drivers typically respond to a given situation, whether by steering, braking, or taking no action, and whether the response in question was typical or optimal.
Use of a driving simulator to evaluate driver responses, response times, and avoidability in unusual scenarios, programmed to replicate the subject vehicle and its performance.
Analysis of where drivers look during maneuvers such as turning, changing lanes, or stopping, using eye-tracking methods to establish when a hazard could have been seen.
Projection and intensity analysis of headlight and taillight beams to determine whether a target was sufficiently illuminated to be seen, and whether lights were on at the time of an incident.
Application of the Wickens human information processing model, the research foundation for forensic human factors analysis of perception, attention, and response.
Evaluation of whether a hazard was detectable and recognizable, accounting for physical obstructions, shadows, contrast, and lighting, and of when it first came into view.
Documentation of a scene using methods that reproduce the brightness a person actually experienced, and explanation of how camera shutter speed, aperture, and ISO can misrepresent real conditions.
Analysis of visibility in dark and low-light conditions, where recognition distance and conspicuity are reduced, to determine whether a hazard could be recognized in time.
Analysis of obstacle detection and avoidance in walking and pedestrian travel, accounting for shadow, contrast, lighting, eye position, and changes in surface elevation.
Determination of the point at which a partially or fully occluded hazard becomes recognizable, which governs when a response should begin and what response is expected.
Determination of the point at which a partially or fully occluded hazard becomes recognizable, which governs when a response should begin and what response is expected.
Analysis of how management decisions, priorities, and production pressures shaped the conditions surrounding an incident.
Analysis of pedestrian response times and reactions to visual, auditory, and tactile cues, and whether a pedestrian could have acted to avoid a collision, trip, or fall.
Analysis of the time between perceiving a hazard and beginning a response, also called perception-reaction time. Adapted from the Wickens human information processing model, it is central to whether a driver could react in time to avoid a collision.
Evaluation of whether risk was reduced at its source through effective controls or left for people to avoid, applying the hierarchy of controls.
Evaluation of safety culture, safety management systems, policies, and procedures, and whether they were adequate and followed.
For highly atypical or unusual motor vehicle accident scenarios, a driving simulator study can be utilized for determining driver responses to a specific motor vehicle accident. Driver response times, response modalities, and general accident avoidability can be determined internally utilizing our moderate fidelity driving simulator. The driving simulator itself can be programmed to replicate the exact interior of the subject vehicle as well as the subject vehicle performance characteristics.
Analysis of how system and task design and operational conditions influenced human performance, decision-making, and the potential for human error.
Analysis of why the organizational and system conditions surrounding an incident allowed it to occur, explaining the why behind an event and complementing analyses of what happened and how.
Analysis of whether training, qualification, supervision, and oversight were adequate for the task and its hazards.
Just because a physical response was made; be it steering, braking, or a combination of both, or doing nothing, does not necessarily mean it was optimal or even typical for a given situation. Different motor vehicle accident configurations tend to illicit different responses from drivers. Determining which response type is optimal and probable can be determined by a human factors expert.
Analysis of whether an object or hazard was conspicuous enough to be seen and recognized under the conditions present, based on contrast, size, motion, and lighting.
Key Experts
Frequently Asked Questions
Accident reconstruction explains the physical sequence of an incident. A human factors expert examines what a person could perceive, whether a hazard was recognizable, how quickly a response could begin, and whether the event was avoidable. The disciplines often work together. Reconstruction establishes the positions, speeds, and timing, while human factors applies research on perception, attention, visibility, and response to evaluate human behavior within that sequence.
A human factors expert can evaluate whether a hazard was detectable and recognizable under the conditions present. Aperture’s analysis may include line of sight, obstruction, contrast, lighting, headlamp output, conspicuity, eye position, and the timing of when the hazard became visible. The opinion should account for the difference between merely seeing an object and recognizing it as a hazard that requires a response.
Yes. Aperture’s experts evaluate perception-response time, expected driver or pedestrian behavior, available response options, and the time and distance available to act. The analysis can help determine whether a typical person could detect the hazard and respond soon enough to avoid or reduce the incident. It should be based on the reconstructed event, established research, and the specific visibility, roadway, environmental, and human conditions in the case.
Yes. Camera settings can make a photograph or video appear brighter or darker than the conditions experienced by a person at the scene. A human factors expert can evaluate lighting, contrast, obstructions, headlamp illumination, and recognition distance and can document a scene using methods intended to reproduce relative brightness. The expert should explain the limits of the imagery and avoid treating a camera image as a direct substitute for human vision.
Human factors is useful when liability depends on whether a warning, hazard, control, path, or product feature was detectable, understandable, and likely to produce an appropriate response. In premises matters, the expert may assess obstacle recognition, lighting, signs, or pedestrian behavior. In product matters, the analysis may address warnings, instructions, foreseeable use, and how users interact with the product. The work can be coordinated with engineering, biomechanics, and incident reconstruction.