Human Factors

Human factors is the study of how the capabilities and limitations of people shape the ways in which they interact with and use products, equipment, and systems in their environments. Human factors is an essential assessment and evaluation tool in a wide range of complex accidents involving commercial trucking, automobiles, railroads, aviation, utilities, construction, mining, oil and gas, chemical process, manufacturing, medical devices, consumer and commercial products, and premises liability issues.

Our human factors experts offer extensive experience evaluating complex issues that involve an understanding of the human contribution to an accident scenario, such as driver behavior, perception-reaction time, visibility and conspicuity, decision-making, fatigue and stress, attention and distraction, memory, human error and risk-taking behavior, human response to alarms and sounds, product design, product and equipment use-misuse, warnings (written, auditory, tactile, olfactory), adequacy of warnings, instructions, and training, human performance and automation, child safety, and many more.

Vehicle Accident Reconstruction

Our human factors consultants are often called upon to assist accident reconstruction experts when complex questions arise regarding the pre-impact stage of the accident reconstruction process. These include addressing the driver behavior, perception-response time, attention, distraction, driver expectation, and driver error. Typical questions addressed by our human factors experts may involve:

  • Was the hazard visible?
  • When was the hazard detected?
  • Could the driver detect the slow moving or stopped vehicle?
  • Was the driver distracted by others in the vehicle or a cell phone:  Was the driver fatigued, or sleepy?
  • How fast could the driver react to another vehicle or a pedestrian’s actions?
  • Did the driver respond reasonably? Did the pedestrian respond reasonably?
  • What is the effect of cell phone usage, impairment, lack of sleep, etc. on accident causation?
  • Was the event a case of pedal confusion?  If so, for how long did the driver press the accelerator pedal rather than the brake?

Perception-Reaction Time Analysis

Perception and response time is often defined as the interval between an obstacles appearance and a user’s response initiation. Rimkus human factors experts can help define the appropriate perception and response time and other complex factors.  Our experts will help break down the various portions of perception response time, such as mental processing time, movement time, and device response time. Key questions related to perception and response time may include:

  • How fast could the driver react to an intruding vehicle?
  • How soon could the pedestrian change their gait and step over an obstacle?

Cell Phone Distraction Assessment

Rimkus experts specialize in determining whether a driver’s cell phone use affected their ability to respond to an impending collision.  Our experts also analyze how other cell phone interactions, such as texting, talking, or simple phone operations, could impact a pedestrian’s ability to detect a hazard or descend a flight of steps.  We help our clients understand cognitive processing issues that are involved with multitasking.  Our experts can help key issues, such as:

  • Did the cell phone distract the driver?
  • What affect did the cell phone have on the outcome of the accident or collision?

Pedal Confusion Assessment

There are circumstances in which a driver thought that they are pressing the brake in an emergency situation, but actually was pressing the accelerator pedal.  Instead of stopping, the vehicle accelerated, resulting in an accident.  Pedal confusion questions can include:

  • Was the event a case of pedal confusion?
  • For how long did the driver press on the accelerator pedal?
  • Could the event have been prevented if the driver would have recognized in a timely fashion that he or she was pressing on the wrong pedal?

Workplace Accident Investigation

Workplaces are complex sociotechnical systems and involve the interaction of workers with work systems that are made up of technical, social, organizational, and environmental elements, all of which can contribute to accidents. Workplace accidents may be caused by equipment failures, design defects, environmental issues, inadequacy of the safety programs, or lack of training.  It has been well established that human error is involved in 85 percent of all workplace accidents due to the complex interactions between humans, machine or processes, and environments. We help our clients answer a wide range of questions related to workplace accidents:

  • What OSHA/MSHA regulations and industry standards are applicable to the accident scenario and were they complied with?
  • Was the worker adequately trained?
  • Did the worker have knowledge and understanding of the hazard?
  • Was the training adequate?
  • What causes workplace violations of training?
  • What causes workers to bypass safety mechanisms such as machine guarding, Lock Out Tag Out, and safety sensors?
  • Was the safety program adequate to ensure worker safety?

Product Liability Evaluation

Product design that considers the capabilities, limitations, and needs of the target users reduces the likelihood of the occurrence of human error. User interaction with the product is also affected by a host of other factors, such as the environment of use, training, safety information (warnings, manuals, instructions), and the prescribed processes and procedures under which the product is used in the work or home environment. Rimkus can assist in accidents involving products or equipment by evaluating the following:

  • What was the user or operator’s role in the accident?
  • Did the product comply with applicable regulations and industry standards?
  • Was the design of the product or equipment reasonable and intuitive?
  • Was the product or equipment being misused?
  • Were design changes needed to address the hazard?
  • What did the user or operator know?
  • What was their understanding of the hazard?
  • How where they trained?
  • What information was available to them about the hazard?
  • What could have been done to prevent the accident?
  • Did the user act reasonably?

Warnings, Signage, and Safety Instruction Analysis

Warnings are ubiquitous in our everyday environment. They appear in the form of written warnings on products, equipment, machinery, tools, medication, roadway signage, and user manuals; auditory warnings, such as alarms, sirens, horns; or other forms that speak to a wide range of our senses. Evaluating whether a warning is appropriate or sufficient involves many variables.  Questions might include:

  • How do individuals process warnings and safety information?
  • What motivates safe behavior or causes unsafe behavior?
  • Was the hazard open and obvious?
  • Was the warning or symbol, roadway or workplace signage sufficient to convey the necessary information?
  • Were the warnings sufficient to prevent the accident?
  • Did the placement, format, or color of warnings affect accident causation?
  • Would additional or alternate warnings have changed the outcome or prevented the accident?
  • Would the operator or pedestrian have heard the sound (train horn, sirens, alarm, etc.)?
  • Did the utility company warn users of the dangers of electricity sufficiently?
  • Is ethyl mercaptan sufficient warning of the hazard associated with natural gas/liquid propane?
  • Was the roadway signage sufficient to alert traffic of construction or lane closure?

Work Zone Accident Investigation

Positive guidance ensures that a driver, equipment operator, or user is able to detect hazard in a roadway, workplace, or other environment that may be visually cluttered, recognize its threat potential, select an appropriate speed and path, and complete the required maneuver safely.  Positive guidance principles ensure that the information needed by travelers to negotiate safely through a work zone or pedestrian travel way are provided. Informational questions may include:

  • Did the construction zone provide the necessary information to guide the driver safely through the zone without conflict?
  • Was the roadway or sidewalk properly signed to give the user the information they needed to properly find their way?

Visibility, Conspicuity, and Attention Evaluation

Visibility and conspicuity of an object, pedestrian, or vehicle can be a major factor in accidents, specifically during conditions of reduced illumination (low lighting and nighttime). Even in adequate lighting conditions, objects, or structures can obstruct our vision and affect the detection of other objects, pedestrians, and vehicles. Reduced illumination at night presents a cognitively and visually challenging environment for individuals. Reduced illumination in parking lots and buildings may affect the visibility and conspicuity of objects and pedestrians.  Similarly, during nighttime driving, along with reduced illumination, there are fewer cues from the environment to guide the driver in navigating appropriately. Inattention and distraction can further increase the susceptibility to accidents. Typical questions addressed by Rimkus experts may include:

  • Was the pedestrian, vehicle or object visible given the lighting conditions?
  • Were the taillights of the vehicle visible?
  • How much illumination is needed to navigate or driver safely under given conditions?
  • Did the signage on the roadway block the visibility of oncoming traffic?
  • How does inattention or distraction affect pedestrian or driver task?
  • When could the pedestrian or vehicle or other object be “seen” and present itself as a hazard to the driver?

Premises Liability Investigation

Investigation of premises accidents require an extensive understanding of: 1) available versus required coefficient of friction to navigate successfully, 2) the visual system and the effect of lighting on the conspicuity of objects in an area, 3) human gait patterns when walking on flat and uneven surfaces, up or down inclines, climbing stairs and ladders, 4) effect of attention and distraction 5) expectation of individual, and 6) geometry of the area. Our premises liability investigation experience includes trip hazards, slips and falls, automatic pedestrian door incidents, ladder use accidents, pool accidents, and related matters. Rimkus human factors experts can help answer the following questions:

  • Was the surface sufficiently slip resistant? Did the footwear or age of the individual affect navigation?
  • Was lighting sufficient?
  • Was the object or level change conspicuous and/or reasonable?
  • How does carrying objects or hurrying affect traction and visibility?
  • Was the swimming pool of sufficient depth?
  • How would impairment affect this accident? Did the automatic door allow safe passage?

Child Safety Evaluation

Children’s perception and understanding of hazards is constantly developing as they mature from childhood to adulthood and can affect their behavior with respect to their interaction with products, situations, and environments. Rimkus consultants can assist in evaluation of childhood understanding and use of toys, products that are not toys, interaction on playground environments, and other situations where the knowledge and understanding of childhood development and understanding of hazards in the environment. Questions that we can evaluate are:

  • Was the child old enough to recognize and appreciate the hazard?
  • Was adult supervision needed and adequate to interact appropriately in the given situation or with the given product?
  • Was the child being adequately supervised?
  • Was the response of the child reasonable given the situation?
  • Would the child have understood and benefited from the warning?