Human factors is an applied science, utilizing engineering in conjunction with normal psychology (the psychology of 'normal' people) to design items and facilities used by persons so that the interaction between persons and the item or facility will be efficient and safe. Human Factors is also part of the engineering analysis of items and facilities to determine if the interaction between persons and these items and facilities will be safe. Such items can be of many physical types, such as industrial equipment, consumer products, components of equipment, and particularly roadways, road systems, traffic control devices, and vehicles used and encountered on roadways.

Human Factors is important in the reconstruction of accidents because human perception, cognition, attention, and the response to hazards, and the practical functioning of the senses, such as eyesight and hearing, can be important aspects of determining how the accident happened, in particular how the human-mechanical interface was involved in the accident.

Human Factors is the basis for Safety Design. Human Factors and Safety Design are the bases for the use of Safeguards, such as seat belts, and Warnings and Controls, such as traffic control devices. Human Factors and Safety Design are an important part of the basis for many generally accepted Codes, Standards and Recommended Practices. These subject areas are all closely related.

In the Forensic Engineering work in the Forensic Specialties, Human Factors is an integral, routine part of our reconstruction and engineering analysis of accidents and our engineering analysis of equipment and facilities involved in these accidents. We routinely use Human Factors in accident reconstruction and engineering analyses regarding the human involvement in accidents.