CHAPTER 3 – ACCIDENT CAUSATION THEORIES CEE 698 – Construction Health and Safety
Accidents in Construction CEE 698 – Construction Health and Safety • Why do accidents happen in construction? • Physical hazards • Environmental hazards • Human factors • No safety regulations or poor ones • Poor communication within, between, and among various trades working on a job site • Accidents should not be viewed as inevitable just because hazards exist. • For every accident that occurs, there is a cause.
Theories of Accident Causation • The most widely known theories of accident causation: • Domino theory • Human factors theory • Accident / incident theory • Epidemiological theory • Systems theory • Combination theory • Behavioral theory CEE 698 – Construction Health and Safety
Domino Theory CEE 698 – Construction Health and Safety • Herbert W. Heinrich – Traveler’s Insurance Company • In the late 1920’s, studying reports of 75,000 workplace accidents, he concluded the following: • 88% of accidents are caused by unsafe acts committed by fellow workers • 10% of accidents are caused by unsafe conditions • 2% of accidents are unavoidable • Contemporary research considers domino theory as outdated however today’s more widely accepted theories can be traced back to Heinrich’s study.
Axioms of Workplace Safety CEE 698 – Construction Health and Safety • Conclusions laid foundation for Axioms of Industrial Safety (came to be known as the Domino Theory) • Injuries result from a completed series of factors, one of which is the accident itself. • An accident can occur only as the result of an unsafe act by a person or a physical or mechanical hazard, or both. • Most accidents are the result of unsafe behavior by people. • An unsafe act by a person or an unsafe condition does not always immediately result in an accident or injury. • The reasons why people commit unsafe acts can serve as helpful guides in selecting corrective actions. • The severity of an accident is largely fortuitous, and the accident that caused it is largely preventable.
Axioms of Workplace Safety CEE 698 – Construction Health and Safety • The best accident prevention techniques are analogous with the best quality and productivity standards. • Management should assume responsibility for safety because it is in the best position to get results. • The supervisor is the key person in the prevention of workplace accidents. • In addition to the direct costs of an accident (i.e., compensation, liability claims, medical costs, and hospital expenses), there are also hidden or indirect costs. • Heinrich believed any safety programs taking all 10 axioms into consideration will likely be effective.
Domino Theory CEE 698 – Construction Health and Safety • Five factors in sequence leading to an accident: • Ancestry and social environment.Negative character traits that may lead people to behave in an unsafe manner can be inherited (ancestry) or acquired as a result of the social environment. • Fault of person. Negative character traits, whether inherited or acquired, are why people behave in an unsafe manner and why hazardous conditions exist. • Unsafe acts and mechanical or physical hazards. Unsafe acts committed by people and mechanical or physical hazards are the direct causes of accidents. • Accident. Typically, accidents that result in injury are caused by falling or being hit by moving objects. • Injury.Typical injuries resulting from accidents include lacerations and fractures.
Domino Theory CEE 698 – Construction Health and Safety • Two central points: • Injuries are caused by preceding factors • By removing the unsafe act or hazardous condition, the action of these preceding factors is negated and the accidents/injuries are prevented.
Domino Theory - Example Construction Products Company (CPC) is a distributor of lumber, pipe and concrete products. Warehouse personnel load most of the orders by hand therefore they are required to wear personal protective gear. Management observed increases in minor injuries among personnel during summer months. However during the last summer they suffered from the serious back injuries of two workers. CEE 698 – Construction Health and Safety
Domino Theory - Example • Investigation revealed a series of events and a central causal behavior which created a domino effect. • Personal protective gear becomes uncomfortable due to hot weather and loaders take it off. • This situation increases the number of minor injuries but management does not pay attention due to the nature of injuries. Therefore it was probably inevitable to suffer from more serious injuries. CEE 698 – Construction Health and Safety
Domino Theory - Example • Solution: • Removing the causal factor - the failure of warehouse personnel to use their personal protective gear during summer months. • Forming a committee. • Committee’s recommendations: • Provide all warehouse personnel with training on the importance and proper use of personal protection • Require warehouse supervisors to monitor the use of personal protection gear more closely • Establish a company policy that contains specific and progressive disciplinary measures for failure to use required personal protection gear • Implement several heat reduction measures to make warehouses cooler. CEE 698 – Construction Health and Safety
Human Factors Theory • Attributes accidents to a chain of events ultimately caused by human error. • Consists of three broad factors that lead to human error: • Overload • Inappropriate Response • Inappropriate Activities CEE 698 – Construction Health and Safety
Factors Leading to Human Error Overload Human Error Factors Inappropriate Activities Inappropriate Response CEE 698 – Construction Health and Safety
Overload CEE 698 – Construction Health and Safety Capacity – product of such factors as a person’s natural ability, training, state of mind, fatigue, stress, and physical condition. Load – consisting of tasks for which a person is responsible and added burdens resulting from environmental factors (noise, heat), internal factors (personal problems, stress), and situational factors (unclear instructions). State – the product of a person’s motivational levels. Overload – an imbalance between a person’s capacity at a any given time and the load that the person is carrying in a given state.
Inappropriate Response or Incompatibility • How a person responds to a given situation can cause or prevent an accident. • Inappropriate response occurs when: • A person detects a hazardous condition but does nothing to correct it • A person disregards an established safety procedure. • Incompatibility of a person’s workstation with regard to size, force, reach, feel and similar factors can lead to accidents and injuries. CEE 698 – Construction Health and Safety
Inappropriate Activities • Human error can be result of inappropriate activities. • Examples: • Person who undertakes a task that he / she does not know how to do. • A person who misjudges the degree of risk involved in a given task and proceeds on that misjudgment. CEE 698 – Construction Health and Safety
Human Factors Theory CEE 698 – Construction Health and Safety
Human Factors Theory - Example Jones Cabinets & Construction Company sees rapid growth in sales which overwhelmed company’s work force. New teams of cabinet makers and installers hired. Authorized unlimited overtime. Numbers of accidents and injuries increased. CEE 698 – Construction Health and Safety
Human Factors Theory - Example • Investigation revealed human errors in the three categories: • Overload: • Employees working beyond their personal limits and beyond their capabilities. • Stress, insufficient training and fatigue • Inappropriate response: • Carpenters removing the safeguards to speed up construction. • Inappropriate activities: • Assigning employees to duties for which they are not fully trained CEE 698 – Construction Health and Safety
Accident / Incident Theory • Extension of human factors theory • Developed by Dan Petersen • New elements: • Ergonomic traps • The decision to err • Systems failures CEE 698 – Construction Health and Safety
Accident/Incident Theory CEE 698 – Construction Health and Safety
Accident / Incident Theory Some of the reasons why systems may fail: Management does not establish a comprehensive safety policy Responsibility and authority with regard to safety are not clearly defined Safety procedures, such as measurement, inspection, correction, and investigation, are ignored or given insufficient attention. Employees do not receive proper orientation Employees are not given sufficient safety training CEE 698 – Construction Health and Safety
Accident / Incident Theory - Example Panhandle Precast Concrete has developed a well-earned reputation as a “safe company”. When the safety manager of the firm, Jack Bond, was elected as the president of a statewide safety organization, safety problems within the firm began. Jack Bond neglected his duties at PPC. Workers stopped following the safety precautions once they realized he had stopped observing and correcting them. CEE 698 – Construction Health and Safety
Epidemiological Theory • Epidemiology: Study of causal relationships between environmental factors and disease. • Epidemiological theory holds that the models used for studying and determining these relationships can also be used to study casual relationships between environmental factors and accidents. • Components: • Predisposition Characteristics • Situational Characteristics CEE 698 – Construction Health and Safety
Epidemiological Theory CEE 698 – Construction Health and Safety
Epidemiological Theory - Example Jane Andrews was the newest member of the loading unit for Construction Products, Inc. She had 2 days of training on proper lifting techniques before beginning the work and mandatory use of back-support belts Her supervisor and colleagues pressured to disregard the proper lifting methods she learned in training. She followed her supervisor and after 2 months had to undergo major surgery to repair two ruptured disks. Predisposition factor: Her susceptibility to pressure from her coworkers and supervisor Situational factors: Peer pressure and priorities of supervisor CEE 698 – Construction Health and Safety
Systems Theory System – a group of regularly interacting and interrelated components that together form a unified whole. An accident may occur as a system which is composed of: Person Machine Environment The likelihood of an accident to occur is determined by how these components interact. Example: A worker who temporarily replaces an experienced crane operator increases the probability of an accident. CEE 698 – Construction Health and Safety
Systems Theory The primary components of the systems model are the person, machine, environment, and information; decisions; risks; and the task to be performed. Each of these components has a bearing on the probability that an accident will occur. CEE 698 – Construction Health and Safety
Systems Theory • Factors which should be considered before collecting information, weighing risks and making a decision: • job requirements • the workers’ abilities and limitations • the gain if the task is successfully accomplished • the loss if the task is attempted but fails • the loss if the task is not attempted CEE 698 – Construction Health and Safety
Systems Theory - Example Construction Service Company (CSC) makes customized trusses for residential construction jobs. Workers including the apprentices use manually operated machines which causes two problems: It is difficult for even experienced workers to make clean accurate cuts Machines are so old that they frequently break down. While working under a major contract, an apprentice gets careless and runs his hand into the saw blade. The person-machine-environment chain: Person involved was inexperienced. Machine involved was old and prone to breakdown The environment was stressful and pressure-packed. CEE 698 – Construction Health and Safety
Combination Theory Often the cause of an accident cannot be adequately described by one theory. Differences between the theory and reality may exist. Combination theory helps explain the actual cause of an accident by combining different parts of several theories. CEE 698 – Construction Health and Safety
Combination Theory - Example Crestview Construction Company (CCC) maintains four large warehouses . Ventilation of these warehouses are important and the vent filters need to be changed periodically. Changing the vents filter involves two potential hazards: Unvented dust and fumes can make breathing difficult. Vents are located 110 feet above the ground level, which can be accessed through a narrow cat walk that has knee-high guardrails. CEE 698 – Construction Health and Safety
Combination Theory - Example CCC has well defined rules which are strictly enforced. However an employee fell from the catwalk while he was trying to change one of the filter. His lifeline held him for 20 minutes. When he panicked and tried to pull himself up he knocked the buckle of his safety harness open and fell to the concrete floor, breaking his neck. Critical factors: Absence of supervisor Inexperience of worker A conscious decision by the worker to disregard the safety procedures A faulty buckling mechanism on the safety harness An unsafe design (only a knee-high guardrail on the catwalk) CEE 698 – Construction Health and Safety
Behavioral Theory CEE 698 – Construction Health and Safety • Referred to as Behavior-based safety (BBS) • E. Scott Geller – Safety Performance Solutions, Inc., and professor of psychology • Believes in 7 basic principles of BBS: • Use intervention that is focused on employee behavior. • Identify external factors that aid in understanding and improving employee behavior.
Behavioral Theory CEE 698 – Construction Health and Safety • Direct behavior with activator or events antecedent to the desired behavior, and motivate employees to behave as desired with incentives and rewards that follow desired behavior. • Focus on the positive consequences that result from the desired behavior as a way to motivate employees. • Apply scientific method to improve attempts at behavioral interventions. • Use theory to integrate information rather than to limit possibilities. • Plan interventions with the feelings and attitudes of the individual employee in mind.
BBS and ABC Model CEE 698 – Construction Health and Safety Behavior-based safety trainers and consultants teach the ABC model (or three-term contingency) as a framework to understand and analyze behavior or to develop interventions for improving behavior. As given in BBS principle 3…the A stands for activators or antecedent events that precede behavior (B), and C refers to the consequences following behavior or produced by it. Activators direct behavior, whereas consequences motivate behavior.
BBS and ABCO Model CEE 698 – Construction Health and Safety Outcome refers to the longer-term results of engaging in safe or unsafe behavior. For example, an antecedent of a sign requiring employees to wear safety goggles could produce the behavior of putting on the goggles, the consequence of avoiding an eye injury, and the outcome of being able to continue working and enjoying time with the family. One the other hand, the consequence of not wearing goggles could be an eye injury with a potential outcome of blindness, time off the job, and a reduced quality of life. Failure to address the issue of outcomes represents a lost opportunity to give employees a good reason for engaging in safe behaviors.
Behavioral Theory - Example • Jack Coker decided to apply the ABC model in turning the unsafe behavior pattern of the workers (not wearing hard hats) in Bonded Builders, Inc. • He removed the old “Hard Hat Area” signs and replaced them with newer, more noticeable signs. • He scheduled a brief seminar on head injuries in which he told a story of two employees. One was in a hospital bed surrounded by family members he did not even recognize; the other was shown enjoying a family outing with happy family members. CEE 698 – Construction Health and Safety