1. Accidents and their causes.
Ch 2
Accidents and their causes.

2. Causes of construction accidents 2005

3. Accidents in Construction
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.

4. Accidents Root Cause Analysis
Incident investigation, whether for safety, quality, or production, can be simple or complex depending upon the severity of the event.
In principle, investigators would be trained to
[a] discover the facts,
[b] collect evidence,
[c] ascertain the root cause(s), and
[d] make recommendations in a written report.
However, many investigators often seize on the first set of ‘symptoms’ as the Root Cause, rather than the Root Cause(s) themselves.
This is why the same type(s) of incidents are often repeated.

5. Root Cause Analyses helps you get to the 'bottom' of events to prevent recurrence. A Root Cause is the most basic cause (s) identified as contributing to an incident, and that is within peoples control to fix. Fishbone analysis

6. Influencing & Causal Factors
is a method used to diagrammatically represent a series of events that lead up to the incident, and any ‘influencers and causal factors' associated with each event 

7. The 5 Why’s Method
helps you systematically peel away the layers of incident related symptoms until you arrive at a cause of a problem. Often, there is more than one cause! By repeatedly asking ‘Why?' 5 times for each aspect of an incident, you identify incident contributors and/or each cause.

8. 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

9. 1- Domino Theory 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Contemporary research considers domino theory as outdated however today’s more widely accepted theories can be traced back to Heinrich’s study.

10. Axioms of Workplace 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.

11. Cont. Axioms of Workplace 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.

12. Cont. Domino Theory 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.

13. Domino Theory 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.

14. 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.

15. 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.

16. 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.

17. 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

18. Factors Leading to Human Error
Overload
Human Error Factors
Inappropriate Activities
Inappropriate Response

19. Overload
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.

20. 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.

21. 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.

22. Human Factors Theory

23. 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.

24. Cont. 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

25. Accident / Incident Theory
Extension of human factors theory
Developed by Dan Petersen
New elements:
Ergonomic traps
The decision to err
Systems failures

26. Accident/Incident Theory

27. 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

28. 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.

29. 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

30. Epidemiological Theory

31. 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

32. 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.

33. 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.

34. 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

35. 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.

36. 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.

37. 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.

38. 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)

39. Behavioral Theory 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.

40. Cont. Behavioral Theory
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.