BIM is a concept that offers software application to integrate building information for hazard identification and safety planning.
Hazard Analysis — Fall from heights
Workers who fit and nail exterior walls and roof sheathing may fall from heights. Falls from heights include worker falls to a lower level which result in injury on impact against an object or the ground.
Workers working above ground level may pose a safety hazard and be at risk of falling from heights. The result of such fall can potentially cause fractures, sprains, strains, contusions, severe damage to internal organs and even death.
Falls from Ladders
Falls from ladders may result from problems with the selection, maintenance or use of a ladder. Common causes of straight ladder falls may be slippage due to failure to properly secure the ladder at the top and/or bottom, erecting the ladder at too steep or too shallow angle, climbing the ladder while using one or both hands to carry tools or supplies, and overreaching while working on the ladder. Falls from adjustable straight ladder may also result from improperly locking the adjusting catches. Falls from ladders may also be caused by climbing above the tipping point of the ladder.
Falls from Scaffolds
Level of Risk:
In The Construction Chart Book 5th edition published by CPWR, Chapter 43 describes falls as the leading cause of fatalities in construction between 1992-2010 (graphs 43a and 43c). Chapter 44 provides detailed information about falls in construction, including the number of fatal falls for each year between 1992 and 2010 (graph 44a), the large number of fall fatalities in small enterprises (graph 44b), the high rates of fatal injuries among power-line installers, roofers and ironworkers (graph 44c) of non-fatal fall injuries in ironworkers, sheetmetal workers, roofers, heating and air conditioning mechanics, and carpenters (graph 44d) and the importance of falls from roofs, ladders and scaffolds as causes of fatal injuries (graph 44e).
U.S. Bureau of Labor Statistics, 1992-2005 Census of Fatal Occupational Injuries.
U.S. Bureau of Labor Statistics, 1992-2005 Survey of Occupational Injuries and Illnesses.
U.S. Bureau of Labor Statistics, 2005 Survey of Occupational Injuries and Illnesses.
U.S. Bureau of Labor Statistics, 2003-2005 Census of Fatal Occupational Injuries.
Assessment of fall hazards should be an integral part of the site safety planning process. For example, for a given construction work activity consider the: 1) height at where the task will be done, 2) time spent above the ground level, 3) slope of the work platform, 4) guarding of the platform edges and 5) surface of the work platform.
A team of safety experts from Washington University developed an auditing tool entitled "St. Louis Audit of Fall Risks" and an associated protocol for assessing fall hazards in residential construction.
Prior to using a ladder, it is best practice to explore other safer alternatives first. Some options would be to consider if it is feasible to: 1) perform the work task with an extension tool on ground level, 2) utilize an elevating work platform (i.e. a scissor lift) or 3) relocate the building component or equipment on ground level. If not possible, there are some ways to assess the risk of falling from a ladder. Although this list is by no means comprehensive, things to take into account would be:
- the platform where the ladder is on
- if the setup of the ladder uses the 4:1 rule (4 feet of ladder length to point of attachment to 1 foot of distance from ladder base to wall)
- if the type and length of ladder for the work task is appropriate
- if the ladder is stable
- if the top and bottom of the ladder is secure when using a straight ladder
- if the the ladder rungs have uniform spacings and parallel allignment
- if the ladder is in good working condition
- if the workers practice good climbing techniques in maintaining 3-points of contact with the ladder
- the frequency of having to ascend and descend the ladder
- if workers follow the manufacturer's recommendations on the ladder use
- if there is a program on safety training and hazard precautions for the workers
In assessing the risk of falling from a roof, although this list is by no means comprehensive, some things to keep in mind would be:
- there are engineering controls in place, such as guardrails or safety nets
- the worker are using personal protective equipments, such as fall arrest and restraint systems
- the tie-off points and safety equipments have the approval for their proper function by a competent person
- there are covers marked with the word "HOLE" or "COVER" for the roof areas with openings before work
- there is a program on safety training and hazard precautions for the workers
In assessing the risk of falling from a scaffold, although this list is by no means comprehensive, some things to consider would be if:
- there is direct supervision of a competent person when erecting or dismantling a scaffold
- the footage or anchorage of the fixed scaffold system is stable
- the loading weight is appropriate with respect to the intended load limit
- there are engineering controls in place, such as guardrails
- the worker are using personal protective equipments, such as fall arrest systems
- the suspension ropes have shielding from hot or corrosive processes, and protection from sharp edges or abrasion for the suspension scaffold
- the anchorage support of the building is structurally sound for the suspension scaffold
- the workers follow the manufacturer's recommendations on the scaffold use
- there is a program on safety training and hazard precautions for the workers
Regulations & Standards:
Regulations adopted by a state must be at least as protective as the corresponding federal standard. Work may also be subject to rules of other federal, state and local agencies. Even where there is no hazard specific standard, OSHA prohibits employers from to work in surroundings or under working conditions which are unsanitary, hazardous, or dangerous to his health or safety.
Federal OSHA Standards are enforced by the U.S. Department of Labor in 26 states. There are currently 22 states and jurisdictions operating complete State plans (covering both the private sector and state and local government employees) and 5 - Connecticut, Illinois, New Jersey, New York and the Virgin Islands - which cover public employees only. If you are working in one of those states or jurisdictions you should ensure that you are complying with their requirements.
In some rare cases, a condition known as orthostatic intolerance or "suspension trauma" may occur when workers are suspended by their fall arrest systems following a fall.
Orthostatic intolerance may be experienced by workers using fall arrest systems. Following a fall, a worker may remain suspended in a harness for a prolonged period. During this time, "venous pooling" may occur where blood may accumulate in the veins due to the force of gravity and a lack of movement in the legs. Normally, blood is returned to the heart by limb movement which in this case, the legs cannot serve as a "pump." Subsequently, this results in the reduction of blood circulation which can lead to weakness and unconsciousness since the brain cannot yield enough oxygen. Depending on the length of time the suspended worker is unconscious/immobile and the level of venous pooling, the resulting orthostatic intolerance may lead to death. While not common, such fatalities often are referred to as "suspension trauma."
The consequences of occupationally related suspension trauma can be compounded by shock, harness fit (reduced circulation), injuries related to the fall, head trauma, or the workers personal medical condition. A further complication is the potential for cardiac arrest caused by the suspended worker being placed too quickly into a horizontal position, resulting in a sudden rush of deoxygenated blood back to the heart. All of these effects point to the need for prompt rescue after a fall.