Provides data on the nature of events resulting in workers being crushed or hit and discusses steps that can be taken to reduce the incidents.
someone crushed or hit by falling or moving objects
Over the last decade, one category of fatalities has steadily increased in Ontario construction.
Among the top four killers, "crushed or hit by object or material" now ranks third, after falls and traffic. This type of fatal accident has affected a broad range of trades and activities, as summarized in Table 1. The cases do not include victims struck by vehicles or heavy equipment; those deaths are classified as traffic-related.
|Table 1: Construction personnel fatally crushed or hit by object or material29 (15%) of 200 fatalities in 1990-1999
was struck by part of shaft of overhead crane being demolished.
Effective hazard analysis involves recognition, assessment, and control.
Crushed/hit deaths include construction people killed by
- collapsing buildings
- falling walls or structures
- heavy objects or loads
- falling material or wreckage.
- demolishing part of a building
- erecting a wall or structure that collapsed
- moving heavy objects or loads
- installing building material that fell.
This information helps us to recognize potential hazards in the workplace. We can then pay special attention to operations such as demolition, erection, and materials handling.
Hazard recognition also requires
- health and safety training and experience
- knowledge of the Occupational Health and Safety Act and Regulations for Construction Projects
- familiarity with the site and the work being done
- familiarity with equipment and materials being used
- regular inspection.
Once crushed/hit hazards are recognized, they need to be assessed. Assessment determines the seriousness of the hazard by identifying
- which workers are exposed
- how long exposure may last
- how serious the effects of exposure would be
- whether existing rules and controls apply or alternate measures are necessary.
Controls can be implemented
- at the worker
- along the hazard path
- at the hazard source.
Control at the worker This is the last resort in protection when hazards can't be controlled at the source or along the path. Control at the worker consists of enclosure, isolation, or personal protective clothing and equipment. Enclosure and isolation would be impractical in most of the situations described in Table 1. Nor would personal protective equipment afford any protection against hazards such as falling beams, collapsing walls, inadequately secured overhead loads, or rock fragments from blasting.
Control along the path Barriers and screens are examples of controls along the hazard path. But they could prevent very few of the fatal accidents listed in Table 1.
Control at the source Ideally the best control for any hazard is elimination at its source. With most crushed/hit hazards, this is the only practical option.
- reduce or eliminate the risk of injury and death
- not make the work significantly more difficult to perform
- not create any new hazards.
Controls at the source should
Generally these controls depend on
- compliance with regulations
- adherence to the company's health and safety policy and program
- accident prevention training for workers and supervision
- site orientation and safety talks
- regular site inspections.
More specifically, controls against crushed/hit hazards entail some clearly defined and engineered safeguards.
Crushed/hit incidents involve different trades, circumstances, and causes. But it's possible to identify some basic prevention measures. Several of these are required by the construction regulation (O. Reg. 213/91).
- Before starting a particular job such as removing steel beams or dismantling a staircase, consider what may happen at each stage of the work. Devise and follow a plan until some new development makes it necessary to reassess your approach.
- On demolition or dismantling projects, determine how frames, beams, and other components are tied into the structure and connected to each other.
- O. Reg. 213/91 prohibits any truss, girder, or other structural member from being disconnected until it is relieved of all loads other than its own weight and is provided with temporary support: Section 220.
- Work above a tier or floor of a structure being demolished or dismantled must be completed before the work affects the support of the tier or floor: Section 216(3).
- Whether being demolished, moved, or erected, structures must be temporarily supported or stabilized where necessary to prevent collapse in whole or in part.
- Under the construction regulation (O. Reg. 213/91), damaged structures that may endanger people must be braced and shored progressively from a safe area towards the hazardous area so that workers installing safeguards are protected: Section 212.
- Sections cut or unfastened from a structure should not be allowed to drop freely unless there's no danger of hitting anyone below.
- O. Reg. 213/91 requires that blocking be installed to prevent the collapse or movement of part or all of any equipment being dismantled, altered, or repaired: Section 108.
- Loads must be arranged and secured so that when banding or other fasteners are removed the load does not come apart uncontrollably.
- Before hoisting any load, inspect all rigging equipment to ensure that it's in good condition and that each component has a stated load rating capable of safely supporting the intended load.
- Loads should not be hoisted or allowed to pass over people below. Specifically O. Reg. 213/91 prohibits the operation of a power shovel, backhoe, or similar excavating device in such a way that it or any part of its load passes over a worker: Section 103(1).
- Avoid pinch points between moving equipment and stationary objects or between stationary objects and equipment or material that may move once you begin work.
- When using boom trucks and forklifts, operate wherever possible on firm, level ground. Handle controls smoothly, without suddenly starting, stopping, raising, or lowering. These actions may dislodge the load or tip the machine.
- Forklifts and other lifting devices should be equipped with overhead protection to prevent loads from striking the operator.
- Try to determine the center of gravity of loads to be lifted or materials to be erected or demolished. Fatalities have occurred when steel beams, precast panels, and other components have twisted, tipped, or pivoted unexpectedly, crushing workers underneath or pinning them against objects. In several cases this happened because material wasn't supported, suspended, or anchored near its center of gravity.
When referring to the Occupational Health and Safety Act and Regulations for Construction Projects, make sure you have the latest, revised version, issued in June 2000.
This is the final article in a series dealing with the four major causes of construction fatalities. Falls were covered in Volume 10, Number 3 (Autumn 1999); traffic in Volume 10, Number 4 (Winter 1999/2000); and electrocution in Volume 11, Number 1 (Spring 2000).