ILO Content Manager

ILO Content Manager

Friday, 14 January 2011 16:24

Elevators, Escalators and Hoists

Elevators

An elevator (lift) is a permanent lifting installation serving two or more defined landing levels, comprising an enclosed space, or car, whose dimensions and means of construction clearly permit the access of people, and which runs between rigid vertical guides. A lift, therefore, is a vehicle for raising and lowering people and/or goods from one floor to another floor within a building directly (single push-button control) or with intermediate stops (collective control).

A second category is the service lift (dumb waiter), a permanent lifting installation serving defined levels, but with a car that is too small to transport people. Service lifts transport foods and supplies in hotels and hospitals, books in libraries, mail in office buildings and so on. Generally, the floor area of such a car does not exceed 1 m2, its depth 1 m, and its height 1.20 m.

Elevators are driven directly by an electric motor (electric lifts; see figure 1) or indirectly, through the movement of a liquid under pressure generated by a pump driven by an electric motor (hydraulic lifts).

Figure 1. A cut-away view of an elevator installation showing the essential components

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Electric lifts are almost exclusively driven by traction machines, geared or gearless, depending on car speed. The designation “traction” means that the power from an electric motor is transmitted to the multiple rope suspension of the car and a counterweight by friction between the specially shaped grooves of the driving or traction sheave of the machine and the ropes.

Hydraulic lifts have become widely used since the 1970s for the transport of goods and passengers, usually for a height not exceeding six floors. Hydraulic oil is used as pressure fluid. The direct-acting system with a ram supporting and moving the car is the simplest one.

Standardization

Technical Committee 178 of the ISO has drafted standards for: loads and speeds up to 2.50 m/s; car and hoistway dimensions to accommodate passengers and goods; bed and service lifts for residential buildings, offices, hotels, hospitals and nursing homes; control devices, signals and additional accessories; and selection and planning of lifts in residential buildings. Each building should be provided with at least one lift accessible to handicapped people in wheelchairs. The Association française de normalisation (AFNOR) is in charge of the Secretariat of this Technical Committee.

General safety requirements

Every industrialized country has a safety code drawn up and kept up to date by a national standards committee. Since this work was started in the 1920s, the various codes have gradually been made more similar, and differences now are generally not fundamental. Large manufacturing firms produce units that comply with the codes.

In the 1970s the ILO, in close cooperation with the International Committee for the Reglementation of Lifts (CIRA), published a code of practice for the construction and installation of lifts and service lifts and, a few years later, for escalators. These directives are intended as a guide for countries engaged in the drafting or modification of safety rules. A standardized set of safety rules for electric and hydraulic lifts, service lifts, escalators and passenger conveyors, the object being the elimination of technical barriers to trade among the member countries of the European Community, is also under the purview of the European Committee for Standardization (CEN). The American National Standards Institute (ANSI) has devised a safety code for lifts and escalators.

Safety rules are aimed at several types of possible accidents with lifts: shearing, crushing, falling, impact, trapping, fire, electric shock, damage to material, accidents due to wear, and accidents due to corrosion. People to be safeguarded are: users, maintenance and inspection personnel and people outside the hoistway and the machine room. Objects to be safeguarded are: loads in the car, components of the lift installation and the building.

Committees drawing up safety rules have to assume that all components are correctly designed, are of sound mechanical and electrical construction, are made of material of adequate strength and suitable quality and are free from defects. Potential imprudent acts of users have to be taken into account.

Shearing is prevented by providing adequate clearances between moving components and between moving and fixed parts. Crushing is prevented by providing sufficient headroom at the top of the hoistway between the roof of the car in its highest position and the top of the shaft and a clear space in the pit where someone can remain safely when the car is in its lowest position. These spaces are assured by buffers or stops.

Protection against falling down the hoistway is obtained by solid landing doors and an automatic cut off that prevents movement of the cab until the doors are fully closed and locked. Landing doors of the power-operated sliding type are preferred for passenger lifts.

Impact is limited by restraining the kinetic energy of closing power-operated doors; trapping of passengers in a stalled car is prevented by providing an emergency unlocking device on the doors and a means for specially trained personnel to open them and extricate the passengers.

Overloading of a car is prevented by a strict ratio between the rated load and the net floor area of the car. Doors are required on all the cars passenger lifts to keep passengers from being trapped in the space between the car sill and the hoistway or the landing doors. Car sills must be fitted with a toe guard of a height of not less than 0.75 m to prevent accidents, as shown in figure 2. Cars have to be provided with safety gear capable of stopping and holding a fully loaded car in the event of overspeed or failure of the suspension. The gear is operated by an overspeed governor driven by the car by means of a rope (see figure 1). As passengers stand upright and move in a vertical direction, the retardation during the operation of the safety device should lie between 0.2 and 1.0 g (m/s2) to guard against injuries (g = standard acceleration of free fall).

Figure 2. Layout of the toe guard on the car sill to prevent trapping

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Depending on national legislation, lifts intended mainly for the transport of goods, vehicles and motor cars accompanied by authorized and instructed users may have one or two opposite car entrances not provided with car doors, under the condition that the rated speed does not exceed 0.63 m/s, the car depth is not less than 1.50 m and the wall of the hoistway facing the entrance, including the landing doors, is flush and smooth. On heavy-duty freight elevators (goods lifts), the landing doors are usually vertical bi-parting power-operated doors, which usually do not meet these conditions. In such a case, the required car door is a vertically sliding mesh gate. The clear width of the lift car and the landing doors must be the same to avoid damage to panels on the lift car by fork trucks or other vehicles entering or leaving the lift. The whole design of such a lift has to take account of the load, the weight of the handling equipment and the heavy forces involved in running, stopping and reversing these vehicles. The lift car guides require special reinforcement. When the transport of people is permitted, the number allowed should correspond to the maximum available area of the car floor. For example, the car floor area of a lift for a rated load of 2,500 kg should be 5 m2, corresponding to 33 persons. Loading and accompanying a load must be done with great care. Figure 3 shows a faulty situation.

Figure 3. Example of dangerous loading of a freight elevator (goods-lift).

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Controls

All modern lifts are push-button and computer controlled, the car switch system operated by an attendant having been abandoned.

Single lifts and those grouped in two- to eight-car arrangements are usually equipped with collective controls which are interconnected in the case of multiple installations. The main feature of collective controls is that calls can be given at any moment, whether the car is moving or standstill and whether the landing doors are open or closed. Landing and car calls are collected and stored until answered. Regardless of the sequence in which they are received, calls are answered in the order that most efficiently operates the system.

Examinations and tests

Before a lift is put into service, it should be examined and tested by an organization approved by the public authorities to establish the lift’s conformity with the safety rules in the country where it has been installed. A technical dossier should be submitted to the inspector by the manufacturers. The elements to be examined and tested and the way the tests should be run are listed in the safety code. Specific tests by an approved laboratory are required for: locking devices, landing doors (possibly including fire tests), safety gear, overspeed governors and oil buffers. Certificates of the corresponding components used in the installation should be included in the register. After a lift is put into service, periodic safety examinations should be conducted, with the intervals depending on traffic volume. These tests are intended to ensure compliance with the code and the proper operation of all safety devices. Components that do not function in normal service, such as the safety gear and buffers, should be tested with a car empty and at reduced speed to prevent excessive wear and stresses that can impair the safety of a lift.

Maintenance and inspection

A lift and its components should be inspected and maintained in good and safe working order at regular intervals by competent technicians who have obtained skill and a thorough knowledge of the mechanical and electrical details of the lift and the safety rules under the guidance of a qualified instructor. Preferably the technician is employed by the supplier or erector of the lift. Normally a technician is responsible for a specific number of lifts. Maintenance involves routine servicing such as adjustment and cleaning, lubrication of moving parts, preventive servicing to anticipate possible problems, emergency visits in the case of breakdowns and major repairs, which are usually done after consultation with a supervisor. The overriding safety hazard, however, is fire. Because of the risk that a lit cigarette or other burning object might fall into the crack between the car sill and the hoistway and ignite lubricating grease in the hoistway or debris at the bottom, the hoistway should regularly be cleaned out. All systems should be at zero energy level before maintenance work is begun. In single-unit buildings, before any work is started, notices should be posted at each landing indicating that the lift is out of service.

For preventive maintenance, careful visual inspection and checks of free movement, the condition of contacts and proper operation of the equipment are generally sufficient. The hoistway equipment is inspected from the top of the car. An inspection control is provided on the car roof comprising: a bi-stable switch to bring it into operation and to neutralize the normal control, including the operation of power-operated doors. Up and down constant pressure buttons allow movement of the car at reduced speed (not exceeding 0.63 m/s). The inspection operation must remain dependent on the safety devices (closed and locked doors and so on) and it should not be possible to overrun the limits of normal travel.

A stop switch on the inspection control station prevents unexpected movement of the car. The safest direction of travel is down. The technician must be in a safe position to observe the work environment when moving the car and possess the appropriate inspection devices. The technician must have a firm hold when the car is in motion. Before leaving, the technician must report to the person in charge of the lift.

Escalators

An escalator is a continuous moving, inclined stairway which conveys passengers upward and downward. Escalators are used in commercial buildings, department stores and railway and underground stations, to guide a stream of people in a confined route from one level to another.

General safety requirements

Escalators consist of a continuous chain of steps moved by a motor-driven machine by means of two roller chains, one at each side. The steps are guided by rollers on tracks which keep the step treads horizontal in the usable area. At the entrance and exit, guides ensure that over a distance of 0.80 to 1.10 m, depending on the speed and rise of the escalator, some steps form a horizontal flat surface. Step dimensions and construction are shown in figure 4. On the top of each balustrade, a handrail should be provided at a height of 0.85 to 1.10 m above the nose of the steps running parallel to the steps at substantially the same speed. The handrail at each extremity of the escalator, where the steps move horizontally, should extend at least 0.30 m beyond the landing plate and the newel including the handrail at least 0.60 m beyond (see figure 5). The handrail should enter the newel at a low point above the floor, and a guard should be installed with a safety switch to stop the escalator if fingers or hands are trapped at this point. Other risks of injury to users are formed by the clearances necessary between the side of the steps and the balustrades, between steps and combs and between treads and step risers, the latter more particularly in the upward direction at the curvature where a relative movement between consecutive steps occurs. The cleating and smoothness of the risers should prevent this risk.

Figure 4. Escalator step unit 1 (X: Height to next step (not greater than 0.24m); Y: Depth (at least 0.38m); Z: Width (between 0.58 and 1.10m); Δ: Grooved step tread; Φ: Cleated step riser)

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Figure 5. Escalator step unit 2

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People may ride with their shoes sliding against the balustrade, which can cause trapping at the points where the steps straighten out. Clearly legible signs and notices, preferably pictographs, should warn and instruct users. A sign should instruct adults to hold the hands of children, who may not be able to reach the handrail, and that children should stand at all times. Both ends of an escalator should be barricaded when it is out of service.

The incline of an escalator should not exceed 30°, though it may be increased to 35° if the vertical rise is 6 m or less and the speed along the incline is limited to 0.50 m/s. Machine rooms and driving and return stations should be easily accessible to specially-trained maintenance and inspection personnel only. These spaces can lie inside the truss or be separate. The clear height should be 1.80 m with covers, if any, opened and the space should be sufficient to ensure safe working conditions. The clear height above the steps at all points should be not less than 2.30 m.

The starting, stopping or reversal of movement of an escalator should be effected by authorized people only. If the country code permits operating a system that starts automatically when a passenger moves past an electric sensor, the escalator should be in operation before the user reaches the comb. Escalators should be equipped with an inspection control system for operation during maintenance and inspection.

Maintenance and inspection

Maintenance and inspection along the lines described above for lifts are usually required by authorities. A technical dossier should be available listing the main calculation data of the supporting structure, steps, step driving components, general data, layout drawings, schematic wiring diagrams and instructions. Before an escalator is put into service, it should be examined by a person or organization approved by the public authorities; subsequently periodic inspections at given intervals are needed.

Moving Walkways (Passenger Conveyors)

A passenger conveyor, or power-driven continuous moving walkway, may be used for the conveyance of passengers between two points at the same or at different levels. Passenger conveyors are used to transport a great number of people in airports from the main station to the gates and back and in department stores and supermarkets. When the conveyors are horizontal, baby carriages, pushcarts and wheelchairs, luggage and food trolleys can be carried without risk, but on inclined conveyors these vehicles, if rather heavy, should be used only if they lock into place automatically. The ramp consists of metal pallets, similar to the step treads of escalators but longer, or rubber belt. The pallets must be grooved in the direction of travel, and combs should be placed at each end. The angle of inclination should not exceed 12° or more than 6° at the landings. The pallets and belt should move horizontally over a distance of not less than 0.40 m before entering the landing. The walkway runs between balustrades that are topped with a moving handrail that travels at substantially the same speed. The speed should not exceed 0.75 m/s unless the movement is horizontal, in which case 0.90 m/s is permitted provided the width does not exceed 1.10 m.

The safety requirements for passenger conveyors are generally similar to those for escalators and should be included in the same code.

Building Hoists

Building hoists are temporary installations used on construction sites for the transport of persons and materials. Each hoist is a guided car and should be operated by an attendant inside the car. In recent years, rack and pinion design has enabled the use of building hoists for efficient movement along radio towers or very tall smoke stacks for servicing. No one should ride a material hoist, except for inspection or maintenance.

The standards of safety vary considerably. In a few cases, these hoists are installed with the same standard of safety as permanent goods and passenger lifts in buildings, except that the hoistway is enclosed by strong wire mesh instead of solid materials to reduce the wind load. Strict regulations are needed although they need not be as strict as for passenger lifts; many countries have special regulations for these building hoists. However, in many cases the standard of safety is low, the construction poor, the hoists driven by a diesel engine winch and the car suspended by only a single steel wire rope. A building hoist should be driven by electric motors to ensure that the speed is kept within safe limits. The car should be enclosed and be provided with car entrance protections. Hoistway openings at the landings should be fitted with doors that are solid up to a height of 1 m from the floor, the upper part in wire mesh of maximum 10 x 10 mm aperture. Sills of landing doors and cars should have suitable toe guards. Cars should be provided with safety gear. One common type of accident results when workers travel on a platform hoist designed only for carrying goods, which do not have side walls or gates to keep the workers from striking a part of the scaffolding or from falling off the platform during the journey. A belt lift consists of steps on a moving vertical belt. A rider is at risk of being carried over the top, being unable to make an emergency stop, striking his or her head or shoulders on the edge of a floor opening, jumping on or off after the step has passed the floor level or being unable to reach the landing because of power failure or the belt’s stopping. Accordingly, such a lift should be used only by specially trained personnel employed by the building owner or a designee.

Fire Hazards

Generally, the hoistway for any lift extends over the full height of a building and interconnects the floors. A fire or the smoke from a fire breaking out in the lower part of a building may spread up the hoistway to other floors and, under certain circumstances, the well or hoistway may intensify a fire because of a chimney effect. Therefore, a hoistway should not form part of a building’s ventilation system. The hoistway should be totally enclosed by solid walls of non-combustible material that would not give off harmful fumes in case of a fire. A vent should be provided at the top of the lift hoistway or in the machine room above it to allow smoke to escape to open air.

Like the hoistway, the entrance doors should be fire resistant. Requirements are usually laid down in national building regulations and vary according to countries and conditions. Landing doors cannot be made smokeproof if they are to operate reliably.

No matter how tall the building, passengers should not use lifts in case of fire, because of the risks of the lift stopping at a floor in the fire zone and of passengers being trapped in the car in the event of failure of the electrical supply. In general, one lift that serves all floors is designated as a lift for firefighters that can be put at their disposal by means of a switch or special key on the main floor. The capacity, speed and car dimensions of the firefighters’ lift have to meet certain specifications. When firefighters use lifts, the normal operational controls are overridden.

The construction, maintenance and refinishing of elevator interiors, installation of carpeting and cleaning of the elevator (inside or out) may involve the use of volatile organic solvents, mastics or glues, which can present a risk to the central nervous system, as well as a fire hazard. Although these materials are used on other metal surfaces, including staircases and doors, the hazard is severe with elevators because of their small space, in which vapour concentrations can become excessive. The use of solvents on the outside of an elevator car can also be risky, again because of limited air flow, particularly in a blind hoistway, where venting may be impeded. (A blind hoistway is one without an exit door, usually extending for several floors between two destinations; where a group of elevators serves floors 20 and above, a blind hoistway would extend between floors 1 and 20.)

Lifts and Health

While lifts and hoists involve hazards, their use can also help reduce fatigue or serious muscle injury due to manual handling, and they can reduce labour costs, especially in building construction work in some developing countries. On some such sites where no lifts are used, workers have to carry heavy loads of bricks and other building materials up inclined runways numerous floors high in hot, humid weather.

 

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Friday, 14 January 2011 16:14

Cranes

A crane is a machine with a boom, primarily designed to raise and lower heavy loads. There are two basic crane types: mobile and stationary. Mobile cranes can be mounted on motor vehicles, boats or railroad cars. Stationary cranes can be of a tower type or mounted on overhead rails. Most cranes today are power driven, though some still operate manually. Their capacity, depending on the type and size, ranges from a few kilograms to hundreds of tonnes. Cranes are also used for pile driving, dredging, digging, demolition and personnel work platforms. Generally, a crane’s capacity is greater when the load is closer to its mast (centre of rotation) and less when the load is further away from its mast.

Crane hazards

Accidents involving cranes are usually costly and spectacular. Injuries and fatalities involve not only workers, but sometimes innocent bystanders. Hazards exist in all facets of crane operation, including assembly, dismantling, travel and servicing. Some of the most common hazards involving cranes are:

  • Electrical hazards. Overhead powerline contact and arcing of electrical current through the air can occur if the machine or hoist line is close enough to the powerline. When powerline contact occurs, the danger is not just limited to the operator of the hoist, but extends to all personnel in the immediate vicinity. Twenty three percent of crane fatalities in the United States, for example, in 1988–1989 involved powerline contact. Aside from injury to humans, electrical current can cause structural damage to the crane.
  • Structural failure and overloading. Structural failure occurs when a crane or its rigging components are overloaded. When a crane is overloaded, the crane and its rigging components are subject to structural stresses that may cause irreversible damage. Swinging or sudden dropping of the load, using defective components, hoisting a load beyond capacity, dragging a load and side-loading a boom can cause overloading.
  • Instability failure. Instability failure is more common with mobile cranes than stationary ones. When a crane moves a load, swings its boom and moves beyond its stability range, the crane has a tendency to topple. Ground conditions can also cause instability failure. When a crane is not levelled, its stability is reduced when the boom is oriented in certain directions. When a crane is positioned on ground that cannot bear its weight, the ground can give way, causing the crane to topple. Cranes have also been known to tip when travelling on poorly compacted ramps on construction sites.
  • Material falling or slipping. Material can fall or slip if not properly secured. Falling material can injure workers in the vicinity or cause property damage. Undesired movement of material can pinch or crush workers involved in the rigging process.
  • Improper servicing, assembling and dismantling procedures. Poor access, lack of fall protection and poor practices have injured and killed workers when servicing, assembling and dismantling cranes. This problem is most common with mobile cranes where service is performed in the field and there is lack of access equipment. Many cranes, particularly older models, do not provide handrails or steps to facilitate getting to some sections of the crane. Servicing around the boom and top of the cab is dangerous when workers walk on the boom without fall-arrest equipment. On lattice-boom cranes, incorrect loading and unloading as well as assembly and disassembly of the boom has caused sections to fall onto the workers. The boom sections were either not properly supported during these operations, or the rigging of the lines to support the boom was improper.
  • Hazard to the helper or oiler. A very hazardous pitch point is created as the upper portion of a crane rotates past the stationary lower section during normal operations. All helpers working around the crane should stay clear of the deck of the crane during operation.
  • Physical, chemical and stress hazards to the crane operator. When the cab is not insulated, the operator can be subjected to excessive noise, causing loss of hearing. Seats that are not properly designed can cause back pain. Lack of adjustment to the seat height and tilt can result in poor visibility from operating positions. Poor cab design also contributes to poor visibility. Exhaust from gasoline or diesel engines on cranes contains fumes that are hazardous in confined areas. There is also concern over the effect of whole-body vibration from the engine, particularly in older cranes. Time constraints or fatigue can also play a part in crane accidents.

 

 Control Measures

Safe operation of a crane is the responsibility of all parties involved. Crane manufacturers are responsible for designing and manufacturing cranes that are stable and structurally sound. Cranes must be rated properly so that there are enough safeguards to prevent accidents caused by overloading and instability. Instruments such as load-limiting devices and angle and boom length indicators aid operators in the safe operation of a crane. (Powerline sensory devices have proved to be unreliable.) Every crane should have a reliable, efficient, automatic safe- load indicator. In addition, crane manufacturers must make accommodations in the design that facilitate safe access for servicing and safe operation. Hazards can be reduced by clear design of control panels, providing a chart at the operator’s fingertips that specifies load configurations, handrails, non-glare windows, windows that extend to the cab floor, comfortable seats and both noise and thermal insulation. In some climates, heated and air-conditioned cabs contribute to the worker’s comfort and reduce fatigue.

Crane owners are responsible for keeping their machines in good condition by ensuring regular inspection and proper maintenance and employing competent operators. Crane owners must be knowledgeable so that they can recommend the best machine for a particular job. A crane assigned to a project should have the capacity to handle the heaviest load it must carry. The crane should be fully inspected by a competent person before being assigned to a project, and then daily and periodically (as suggested by the manufacturer), with a maintenance record kept. Ventilation should be provided to remove or dilute engine exhaust from cranes working in enclosed areas. Hearing protection, when necessary, should be provided. Site supervisors must plan ahead. With proper planning operating near overhead powerlines can be avoided. When work must be done near high-voltage power lines, clearance requirements should be followed (see table 1). When working near powerlines cannot be avoided, the line should either be de-energized or insulated.

Table 1. Required clearance for normal voltage in operation near high-voltage power lines

Normal voltage in kilovolts
(phase to phase)
Minimum required clearance in metres
(and feet)*
Up to 50 3.1 (10)
From 50 to 200 4.6 (15)
From 200 to 350 6.1 (20)
From 350 to 500 7.6 (25)
From 500 to 750 10.7 (35)
From 750 to 1,000 13.7 (45)

* Meters have been converted from recommendations in feet.

Source: ASME 1994.

Signallers should be used to aid the operator near the limit of approach around powerlines. The ground, including access in and around the site, must have the ability to bear the weight of the crane and the load it is lifting. If possible, the crane operating area should be roped off to prevent injuries from overhead lifting. A signaller must be used when the operator cannot see the load clearly. The crane operator and the signaller must be trained and competent in hand signals and other aspects of the job. Proper rigging attachments must be supplied so that riggers can secure the load from falling or slipping. The rigging crew must be trained in the attachment and dismantling of loads. Good communication is vital in safe crane operations. The operator must carefully follow the manufacturer’s recommended procedures when assembling and disassembling the boom before operating the crane. All safety features and warning devices should be in working order and should not be disconnected. The crane must be levelled and be operated according to the crane load chart. Outriggers must be fully extended or set according to manufacturers’ recommendations. Overloading can be prevented by the operator’s knowing the weight to be lifted in advance and by using load-limiting devices as well as other indicators. The operator should always use sound craning practices. All loads must be fully secured before they are lifted. Movement with a load must be slow; the boom should never be extended or lowered so that it compromises the stability of the crane. Cranes should not be operated when visibility is poor or when the wind can cause the operator to lose control of the load.

Standards and Legislation

There are numerous written standards or guidelines for recommended manufacturing and operating practices. Some are based on design principles, some on performance. Subjects covered in these standards include methods of testing various safety devices; design, construction and characteristics of the cranes; inspection, testing, maintenance and operation procedures; recommended equipment and control lay-out. These standards form the basis of government and company health and safety regulations and operator training.

 

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Friday, 14 January 2011 16:06

Equipment, Machinery and Materials

Construction work has undergone major changes. Once dependent upon craftsmanship with simple mechanical aids, the industry now relies largely on machines and equipment.

New equipment, machinery, materials and methods have contributed to the industry’s development. Around the middle of the 20th century, building cranes appeared, as did new materials like light-weight concrete. As time went on, the industry began using prefabricated construction units along with new techniques in the construction of buildings. Designers began to use computers. Thanks to such equipment as lifting devices, some of the work has become easier physically, but it has also become more complicated.

Instead of small, basic materials, such as bricks, tiles, board and light concrete, prefabricated construction units are commonly used today. Equipment has expanded from simple hand tools and transport facilities to complex machinery. Similarly, methods have changed, for instance, from wheelbarrowing to the pumping of concrete and from manual lifting of materials to the lifting of integrated elements with the assistance of cranes.

Innovations in equipment, machinery and materials can be expected to continue to appear.

European Community Directives Relating to Workers’ Health and Safety

In 1985, the European Community (EC) decided on a “New Approach to Technical Harmonization and Standards” in order to facilitate the free movement of goods. The New Approach directives are Community laws which set out essential requirements for health and safety that must be met before products may be supplied among member countries or imported to the Community. One example of a directive with a fixed level of demands is the Machine Directive (Council of the European Communities 1989). Products meeting the requirements of such a directive are marked and can be supplied anywhere in the EC. Similar systems exist for products covered by the Construction Products Directive (Council of the European Communities 1988).

Besides the directives with such a fixed level of demands, there are directives setting minimum criteria for workplace conditions. Community member states must meet these criteria or, if they exist, satisfy a more stringent safety level stipulated in their national regulations. Of specific relevance to construction work are the Directive on the Minimum Safety and Health Requirements for the Use of Work Equipment by Workers at Work (89/655/EEC) and the Directive on the Minimum Safety and Health Requirements at Temporary or Mobile Construction sites (92/57/EEC).

Scaffolding

One of the types of construction equipment that frequently affects worker safety is scaffolding, the primary means of providing a work surface at elevations. Scaffolds are used in connection with construction, rebuilding, restoration, maintenance and servicing of buildings and other structures. Scaffold components may be used for other constructions such as support towers (which are not considered scaffolds) or for the erection of temporary structures such as grandstands (i.e., seating for spectators) and stages for concerts and other public presentations. Their use is associated with many occupational injuries, particularly those caused by falls from heights (see also the article “Lifts, escalators and hoists” in this chapter).

Types of scaffolds

Support scaffolds may be erected using vertical and horizontal tubing connected by loose couplers. Prefabricated scaffolds are assembled from parts manufactured in accord with standardized procedures that are permanently attached to fixation devices. There are several types: the traditional frame or modular type for building facades, mobile access towers (MATs), craftsmen scaffolds and suspended scaffolds.

Vertical adjustment of the scaffold

The working planes of a scaffold are normally stationary. Some scaffolds, however, have working planes that may be adjusted to different vertical positions; they may be suspended from wires that raise and lower them, or they may stand on the ground and be adjusted by hydraulic lifts or winches.

Erection of prefabricated facade scaffolds

The erection of prefabricated facade scaffolds should follow the following guidelines:

  • Detailed erection instructions should be provided by the manufacturer and kept at the building site, and the work should be supervised by trained personnel. Precautions should be taken to protect anyone walking under the scaffold by blocking off the area, erecting additional scaffolding for the pedestrians to walk under or creating a protective overhang.
  • The base of the scaffold should be placed on a firm, level surface. An adjustable steel base plate should be placed on planking or boards to create a sufficient surface area for weight distribution.
  • A scaffold that is more than 2 to 3.5 m off the ground should be equipped with fall protection comprising a guard rail at a height of at least 1 m above the platform, an intermediate guard rail and a toe board. To move tools and supplies on or off the platform, the smallest possible opening in the guard rail may be created with a foot stop and guard rail on either side of it.
  • Access to the scaffold should normally be provided by stairs and not ladders.
  • The scaffold should be firmly secured to the wall of the building as directed by the manufacturer’s instructions.
  • The stability of the scaffold should be reinforced using diagonal elements (braces) according to the manufacturer’s instructions.
  • The scaffold should be as close as possible to the facade of the building; if more than 350 mm, a second guard rail on the inside of the platform may be needed.
  • If planks are used for the platform, they must be secured to the scaffold structure. A forthcoming European standard stipulates that the deflection (bending) should be not more than 25 mm.

 

Earth-moving machinery

Earth-moving machinery is designed primarily to loosen, pick up, move, transport and distribute or grade rock or earth and is of great importance in construction, road-building and agricultural and industrial work (see figure 1). Properly used, these machines are versatile and can eliminate many of the risks associated with the manual handling of materials. This type of equipment is highly efficient and is used worldwide.

Figure 1. Mechanical excavation at a construction site in France

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Earth-moving machines that are used in construction work and in road-building include tractor-dozers (bulldozers), loaders, backhoe loaders (figure 2), hydraulic excavators, dumpers, tractor-scrapers, graders, pipelayers, trenchers, landfill compactors and rope excavators.

Figure 2. Example of an articulated steer backhoe loader

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The machine is versatile. It can be used for excavating, loading and lifting. The angling of the machine (articulation) enables it to be used in confined spaces.

Earth-moving machinery can endanger the operator and people working nearby. The following summary of the hazards associated with earth-moving machines is based on the European Community’s Standard EN 474-1 (European Committee for Standardization 1994). It points out the safety related factors to be considered when acquiring and using these machines.

Access

The machine should provide safe access to the operator’s station and maintenance areas.

Operator’s station

The minimum space available to the operator should allow for all manoeuvres necessary for the safe operation of the machinery without excessive fatigue. It should not be possible for the operator to have accidental contact with the wheels or tracks or the working equipment. The engine exhaust system should direct the exhaust gas away from the operator’s station.

A machine with an engine performance above 30 kW should be equipped with an operator’s cab, unless the machine is being operated where the year-round climate permits comfortable operation without a cab. Machines having an engine performance less than 30 kW should be fitted with a cab when intended for use where the air quality is poor. The airborne sound power level of excavators, dozers, loaders and backhoe loaders should be measured according to the international standard for measurement of airborne exterior noise emitted by earth-moving machinery (ISO 1985b).

The cab should protect the operator against foreseeable weather conditions. The interior of the cab should not present any sharp edges or acute angles that may injure the operator if he or she falls or is thrown against them. Pipes and hoses located inside the cab containing fluids that are dangerous because of their pressure or temperature should be reinforced and guarded. The cab should have an emergency exit separate from the usual doorway. The minimum height of the ceiling above the seat (i.e., seat-index point) depends on the size of the machine’s engine; for engines between 30 and 150 kW it should be 1,000 mm. All glass should be shatter-proof. The sound pressure level at the operator’s station should not exceed 85 dBA (ISO 1985c).

The design of the operator’s station should enable the operator to see the travelling and work areas of the machine, preferably without having to lean forward. Where the operator’s view is obscured, mirrors or remote cameras with a monitor visible to the operator should enable him or her to see the work area.

The front window and, if required, the rear window, should be fitted with motorized windscreen wipers and washers. Equipment for defogging and defrosting at least the front window of the cab should be provided.

Roll-over and falling object protection

Loaders, dozers, scrapers, graders, articulated steer dumpers and backhoe loaders with an engine performance of more than 15 kW should have a structure that will protect against roll-over. Machines intended for use where there is a risk of falling objects should be designed for and fitted with a structure that will protect the operator against falling material.

Operator’s seat

Machinery with provision for a seated operator should be fitted with an adjustable seat that keeps the operator in a stable position and allows him or her to control the machine under all expected operating conditions. Adjustments to accommodate to the operator’s size and weight should be easily made without the use of any tool.

The vibrations transmitted by the operator’s seat shall comply with the relevant international vibration standard (ISO 1982) for tractor-dozers, loaders and tractor-scrapers.

Controls and indicators

The main controls, indicators, hand levers, pedals, switches and so on should be selected, designed and arranged so that they are clearly defined, legibly labelled and within easy reach of the operator. Controls for machine components should be designed so that they cannot accidentally start or be moved, even if exposed to interference from radio or telecommunications equipment.

Pedals should have an appropriate size and shape, be surfaced with a non-skid tread to prevent slipping and be adequately spaced. To avoid confusion the machine should be designed to be operated like a motor vehicle, with pedals located in the same way (i.e., with the clutch on the left, the brake in the centre and the accelerator on the right).

Remote-controlled earth-moving machinery should be so designed that it stops automatically and remains immobile when controls are deactivated or the power supply to them is interrupted.

Earth-moving machinery should be equipped with:

  • stop lights and direction indicators for machines designed with a permissible travelling speed over 30 km/h
  • an audible warning device controlled from the operator’s station and of which the sound level should be at least 93 dBA at a 7 m distance from the front-end of the machine and
  • a device which allows a flashing light to be fitted.

 

Uncontrolled movement

Creep (drift away) from the stopping position, for whatever reason (e.g., internal leakage) other than action of the controls, should be such that it does not create a hazard to bystanders.

Steering and braking systems

The steering system should be such that the movement of the steering control shall correspond to the intended direction of steering. The steering system of rubber-tyred machinery with a travelling speed of more than 20 km/h should comply with the international steering system standard (ISO 1992).

Machinery should be fitted with service, secondary and parking brake systems that are efficient under all foreseeable conditions of service, load, speed, ground conditions and slope. The operator should be able to slow down and stop the machine by means of the service brake. In case it fails, a secondary brake should be provided. A mechanical parking device should be provided to keep the stopped machine from moving, and it should be capable of remaining in the applied position. The braking system should comply with the international braking system standard (ISO 1985a).

Lighting

To permit night work or work in dusty conditions, earth-moving machines should be fitted with large enough and bright enough lights to adequately illuminate both the travelling and the work areas.

Stability

Earth-moving machinery, including components and attachments, should be designed and constructed to remain stable under anticipated operating conditions.

Devices intended to increase the stability of earth-moving machinery in working mode, such as outriggers and oscillating axle locking, should be fitted with interlocking devices which keep them in position, even in case of hydraulic hose failure.

Guards and covers

Guards and covers should be designed to be securely held in place. When access is rarely required, the guards should be fixed and fitted so that they are detachable only with tools or keys. Whenever possible, guards should remain hinged to the machine when open. Covers and guards should be fitted with a support system (springs or gas cylinders) to secure them in the opened position up to a wind speed of 8 m/s.

Electrical components

Electrical components and conductors should be installed in such a way as to avoid abrasion of wires and other wear and tear as well as exposure to dust and environmental conditions which can cause them to deteriorate.

Storage batteries should be provided with handles and be firmly attached in proper position while being easily disconnected and removed. Or, an easily accessible switch placed between the battery and the earth should allow the isolation of the battery from the rest of the electrical installation.

Tanks for fuel and hydraulic fluid

Tanks for fuel and hydraulic and other fluids should have means for relieving any internal pressure in case of opening and repair. They should have easy access for filling and be provided with lockable filler caps.

Fire protection

The floor and interior of the operator’s station should be made of fire-resistant materials. Machines with an engine performance exceeding 30 kW should have a built-in fire extinguisher system or a location for installing a fire extinguisher that is easily reached by the operator.

Maintenance

Machines should be designed and built so that lubrication and maintenance operations can be conducted safely, whenever possible with the engine stopped. When maintenance can be performed only with equipment in a raised position, the equipment should be mechanically secured. Special precautions such as erecting a shield or, at least, warning signs, must be taken if maintenance must be performed when the engine is running.

Marking

Each machine should bear, legibly and indelibly, the following information: the name and address of the manufacturer, mandatory marks, designation of series and type, the serial number (if any), the engine power (in kW), the mass of the most usual configuration (in kg) and, if appropriate, the maximum drawbar pull and maximum vertical load.

Other markings that may be appropriate include: conditions for use, mark of conformity (CE) and reference to instructions for installation, use and maintenance. The CE mark means that the machine meets the requirements of European Community directives relevant to the machine.

Warning signs

When the movement of a machine creates hazards not obvious to a casual spectator, warning signs should be affixed to the machine to warn against approaching it while it is in operation.

Verification of safety requirements

It is necessary to verify that safety requirements have been incorporated in the design and manufacture of an earth-moving machine. This should be achieved through a combination of measurement, visual examination, tests (where a method is prescribed) and assessment of the contents of the documentation that is required to be maintained by the manufacturer. The manufacturer’s documentation would include evidence that bought-in components, such as windscreens, have been manufactured as required.

Operating manual

A handbook giving instructions for operation and maintenance should be supplied and kept with the machine. It should be written in at least one of the official languages of the country in which the machine is to be used. It should describe in simple, readily understood terms the health and safety hazards that may be encountered (e.g., noise and hand-arm or whole-body vibration) and specify when personal protective equipment (PPE) is needed. A space intended for the safekeeping of the handbook should be provided in the operator’s station.

A service manual giving adequate information to enable trained service personnel to erect, repair and dismantle machinery with minimum risk should also be provided.

Operating conditions

In addition to the above requirements for design, the instruction handbook should specify conditions that limit use of the machine (e.g., the machine should not travel at a greater angle of inclination than is recommended by the manufacturer). If the operator discovers faults, damage or excessive wear that may present a safety hazard, the operator should immediately inform the employer and shut down the machine until the necessary repairs are completed.

The machine must not attempt to lift a load heavier than specified in the capacity chart in the operating manual. The operator should check how the slings are attached to the load and to the lifting hook and if he or she finds that the load is not attached safely or has any concerns about its safe handling, the lift should not be attempted.

When a machine is moved with a suspended load, the load should be kept as near to the ground as possible to minimize potential instability, and the travel speed should be adjusted to prevailing ground conditions. A rapid change of speed should be avoided and care should be taken so the load does not begin to swing.

When the machine is in operation, no one should enter the work area without warning the operator. When the work requires individuals to remain within a machine’s work area, they should observe great care and avoid unnecessarily moving or remaining under a raised or suspended load. When someone is within the work area of the machine, the operator should be particularly careful and operate the machine only when that person is in the operator’s view or his or her location has been signalled to the operator. Similarly, for rotating machines, such as cranes and backhoes, the swing radius behind the machine should be kept clear. If a truck must be positioned for loading in a way such that falling debris might hit the driver’s cab, no one should remain in it, unless it is strong enough to withstand impact of the falling materials.

At the beginning of the shift, the operator should check brakes, locking devices, clutches, steering and the hydraulic system in addition to making a functional test without a load. When checking the brakes, the operator should make certain that the machine can be slowed down rapidly, then stopped and safely held in position.

Before leaving the machine at the end of the shift, the operator should place all operating controls in the neutral position, turn off the power supply and take all necessary precautions to prevent unauthorized operation of the machine. The operator should consider potential weather conditions that might affect the supporting surface, perhaps causing the machine to be frozen fast, tipped over or sunk, and take appropriate measures to prevent such occurrences.

Replacement parts and components, such as hydraulic hoses, should be in compliance with the specifications in the operating manual. Before attempting any replacement or repair work in the hydraulic or compressed air systems, the pressure should be relieved. The instructions and precautions issued by the manufacturer should be observed when, for instance, a working attachment is installed. PPE, such as a helmet and safety glasses, should be worn when repair and maintenance work are done.

Positioning a machine for work

When positioning a machine, the hazards of overturning, sliding and subsidence of the ground beneath it should be considered. When these appear to be present appropriate blocking of adequate strength and surface area should be provided to assure stability.

Overhead power lines

When operating a machine near overhead power lines, precautions against contact with the energized lines should be taken. In this connection, cooperation with the power distributor is advisable.

Underground pipes, cables and power lines

Prior to starting a project, the employer has the responsibility to determine if any underground power lines, cables or gas, water or sewer pipes are located within the work site and, if so, to determine and mark their precise location. Specific instructions for avoiding them must be given to the machine operator, for instance, through a “call before you dig” program.

Operation on roads with traffic

When a machine is operated on a road or other place open to public traffic, road signs, barriers and other safety arrangements appropriate for the traffic volume, vehicle speed and local road regulations should be used.

It is recommended that transport of a machine on a public highway should be executed by truck or trailer. The hazard of overturning should be considered when the machine is being loaded or unloaded, and it should be secured so that it will not shift while in transit.

Materials

Materials used in construction include asbestos, asphalt, brick and stone, cement, concrete, flooring, foil sealing agents, glass, glue, mineral wool and synthetic mineral fibres for insulation, paints and primers, plastic and rubber, steel and other metals, wallboard, gypsum and wood. Many of these are covered in other articles in this chapter or elsewhere in this Encyclopaedia.

Asbestos

The use of asbestos for new construction is prohibited in some countries but, almost inevitably, it will be encountered during the renovation or demolition of older buildings. Accordingly, stringent precautions are required to protect both the workers and the public against exposures to asbestos that was previously installed.

Bricks, concrete and stone

Bricks are made of fired clay and grouped into facing bricks and brick stones. They can be solid or designed with holes. Their physical properties depend on the clay used, any added materials, the method of manufacture and the incineration temperature. The higher the incineration temperature, the less absorbency the brick will exhibit.

Bricks, concrete and stone containing quartz can produce silica dust when cut, drilled or blasted. Unprotected exposures to crystalline silica can increase susceptibility to tuberculosis and cause silicosis, a disabling, chronic and potentially fatal lung disease.

Flooring

Materials commonly used for interior flooring include stone, brick, floorboard, textile carpeting, linoleum and plastic. The installation of terrazzo, tile or wood flooring can expose a worker to dusts that can cause skin allergies or damage the nasal passages or lungs. In addition, the glues or adhesives used for installing tiles or carpeting often contain potentially toxic solvents.

Carpetlayers can damage their knees from kneeling and striking a “kicker” with the knee in stretching the carpeting to fit the space.

Glue

Glue is used to join materials through adhesion. Water-based glue contains a binding agent in water and hardens when water evaporates. Solvent glues harden when the solvent evaporates. Since the vapours can be harmful to health, they should not be used in very close or poorly ventilated areas. Glues consisting of components that harden when mixed can produce allergies.

Mineral wool and other insulation

The function of insulation in a building is to achieve thermal comfort and to reduce energy consumption. To achieve acceptable insulation, porous materials, such as mineral wool and synthetic mineral fibres, are used. Great care must be taken to avoid inhaling the fibres. Sharp fibres can even penetrate the skin and cause an annoying dermatitis.

Paints and primers

Paints are used to decorate the exterior and interior of the building, protect materials like steel and wood against corrosion or decay, make objects easier to clean and provide signals or road-markings.

Lead-based paints are now being avoided, but they may be encountered during the renovation or demolition of older structures, particularly those made of metal, such as bridges and viaducts. Inhaled or swallowed fumes or dusts can cause lead poisoning with kidney damage or permanent nervous system damage; they are particularly dangerous for children who may be exposed to lead dusts carried home on work clothes or shoes. Precautionary measures must be taken whenever lead-based paints are used or encountered.

Use of cadmium- and mercury-based paints is prohibited for use in most countries. Cadmium can cause kidney problems and some forms of cancer. Mercury can damage the nervous system.

Oil-based paints and primers contain solvents which may be potentially hazardous. To minimize solvent exposures, the use of water-based paints is recommended.

Plastic and rubber

Plastic and rubber, known as polymers, can be grouped into thermoplastic or thermosetting plastic and rubber. These materials are used in construction for tightening, insulation, coating, and for products like piping and fittings. Foil made of plastic or rubber is used for tightening and moisture-proof lining and may cause reactions in workers sensitized to these materials.

Steel, aluminium and copper

Steel is used in construction work as a supporting structure, in reinforcement rods, mechanical components and facing material. Steel may be carbon or alloy; stainless steel is a type of alloy. Important steel properties are its strength and toughness. Fracture toughness is important in order to avoid brittle fractures.

The properties of steel depends on its chemical composition and structure. Steel is heat-treated in order to release internal strain and to improve weldability, strength and fracture toughness.

Concrete can withstand considerable pressure, but reinforcement bars and nets are required for acceptable tensile strength. These bars typically have a considerable carbon content (0.40%).

Carbon steel or “mild” steel contains manganese, which, when released in fumes during welding, can cause a Parkinson’s disease-like syndrome, which can be a crippling nervous disorder. Aluminium and copper can also, under certain conditions, be harmful to health.

Stainless steels contain chromium, which increases corrosion resistance, and other alloy elements, such as nickel and molybdenum. But welding of stainless steel can expose workers to chromium and nickel fumes. Some forms of nickel can cause asthma or cancer; some forms of chromium can cause cancer and sinus problems and “nose holes” (erosion of the nasal septum).

Next to steel, aluminium is the most commonly used metal in construction, because the metal and its alloys are light, strong and corrosion-resistant.

Copper is one of the most important metals in engineering, because of its corrosion-resistance and high conductivity for electricity and heat. It is used in energized lines, as roof and wall coating and for piping. When used as a roof coating, copper salts in the rain runoff can be harmful to the immediate environment.

Wallboard and gypsum

Wallboard, often coated with asphalt or plastic, is used as a protective layer against water and wind and to prevent seepage of moisture through the building elements. Gypsum is crystallized calcium sulphate. Gypsum board consists of a sandwich of gypsum between two layers of cardboard; it is widely used as wall covering, and is fire-resistant.

Dust produced when cutting wallboard can lead to skin allergies or lung damage; carrying oversize or heavy board in awkward postures can cause musculoskeletal problems.

Wood

Wood is widely used for construction. It is important to use seasoned timber for construction work. For beams and roof trusses of considerable span, glue-laminated wood units are used. Measures are advisable to control wood dust, which, depending on the species, can cause a variety of ailments including cancer. Under certain conditions, wood dust can also be explosive.

 

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Friday, 14 January 2011 16:05

Tools

Tools are particularly important in construction work. They are primarily used to put things together (e.g., hammers and nail guns) or to take them apart (e.g., jackhammers and saws). Tools are often classified as hand tools and power tools. Hand tools include all non-powered tools, such as hammers and pliers. Power tools are divided into classes, depending on the power source: electrical tools (powered by electricity), pneumatic tools (powered by compressed air), liquid-fuel tools (usually powered by gasoline), powder-actuated tools (usually powered by an explosive and operated like a gun) and hydraulic tools (powered by pressure from a liquid). Each type presents some unique safety problems.

Hand tools include a wide range of tools, from axes to wrenches. The primary hazard from hand tools is being struck by the tool or by a piece of the material being worked on. Eye injuries are very common from the use of hand tools, as a piece of wood or metal can fly off and lodge in the eye. Some of the major problems are using the wrong tool for the job or a tool that has not been properly maintained. The size of the tool is important: some women and men with relatively small hands have difficulty with large tools. Dull tools can make the work much harder, require more force and result in more injuries. A chisel with a mushroomed head might shatter on impact and send fragments flying. It is also important to have the proper work surface. Cutting material at an awkward angle can result in a loss of balance and an injury. In addition, hand tools can produce sparks that can ignite explosions if the work is being done around flammable liquids or vapours. In such cases, spark-resistant tools, such as those made from brass or aluminium, are needed.

Power tools, in general, are more dangerous than hand tools, because the power of the tool is increased. The biggest dangers from power tools are from accidental start-up and slipping or losing one’s balance during use. The power source itself can cause injuries or death, for example, through electrocution with electrical tools or gasoline explosions from liquid-fuel tools. Most power tools have a guard to protect the moving parts while the tool is not in operation. These guards need to be in working order and not overridden. A portable circular saw, for example, should have an upper guard covering the top half of the blade and a retractable lower guard which covers the teeth while the saw is not operating. The retractable guard should automatically return to cover the lower half of the blade when the tool is finished working. Power tools often also have safety switches that shut off the tool as soon as a switch is released. Other tools have catches that must be engaged before the tool can operate. One example is a fastening tool that must be pressed against the surface with a certain amount of pressure before it will fire.

One of the main hazards of electrical tools is the risk of electrocution. A frayed wire or a tool that does not have a ground (that directs the electrical circuit to the ground in an emergency) can result in electricity running through the body and death by electrocution. This can be prevented by using double-insulated tools (insulated wires in an insulated housing), grounded tools and ground-fault circuit interrupters (which will detect a leak of electricity from a wire and automatically shut off the tool); by never using electrical tools in damp or wet locations; and by wearing insulated gloves and safety footwear. Power cords have to be protected from abuse and damage.

Other types of power tools include powered abrasive-wheel tools, like grinding, cutting or buffing wheels, which present the risk of flying fragments coming off the wheel. The wheel should be tested to make sure it is not cracked and will not fly apart during use. It should spin freely on its spindle. The user should never stand directly in front of the wheel during start-up, in case it breaks. Eye protection is essential when using these tools.

Pneumatic tools include chippers, drills, hammers and sanders. Some pneumatic tools shoot fasteners at high speed and pressure into surfaces and, as a result, present the risk of shooting fasteners into the user or others. If the object being fastened is thin, the fastener may go through it and strike someone at a distance. These tools can also be noisy and cause hearing loss. Air hoses should be well connected before use to prevent them from disconnecting and whipping around. Air hoses should be protected from abuse and damage as well. Compressed-air guns should never be pointed at anyone or against oneself. Eye, face and hearing protection should be required. Jackhammer users should also wear foot protection in case these heavy tools are dropped.

Gas-powered tools present fuel explosion hazards, particularly during filling. They should be filled only after they have been shut down and allowed to cool off. Proper ventilation must be provided if they are being filled in a closed space. Using these tools in a closed space can also cause problems from carbon monoxide exposure.

Powder-actuated tools are like loaded guns and should be operated only by specially trained personnel. They should never be loaded until immediately before use and should never left loaded and unattended. Firing requires two motions: bringing the tool into position and pulling the trigger. Powder-actuated tools should require at least 5 pounds (2.3 kg) of pressure against the surface before they can be fired. These tools should not be used in explosive atmospheres. They should never be pointed at anyone and should be inspected before each use. These tools should have a safety shield at the end of the muzzle to prevent the release of flying fragments during firing. Defective tools should be taken out of service immediately and tagged or locked out to make sure no one else uses them until they are fixed. Powder-actuated fastening tools should not be fired into material where the fastener could pass through and hit somebody, nor should these tools be used near an edge where material might splinter and break off.

Hydraulic power tools should use a fire-resistant fluid and be operated under safe pressures. A jack should have a safety mechanism to prevent it from being jacked up too high and should display its load limit prominently. Jacks have to be set up on a level surface, centred, bear against a level surface and apply force evenly to be used safely.

In general, tools should be inspected before use, be well-maintained, be operated according to the manufacturer’s instructions and be operated with safety systems (e.g., guards). Users should have proper PPE, such as safety glasses.

Tools can present two other hazards that are often overlooked: vibration and sprains and strains. Power tools present a considerable vibration hazard to workers. The most well-known example is chain-saw vibration, which can result in “white-finger” disease, where the nerves and blood vessels in the hands are damaged. Other power tools can present hazardous exposures to vibration for construction workers. As much as possible, workers and contractors should purchase tools where vibration has been dampened or reduced; anti-vibration gloves have not been shown to solve this problem.

Poorly designed tools can also contribute to fatigue from awkward postures or grips, which, in turn, can also lead to accidents. Many tools are not designed for use by left-handed workers or individuals with small hands. Use of gloves can make it harder to grip a tool properly and requires tighter gripping of power tools, which can result in excessive fatigue. Use of tools by construction workers for repetitive jobs can also lead to cumulative trauma disorders, like carpal tunnel syndrome or tendinitis. Using the right tool for the job and choosing tools with the best design features that feel most comfortable in the hand while working can assist in avoiding these problems.

 

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Friday, 14 January 2011 15:52

Trenching

Trenches are confined spaces usually dug to bury utilities or to place footings. Trenches are normally deeper than they are wide, as measured at the bottom, and are usually less than 6 m deep; they are also known as shallow excavations. A confined space is defined as a space that is large enough for a worker to enter and perform work, has limited means of entry and exit, and is not designed for continuous occupancy. Several ladders should be provided to enable workers to escape the trench.

Typically trenches are open only for minutes or hours. The walls of any trench will eventually collapse; it is merely a matter of time. Short-term apparent stability is a temptation for a contractor to send workers into a dangerous trench in hopes of rapid progress and financial gain. Death or serious injuries and mutilations can result.

In addition to being exposed to the possibility of collapsing trench walls, workers in trenches, can be harmed or killed by engulfment in water or sewage, exposure to hazardous gases or reduced oxygen, falls, falling equipment or materials, contact with severed electrical cables and improper rescue.

Cave-ins account for at least 2.5% of annual work-related deaths in the United States, for example. The average age of workers killed in trenches in the US is 33. Often a young person is trapped by a cave-in and other workers attempt a rescue. With failed rescue attempts, most of the dead are would-be rescuers. Emergency teams trained in trench rescue should be contacted immediately in the event of a cave-in.

Routine inspections of the trench walls and worker protection systems are essential. Inspections should occur daily before the start of work and after any occurrence—such as rainstorms, vibration or broken pipes—that may increase hazards. Following are descriptions of the hazards and how to prevent them.

Trench Wall Collapse

The main cause of deaths related to trenching is collapsed trench walls, which can crush or suffocate workers.

Trench walls may be weakened by activities outside but near a trench. Heavy loads must not be placed on the edge of the wall. Trenches should not be dug close to structures, such as buildings or railroads, because the trenching may undermine the structures and weaken the foundations, thus causing the structures and trench walls to collapse. Competent engineering assistance should be sought in the planning stages. Vehicles must not be permitted to approach too close to the sides of a trench; stop logs or soil berms should be in place to prevent vehicles from doing so.

Types of soil and environment

Proper selection of a worker protection system depends on soil and environmental conditions. Soil strength, the presence of water and vibration from equipment or nearby sources affect the stability of trench walls. Previously excavated soils never regain their strength. Accumulation of water in a trench, regardless of depth, signals the most dangerous situation.

The soil must be classified and the construction scene evaluated before an appropriate worker protection system is selected. A project safety and health plan should address unique conditions and hazards related to the project.

Soils can be divided into two main groups: cohesive and granular. Cohesive soils contain a minimum of 35% clay and will not break when rolled into threads 50 mm long and 3 mm in diameter and held by one end. With cohesive soils, trench walls will stand vertically for short periods of time. These soils are responsible for as many cave-in deaths as any other soil, because the soil appears stable and precautions often are not taken.

Granular soils consist of silt, sand, gravel or larger material. These soils exhibit apparent cohesion when wet (the sand-castle effect); the finer the particle, the greater the apparent cohesion. When submerged or dry, however, the coarser granular soils will immediately collapse to a stable angle, 30 to 45°, depending on their particle angularity or roundness.

Worker protection

Sloping prevents trench failure by removing the weight (of the soil) that can lead to trench instability. Sloping, including benching (sloping done in a series of steps), requires a wide opening at the top of a trench. The angle of a slope depends on the soil and environment, but slopes range from 0.75 horizontal: 1 vertical to 1.5 horizontal: 1 vertical. The slope of 1.5 horizontal: 1 vertical is set back 1.5 m on each side at the top for each meter of depth. Even the slightest slope is beneficial. However, the width requirements of slopes often make this approach impracticable on construction sites.

Shoring can be used for all conditions. A shore consists of an upright on each side of a trench, with braces in between (see figure 1). Shores help prevent trench wall collapse by exerting outward forces on a trench wall. Skip shores consist of vertical uprights and cross braces with soil arching between; they are used in clays, the most cohesive soils. Shores must be no more than 2 m apart from each other. Greater distances between cross braces can be achieved by using wales (or walings) to hold the uprights in place (see figure 2). Close sheeting is used in granular and weaker cohesive soils; the trench walls are covered entirely with sheeting (see figure 3). Sheeting can be made of wood, metal or fibreglass; steel trench sheets are common. Tight sheeting is used when flowing or seeping water is encountered. Tight sheeting prevents water from eroding and bringing soil particles into a trench. A shoring system must always be kept tight against the soil to prevent collapse. Braces can be of wood or of screw, hydraulic or pneumatic jacks. Wales can be of wood or metal.

Figure 1. Shores consist of uprights on each side of a trench with cross braces in between

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Figure 2. Wales hold uprights in place, allowing greater distance between cross braces

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Figure 3. Close sheeting is used in granular soils

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Shields, or trench boxes, are large personal protective devices; they do not prevent trench wall collapse but protect workers who are inside. Shields are generally made of steel or aluminium and their size commonly ranges from approximately 1 m to 3 m high and 2 to 7 m long; many other sizes are available. Shields may be stacked on top of each other (figure 4). Guard systems must be in place against hazardous movements of shields in the event of a trench wall collapse. One way is to backfill on both sides of a shield.

Figure 4. Shields protect workers from trench wall collapse

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New products are available that combine the qualities of a shore and a shield; some devices are useable in particularly hazardous ground. Shield-shore units can be used as static shields or can act as a shore by hydraulically or mechanically exerting forces on the trench wall. The smaller units are particularly useful when repairing breaks in utility pipes in city streets. Massive units with shield panels can be forced into the ground by mechanical or hydraulic means. Soil is then excavated from inside the shield.

Drowning

Several steps are recommended to prevent engulfment by water or sewage in a trench. First, known utilities should be contacted before digging to learn where water (and other) pipes are located. Second, water valves that feed pipes into the trench should be closed. Cave-ins that break water mains or cause accumulations of water or sewage must be avoided. All utility pipes and other utility equipment need to be supported.

Deadly Gases and Fumes and Insufficient Oxygen

Harmful atmospheres can lead to worker death or injury resulting from a lack of oxygen, fire or explosion or toxic exposures. All trench atmospheres where abnormal conditions are present or suspected should be tested. This is especially true around buried garbage, vaults, fuel tanks, manholes, swamps, chemical processors and other facilities that can release deadly gases or fumes or deplete oxygen in the air. Construction equipment exhausts must be dispersed.

Air quality should be determined with instruments from outside the trench. This can be done by lowering a meter or its probe into the trench. The air in trenches should be tested in the following order. First, oxygen must be 19.5 to 23.5%. Second, flammability or explosibility must be no higher than 10% of the lower flammable or explosive limits (LFLs or LELs). Third, levels of potentially toxic substances—such as hydrogen sulphide —should be compared with published information. (In the US, one source is the National Institute for Occupational Safety and Health Pocket Guide to Chemical Hazards, which gives, permissible exposure limits (PELs)). If the atmosphere is normal, workers may enter. Ventilation may correct an abnormal atmosphere, but monitoring must continue. Sewers and similar spaces where the air is constantly changing usually require (or should require) a permit-entry procedure. Permit-entry procedures require full equipment and a three-person team: a supervisor, an attendant and an entrant.

Falls and Other Hazards

Falls into and within trenches can be prevented by providing safe and frequent means for entering and exiting a trench, safe walkways or bridges where workers or equipment are permitted or required to cross over trenches and barriers adequate to stop other workers or bystanders or equipment from approaching a trench.

Falling equipment or materials can cause death or injury through blows to the head and body, crushing and suffocation. The spoil pile should be kept at least 0.6 m from the edge of a trench, a barrier should be provided that will prevent soil and rock material from rolling into the trench. All other materials, such as pipes, must also be prevented from falling or rolling into a trench. Workers must not be permitted to work under suspended loads or loads handled by digging equipment.

All utilities should be marked prior to digging in order to prevent electrocution or severe burns caused by contact with live power lines. Equipment booms must not be operated near overhead power lines; if necessary, overhead lines must be grounded out or removed.

Often, one death or severe injury in a trench is compounded by a poorly thought-out rescue attempt. The victim and rescuers may become trapped and overcome by deadly gases, fumes or lack of oxygen; drowned; or mutilated by machines or rescue ropes. These compounded tragedies can be prevented by following a safety and health plan. Equipment such as air testing meters, water pumps and ventilators should be well-maintained, properly assembled and available on the job. Management should train and require workers to follow safe work practices and wear all necessary personal protective equipment.

 

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Thursday, 13 January 2011 15:27

Staffing Issues

Contingent Workforce

The nations of the world vary dramatically in both their use and treatment of employees in their contingent workforce. Contingent workers include temporary workers hired through temporary help agencies, temporary workers hired directly, voluntary and “non-voluntary” part-timers (the non-voluntary would prefer full-time work) and the self-employed. International comparisons are difficult due to differences in the definitions of each of these categories of worker.

Overman (1993) stated that the temporary help industry in Western Europe is about 50% larger than it is in the United States, where about 1% of the workforce is made up of temporary workers. Temporary workers are almost non-existent in Italy and Spain.

While the subgroups of contingent workers vary considerably, the majority of part-time workers in all European countries are women at low salary levels. In the United States, contingent workers also tend to be young, female and members of minority groups. Countries vary considerably in the degree to which they protect contingent workers with laws and regulations covering their working conditions, health and other benefits. The United Kingdom, the United States, Korea, Hong Kong, Mexico and Chile are the least regulated, with France, Germany, Argentina and Japan having fairly rigid requirements (Overman 1993). A new emphasis on providing contingent workers with greater benefits through increased legal and regulatory requirements will help to alleviate occupational stress among those workers. However, those increased regulatory requirements may result in employers’ hiring fewer workers overall due to increased benefit costs.

Job Sharing

An alternative to contingent work is “job sharing,” which can take three forms: two employees share the responsibilities for one full-time job; two employees share one full-time position and divide the responsibilities, usually by project or client group; or two employees perform completely separate and unrelated tasks but are matched for purposes of headcount (Mattis 1990). Research has indicated that most job sharing, like contingent work, is done by women. However, unlike contingent work, job sharing positions are often subject to the protection of wage and hour laws and may involve professional and even managerial responsibilities. Within the European Community, job sharing is best known in Britain, where it was first introduced in the public sector (Lewis, Izraeli and Hootsmans 1992). The United States Federal Government, in the early 1990s, implemented a nationwide job sharing programme for its employees; in contrast, many state governments have been establishing job sharing networks since 1983 (Lee 1983). Job sharing is viewed as one way to balance work and family responsibilities.

Flexiplace and Home Work

Many alternative terms are used to denote flexiplace and home work: telecommuting, the alternative worksite, the electronic cottage, location-independent work, the remote workplace and work-at-home. For our purposes, this category of work includes “work performed at one or more ‘predetermined locations’ such as the home or a satellite work space away from the conventional office where at least some of the communications maintained with the employer occur through the use of telecommunications equipment such as computers, telephones and fax machines” (Pitt-Catsouphes and Marchetta 1991).

LINK Resources, Inc., a private-sector firm monitoring worldwide telecommuting activity, has estimated that there were 7.6 million telecommuters in 1993 in the United States out of the over 41.1 million work-at-home households. Of these telecommuters 81% worked part-time for employers with less than 100 employees in a wide array of industries across many geographical locations. Fifty-three% were male, in contrast to figures showing a majority of females in contingent and job-sharing work. Research with fifty US companies also showed that the majority of telecommuters were male with successful flexible work arrangements including supervisory positions (both line and staff), client-centred work and jobs that included travel (Mattis 1990). In 1992, 1.5 million Canadian households had at least one person who operated a business from home.

Lewis, Izraeli and Hootsman(1992) reported that, despite earlier predictions, telecommuting has not taken over Europe. They added that it is best established in the United Kingdom and Germany for professional jobs including computer specialists, accountants and insurance agents.

In contrast, some home-based work in both the United States and Europe pays by the piece and involves short deadlines. Typically, while telecommuters tend to be male, homeworkers in low-paid, piece-work jobs with no benefits tend to be female (Hall 1990).

Recent research has concentrated on identifying; (a) the type of person best suited for home work; (b) the type of work best accomplished at home; (c) procedures to ensure successful home work experiences and (d) reasons for organizational support (Hall 1990; Christensen 1992).

Welfare Facilities

The general approach to social welfare issues and programmes varies throughout the world depending upon the culture and values of the nation studied. Some of the differences in welfare facilities in the United States, Canada and Western Europe are documented by Ferber, O’Farrell and Allen (1991).

Recent proposals for welfare reform in the United States suggest overhauling traditional public assistance in order to make recipients work for their benefits. Cost estimates for welfare reform range from US$15 billion to $20 billion over the next five years, with considerable cost savings projected for the long term. Welfare administration costs in the United States for such programmes as food stamps, Medicaid and Aid to Families with Dependent Children have risen 19% from 1987 to 1991, the same percentage as the increase in the number of beneficiaries.

Canada has instituted a “work sharing” programme as an alternative to layoffs and welfare. The Canada Employment and Immigration Commission (CEIC) programme enables employers to face cutbacks by shortening the work week by one to three days and paying reduced wages accordingly. For the days not worked, the CEIC arranges for the workers to draw normal unemployment insurance benefits, an arrangement that helps to compensate them for the lower wages received from their employer and to relieve the hardships of being laid off. The duration of the programme is 26 weeks, with a 12-week extension. Workers can use work-sharing days for training and the federal Canadian government may reimburse the employer for a major portion of the direct training costs through the “Canadian Jobs Strategy”.

Child Care

The degree of child-care support is dependent upon the sociological underpinnings of the nation’s culture (Scharlach, Lowe and Schneider 1991). Cultures that:

  1. support the full participation of women in the workplace
  2. view child care as a public responsibility rather than a concern of individual families
  3. value child care as an extension of the educational system, and
  4. view early childhood experiences as important and formative

will devote greater resources to supporting those programmes. Thus, international comparisons are complicated by these four factors and “high quality care” may be dependent on the needs of children and families in specific cultures.

Within the European Community, France provides the most comprehensive child-care programme. The Netherlands and the United Kingdom were late in addressing this issue. Only 3% of British employers provided some form of child care in 1989. Lamb et al. (1992) present nonparental child-care case studies from Sweden, the Netherlands, Italy, the United Kingdom, the United States, Canada, Israel, Japan, the People’s Republic of China, Cameroon, East Africa and Brazil. In the United States, approximately 3,500 private companies of the 17 million firms nationwide offer some type of child-care assistance to their employees. Of those firms, approximately 1,100 offer flexible spending accounts, 1,000 offer information and referral services and fewer than 350 have onsite or near-site child-care centres (Bureau of National Affairs 1991).

In a research study in the United States, 44% of men and 76% of women with children under six missed work in the previous three months for a family-related reason. The researchers estimated that the organizations they studied paid over $4 million in salary and benefits to employees who were absent because of child-care problems (see study by Galinsky and Hughes in Fernandez 1990). A study by the United States General Accounting Office in 1981 showed that American companies lose over $700 million a year because of inadequate parental leave policies.

Elder Care

It will take only 30 years (from the time of this writing, 1994) for the proportion of elderly in Japan to climb from 7% to 14%, while in France it took over 115 years and in Sweden 90 years. Before the end of the century, one out of every four persons in many member States of the Commission of the European Communities will be over 60 years old. Yet, until recently in Japan, there were few institutions for the elderly and the issue of eldercare has found scant attention in Britain and other European countries (Lewis, Izraeli and Hootsmans 1992). In America, there are approximately five million older Americans who require assistance with day-to-day tasks in order to remain in the community, and 30 million who are currently age 65 or older. Family members provide more than 80% of the assistance that these elderly people need (Scharlach, Lowe and Schneider 1991).

Research has shown that those employees who have elder-care responsibilities report significantly greater overall job stress than do other employees (Scharlach, Lowe and Schneider 1991). These caretakers often experience emotional stress and physical and financial strain. Fortunately, global corporations have begun to recognize that difficult family situations can result in absenteeism, decreased productivity and lower morale, and they are beginning to provide an array of “cafeteria benefits” to assist their employees. (The name “cafeteria” is intended to suggest that employees may select the benefits that would be most helpful to them from an array of benefits.) Benefits might include flexible work hours, paid “family illness” hours, referral services for family assistance, or a dependent-care salary-reduction account that allows employees to pay for elder care or day care with pre-tax dollars.

The author wishes to acknowledge the assistance of Charles Anderson of the Personnel Resources and Development Center of the United States Office of Personnel Management, Tony Kiers of the C.A.L.L. Canadian Work and Family Service, and Ellen Bankert and Bradley Googins of the Center on Work and Family of Boston University in acquiring and researching many of the references cited in this article.


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Thursday, 13 January 2011 15:26

Performance Measures and Compensation

There are many forms of compensation used in business and government organizations throughout the world to pay workers for their physical and mental contribution. Compensation provides money for human effort and is necessary for individual and family existence in most societies. Trading work for money is a long-established practice.

The health-stressor aspect of compensation is most closely linked with compensation plans that offer incentives for extra or sustained human effort. Job stress can certainly exist in any work setting where compensation is not based on incentives. However, physical and mental performance levels that are well above normal and that could lead to physical injury or injurious mental stress is more likely to be found in environments with certain kinds of incentive compensation.

Performance Measures and Stress

Performance measurements in one form or another are used by most organizations, and are essential for incentive programmes. Performance measures (standards) can be established for output, quality, throughput time, or any other productivity measure. Lord Kelvin in 1883 had this to say about measurements: “I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.”

Performance measures should be carefully linked to the fundamental goals of the organization. Inappropriate performance measurements have often had little or no effect on goal attainment. Some common criticisms of performance measures include unclear purpose, vagueness, lack of connection (or even opposition, for that matter) to the business strategy, unfairness or inconsistency, and their liability to be used chiefly for “punishing” people. But measurements can serve as indispensable benchmarks: remember the saying, “If you don’t know where you are, you can’t get to where you want to be”. The bottom line is that workers at all levels in an organization demonstrate more of the behaviours that they are measured on and rewarded to evince. What gets measured and rewarded gets done.

Performance measures must be fair and consistent to minimize stress among the workforce. There are several methods utilised to establish performance measures ranging from judgement estimation (guessing) to engineered work measurement techniques. Under the work measurement approach to setting performance measures, 100% performance is defined as a “fair day’s work pace”. This is the work effort and skill at which an average well-trained employee can work without undue fatigue while producing an acceptable quality of work over the course of a work shift. A 100% performance is not maximum performance; it is the normal or average effort and skill for a group of workers. By way of comparison, the 70% benchmark is generally regarded as the minimum tolerable level of performance, while the 120% benchmark is the incentive effort and skill that the average worker should be able to attain when provided with a bonus of at least 20% above the base rate of pay. While a number of incentive plans have been established using the 120% benchmark, this value varies among plans. The general design criteria recommended for wage incentive plans provide workers the opportunity to earn approximately 20 to 35% above base rate if they are normally skilled and execute high effort continuously.

Despite the inherent appeal of a “fair day’s work for a fair day’s pay”, some possible stress problems exist with a work measurement approach to setting performance measures. Performance measures are fixed in reference to the normal or average performance of a given work group (i.e., work standards based on group as opposed to individual performance). Thus, by definition, a large segment of those working at a task will fall below average (i.e., the 100% performance benchmark) generating a demand–resource imbalance that exceeds physical or mental stress limits. Workers who have difficulty meeting performance measures are likely to experience stress through work overload, negative supervisor feedback, and threat of job loss if they consistently perform below the 100% performance benchmark.

Incentive Programmes

In one form or another, incentives have been used for many years. For example, in the New Testament (II Timothy 2:6) Saint Paul declares, “It is the hard-working farmer who ought to have the first share of the crops”. Today, most organizations are striving to improve productivity and quality in order to maintain or improve their position in the business world. Most often workers will not give extra or sustained effort without some form of incentive. Properly designed and implemented financial incentive programmes can help. Before any incentive programme is implemented, some measure of performance must be established. All incentive programmes can be categorized as follows: direct financial, indirect financial, and intangible (non-financial).

Direct financial programmes may be applied to individuals or groups of workers. For individuals, each employee’s incentive is governed by his or her performance relative to a standard for a given time period. Group plans are applicable to two or more individuals working as a team on tasks that are usually interdependent. Each employee’s group incentive is usually based on his or her base rate and the group performance during the incentive period.

The motivation to sustain higher output levels is usually greater for individual incentives because of the opportunity for the high-performing worker to earn a greater incentive. However, as organizations move toward participative management and empowered work groups and teams, group incentives usually provide the best overall results. The group effort makes overall improvements to the total system as compared to optimizing individual outputs. Gainsharing (a group incentive system that has teams for continuous improvement and provides a share, usually 50%, of all productivity gains above a benchmark standard) is one form of a direct group incentive programme that is well suited for the continuous improvement organization.

Indirect financial programmes are usually less effective than direct financial programmes because direct financial incentives are stronger motivators. The principal advantage of indirect plans is that they require less detailed and accurate performance measures. Organizational policies that favourably affect morale, result in increased productivity and provide some financial benefit to employees are considered to be indirect incentive programmes. It is important to note that for indirect financial programmes no exact relationship exists between employee output and financial incentives. Examples of indirect incentive programmes include relatively high base rates, generous fringe benefits, awards programmes, year-end bonuses and profit-sharing.

Intangible incentive programmes include rewards that do not have any (or very little) financial impact on employees. These programmes, however, when viewed as desirable by the employees, can improve productivity. Examples of intangible incentive programmes include job enrichment (adding challenge and intrinsic satisfaction to the specific task assignments), job enlargement (adding tasks to complete a “whole” piece or unit of work output), nonfinancial suggestion plans, employee involvement groups and time off without any reduction in pay.

Summary and Conclusions

Incentives in some form are an integral part of many compensation plans. In general, incentive plans should be carefully evaluated to make sure that workers are not exceeding safe ergonomic or mental stress limits. This is particularly important for individual direct financial plans. It is usually a lesser problem in group direct, indirect or intangible plans.

Incentives are desirable because they enhance productivity and provide workers an opportunity to earn extra income or other benefits. Gainsharing is today one of the best forms of incentive compensation for any work group or team organization that wishes to offer bonus earnings and to achieve improvement in the workplace without risking the imposition of negative health-stressors by the incentive plan itself.


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Thursday, 13 January 2011 15:24

Organizational Climate and Culture

The organizational context in which people work is characterized by numerous features (e.g., leadership, structure, rewards, communication) subsumed under the general concepts of organizational climate and culture. Climate refers to perceptions of organizational practices reported by people who work there (Rousseau 1988). Studies of climate include many of the most central concepts in organizational research. Common features of climate include communication (as describable, say, by openness), conflict (constructive or dysfunctional), leadership (as it involves support or focus) and reward emphasis (i.e., whether an organization is characterized by positive versus negative feedback, or reward- or punishment-orientation). When studied together, we observe that organizational features are highly interrelated (e.g., leadership and rewards). Climate characterizes practices at several levels in organizations (e.g., work unit climate and organizational climate). Studies of climate vary in the activities they focus upon, for example, climates for safety or climates for service. Climate is essentially a description of the work setting by those directly involved with it.

The relationship of climate to employee well-being (e.g., satisfaction, job stress and strain) has been widely studied. Since climate measures subsume the major organizational characteristics workers experience, virtually any study of employee perceptions of their work setting can be thought of as a climate study. Studies link climate features (particularly leadership, communication openness, participative management and conflict resolution) with employee satisfaction and (inversely) stress levels (Schneider 1985). Stressful organizational climates are characterized by limited participation in decisions, use of punishment and negative feedback (rather than rewards and positive feedback), conflict avoidance or confrontation (rather than problem solving), and nonsupportive group and leader relations. Socially supportive climates benefit employee mental health, with lower rates of anxiety and depression in supportive settings (Repetti 1987). When collective climates exist (where members who interact with each other share common perceptions of the organization) research observes that shared perceptions of undesirable organizational features are linked with low morale and instances of psychogenic illness (Colligan, Pennebaker and Murphy 1982). When climate research adopts a specific focus, as in the study of climate for safety in an organization, evidence is provided that lack of openness in communication regarding safety issues, few rewards for reporting occupational hazards, and other negative climate features increase the incidence of work-related accidents and injury (Zohar 1980).

Since climates exist at many levels in organizations and can encompass a variety of practices, assessment of employee risk factors needs to systematically span the relationships (whether in the work unit, the department or the entire organization) and activities (e.g., safety, communication or rewards) in which employees are involved. Climate-based risk factors can differ from one part of the organization to another.

Culture constitutes the values, norms and ways of behaving which organization members share. Researchers identify five basic elements of culture in organizations: fundamental assumptions (unconscious beliefs that shape member’s interpretations, e.g., views regarding time, environmental hostility or stability), values (preferences for certain outcomes over others, e.g., service or profit), behavioural norms (beliefs regarding appropriate and inappropriate behaviours, e.g., dress codes and teamwork), patterns of behaviours (observable recurrent practices, e.g., structured performance feedback and upward referral of decisions) and artefacts (symbols and objects used to express cultural messages, e.g., mission statements and logos). Cultural elements which are more subjective (i.e., assumptions, values and norms) reflect the way members think about and interpret their work setting. These subjective features shape the meaning that patterns of behaviours and artefacts take on within the organization. Culture, like climate, can exist at many levels, including:

  1. a dominant organizational culture
  2. subcultures associated with specific units, and
  3. countercultures, found in work units that are poorly integrated with the larger organization.

 

Cultures can be strong (widely shared by members), weak (not widely shared), or in transition (characterized by gradual replacement of one culture by another).

In contrast with climate, culture is less frequently studied as a contributing factor to employee well-being or occupational risk. The absence of such research is due both to the relatively recent emergence of culture as a concept in organizational studies and to ideological debates regarding the nature of culture, its measurement (quantitative versus qualitative), and the appropriateness of the concept for cross-sectional study (Rousseau 1990). According to quantitative culture research focusing on behavioural norms and values, team-oriented norms are associated with higher member satisfaction and lower strain than are control- or bureaucratically -oriented norms (Rousseau 1989). Furthermore, the extent to which the worker’s values are consistent with those of the organization affects stress and satisfaction (O’Reilly and Chatman 1991). Weak cultures and cultures fragmented by role conflict and member disagreement are found to provoke stress reactions and crises in professional identities (Meyerson 1990). The fragmentation or breakdown of organizational cultures due to economic or political upheavals affects the well-being of members psychologically and physically, particular in the wake of downsizings, plant closings and other effects of concurrent organizational restructurings (Hirsch 1987). The appropriateness of particular cultural forms (e.g., hierarchic or militaristic) for modern society has been challenged by several culture studies (e.g., Hirschhorn 1984; Rousseau 1989) concerned with the stress and health-related outcomes of operators (e.g., nuclear power technicians and air traffic controllers) and subsequent risks for the general public.

Assessing risk factors in the light of information about organizational culture requires first attention to the extent to which organization members share or differ in basic beliefs, values and norms. Differences in function, location and education create subcultures within organizations and mean that culture-based risk factors can vary within the same organization. Since cultures tend to be stable and resistant to change, organizational history can aid assessment of risk factors both in terms of stable and ongoing cultural features as well as recent changes that can create stressors associated with turbulence (Hirsch 1987).

Climate and culture overlap to a certain extent, with perceptions of culture’s patterns of behaviour being a large part of what climate research addresses. However, organization members may describe organizational features (climate) in the same way but interpret them differently due to cultural and subcultural influences (Rosen, Greenlagh and Anderson 1981). For example, structured leadership and limited participation in decision making may be viewed as negative and controlling from one perspective or as positive and legitimate from another. Social influence reflecting the organization’s culture shapes the interpretation members make of organizational features and activities. Thus, it would seem appropriate to assess both climate and culture simultaneously in investigating the impact of the organization on the well-being of members.


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Thursday, 13 January 2011 15:23

Organizational Structure

Most of the articles in this chapter deal with aspects of the work environment that are proximal to the individual employee. The focus of this article, however, is to examine the impact of more distal, macrolevel characteristics of organizations as a whole that may affect employees’ health and well-being. That is, are there ways in which organizations structure their internal environments that promote health among the employees of that organization or, conversely, place employees at greater risk of experiencing stress? Most theoretical models of occupational or job stress incorporate organizational structural variables such as organizational size, lack of participation in decision making, and formalization (Beehr and Newman 1978; Kahn and Byosiere 1992).

Organizational structure refers to the formal distribution of work roles and functions within an organization coordinating the various functions or subsystems within the organization to efficiently attain the organization’s goals (Porras and Robertson 1992). As such, structure represents a coordinated set of subsystems to facilitate the accomplishment of the organization’s goals and mission and defines the division of labour, the authority relationships, formal lines of communication, the roles of each organizational subsystem and the interrelationships among these subsystems. Therefore, organizational structure can be viewed as a system of formal mechanisms to enhance the understandability of events, predictability of events and control over events within the organization which Sutton and Kahn (1987) proposed as the three work-relevant antidotes against the stress-strain effect in organizational life.

One of the earliest organizational characteristics examined as a potential risk factor was organizational size. Contrary to the literature on risk of exposure to hazardous agents in the work environment, which suggests that larger organizations or plants are safer, being less hazardous and better equipped to handle potential hazards (Emmett 1991), larger organizations originally were hypothesized to put employees at greater risk of occupational stress. It was proposed that larger organizations tend to adapt a bureaucratic organizational structure to coordinate the increased complexity. This bureaucratic structure would be characterized by a division of labour based on functional specialization, a well-defined hierarchy of authority, a system of rules covering the rights and duties of job incumbents, impersonal treatment of workers and a system of procedures for dealing with work situations (Bennis 1969). On the surface, it would appear that many of these dimensions of bureaucracy would actually improve or maintain the predictability and understandability of events in the work environment and thus serve to reduce stress within the work environment. However, it also appears that these dimensions can reduce employees’ control over events in the work environment through a rigid hierarchy of authority.

Given these characteristics of bureaucratic structure, it is not surprising that organizational size, per se, has received no consistent support as a macro-organization risk factor (Kahn and Byosiere 1992). Payne and Pugh’s (1976) review, however, provides some evidence that organizational size indirectly increases the risk of stress. They report that larger organizations suffered a reduction in the amount of communication, an increase in the amount of job and task specifications and a decrease in coordination. These effects could lead to less understanding and predictability of events in the work environment as well as a decrease in control over work events, thus increasing experienced stress (Tetrick and LaRocco 1987).

These findings on organizational size have led to the supposition that the two aspects of organizational structure that seem to pose the most risk for employees are formalization and centralization. Formalization refers to the written procedures and rules governing employees’ activities, and centralization refers to the extent to which the decision-making power in the organization is narrowly distributed to higher levels in the organization. Pines (1982) pointed out that it is not formalization within a bureaucracy that results in experienced stress or burnout but the unnecessary red tape, paperwork and communication problems that can result from formalization. Rules and regulations can be vague creating ambiguity or contradiction resulting in conflict or lack of understanding concerning appropriate actions to be taken in specific situations. If the rules and regulations are too detailed, employees may feel frustrated in their ability to achieve their goals especially in customer or client-oriented organizations. Inadequate communication can result in employees feeling isolated and alienated based on the lack of predictability and understanding of events in the work environment.

While these aspects of the work environment appear to be accepted as potential risk factors, the empirical literature on formalization and centralization are far from consistent. The lack of consistent evidence may stem from at least two sources. First, in many of the studies, there is an assumption of a single organizational structure having a consistent level of formalization and centralization throughout the entire organization. Hall (1969) concluded that organizations can be meaningfully studied as totalities; however, he demonstrated that the degree of formalization as well as decision-making authority can differ within organizational units. Therefore, if one is looking at an individual level phenomenon such as occupational stress, it may be more meaningful to look at the structure of smaller organizational units than that of the whole organization. Secondly, there is some evidence suggesting that there are individual differences in response to structural variables. For example, Marino and White (1985) found that formalization was positively related to job stress among individuals with an internal locus of control and negatively related to stress among individuals who generally believe that they have little control over their environments. Lack of participation, on the other hand, was not moderated by locus of control and resulted in increased levels of job stress. There also appear to be some cultural differences affecting individual responses to structural variables, which would be important for multinational organizations having to operate across national boundaries (Peterson et al. 1995). These cultural differences also may explain the difficulty in adopting organizational structures and procedures from other nations.

Despite the rather limited empirical evidence implicating structural variables as psychosocial risk factors, it has been recommended that organizations should change their structures to be flatter with fewer levels of hierarchy or number of communication channels, more decentralized with more decision- making authority at lower levels in the organization and more integrated with less job specialization (Newman and Beehr 1979). These recommendations are consistent with organizational theorists who have suggested that traditional bureaucratic structure may not be the most efficient or healthiest form of organizational structure (Bennis 1969). This may be especially true in light of technological advances in production and communication that characterize the postindustrial workplace (Hirschhorn 1991).

The past two decades have seen considerable interest in the redesign of organizations to deal with external environmental threats resulting from increased globalization and international competition in North America and Western Europe (Whitaker 1991). Straw, Sandelands and Dutton (1988) proposed that organizations react to environmental threats by restricting information and constricting control. This can be expected to reduce the predictability, understandability and control of work events thereby increasing the stress experienced by the employees of the organization. Therefore, structural changes that prevent these threat-ridigity effects would appear to be beneficial to both the organization’s and employees’ health and well-being.

The use of a matrix organizational structure is one approach for organizations to structure their internal environments in response to greater environmental instability. Baber (1983) describes the ideal type of matrix organization as one in which there are two or more intersecting lines of authority, organizational goals are achieved through the use of task-oriented work groups which are cross-functional and temporary, and functional departments continue to exist as mechanisms for routine personnel functions and professional development. Therefore, the matrix organization provides the organization with the needed flexibility to be responsive to environmental instability if the personnel have sufficient flexibility gained from the diversification of their skills and an ability to learn quickly.

While empirical research has yet to establish the effects of this organizational structure, several authors have suggested that the matrix organization may increase the stress experienced by employees. For example, Quick and Quick (1984) point out that the multiple lines of authority (task and functional supervisors) found in matrix organizations increase the potential for role conflict. Also, Hirschhorn (1991) suggests that with postindustrial work organizations, workers frequently face new challenges requiring them to take a learning role. This results in employees having to acknowledge their own temporary incompetencies and loss of control which can lead to increased stress. Therefore, it appears that new organizational structures such as the matrix organization also have potential risk factors associated with them.

Attempts to change or redesign organizations, regardless of the particular structure that an organization chooses to adopt, can have stress-inducing properties by disrupting security and stability, generating uncertainty for people’s position, role and status, and exposing conflict which must be confronted and resolved (Golembiewski 1982). These stress-inducing properties can be offset, however, by the stress-reducing properties of organizational development which incorporate greater empowerment and decision making across all levels in the organization, enhanced openness in communication, collaboration and training in team building and conflict resolution (Golembiewski 1982; Porras and Robertson 1992).

Conclusion

While the literature suggests that there are occupational risk factors associated with various organizational structures, the impact of these macrolevel aspects of organizations appear to be indirect. Organizational structure can provide a framework to enhance the predictability, understandability and control of events in the work environment; however, the effect of structure on employees’ health and well-being is mediated by more proximal work-environment characteristics such as role characteristics and interpersonal relations. Structuring organizations for healthy employees as well as healthy organizations requires organizational flexibility, worker flexibility and attention to the sociotechnical systems that coordinate the technological demands and the social structure within the organization.


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Thursday, 13 January 2011 15:19

Managerial Style

Selye (1974) suggested that having to live with other people is one of the most stressful aspects of life. Good relations between members of a work group are considered a central factor in individual and organizational health (Cooper and Payne 1988) particularly in terms of the boss–subordinate relationship. Poor relationships at work are defined as having “low trust, low levels of supportiveness and low interest in problem solving within the organization” (Cooper and Payne 1988). Mistrust is positively correlated with high role ambiguity, which leads to inadequate interpersonal communications between individuals and psychological strain in the form of low job satisfaction, decreased well-being and a feeling of being threatened by one’s superior and colleagues (Kahn et al. 1964; French and Caplan 1973).

Supportive social relationships at work are less likely to create the interpersonal pressures associated with rivalry, office politics and unconstructive competition (Cooper and Payne 1991). McLean (1979) suggests that social support in the form of group cohesion, interpersonal trust and liking for a superior is associated with decreased levels of perceived job stress and better health. Inconsiderate behaviour on the part of a supervisor appears to contribute significantly to feelings of job pressure (McLean 1979). Close supervision and rigid performance monitoring also have stressful consequences—in this connection a great deal of research has been carried out which indicates that a managerial style characterized by lack of effective consultation and communication, unjustified restrictions on employee behaviour, and lack of control over one’s job is associated with negative psychological moods and behavioural responses (for example, escapist drinking and heavy smoking) (Caplan et al. 1975), increased cardiovascular risk (Karasek 1979) and other stress-related manifestations. On the other hand, offering broader opportunities to employees to participate in decision making at work can result in improved performance, lower staff turnover and improved levels of mental and physical well-being. A participatory style of management should also extend to worker involvement in the improvement of safety in the workplace; this could help to overcome apathy among blue-collar workers, which is acknowledged as a significant factor in the cause of accidents (Robens 1972; Sutherland and Cooper 1986).

Early work in the relationship between managerial style and stress was carried out by Lewin (for example, in Lewin, Lippitt and White 1939), in which he documented the stressful and unproductive effects of authoritarian management styles. More recently, Karasek’s (1979) work highlights the importance of managers’ providing workers with greater control at work or a more participative management style. In a six-year prospective study he demonstrated that job control (i.e., the freedom to use one’s intellectual discretion) and work schedule freedom were significant predictors of risk of coronary heart disease. Restriction of opportunity for participation and autonomy results in increased depression, exhaustion, illness rates and pill consumption. Feelings of being unable to make changes concerning a job and lack of consultation are commonly reported stressors among blue-collar workers in the steel industry (Kelly and Cooper 1981), oil and gas workers on rigs and platforms in the North Sea (Sutherland and Cooper 1986) and many other blue-collar workers (Cooper and Smith 1985). On the other hand, as Gowler and Legge (1975) indicate, a participatory management style can create its own potentially stressful situations, for example, a mismatch of formal and actual power, resentment of the erosion of formal power, conflicting pressures both to be participative and to meet high production standards, and subordinates’ refusal to participate.

Although there has been a substantial research focus on the differences between authoritarian versus participatory management styles on employee performance and health, there have also been other, idiosyncratic approaches to managerial style (Jennings, Cox and Cooper 1994). For example, Levinson (1978) has focused on the impact of the “abrasive” manager. Abrasive managers are usually achievement-oriented, hard-driving and intelligent (similar to the type A personality), but function less well at the emotional level. As Quick and Quick (1984) point out, the need for perfection, the preoccupation with self and the condescending, critical style of the abrasive manager induce feelings of inadequacy among their subordinates. As Levinson suggests, the abrasive personality as a peer is both difficult and stressful to deal with, but as a superior, the consequences are potentially very damaging to interpersonal relationships and highly stressful for subordinates in the organization.

In addition, there are theories and research which suggest that the effect on employee health and safety of managerial style and personality can only be understood in the context of the nature of the task and the power of the manager or leader. For example, Fiedler’s (1967) contingency theory suggests that there are eight main group situations based upon combinations of dichotomies: (a) the warmth of the relations between the leader and follower; (b) the level structure imposed by the task; and (c) the power of the leader. The eight combinations could be arranged in a continuum with, at one end (octant one) a leader who has good relations with members, facing a highly structured task and possessing strong power; and, at the other end (octant eight), a leader who has poor relations with members, facing a loosely structured task and having low power. In terms of stress, it could be argued that the octants formed a continuum from low stress to high stress. Fiedler also examined two types of leader: the leader who would value negatively most of the characteristics of the member he liked least (the lower LPC leader) and the leader who would see many positive qualities even in the members whom he disliked (the high LPC leader). Fiedler made specific predictions about the performance of the leader. He suggested that the low LPC leader (who had difficulty in seeing merits in subordinates he disliked) would be most effective in octants one and eight, where there would be very low and very high levels of stress, respectively. On the other hand, a high LPC leader (who is able to see merits even in those he disliked) would be more effective in the middle octants, where moderate stress levels could be expected. In general, subsequent research (for example, Strube and Garcia 1981) has supported Fiedler’s ideas.

Additional leadership theories suggest that task-oriented managers or leaders create stress. Seltzer, Numerof and Bass (1989) found that intellectually stimulating leaders increased perceived stress and “burnout” among their subordinates. Misumi (1985) found that production-oriented leaders generated physiological symptoms of stress. Bass (1992) finds that in laboratory experiments, production-oriented leadership causes higher levels of anxiety and hostility. On the other hand, transformational and charismatic leadership theories (Burns 1978) focus upon the effect which those leaders have upon their subordinates who are generally more self-assured and perceive more meaning in their work. It has been found that these types of leader or manager reduce the stress levels of their subordinates.

On balance, therefore, managers who tend to demonstrate “considerate” behaviour, to have a participative management style, to be less production- or task-oriented and to provide subordinates with control over their jobs are likely to reduce the incidence of ill health and accidents at work.


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Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides