Working positions, tools and equipment
Fitting work to people: Ergonomics
The technical development of the construction industry has led to reliance on machines and technical equipment for much heavy work previously done by hand. Although there are still many tasks on site which are carried out using manual labour, it is difficult to envisage high-rise building construction without cranes, excavators, concrete mixers or pile drivers. Mechanization has, however, brought new problems to the workplace.
Technology changes faster than people and technological change often exceed people’s ability to adapt. As a construction worker, you know the difference between a tool that is well suited for you and for the job, and one that is not. You also soon become aware of the difference between a comfortable working posture and one that is uncomfortable. Ergonomics or human engineering is a multidisciplinary way of looking at the interrelationship between the worker, the workstation and the working environment. Ergonomics plays a key role in the humanization of work, in increasing productivity, and in improving safety and health.
Even with new and modern technologies a lot of heavy work is still done by hand. Tools, machines and equipment are in many cases old-fashioned, poorly designed or badly maintained. Many operatives on construction sites are unskilled. Heavy loads frequently have to be carried up and down stairs, ladders and scaffolds, and people working on construction sites often suffer from low back pain or injury to muscles and joints.
The construction industry has a wide range of jobs and processes. These change according to the stage of the project. They involve consideration of:
– working positions, both standing and sitting;
– work which is especially strenuous;
– the use of hand tools and equipment.
Discussion
• How have various machines changed work methods in the construction industry in the past few years?
• What are the positive and negative effects of tower cranes and excavators on your work?
Strenuous and heavy physical work
Continuous heavy manual work increases the rate of breathing and the heart. If you are not in good physical shape, you will tire easily. There are risks involved in working at maximum physical capacity. The use of mechanical power to replace heavy work helps reduce these risks. Mechanical power also helps increase the work opportunities for people with less muscle power. On the other hand, jobs that require no physical effort are often mentally tiring and boring. It is important that the workload is not too heavy and changes during the day. Effective rest periods should always be included in the day’s work.
Discussion
• Is work affected by differences in workers’ heights and weights?
• Are there any jobs on your site that workers try to avoid?
• Name some jobs which are strenuous. Are there any alternative methods to carry out the task with less strain?
Static loads
The most natural way to work is rhythmically. When sawing with a handsaw, the hand holding the saw is doing dynamic work and the other hand static work. This “dynamic” load enables the muscles to alternate between contraction and relaxation. If an object is lifted up and held in this position, this puts the muscles under a uniform “static” load. Muscles under static load become tired because they are continually contracted, and after a short time the muscles feel painful. A static load on the muscles over a long period will also increase pressure on the heart. The pulse increases because the blood remains in the muscles.
On building sites there are many jobs where the worker is exposed to heavy static loading. Finishing work on walls and ceilings, painting and electrical wiring work frequently require you to work with arms above your shoulder line, and frequent changes of posture are desirable.
Working Postures
On construction sites people work in a variety of different positions. Some workers are climbing up scaffolds, others are using hammers while on their knees, while others are working on surfaces above their heads. Until recently, little attention has been paid to good working positions. It is frequently argued that construction work unavoidably requires many different and changing postures, but it is clear that the principles developed for good working positions in industry apply also to construction.
Difficult working positions lead to spending longer over tasks and lead to fatigue. For example, working with one’s arms raised rapidly tires the shoulder muscles and work requiring bending or twisting can easily cause back strain. A poor working posture translates into a gradual increase in operation time and an increased possibility of injury or damage to material or equipment.
Sitting and standing positions
Posture is defined by the working method applied and by the tool in use. When considering posture, you have to take into account the reach and muscular power of the worker involved. Where possible, work should be done in a sitting position. However, a standing position is often unavoidable in construction work where high muscular power, greater reach or considerable movement is involved.
A well-designed workstation provides possibilities for the worker to carry out the operation in many positions and postures, both sitting and standing. It also allows the worker to walk a little during the working day.
Although there are very few fixed sites in the construction industry, there are many operations where difficult postures can be improved by simple, low-cost measures. For example, welders often have awkward working postures and a simple, light three-legged stool or chair is useful.
Discussion
• Describe several different working postures you have seen on your site and how they could be improved.
• Hold your hands out straight for a while. How do you feel?
• Bend your body forwards and hold that position. How do you feel?
Work in cabins
Machines with cabins for the operator are frequently used on construction sites. Examples include excavators, tower cranes, bulldozers and trucks. In recent years manufacturers of these machines have paid a great deal of attention to the working conditions of the operator. Regular checking and maintenance are needed if these conditions are to remain intact over the working life of the machine. Here are some key points to check:
– Is there easy access to the cabin?
– Are controls in good working order and within easy reach?
– Is the construction of the cabin solid, is windows and noise insulation in place, and are lights working?
– Is the operator’s seat in good condition, adjustable and securely anchored?
– Is the instrumentation functioning?
– Is the engine exhaust pipe placed away from the cabin and in good condition?
– Are the engine covers and enclosures in place?
Hand tools
There are many different types of hand tool for different kinds of work, such as shovels, axes, crowbars, chisels, screwdrivers, hammers and wrenches. In many instances these tools are bought from an outside vendor without paying any attention to their design or quality.
A good-quality hand tool should be designed to fit the hand and the task. It will earn money and reduce the possibility of accidents. With the proper design of hand tools, work posture can be improved and stress can be reduced, resulting in an improved quality of work.
Accidents with hand tools nearly always arise from some human failing – carelessness, not knowing the right tool for the job,
Points to remember:
• Arrange to sit whenever possible.
• Keep materials, tools and controls within easy reach.
• Make sure you got close enough to the task.
maintain tools and to keep them properly. You need to be correctly instructed in how to use tools and how to look after them.
10.2.1 Selection, use and maintenance
There are basic considerations in selecting, using and maintaining hand tools:
– avoid static load at the shoulder or arm due to the continuous holding of a tool at a raised position or the gripping of a heavy tool;
– avoid awkward wrist angles while using tools such as snips and pliers;
– reduce uncomfortable pressure on the palm or joints of the hand, e.g. from pliers that are too small;
– select the correct weight, size and tool for the job;
– use only tools of good-quality steel – tools made of inferior steel chip and may even shatter when struck, tool heads mushroom, tool jaws open out and cutting tools lose their edge;
– handles should have a smooth finish, should be easy to grasp and should have no sharp edges or corners;
– tools should be firmly fixed and should be regularly checked for splits and cracks; wedges should be checked for tightness of fit;
– tools should be kept free of grease and dirt, and moving and adjustable parts should be well oiled;
– cutting edges should be kept sharp for accurate working and to avoid the need for unnecessary pressure;
– for work on or near electrical apparatus only properly insulated tools should be used;
– tools should be properly stored in boxes, racks, holders or pocket belts and should not be left so that they can fall, roll or be tripped over; cutting edges should be sheathed;
– damaged tools should be immediately repaired or replaced.
Figure 40 illustrates some worn hand tools and those in good condition.
Discussion
• Think of the hand tools commonly used in construction – how would you classify the risks of each and minimize them?
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