Reducing musculoskeletal injury in rail construction work

Placing and securing steel bars used in reinforced concrete involves heavy manual materials handling and work in awkward postures.

Researchers from RMIT used wearable sensors to understand the risk factors for work-related musculoskeletal injury for construction workers who fix steel reinforcement bars.

The research showed hotspots for musculoskeletal injury in steelfixing are the back, the shoulder and the wrist. Steelfixing is typically carried out using a pincer cutter tool which is used to grasp, twist and then cut the two ends of the fixing wire.

When working at ground level using this tool, a steel fixer needs to bend their back and reach down.

Over long periods of time, poor back postures can lead to lower back injury.

Now let’s look at the same steel-fixing action using a long handled stapler tool, instead of conventional pincer cutters.

The long handled stapler tool reduces the need to reach down when working at ground level and introduces significantly less bending of the lower back.

While this tool reduces back movement when working at ground level, some back bending is still required in addition to the rapid and forceful movement needed to use the tool.

Repetitive risk movements can be hazardous when using pincer cutters to fix steel, because it involves twisting and turning.

Repeating this action over a working day increases the risk of injury.

A power tying tool was compared to the conventional pincer cutter tool.

The tool mechanically wraps, twists and releases the wire tie when the trigger is pulled.

The hazardous twisting action of the wrist was significantly reduced by the power tool – an important improvement in reducing wrist, forearm and shoulder injuries.

But while this tool reduces excessive manual wrist movement, it does not reduce the need to bend while working below knee level.

However, using this type of power tool may require static holding of the tool for long periods of time and the tool does not help to improve back or shoulder postures when working at very low and very high positions.

Working overhead uses awkward shoulder postures and movements that may lead to shoulder injury.

Working overhead should be avoided wherever possible.

However, if working overhead cannot be eliminated, the long-handled stapler tool reduces awkward shoulder movements, reducing the risk of shoulder injury.

Ergonomic tools can make a difference in reducing the risk of musculoskeletal injury in steelfixing.

But the tools need to fit the job that is being done.

Although the long handled tool reduced the need to bend the back, while working at ground level, it requires the use of a forceful pushing and pulling action to fix and twist the wire tie.

And although the power tool reduces excessive manual wrist movement, it does not reduce the need to bend while working below knee level.

Wherever possible, work should always be designed to avoid awkward postures, excessive bending of the back or work above shoulder height.

However, where this is not possible, selecting the best tool for the job can reduce the risk of injury.

The challenge for the construction industry is to encourage the development and use of new methods and tools that can improve postures and movements and reduce the risk of work-related musculoskeletal injury.

Construction work involves many manual work tasks that expose workers to the risk of musculoskeletal injury.

Some work tasks involve awkward postures, performing repetitive physical actions, the use of excessive force and being exposed to vibration.

All of these factors contribute to the risk of injury to the musculoskeletal system.

The parts of the body most affected by musculoskeletal injury are:

• the back

• the shoulder

• the knee

• the ankle, and

• the wrist.

Researchers from RMIT used wearable sensors to understand the risk factors for work-related musculoskeletal injury in manual construction tasks, that included jackhammering and shotcreting.

Data was collected while breaking down the top section of concrete piles using a jackhammer.

This work involved bending the back and the use of excessive force when lifting the jackhammer into position and when maintaining the jackhammer in position over an extended period of time.

Workers were also exposed to noise, dust and vibration during jackhammering.

The potential for injury to the back in mechanical pile breaking with a jackhammer is high.

In this case, an integrated de-bonding material, was to be incorporated in the pile around the steel bars, above the cut-off level before the concrete was poured.

This would reduce the duration of jackhammering for each pile.

However, if the de-bonding material is not correctly installed when the concrete piles are poured, pile-breaking involves significantly greater time and increased injury risk.

Alternative, active pile breaking technologies that do not require mechanical breaking with a jackhammer can also be considered in the design of work systems.

However, these need to be incorporated during the design and planning stages of work.

The RMIT team also collected data for the task of shotcreting, which involves using compressed air to spray concrete onto a surface at high velocity to create a dense and strong concrete layer.

Shotcreting involves repetitive forward leaning movements that coincide with the pumping cycle. This work also involves awkward arm, wrist and hand postures that result from grasping and holding the hose in front of the operator’s body or over their shoulder for sustained periods to direct and control the flow of concrete.

Muscle activity measurements showed high levels of force exertion to lift and hold the shotcreting hose over the operator’s shoulder, while their arms were also raised to hold and control the hose in this position.

Shotcreters were also observed to work on rough and uneven ground surfaces and frequently drag the concrete and compressed air hoses for long distances as they moved position.

The provision of firm and flat work surfaces, attention to good housekeeping and assistance with moving equipment can also reduce the risk of slips, trips and falls, and the potential for strain and sprain injuries.

The potential for injury to the back in manual shotcreting was found to be high.

Excavator mounted hoses have been trialled and can reduce the need for someone to hold the hose while concrete is applied.

Robotic shotcreting equipment is also commercially available.

The potential benefits of adopting or adapting mechanised shotcreting methods to reduce physical work demands and injury risks for shotcreters are significant.

Where possible, mechanised options should be considered when designing safe work processes for shotcreting.

Providing a safe system of work involves careful planning and consideration of the interaction between workers, their equipment, the materials they are using and the broader work environment.

Effective control measures for the risk of work-related musculoskeletal injury should be identified and specified during the design stage of a project, when important decisions that affect workers’ health and safety are made.

Considering ways to change systems of work to reduce the risk of work-related musculoskeletal injury is an important aspect of improving the construction industry’s health and safety outcomes and ensuring construction workers are able to enjoy productive and healthy working lives.