Mounted roadbreaker

The task

Breaking road surfaces

The problem

The most common tool used to break up road and pavement surfaces is the hand-held percussive breaker. These tools typically produce hand-arm vibration magnitudes of between 5 and 20 m/s² with an average of around 12 m/s². A full-time breaker operator working on a road excavation job might be exposed to this vibration for an average of 3 hours per day which would give a typical exposure of 7 m/s² A(8) which is above the exposure limit value. The amount of work that an operator can do with one of these tools in a day varies depending on the depth and hardness of the surface to be broken up.

The solution

In some circumstances it is possible to greatly reduce the vibration exposure by using a larger breaker attachment mounted on the arm of an excavator. This method was used by a utilities contractor for digging telecommunications trenches in the road in a busy urban area. There was already an excavator on site for digging out the trenches once the surface had been broken, and the bucket was replaced with a breaker attachment, which took about 5 minutes, whenever required. The breaker is powered using the excavator hydraulics and is activated by a foot pedal. The arm position is controlled by a pair of levers, passing very little vibration (vibration magnitude is less than 1 m/s²) to the operator’s hands. A hand-held breaker, fitted with a sharp cutting tool, was used for about 5 minutes at the beginning of the day to score the edges of the area to be broken up with the mounted breaker.

Mounted breaker being used to break roadway

The result

This method reduces the time the operators are exposed to vibration. The exposure for the hand-held breaker operator was reduced to little more than 1 m/s² A(8).
On the type of surface found in this example, the mounted breaker works approximately 10 times as fast as one person with a hand-held tool.
The attachments on the excavator can be changed very quickly.
Overall there is less disruption and noise.