According to a study by the Finnish Institute of Occupational Health, the exposure of drivers to whole-body vibration and the resulting health risks when moving excavators can be significantly reduced by using Sleipner dollies instead of driving on the excavator’s own tracks.

The vibration measurements were conducted at a Finnish mine at the end of May 2023.

The aim of the measurements was to measure the level of the workers’ exposure to whole-body vibration when driving an excavator from one site to another at the mine. Vibration measurements were taken when driving an excavator from one site to another on tracks and when using the E190 Sleipner E Series dollies. The excavator used for the test was a Komatsu PC 2000 and, when using dollies, the excavator was pulled with a Komatsu 830 E haul truck. During the measurements – 26 minutes on dollies and 20 minutes on tracks – the driver and the person conducting the measurements were in the excavator cab.

Ville Hyvärinen, Specialised Occupational Hygienist from the Oulu office of the Finnish Institute of Occupational Health, who conducted the measurements and prepared the report, says: “According to our research results, using dollies significantly reduces the workers’ exposure to whole-body vibration and the resulting health risk, emerging as an excellent way to mitigate vibration. Reducing vibration also improves work comfort, as does a lower sensory noise level in the excavator cab.”

The values obtained from the vibration tests for the excavator are also comparable, for example, when driving a bulldozer and drill on tracks.

When moving the bulldozer and drill, whole-body vibration can be effectively reduced by using Sleipner’s DB Series lowboy trailers, according to the company.

The measurements were carried out on the transport route of the mine’s open pit area. The testing route was kept the same during both tests.

The surface was a gravel road, and its condition had been achieved using a road grader. During the measurements, the weather was clear.

The action value for daily whole-body vibration is 0.5 m/s2 and the limit value is 1.15 m/s2. If the daily exposure of workers exceeds the action value, the employer must draw up and implement a vibration prevention programme and regularly monitor the health of workers. If the exposure also exceeds the limit value, measures to reduce exposure must be carried out immediately.

When using Sleipner dollies, neither the action value nor the limit value are exceeded during a normal 12-hour working day. When driving on tracks, the action value level is exceeded after just three hours of exposure.

When driving on Sleipner dollies, the highest average vibration acceleration is 0.23 m/s2, which was measured in the driver’s front-facing direction (forwards-backwards direction). At the measured level of vibration acceleration, neither the action value nor the limit value are exceeded during a normal 12-hour working day.

When driving on tracks, the highest average vibration acceleration of 0.82 m/s2 was measured in the driver’s front-facing and lateral directions. At the measured level of vibration acceleration, the action value level is exceeded after three hours of exposure. Exposure exceeding the limit value requires about 16 hours of driving, which means that the value is not exceeded during a normal 12-hour working day. However, 16 hours of exposure to whole-body vibration while driving on tracks is already a serious situation.

Hyvärinen says: “When driving on tracks, the movements directed to the front and to the side are greatly exceeded if driven for a total of three hours during the working day. The driving does not even have to be continuous. When driving on tracks for more than three hours during the working day, the employer is obliged to take measures to prevent the driver from being exposed to excessive vibration. Otherwise, the driver runs the risk of being exposed to pain and discomfort in the lower back, hip, musculoskeletal joints and neck area. The risks are higher especially for pregnant women, for whom vibration exposure should be avoided to protect the health of the fetus.”

Using Sleipner’s dollies significantly extends the service life of mining machinery and improves work efficiency. Dollies also improve the occupational safety and comfort of drivers.

Vili Tuominen, Product Engineer at Sleipner Finland, who participated in the measurements, says: “In several countries, whole-body vibration is already classified as an occupational disease, and regular exposure to vibration has been shown to have clearly detrimental effects on health. The results of the vibration study exceeded even our own expectations and showed significant benefits for drivers when using Sleipner dollies. It was great to get confirmation that using our products can reduce occupational diseases caused by whole-body vibration.”

The methods for measuring whole-body vibration and processing data used by the Finnish Institute of Occupational Health are specified in standard ISO 2631-1:1997. Vibration exposure A(8) is calculated from the strength of the vibration (measurement result) and estimated exposure times, as required by Government Decree 48/2005. The exposure was determined in proportion to an eight-hour comparison period, according to which the action value for daily whole-body vibration A(8) is 0.5 m/s2 and the limit value is 1.15 m/s2. Another way to assess the risk is to determine the calculated time after which the measured level of vibration causes exposure that exceeds the action value or limit value.

The risk is considered significant when the daily exposure exceeds the action value (whole-body vibration 0.5 m/s2). In this case, a vibration prevention program and measures to reduce vibration are needed. If the exposure also exceeds the limit value (1.15 m/s2), the measures to reduce exposure must be carried out immediately. The risk is considered moderate when the exposing vibration can exceed the action value but the daily exposure level does not reach the action value (50–99%). The risk is considered minor when the exposure is sporadic and/or low (less than 50% of the action value).