Solution Summary: Quieter Backhoes
Quieter backhoes are designed to limit noise exposure from loud equipment engines by enclosing the operator.
Description:
Quieter backhoes use engineering controls to limit noise exposure. Backhoes use diesel engines to move large amounts of earth or other materials during construction or demolition. These quieter machines are designed to reduce the amount of noise from the engine that reaches the operator. The backhoe operator’s noise exposure is reduced through the use of specially designed cabin enclosures and redesigned drivetrains.
Through the use of specially designed cabin enclosures, the noise entering the backhoe’s cabin is mitigated and exposures are reduced. Sound pressure levels on the construction site, however, may still be above the OSHA permissible exposure limit and workers should wear hearing protection for more than intermittent visits.
Case Construction Backhoes
| Model | Engine (horsepower) | Vehicle Weight (pounds) | Vehicle Height | Backhoe Dig Depth |
| 580 N | 83 | 17,225 | 10 feet, 9.9 inches | 14 feet, 9 inches |
| 590 Super N | 110 | 20,458 | 11 feet, 7.3 inches | 15 feet, 6 inches |
- Fuel: Diesel
- Operator Sound Pressure Level: 72 dBA
- Exterior Sound Pressure Level: 84-94 dBA at 10 feet away
- OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA
- Noise Control Methods: re-designed cabin enclosure
Caterpillar Backhoes
| Model | Engine (horsepower) | Vehicle Weight (pounds) | Vehicle Height | Backhoe Dig Depth | Operator Sound Pressure Level (dBA) |
| 420E | 93 | 24,251 | 11 feet, 9 inches | 14 feet, 4 inches | 79 |
| 450E | 137 | 27,115 | 13 feet, 7 inches | 17 feet, 2 inches | 83 |
- Fuel: Diesel
- Exterior Sound Pressure Level: 76-79 dBA at 49.2 feet (15 meters)
- OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA
- Noise Control Methods: re-designed cabin enclosure, high contrast ratio/gear drivetrain
Risks Addressed:
Over time, exposure to noise levels at or above 85 decibels will lead to permanent hearing loss. The NIOSH recommended exposure limit (REL) for occupational noise is 85 decibels on an A-weighted scale as an 8-hour time weighted average (U.S. Department of Health and Human Services, 1998). OSHA limits noise exposure to 90 decibels, also on an A-weighted scale and as an 8-hour time weighted average (U.S. Department of Labor, 2008). A-weighting is an adjustment that gives lower frequencies less weight or significance than higher frequencies. An A-weighted sound level more closely resembles the human ear’s response to noise.
The American Conference of Governmental Industrial Hygienists (ACGIH) assigned noise a Threshold Limit Value (TLV) of 85 dBA as an 8-hour time weighted average. Exposure to 88 dBA is limited to 4 hour, exposure to 91 dBA is limited to 2 hours, exposure to 94 dBA is limited to 1 hour and so on (ACGIH, 2011).
|
ACGIH TLVs for Noise |
||
|
|
Duration per Day |
Sound Level (dBA) |
|
Hours |
24 |
80 |
|
16 |
82 |
|
|
8 |
85 |
|
|
4 |
88 |
|
|
2 |
91 |
|
|
1 |
94 |
|
|
Minutes |
30 |
97 |
|
15 |
100 |
|
|
7.50 |
103 |
|
|
3.75 |
106 |
|
|
1.88 |
109 |
|
|
0.94 |
112 |
|
Noise exposure has also been associated with temporary hearing loss, decreased perception of noisiness and masking, increased stress, increased fatigue, disturbance of sleep and decreased concentration and mental performance (Osada, 1988). Noise-induced hearing loss starts in the higher frequencies (3,000 to 6,000 Hz) and slowly develops from chronic exposure to excessive sound. Sound must exert a shearing force on the hair cells lining the inner ear to be perceived, and if the force is too strong, cell damage and cell death can occur (Berger et al., 2003).
In a 2004 report from the University of Washington, full-shift noise dosimetry measurements indicated an average exposure of 89.3 dBA for backhoe operators (Seixas, 2004).
In a study to determine time-weighted average noise exposures for heavy equipment operators, eight noise dosimetry samples were collected for five backhoes. The average sample duration was 384 minutes. The time-weighted average daily noise exposure for backhoe operators ranged from 79 to 89 dBA with an average exposure of 84 dBA. Equipment with insulated cabs were found to reduce noise levels for machinery operators (Legris, 1998).
How Risks are Reduced:
These diesel-powered backhoes move large amounts of earth or other materials and are designed to reduce the amount of noise from the engine that reaches the operator. Through the use of specially designed isolating cabins and re-designing the drivetrains on the machines, the operator’s noise exposure is reduced.
While there are no published sampling data on these specific backhoes, safety and health experts believe exposure to noise can be significantly reduced through the use of noise control techniques. The extent of the reduction is dependent on the type of work being performed, the size of the engine, the amount of noise in the environment, the level of effort required by the machine, and the operator’s proximity to the engine.
Industrial hygienists use sound level meters or noise dosimeters to determine noise levels and recommend the use of quieter techniques to prevent hearing loss and reduce the risk of accidents. Proper maintenance and retrofitting existing equipment can decrease excess sound as well (Suter, 2002).
Case, an equipment manufacturer, states that its backhoes’ sound reduction package reduces sound levels to 72 dBA.
Another firm, Terex, claims that its quieter cab keeps sound levels below 78 dBA.
Effects on Productivity:
Lower noise levels are expected to reduce stress and fatigue, and increase the concentration and mental performance of workers. Improved worker health, comfort and concentration may lead to greater productivity. Reduced sound levels can also lower the risk of accidents as communication among workers is easier and more effective.
Additional Considerations:
The use of diesel-powered equipment poses the risk of carbon monoxide exposure, especially in areas where airflow is reduced. Steps to control exposure are important because the gas is invisible, odorless and tasteless. Poisoning by carbon monoxide can occur quickly indoors, but working outdoors does not ensure operators won’t be overcome. Small, inexpensive personal monitors should be worn by the operator to warn of unacceptable exposures. Equipment should not be left idling to cut down on carbon monoxide and to conserve fuel.
As is the case with any construction equipment, users should follow manufacturer scheduled maintenance safety recommendations and comply with any applicable local, state or federal regulations.
Contributors:
Andrew Kingston, Michael R. Cooper and Bruce Lippy - The Lippy Group, LLC
Availability
NIOSH Workplace Solutions Sheet
The National Institute of Safety and Health (NIOSH) has published a series of “Workplace Solutions”, which are easy-to-understand recommendations from NIOSH research results. Related to this Construction Solution, please find more information on:
Preventing Injuries When Working with Hydraulic Excavators and Backhoe Loaders
Caterpillar Backhoes
To obtain information, visit http://www.cat.com/en_US.html
or contact 1-309-675-1000
Case Backhoes
To obtain information, visit http://www.casece.com/en_us/Pages/home.aspx
or contact 1-866-542-2736
