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Noise in Road Construction
Developed by the Division of Occupational Safety and Health (DOSH) August, 2009
What this presentation covers
Hearing loss rates and claims facts
Noise levels of construction equipment
Control methods to reduce harmful noise exposures
Resources
Hearing loss is expensive!
Hearing loss is 1/3 of all costs of permanent impairments.
Hearing loss is the most expensive occupational disease for road construction workers.
Incidence rate is 10 times higher for “Road Construction” risk class than for all other risk classes.
Hearing loss claims rate is highest of all construction risk classes.
In Washington State,
The result is higher industrial insurance premiums paid by road construction contractors.
Noise and hearing loss
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Noise level (dBA)
• Noise is measured in units called decibels (dBA).
For more information on noise and hearing, see DOSH webpage: Noise Exposure – Hearing Loss
• Scientific studies have shown that hearing loss can occur when 8-hour average noise exposure exceeds 85 decibels.
Threshold of pain
Freeway noise
City traffic
Normal conversation (3’)
Urban residence
Threshold of hearing
Construction noise levels
are often above 85 dBA
(“A-weighting” is a standard of sound measurement used to evaluate continuous noise levels; designated as “dBA”) Bulldozer
JackhammerChipping hammer
Soft whisper (5’)
Jet take-off (200’)
Some Common Noise Levels in ConstructionSource: Center to Protect Worker’s Rights
Decibels (dBA)
60 70 80 85 90 100 110 120
Jackhammer
Concrete joint cutterSkilsaw
Bulldozer
Earth Tamper
Crane
Hammer
Gradeall
Front end loader
Backhoe
110-113
102-111
99-102
88-102
93-96
90-96
90-96
87-95
87-94
86-94
84-93
Pneumatic chipping hammer
Source: OSHA case files
Road Equipment Noise Level Measurements
Concrete Saw Operator 95 dBA (7-hour sample)
Road Equipment Noise Level Measurements
Jackhammering 102 dBA (7.5-hour sample)
Source: OSHA case files
Road Equipment Noise Level Measurements
Breaking pavement 112 dBA (7-hour sample)
Source: OSHA case files
Road Equipment Noise Level Measurements
97 dBA (6.5-hour sample)
104 dBA (7-hour sample)
Lateral drilling (2 examples)
Source: OSHA case files
Sample Noise Level Measurements
Source: OSHA case files
Bridge Sandblasting 125 dBA (4-hour sample)
109 dBA (inside hood)
Sample Noise Level Measurements
Source: OSHA case files
Dumping concrete 96 dBA (4-hour sample)
Noise Sources in Road Work
Type and condition of equipment being operated
Other equipment running at the same time
Enclosed or partially enclosed spaces (e.g., underpass)
Traffic around work site
Several factors influence the noise levels to which workers are exposed:
Underpass
Underpass work
When is hearing protection required?
• At noise exposures of 85 dBA TWA8* and higher, you must use a hearing protection device.
• Wherever the noise exposure is 90 dBA TWA8 and higher, feasible controls must be used to reduce your exposure.
*Time-weighted average during an 8-hour period
High Noise Exposures “Rules of Thumb”
You need protection:
• If you have to shout at someone 3 feet away to be heard• When using electric, gasoline, or air powered tools• When sitting in an open cab of dozers, rollers, some cranes,
earth moving or road building equipment
What are some methods to controlnoise exposures?
• Substitute quieter process or equipment
• Eliminate or minimize at the source
• Isolate/enclose the process or operator
• Increase distance from the source
• Change work practices
• Implement a hearing conservation program
The most desirable methods of controlling a noise problem are to use quieter process/equipment, eliminate the noise at the source, or to block the noise from reaching you.
Using hearing protection devices (ear plugs, muffs) isn't considered a control of the noise hazard. There are many drawbacks and using them will not always be effective.
Noise control methods
Substitute quieter process or equipment:
Replacing a large jackhammer with a middle range one reduced the noise level by 10 dBA.
New quieter generators have sound-proofing and produce only 75 dBA at 1 meter and 65 dBA at 7 meters under load.
Noise control methods
– Install silencers/mufflers
– Retrofit old equipment
– Operate equipment as designed per manufacturer’s instructions
– Damp noisy equipment and parts install sound-absorbing material or vibration
isolation systems
– Maintain equipment properly replace worn, loose, or unbalanced machine
parts that cause vibration
keep machine parts well lubricated to reduce friction
adjust belts and valves, tighten bolts
Eliminate or minimize noise at the source:
Acoustically treated operator cabins on earth-moving equipment have noise levels of 75 dBA or below.
Noise control measures
– Noise enclosures
– Noise barriers must be higher and wider than noise source
to work effectively
may be simple walls or curtains of acoustic materials
½-inch plywood can provide a 10dB noise reduction
place close to noise source
– Include acoustic panels or baffles to walls/ceilings
– Minimize leaks and openings e.g., cover joints with 1/8-inch thick neoprene
strip or duct tape
Isolate/enclose the process or operator:
A portable screen set up around a power pack reduced the noise level from 98 to 90 dBA at 1 meter.
Noise control measuresIsolating or enclosing noisy equipment with operator- a caveat:
This method will reduce noise levels outside the barrier, but may increase noise levels inside the barrier.
if the source of noise is equipment operated by a worker, his or her noise exposure may be increased because of reflected noise.
Lining the barrier with sound absorbing material will reduce the reflected noise to operator.
Reflected Noise
Noise from source
BARRIER
TransmittedNoise
Noise Control measures
– Keep noisy equipment away from walls or other surfaces that will reflect noise toward you.
– Combine distancing and barriers to further reduce noise exposure. Using both methods results in greater noise reduction than would be achieved from either method alone.
Increase the distance between the noise source and you:
– Every doubling of the distance between you and the noise source results in as much as a 6 dB decrease in noise level – that’s a four-fold reduction!
-This is true if there is no reflected noise. The reduction will be less if there are walls or partitions between you and the noise source.
Other Noise Control Measures
Change employee work practices:
– limit time exposed: job rotation, rescheduling work
– limit use of noisy equipment
– provide breaks away from the noisy area
– turn off equipment not in use
Hearing Conservation ProgramWhen noise levels can’t be controlled through other means, you must implement a hearing conservation program which consist of the following:
– Provide baseline and annual audiometric testing
– Measure noise exposure levels
– Provide hearing protection
– Do employee training and education
– Maintain employee exposure and hearing loss records
Chapter 296-817 WAC Details of requirements:
Summary
• Substitute quieter process or equipment
• Eliminate or minimize at the source
• Isolate/enclose the process or operator
• Increase distance from the source
• Change work practices
• Implement hearing conservation program
Hearing loss is expensive!
Many construction noise levels are high and require controls to reduce workers’ exposures.
Control methods:
DOSH Consultation Services
Safety & Health program review and worksite evaluation
• By employer invitation only• Free• Confidential• No citations or penalties• Letter explains findings• Follow-up all serious hazards
For additional assistance, you can call one of our consultants. Click below for local L & I office locations:http://www.lni.wa.gov/wisha/consultation/regional_consultants.htm
More Information
DOSH: Noise Exposure – Hearing Loss
NIOSH: Noise and Hearing Loss Prevention
OSHA: Noise and Hearing Conservation
National Hearing Conservation Association
MSHA Noise Control Manual: Surface Mining Equipment
Institute of Noise Control Engineering of the USA