Noise in Road Construction

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Noise in Road Construction
Developed by the Division of Occupational Safety
and Health (DOSH) August, 2009
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What this presentation covers

• Hearing loss rates and claims facts
• Noise levels of construction equipment
• Control methods to reduce harmful noise exposures
• Resources

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Hearing loss is expensive!
In Washington State,

• 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.

The result is higher industrial insurance
premiums paid by road construction contractors.
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Noise and hearing loss
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0

• Noise is measured in units called decibels (dBA).

Threshold of pain














Construction noise levels are often above 85 dBA
Jet take-off (200)
(A-weighting is a standard of sound measurement
used to evaluate continuous noise levels
designated as dBA)
Chipping hammer
Jackhammer
Bulldozer
Freeway noise
City traffic

• Scientific studies have shown that hearing loss
  can occur when 8-hour average noise exposure
  exceeds 85 decibels.

Normal conversation (3)
Urban residence
Soft whisper (5)
For more information on noise and hearing, see
DOSH webpage Noise Exposure Hearing Loss
Threshold of hearing
Noise level (dBA)
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Some Common Noise Levels in Construction
Source Center to Protect Workers Rights
Decibels (dBA)
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Road Equipment Noise Level Measurements
Concrete Saw Operator 95 dBA (7-hour sample)
Source OSHA case files
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Road Equipment Noise Level Measurements
Jackhammering 102 dBA (7.5-hour sample)
Source OSHA case files
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Road Equipment Noise Level Measurements
Breaking pavement 112 dBA (7-hour sample)
Source OSHA case files
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Road Equipment Noise Level Measurements
Lateral drilling (2 examples)
97 dBA (6.5-hour sample)
104 dBA (7-hour sample)
Source OSHA case files
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Sample Noise Level Measurements
Bridge Sandblasting 125 dBA (4-hour sample)
109 dBA (inside hood)
Source OSHA case files
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Sample Noise Level Measurements
Dumping concrete 96 dBA (4-hour sample)
Source OSHA case files
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Noise Sources in Road Work
Several factors influence the noise levels to
which workers are exposed

• 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

Underpass
Underpass work
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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

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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.
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Noise control methods
Substitute quieter process or equipment
New quieter generators have sound-proofing and
produce only 75 dBA at 1 meter and 65 dBA at 7
meters under load.
Replacing a large jackhammer with a middle range
one reduced the noise level by 10 dBA.
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Noise control methods
Eliminate or minimize noise at the source

• Install silencers/mufflers
• Retrofit old equipment
• Operate equipment as designed per
  manufacturers 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

Acoustically treated operator cabins on
earth-moving equipment have noise levels of 75
dBA or below.
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Noise control measures
Isolate/enclose the process or operator

• 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

A portable screen set up around a power pack
reduced the noise level from 98 to 90 dBA at 1
meter.
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Noise control measures
Isolating 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.
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Noise Control measures
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 thats 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.

• 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.

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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

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Hearing Conservation Program
When noise levels cant 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
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Summary
Hearing loss is expensive!
Many construction noise levels are high and
require controls to reduce workers exposures.
Control methods

• 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

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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/cons
ultation/regional_consultants.htm
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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