Self-Adjusting and Directional Backup Alarms

Self-adjusting and directional backup alarms are an engineering control that can limit noise exposure. These alarms are designed to focus the noise to a certain area or only be slightly louder than the ambient noise in the vicinity of the vehicle. By focusing the noise created by the alarm, only those who are directly behind the vehicle will hear it. By automatically adjusting the sound level of the alarm to be as low as possible, while still loud enough to be heard by workers near the vehicle, pedestrians, neighbors and bystanders will not be exposed to unnecessary noise from construction vehicles.  Using these alarms is also a safe work practice which can also serve as warning indicators to prevent work zone struck-by accidents by heavy equipment.

Description:

Self-adjusting and directional backup alarms are an engineering control that can limit noise exposure. These alarms are designed to focus the noise to a certain area or only be slightly louder than the ambient noise in the vicinity of the vehicle. By focusing the noise created by the alarm, only those who are directly behind the vehicle will hear it. By automatically adjusting the sound level of the alarm to be as low as possible, while still loud enough to be heard by workers near the vehicle, pedestrians, neighbors and bystanders will not be exposed to unnecessary noise from construction vehicles.  Using these alarms is also a safe work practice which can also serve as warning indicators to prevent work zone struck-by accidents by heavy equipment.

Through the use of specially designed backup alarms, the noise produced by these devices is limited and exposures are reduced. However, sound pressure levels may still be above the OSHA permissible exposure limit and workers should wear hearing protection for more than intermittent use.

Preco Backup Alarms

ModelPower RequirementsSound Level (dBA)
102012 to 24 volts, 0.2 amps, direct current77 to 102*
106012 to 24 volts, 0.5 amps, direct current97 to 112**
6002SRS12-24 volts, 0.5 amps, direct current97 or 107***

*Adjusts to a minimum of 5 dBA above the background noise

**Self-adjusting to 10 dBA above the background noise

***Manually switchable

  • The 6002SRS™ (Short Range Sound) Alarm has a speaker/driver combination that produces sound at multiple frequencies within a narrow range to achieve the optimum level of warning capability while minimizing annoyance
  • Sealed in epoxy to protect the unit from dust, moisture, and vibration
  • Preco backup alarms must be positioned to direct the warning signal toward the rear of the vehicle

ECCO Backup Alarms

ModelPower RequirementsSound Level (dBA)
SA94012 to 24 volts, 0.6 amps, direct current87 to 112
SA95512 to 24 volts, 0.4 amps, direct current82 to 102
  • Self-adjusting to 5 dBA above the background noise
  • Sealed in epoxy to protect the unit from dust, moisture, and vibration
  • Ecco SA or Smart Alarms® must be positioned to direct the warning signal toward the rear of the vehicle

Brigade Electronics Backup Alarms

ModelSound Level (dBA)
SA-BBS-10787 to 107
SA-BBS-9777 to 97
  • Self-adjusting to 5-10 dBA above the background noise
  • Power Requirements: 12 to 24 volts, 1 amp, direct current
  • Brigade Electronics BBS TEK alarms must be positioned to direct the warning signal toward the rear of the vehicle direct the warning signal to the rear of the vehicle

North American Signal Company Backup Alarms

These alarms use a piezo element, which is a ceramic coated diaphragm that vibrates when a current is run through it, to produce sound.

ModelSound Level (dBA)
BA2A82-107
BA287-112
  • Self-adjusting to 10 dBA above the background noise
  • Power Requirements: 12 to 48 volts, 0.1 amps, direct current

Brigade Electronics BBS TEK alarms must be positioned to direct the warning signal toward the rear of the vehicle direct the warning signal to the rear of the vehicle

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. 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 Health and Human Services, 1998).

Noise exposure has also been associated with temporary hearing loss, perception of noisiness and masking, increased stress, 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 in order to be perceived, and if the force is too strong, cell damage and cell death can occur (Berger et al., 2003).

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 hours, exposure to 91 dBA is limited to 2 hours, exposure to 94 dBA is limited to 1 hour and so on. (ACGIH, 2011).

TLV 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

 

How Risks are Reduced:

These backup alarms are designed to focus the noise to a certain area or only be slightly louder than the ambient noise in the vicinity of the vehicle. By focusing the noise created by the alarm, only those who are directly behind the vehicle will hear it. By automatically adjusting the sound level of the alarm to be as low as possible, while still loud enough to be heard by workers near the vehicle, pedestrians, neighbors and bystanders will not be exposed to unnecessary noise from construction vehicles.  Using sound as a signal can also alert workers for heavy equipment that are backing up.

While there are no published sampling data on these specific backup alarms, general industrial hygiene practice indicates exposure to noise can be significantly reduced through the use of self-adjusting or directional backup alarms. Using noise control techniques in backup alarms will reduce workers’ exposure to hazardous levels of noise, reduce environmental or community noise, and improve the effectiveness of the alarms. The extent that it reduces noise exposure and increases effectiveness is expected to be significant. The extent of the reduction is dependent on the type of alarm used, the method of noise reduction, the vehicle to which the alarm is mounted, other sources of noise in the area, and the proximity to the alarm.

Sound localization of a backup alarm is important due to ambient noise levels on a construction site. A study involved blindfolded listeners and backup alarms mounted in different locations on a vehicle during quiet and in situations with ambient noise. The subjects were asked to determine the direction from which the alarm was coming. There was no confusion when the alarm was to the right or left of the listener, but alarms originating from behind generally produced the worst performance and the most directional confusion. Therefore, directional alarms that are mounted with no obstructions blocking the sound path are a solution for sound localization (Heckman et al., 2011).

In 2005, Caterpillar conducted a study to determine if self-adjusting backup alarms were appropriate for large construction equipment. The test was completed on a motor grader and included seven different locations where sound was measured to see if the “self-adjusting” feature was working properly. They concluded that the temporal, spectral, and amplitude characteristics of the alarm were appropriate as an effective warning device during operation. When operating in an environment with varying ambient noise, the alarm ensures a relevant and distinct warning to those near the machine, and will be less objectionable to those farther from the machine (Mcdaniel et al., 2005).

Industrial hygienists determine hazardous levels of noise on construction sites 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).

Preco states that its SRS backup alarm “is an effective solution to excessive noise pollution created by backup alarms.”

Additional Considerations:

Alerting workers through the use of back-up alarms is not limited to only self-adjusting and directional models.  Universal alarms can also be installed to provide the same warning properties.

Despite the use of backup alarms, there are human factors that contribute to reverse collisions. The operator’s decreased perception of responsibility due to the presence of the alarm may lead to careless backing. Workers may become habituated to the alarm, since it always sounds the same and can be heard over a large area, and perceive the alarm to be non-threatening. The noise pollution created by the use of multiple alarms combined with other noise from the site may confuse and irritate the workers (Duchon et al., 1986).

As is the case with any equipment, users should follow manufacturer scheduled maintenance and safety recommendations and comply with any applicable regulations.

Hazards Addressed:

Availability

North American Signal Company Backup Alarms
contact 1-877-246-6274 sales@nasig.com

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 Worker Injuries and Deaths from Backing Construction Vehicles and Equipment at Roadway Construction Worksites

Preco Backup Alarms
To obtain information, visit http://www.precosafety.com or contact 1-208-323-1010

Brigade Electronics Backup Alarms
contact 1-610-826-7870 infousa@brigade-electronics.com

Ecco Group Backup Alarms
To obtain information, visit http://www.eccolink.com or contact 1-800-635-5900

Return on Investment

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