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

*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

• 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

• 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.

• 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

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.