OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

November 3, 1998

Ms. Sue Nunn
1005 Caribbean Avenue
Ft. Pierce, FL 34982

Re: §1926.52, 1926.601(b)(4), and 1926.602(a)(9)

Dear Ms. Nunn:

Thank you for your letter of June 18 regarding the Occupational Safety and Health Administration (OSHA) requirements for back-up alarms on construction vehicles. Your letter expressed concern that electronic high-pitched alarm sounds can irritate the nervous system, which you assert can affect construction workers physically and emotionally. You also note that the noise can affect others who are near construction sites, and you ask that the Agency ensure that there is a balance between the safety merits of back-up alarms with the detrimental effects from the sounds they make. You explain that over the past 15 years, mechanical bell alarms have been replaced by high-pitched electronic sound-producing devices and request that OSHA study the effects of the noise made by this type alarm.

In response, we discussed your letter with staff from OSHA's [Directorate of Standards and Guidance], but they indicated they had no data or evidence to indicate that exposure to such alarms caused the symptoms you describe.

Two OSHA requirements, 29 CFR 1926.601(b)(4) and 1926.602(a)(9), relate to back-up alarms in construction. Both provisions apply only to the motor vehicles and materials handling equipment used in construction operations. The Agency has explained that these requirements allow employers some flexibility in determining the best method to warn of the danger of a backing vehicle. Specifically, when a driver's view to the rear is obstructed, the vehicle must be either equipped with an alarm or an observer must signal the driver that it is safe to proceed. If an alarm is used, it must be loud enough to be distinguishable from other sounds. Furthermore, OSHA's experience has shown the value of back-up alarms in protecting workers and the general public from serious injury.

The National Institute for Occupational Safety and Health (NIOSH) conducts workplace safety and health research, and attempts to identify the causes of work-related diseases and injuries and potential hazards of new work technologies and practices. For your information, we have enclosed a copy of a recent NIOSH document published in the Federal Register that addresses the effects of noise on workers.


Russell B. Swanson, Director
Directorate of Construction

[Corrected 10/18/2004]