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.

October 29, 1991

The Honorable Tom Harkin
United States Senator
Post Office Box 74884
Cedar Rapids, Iowa 52407-4884

Dear Senator Harkin:

Thank you for your letter of September 24 on behalf of your constituent, Mr. Waldo Morris, concerning the added noise and potential hazard of backup alarms on equipment at construction sites.

The Occupational Safety and Health Administration (OSHA) has two requirements relating to backup alarms. Both requirements are in the construction safety and health standards and apply only to motor vehicles and materials handling equipment used in construction operations. The OSHA requirements allow employers some flexibility in determining the best method to warn of the danger of backing vehicles. Specifically, when a driver's view to the rear is obstructed, the vehicle must either be equipped with an alarm, or an employee 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.

Mr. Morris questioned the benefits of "noisy" backup alarms and stated the noise was a hazard on the jobsite. An analysis was made in 1971 when the standards were first promulgated. At that time, it was determined that backup alarms saved lives. We believe the benefits of backup alarms still exist. However, as Mr. Morris pointed out, when the alarm sounds constantly, its usefulness as a warning device may be lost. This need not be a problem, however, as there are alarms which sound only after motion has been detected at the rear of a backing vehicle. Such alarms have been successfully used on a variety of vehicles and their use may be appropriate in the type of situation described by Mr. Morris. In addition, this type of intermittent alarm would also alleviate the potential for hearing loss mentioned by Mr. Morris.

Your interest in safety is appreciated.


Gerard F. Scannell
Assistant Secretary