Section 1926.602(a)(9)(ii) states

5:19 a.m.: I could have slept through the racket except for the blaring beep-beep-beep of heavy equipment rolling in reverse.  Other than the beep, it was just a lot of machine droning, the deep chugging of loaded trucks.  Since I was up, I stepped to the porch to get a closer look at the commotion, at the mulch-loading operation. Beep-beep-beep: the audio track from my dream played.

The whole event lasted fewer than forty minutes.  Loading leaf piles at the crack of dawn makes sense, I guess.  Nobody to blame who would care about being blamed.  So I shook my fist in the air and bellered, "Trying to sleep, buddy!"  Okay, really I didn't. But I couldn't go back to sleep; I felt some kind of nervous system irritation.

I did read a few weblogs, and decide I had time for an entry.  Then I set to googling the net for OSHA codes on the horns that warn of backing up (relevant to my early morning work on the rhetoric of alarm systems, the mal-ethos of warning sounds, etcetera).  Clearly, I'm not the first person to be irritated by the sound.  OHSA.gov offers this standard interpretation of alternatives in reply to a letter from a resident in Newton, PA:

Dear Mr. Buchichio:

Thank you for your letter of April 30, 2004, regarding noise emanating from excavating equipment and the Occupational Safety and Health Administration (OSHA) requirements for back-up alarms on construction equipment. We apologize for the delay in responding.

We have paraphrased your question as follows:

Question: The repetitive, piercing beeping noise emitted from back-up alarms on excavating equipment at a construction site is stressful to residents who live nearby. Other methods of alerting or warning employees have become available in recent years. Do OSHA back-up alarm requirements allow for the use of methods that would be less noise-intrusive to nearby residents?

Answer
Yes. Two OSHA requirements, 29 CFR 1926.601(b)(4) and 1926.602(a)(9), relate to back-up alarms in construction. Those provisions were promulgated in 1971 and were derived from Army Corps of Engineers standards.

Title 29 CFR 1926.601(b)(4) states:
1926.601 Motor vehicles.
* * *
(b) General requirements.
* * *
(4) No employer shall use any motor vehicle equipment having an obstructed view to the rear unless:
(i) The vehicle has a reverse signal alarm audible above the surrounding noise level or:
(ii) The vehicle is backed up only when an observer signals that it is safe to do so.
 
Section 1926.602(a)(9)(ii) states: 
1926.602 Material handling equipment.
* * *
(a) Earthmoving equipment; General.
* * *
(9) Audible alarms.
* * *
(ii) No employer shall permit earthmoving or compacting equipment which has an obstructed view to the rear to be used in reverse gear unless the equipment has in operation a reverse signal alarm distinguishable from the surrounding noise level or an employee signals that it is safe to do so.

I feel you, Mr. Buchichio. But neither of us has it as bad off as Ms. Nunn who, according to OSHA, "expressed concern that electronic high-pitched alarm sounds can irritate the nervous system."  Nunn was supposedly addressing workers' wellness, not the residents whose poor souls were pierced by the equipment's un-melodious song.  But OSHA concluded--to Ms. Nunn--that "they had no data or evidence to indicate that exposure to such alarms caused [nervous system irritation]."  OSHA code explains that are alternatives (flaggers, a lower volume, and so on) if we must have street makeovers at 5:00 a.m., and now--although I captured just a few seconds--there's evidence of the nervous system irritation that results from exposure to the unbearable industrial cry. Hard data: just turn the volume up on the video, play it in loop fashion for forty minutes. You'll see.