Noise from Site Equipment; Challenges and Solutions

Certain equipment used on construction and infrastructure projects present very specific challenges when it comes to protecting both workers and nearby residents from the noise generated. This best practice article discusses these challenges and suggests how they can be handled.

Although the challenges that each type of machine creates are very different, the fundamental principles of noise control are what each solution is designed to achieve: positioning the acoustic barrier as close as possible to the source, and blocking the line of sight between it and the people affected.

What the law says

The Control of Noise at Work Regulations 2005 are in place to protect workers’ hearing from excessive noise. They require you to eliminate or reduce risks to health and safety from noise at work.

The Control of Pollution Act 1974 allows councils to set times during which works can be carried out and the methods of work to be used. Contractors may apply for prior approval for their works by completing a section 61 application.

Typical noise levels associated with site activities (HSE figures):

Sound levels are measured in decibels (dB). 1 decibel is the just noticeable difference (JND) in sound intensity for the normal human ear. Decibels measure the intensity, not the loudness of sound. Below are some of the exposure levels:

• Running power packs/compressors: 85 - 91dB
• Grinding: 85 - 109dB
• Breaking concrete, asphalt and similar with hand operated breakers: 95 - 105dB
• Abrasive disc cutters/angle grinders: 98 - `104dB
• Driven piling: 115 - 132dB

In comparison, a typical office with reach levels of up to 60dB, and a living room in a home, 50dB.

Generators

The noise from generators emanates at very low frequencies, and moves in waves that travel a lot further and through materials that high frequency sounds don’t penetrate.

During the normal working day, generator noise is usually masked by general ambient noise, but generators are typically used to power critical applications that need to be kept going around the clock. Consequently, complaints usually arise outside normal working hours, especially overnight. The low ‘throb’ of a generator is then perceived as a real nuisance by people trying to sleep.

To be effective at tackling this problem, the control measures used must have high absorption levels and the highest possible density to ‘catch’ and retain the low frequency soundwaves.

As with all noise control, the line of sight between the source and the people suffering needs to be blocked. A good proportion of the noise from a generator is actually from the exhaust, which is typically sited on top of the generator itself. We therefore recommend a combination of sound control measures to deal with the specific noise from the exhaust and then the generator as a whole.

Below, a generator has been wrapped by RVT Group’s SOUNDEX® Generator Enclosure. This delivers noise attenuation of between 14.9dB at 50Hz to 59.9dB at 5000Hz. In addition, an A2/3 Soundex Exhaust attenuator sits on top of the generator to subdue noise from the exhaust outlet.

Excavator with Breaker Attachment

An excavator fitted with a hydraulic breaker attachment is very effective at breaking up concrete, tarmac and the like, but also extremely loud– well in excess of 100dB. This repetitive loud noise is often continued for a long period of time and is very intrusive for those in homes, shops or offices nearby.

The best solution here is an enclosure that surrounds the breaker as much as possible without impeding the work. The enclosure achieves the aim of containing the noise as close as possible to the source, but can also easily be moved, enabling it to follow the breaking work as it moves across the site.

Below is the SOUNDEX® Breaker Shroud, it features 3 acoustic barrier walls and a roof, with an open side for heavy machinery operation, reducing noise by up to 32.3dB. The superior noise retention of the acoustic shroud takes the pressure off of additional noise control requirements when using breakers or similar equipment on your project.

Sawing/Cutting

The noise generated from machines used in the process of sawing and cutting can easily exceed 100 dB(A), leading to health and safety risks for workers and disturbance to those nearby.

The process of cutting materials on a project requires the use of high powered equipment that regularly attracts complaints, owing to its distinctive, sharp sound. Though it is possible to isolate the machinery to one portion of the site, the high-decibel nature of the process means that during cutting, the sound is easily audible over general construction site activity.

To be effective in minimising the sound produced, the solution used must be able to contain the sound around the source. While this can take the form of acoustic panels being setup around the site of work, an even better solution is often to carry out cutting work within an acoustic enclosure. This will contain the noise on all sides, including over the cutting activity, and has the additional benefit of being easily relocated around a site as the need dictates.

Below shows RVT Group's SOUNDEX® Cutting Enclosure, an all-round acoustic cutting station certified to reduce noise by up to 33.6 dB and complete with cutting deck, side ports and dust extraction vent.

Hand-Held Breakers

A heavy-duty, hand-held breaker regularly operates at dangerously high decibel levels. The potential health risk posed by this piece of machinery has led to a government directive, specifying that hand-held breakers must not be able to exceed 105 dB/1 pW. Evidence suggests any exposure to sound levels in excess of 85 dB(A) can cause hearing loss meaning the hand-held breaker must be used in conjunction with sufficient noise control measures. While the breaker operator will be protected by PPE, protecting other workers and nearby members of the public requires other measures.

As the hand-held breaker is commonly used in isolated areas of a construction or infrastructure project, we advise that the control measures put in place be both light weight and easily erected, so as to be adaptable to the ever-changing environment.

Small generators and compressors

Generators and compressors are capable of producing high levels of noise at low frequencies. The challenge that this presents is that lower frequencies of noise can travel across longer distances, resulting in greater disruption across a wider area. The use of compressors and generators often accompanies construction or infrastructure work in noise-sensitive areas, potentially throughout the night. This makes the use of noise control designed to counter low frequency noise crucial to ensuring minimal disruption.

Below shows RVT Group's SOUNDEX® Generator Exhaust Attenuator out on site, designed primarily for generator exhaust, but can also be used for enclosing smaller items of plant.

In conclusion, it's important to consider the risks to workers the public when exposed to noise from your project. RVT Group provide a range of noise control solutions that are suitable for an array of projects across the UK, and offer free hazard control assessment if you're struggling.