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Silence is golden

September 23, 2015

Noise pollution, particularly in urban environments, is an area of growing concern. Fortunately, the volume is being turned down at large industrial sites.

You might think of noise pollution as a mere annoyance. Loud construction work on city streets, for example, is usually no more than a temporary, frustrating distraction – most often departing from our daily lives as swiftly as it enters. We may also associate the phrase with loud music being played in public places, an imposition for the more sensitive passersby. Distracting yes, but hardly a social problem worth discussing on the governmental level. 

But in fact, noise pollution is a more serious and potentially dangerous problem than is commonly understood. According to the World Health Organization (WHO), one in five residents of the EU is regularly exposed to sound levels at night that could significantly damage their health. 

Clear evidence is growing that noise may cause emotional responses such as anger, anxiety and depression, particularly when in relation to sleep disturbance. In the case of children, exposure to excessive noise has been linked to such conditions as learning difficulties, and motivation and attention deficits. Some researchers have even suggested a connection to heart disease.

The perception of noise as a problem deserving of legislative attention began in the 1970s, when the EU first launched a directive on vehicle noise. In the same decade, the first noise-related laws were enacted in certain US states.

Despite developments like these, by the late 2000s, the number of documented noise pollution complaints had nevertheless reached staggering figures. In the UK alone, councils reported receiving complaints about noise pollution from private residences in the hundreds of thousands. High-profile court cases reached as high as the European Court of Human Rights. The general public had clearly woken up to the problem. And they weren’t alone.

THE INDUSTRIAL RESPONSE 

In industry too, concerns have gradually risen in step with those of the general public. As well as the impact of industrial sites on neighboring residential areas, there is the effect of noise on machinery operators and other personnel to consider. Konecranes has been a forerunner in noise reduction technology in the lifting industry, recognizing the rising tide of both social and industrial awareness. 

Ari Nieminen, Chief R&D Engineer for the Port Cranes business unit at Konecranes, charts the growth of concern over noise and describes the core noise-related issues in Konecranes’ lifting equipment:

“Noise is problematic in two main ways. The most pressing dimension is environmental noise. Here the current tendency is to apply more and more strict requirements, to port areas in particular. This has been a growing concern worldwide over the last decade, driving the need for equipment suppliers to create less noisy machines.

“Then there is the question of occupational health in the workplace,” he continues. “Operators in crane cabins, of course, experience noise in their daily work most of the time, but there are also the assisting workers around the crane to take into account, as well as the service technicians visiting the machinery rooms.”

NEIGHBORLY CONSIDERATION 

In response to this multi-faceted challenge, Konecranes has been placing an ever-increasing emphasis on noise reduction in its R&D work. In a world that is gradually becoming more aware of the problem, this is becoming a point of differentiation for the company.

In Oslo, for example, the city’s highly active harbor is in close vicinity to residential areas. While the town’s inhabitants enjoy the benefits of its constant cargo flow in terms of both imported goods and the sheer volume of business that the site brings, the importance of noise reduction cannot be overstated. 

Svein Olav Lunde, Chief Technology Officer (CTO) at the Port of Oslo, underlines the criticality of this consideration during the port’s partner selection process: “When we prepared our specification for new harbor cranes,” he says, “we put in place very hard criteria on noise. In fact, noise-related criteria were among the primary factors in our evaluation of bidders in the tender phase.” “We have been in the port for decades,” Lunde explains. 

“We have a great deal of shared experience with our residential neighbors, and nowadays we even employ a consulting company to manage our dealings with the issue of noise and handle those activities in our daily business. That’s how important the topic has become.”

The requirements to reduce noise pollution in Oslo may represent an extreme case, but it is one which the world’s port cities are no doubt observing closely. The permitted level of emitted noise from a single harbor crane is, by one account, comparable to that of a normal car. When one sees the residential buildings less than 300 meters from the site, the reasons for such strict regulation are perfectly clear. People really do live in close proximity to the port’s equipment, which runs day and night.

Far from interpreting neighborly intervention in its affairs as a threat, the Port of Oslo has welcomed the input of the city’s inhabitants to shape the technological footprint of the site. “We have been fully committed from the beginning,” Lunde affirms. “We realized that we must have the best available technologies, and by calling attention to the problem with our suppliers and making targeted investments, we were sure a solution would be found.” This is one determining factor in their choice of Konecranes as a crane supplier in April 2014.

When planning the expansion of the port, which necessitates the addition of two shipto-shore (STS) container cranes, the port’s noise reduction portfolio was under intense scrutiny. “Konecranes demonstrated an understanding of the big picture,” Lunde tells us. “They showed that they understand the noise problem and they know how to find working solutions. Their presentation and specifications showed them to be among the best crane suppliers where noise is concerned.” 

DEVELOPING QUIETUDE 

But what precisely can you do to a crane to win the confidence of one of the world’s most noise-conscious customers? Nieminen talks us through Konecranes’ development work on the path to quiet crane operation. First, the basics: the crane’s main sources of noise. “In terms of noise emissions, our larger cranes have sound sources like electric drives and motors, machinery, and gears. Noise is also emitted from electric power supply components.” 

As well as the components themselves, the load-carrying steel structures upon which the equipment works are very prone to emitting unwanted sound. “Traditionally these structures are optimized for strength and fatigue resistance,” Ari explains. “When taking noise into consideration, we have to optimize backwards – to look at the situation from an engineering point of view, typical steel structures are too efficient as noise radiators.” 

Getting to the root of the noise problem involves examining the details, analyzing how the structures are constructed at a detailed level, and employing more material in areas from which noise is easily radiated. Stiffeners can be used to dampen vibration, and sound barriers can be built at key positions on the crane’s structure. Special joints can also be used, to prevent the structure-borne noise from traveling from one part of the structure to another. 

However, whenever possible, the primary method is to reduce noise directly at source, by selecting a more silent component. Konecranes builds cranes with many components that it designs and manufactures in-house, so the company can purposefully select and install components that intrinsically produce less noise. 

THE DEVIL IS IN THE DETAIL

Ari emphasizes that noise reduction work has to be undertaken for every component, not just the obviously large candidates. “It’s understandable to be drawn to the hoisting mechanism: it’s very big and noisy, and it’s a significant part of the investment. You can tackle that first, but you shouldn’t neglect smaller components like the walkways, which are very simple steel-plate structures. They can radiate as much noise as the larger parts if they are manufactured and installed incorrectly. Every detail of the crane must be examined when reducing overall noise output.”
 
Finally, more speed and power means more noise in the majority of cases, so equipment can be operated in lowspeed modes to reduce sound output. This is one of the techniques that have been brought to bear in Oslo, where the speed of machinery is slowed at night to ensure the site’s noise emissions adjust to the surrounding environment’s ambient level. While noise reduction has evidently been subject to a wide-ranging, inquisitive investigation by Konecranes and others, it should be observed that the process is far from complete.
 
Active Noise Control (ANC), for example, a method for reducing unwanted output by the addition of a second sound specifically designed to cancel the first, has yet to be applied to cranes. Technologies such as these could have a transformative role for industry in general, particularly as regards the central problem of the Oslo case: its proximity to urban dwellings.
 
Another emerging research area is centered upon the distinct qualities of noise. Not all noise is the same, and people may react to certain varieties of sound in more extreme ways. By changing the quality of noise a crane is emitting to one less distracting or unpleasant to people, the problem could be moved into a wholly new context. Rather than considering sound volume alone, the type of sound being emitted could also become a consideration.
 
Whichever technique or development finds application in the wider world, one fact can be relied upon: the problem of noise isn’t going anywhere. With populations in both developed and emerging economies less and less willing to tolerate loud disturbances, the future will almost certainly sound better than today. 
 
 
Text: Ian Fenton
Photos: Port of Oslo and Shutterstock
 
 

TIMELINE

The EU recognizes noise as one of the region's most pressing environmental and health problems, with an impact second only to poor air quality. Here are some of the EU's key actions to control noise emissions.

  • 1999 The World Health Organization (WHO) released EU Guidelines for Community Noise, which addressed sources of noise in communities and acknowledged the effects of noise as a serious health problem.
  • 2002 The EU Directive on Environmental Noise required countries to map noise hotspots and reduce exposure and made periodic reporting obligatory for member states.
  • 2004 July 18 – the date by which EU Member States were expected to have laws, regulations and administrative provisions in place in order to comply with the Directive.
  • 2009 The WHO’s Night Noise Guidelines provided evidence and recommendations that European countries could easily use to introduce targeted limits for night noise.
  • 2010 Through the Parma Declaration, the EU and the WHO committed to reducing children's exposure of to harmful noise in different settings, including noise from electronics, recreation and traffic.