Actualizado: 17 de abr de 2019
A lot has been said about parking lots (or car parks as it is commonly called here), but paradise is not one of them. The scarcity of vacant lots, ridiculous rates and encounters with ill-mannered drivers jostling for a parking space, seem far from a blissful scene. It gets worse when it is underground. The overwhelming acrid humid air from poorly ventilated underground space, the loud and excessive noise and the safety risks, are known to cause some degree of unpleasantness, even to the very best of us.
The rise of underground car parks
As new buildings are developed in various parts of the city, predictions are ubiquitous that more underground car parks are to be built, too. Defined as under a street or an open space and as a basement to a building which includes any floors constructed under ground level, the need to build underground car parks is augmented by the limited resources of land for development. It is also preferred over a separate elevated multi-storey car park complex, as it helps preserve the aesthetic value, as well as, retain the environmental desirability of the development. New environmental-friendly regulations, too, seem to pave the way for underground car parks. For example, Kuala Lumpur city, in its bid to be greener, will have no more open car parks in 20 years’ time. Dr. Azmizam Abdul Rashid, Director of Knowledge Management and Advisory of Urban Wellbeing Centre of Excellence (Urbanice) Malaysia, in the 9th World Urban Forum, in February this year, said, “with the green innovation plan, 30% of the city would be green areas.”  This green initiative signals that the only possible way to meet the rising demand of car parks is to go under.
The perils of underground car parks
Yet, the bane with underground car parks are the two major pollution issues: air and noise. While much has been said about air pollution, noise remains unbridled; largely ignored, despite being a significant problem.
Underground car parks produce strong reverberant effect that is harmful to its patrons. Its huge enclosed space creates insufficient natural ventilation. Along with its hard-surfaced walls and floors, architectural structures, frames, pipes and ducts, the enclosed space traps, reflects and amplifies noise manifold, as compared to noise in an open space. Underground car park patrons absorb most of these reverberant sounds, often dangerously exceeding the 55 decibels (db.) recommended by the World Health Organization (WHO) External Noise Criteria.
The Pain of Noise
The World Health Organization (WHO) in 2011, analysed environmental noise from planes, trains and vehicles, as well as other Western Europe city sources, that looked at links to health conditions such as cardiovascular disease, sleep disturbance, tinnitus, cognitive impairment in children, and annoyance. The results, published in “Burden of Disease from Environmental Noise” found that “at least one million healthy years of life are lost each year in Europe alone due to noise pollution and that while other forms of pollution are decreasing, noise pollution is increasing.”
Not surprising, the number of people affected by noise induced hearing loss is on the rise, too. In America alone, a CDC study in 2011-2012 on Noise Induced Hearing Loss found at least 10 million adults (6 percent) under age 70 and perhaps as many as 40 million adults (24 percent) have features of their hearing test that suggest hearing loss in one or both ears from exposure to loud noise. It goes on to state that repeated exposures to sounds at or above 85 db will cause hearing loss. Motorcycles emit sounds of 95db and the heavy city traffic is at 85 db. It is not uncommon then, to have noise at or above 85 db in underground car parks as the barriers, concrete structure, hard surface compounded its effect. Figure 1A below shows how our ears are prone to damages from loud noise.
Additionally, prolonged exposure to excessive and loud noise is an occupational hazard to those who work in the underground car parks including cleaners, car wash attendants, parking attendants and for those whose offices are located underground such as the Human Resource Department and Engineering Department as in the case in some hotels. Aside from its imminent risk of a hearing loss, noise is known to have adverse effects on mental and physiological health; causing lack of focus, disorientation, hypertension, elevating stress levels, increasing heartbeat frequencies, causing palpitations and breathlessness, and in some cases, gastrointestinal problems, too.
By virtue of its design, underground car parks pose safety risks, too. It has many perfect spots for hiding especially, in poorly lit places. Combined with loud noises coming from mechanical and electrical equipment, such as air conditioning units, pumps and generators, that are usually placed in the underground level, these noises could potentially drown any screams for help. In a National Crime Victimization Survey (NCVS) conducted by the US Bureau of Justice Statistics, more than 1 in 10 property crimes occur in parking lots or garages. Roughly 80 percent of the criminal acts in shopping centres, strip malls and business blocks occur in parking lots. Apart from that, loud noise may mask the sound of approaching cars and lead to accidents. Evidently, the inability to hear your surrounding distinctively exposes you to danger.
So, if it is just noise, surely it is easy to control? Well, yes and no. The impermanence nature of noise and the multiple ways it is distributed across spaces makes assessing it difficult. It is almost impossible to pin down noise in underground car parks to just a single source. You will need a trained and experienced acoustic engineer or noise control specialists to correctly assess, evaluate and recommend the right solutions to control noise levels.
For example, within a parking space, noise is emitted from movements of vehicles maneuvering within the space, closing of doors and boots, starting or revving and idle engines. Then, there are additional noise from trolleys in shopping complexes, footsteps from passing pedestrians, car audio music, chatting or talking over phone; that varies greatly at different parts of the car park. The type of vehicle used also emits different noise levels. Larger four-wheel drive understandably emits louder noise than a saloon car.
Underground car park noise depends on the time of the day, too. Some car parks experience heavy traffic only at a specific time of the day, for instance car parks in office blocks, will see more cars in the mornings and evenings which corresponds with the office working hours. Similarly, shopping complexes and entertainment spots such as restaurants, hotels, clubs, record higher readings after working hours.
The next challenge in assessing noise emission lies with the car park facades. Different build up and geometric spaces of the car park, materials used for floors, concrete barriers, ramps, wall and ceiling insulation will greatly influence the reverberating effect.
Proximity to entrance
Parking spaces located nearby to entrances contribute a higher noise level. Similarly, loading bays generate more noise due to the frequent and intense activity of unloading and loading goods from heavy vehicles.
Despite the dire need to control noise in underground car parks, there is unfortunately no law set out in building codes or other statutory documents for buildings in relation to sound levels or sound transmission. The onus is on the developer, property management and the statutory limits agreed in the building lease agreement, to determine whether or not a noise has become a problem that needs to be remedied. Often this discretion is poorly exercised with the excuse that the noise is considered normal and acceptable. A remedy is initiated only when there are complaints from patrons.
In order to avoid potentially complicated (and often expensive) consequences, it may be worth having an acoustic expert or a noise control specialist to assess and determine if the noise transmitted in your underground car park is beyond its reasonable limit. This is highly recommended for noise sensitive receivers (NSR) that requires mitigation efforts such as domestic premises, educational institutions, hospitals and clinics, hotels and hostels. An experienced noise control specialist will study the ducting and structure layouts, positioning of equipment and road surface materials and make necessary mitigation design recommendations. Usually through assessment, we are able to determine if walls or floor assemblies tested meet building code criteria or are properly insulated against noise. The right noise control measures will then be implemented to achieve the desired noise criteria within the parking space, hence ensuring a safer and more comfortable underground parking experience.
1. Burnett, J. and Chan, M.L, (1997), Air Quality in Enclosed Car Park, The Hong Kong Polytehcnic University
2. The Sun Daily, No more open car parks in KL in 20 years Posted on 13 February 2018 - 05:56pm (http://www.thesundaily.my/news/2018/02/13/no-more-open-car-parks-kl-20-years
3. http://www.who.int/quantifying_ehimpacts/publications/e94888/en/ Burden of Disease from Environmental
4. National Institute on Deafness and Other Communication Disorders (NIDCD), NIDCD NIH Publication No. 14-4233
5. Parking lots, garages can be dangerous; know the risks Posted on Monday, September 30, 2013 (citing National Crime Victimization Survey (NCVS) conducted by the U.S. Bureau of Justice Statistics)
If you would like to know how to mitigate the noise level in your underground car parks, we are ready to assist and partner with you in finding the right solutions. Engage us at email@example.com
KSM Group (www.ksmgroup.co) provides proven noise control solutions to commercial and industrial sectors and are dedicated to making our environment smarter and more efficient for the future.
KSM Group are specialists in the Electrical, Instrumentation, Noise and Vibration control sectors, dedicated to making environments smarter and more efficient. Established in 1983, KSM Group has since evolved from a humble electrical company to trusted distributed and partner to some of the world’s biggest brands. In addition, we design and manufacture our Phoenix range of in-house noise control equipment. We are the first local manufacturer of top quality blowdown silencers. We achieve ISO 9001 recognition in 2000, a global standard for quality management systems. Our testing lab is the first in Malaysia for air distribution system silencers based on ISO 7235.