Can Indians be less loud? : 07 Apr 2008

Can Indians ever be less loud?
By Maxwell Pereira

Mumbai Police’s initiative to observe a 'No Honking Day' on Monday April 07 has a deeper message. It being World Health Day, it aims to focus on noise pollution that impacts citizens’ health. In their initiative, a host of NGOs, automobile associations, as well as schools and colleges were roped in to sensitize motorists about the campaign. Also the local FM radio stations and a lot of publicity through hoardings, banners, posters and stickers across the city to promote their appeal, asking motorists to abstain from honking for a day.

Not many are conversant about noise pollution laws. Basically noise levels above 80dB (decibels) are considered detrimental to healthy hearing. And for normal tension free conversation one requires a background noise level of <55dB.

However, Government itself is the first violator of these norms – since noise standards prescribed in the Central Motor Vehicle Rules–1989 (CMVR) for most categories of vehicle are above 80dB. Except for petrol-driven two-wheelers for which the limit is 80 dB(A), for passenger cars and other petrol-driven vehicles it is 82 dB(A). For passenger or LCVs including three-wheeled vehicles with diesel engines upto 4000 Kgs. – 85 dB(A); for passenger or commercial vehicles above 4000 and upto 12000 Kgs - 89 dB(A); and above 12000 Kgs. - 91 dB(A).

Compared to this, the acceptable noise levels prescribed in USA by the Federal Highway Administration are – for parks and open spaces, the exterior limits to be not above 60 dB(A), for residential areas within the buildings - 55 dB(A) and outside the buildings - 70 dB(A) and for other developed areas 75 dB(A).

Noise has been defined variously. Physically, ‘Noise is a complex sound with little or no periodicity’. Acoustically, ‘Noise is defined as a signal that bears no information and whose intensity varies randomly and in time’. Psychologically, ‘Noise is any sound which is unpleasant or unwanted’. Commonly, it is the last definition that affects and touches every soul.

Increasing urbanization has led to mounting volumes of noise, intruding upon the quality of life and privacy of urban dwellers. The annoyance and discomfort caused by noise at times assume serious proportion meriting urgent attention.

Noise is conventionally measured in terms of the pressure of sound wave. All government authorities and international standards specify exposure levels in terms of decibels applicable over an eight-hour exposure, with a peak exposure level. Noise in cities is a result of a number of activities and factors such as road traffic, aircraft, railways and industrial and constructional works. Widespread prevalence of high intensity levels of sound from all these activities in our environment is termed as noise pollution.

Without going into the wide gamut of noise sources, let me herein tackle noise emanating from road traffic. The generation of noise from automobile machinery as well as the widespread use of horns is a major contributor to the level of ambient noise in Indian cities today.

Detrimental effects of traffic noise can be under 3 major groups – subjective, behavioural, and physiological. Subjective effects are annoyance, disturbance, dissatisfaction, bother and noisiness – difficult to measure precisely, because of wide variation among subjects in describing what level of sound causes them discomfort. Behavioural effects cover – interference with sleep, speech or any general task. Noise wakens people, or impairs quality of sleep and its duration. Sleep disturbance is common in high noise areas where it takes longer to fall off to sleep with greater chances of waking up. Noise can cause interference in speech and in the enjoyment of audio and visual programmes; also cause disturbance in studies and intellectual pursuits. It can upset balance between stress and recuperation and thus cause chronic fatigue, reduced efficiency and increase incidence of ailments.

Physiological effects are those that startle or cause fright phenomenon that can result in harmful effects on various parts of the body. Exposure to noise can raise blood pressure; accelerate heart rate, contract blood vessels; increase muscular tension and at extremely high levels and long periods of exposure, may produce deafness.

Noise caused by road traffic can be – that from various parts of the vehicle; that contributed by interaction between vehicle and road surface; and noise dependant on speed, and flow or density of traffic. Contributing elements from the vehicle itself being – engine (power unit, especially during acceleration); the inlet and exhaust; propulsion and transmission including gears and brakes; the horn; the chassis and body structure; the load factor in the vehicle and also ‘door slamming’. In effect, the horn is just one of the contributors!

Two-wheelers are generally noisier than cars. Commercial trucks worse, because of the larger horse power of the diesel engine and the heavy loads they carry. As vehicles grow older and their mechanical conditions deteriorate, their noise condition becomes more. In tyre/road-surface interaction, smooth surfaces generally produce less noise than rough ones. Grooved cement concrete pavements and wet surfaces too being a source of annoying noise to the neighbourhood.

As traffic increases, the noise level inevitably rises. Higher speeds cause higher noise levels – at lower speeds influence of engine and transmission more predominant – at high, the tyre-surface interaction assuming greater importance. Noise levels increase during acceleration.

Control of traffic noise can be considered with – changes in vehicle design; changes in tyres or road surfaces; elimination of noisier vehicles; modification in traffic operations and designing streets, buildings and areas that produce less noise. Changes in tyre-tread design and composition can reduce noise. Smoother surfaces result in less noisier roads – but this has simultaneously to be balanced against the required skid resistance factor of the tyres too. And legislative measures can prevent old vehicles from being used on roads.

Measures possible in traffic operations are – re-routing of commercial vehicles and buses to the extent possible from predominantly residential areas; providing bypasses on Ring Roads to siphon-off through traffic entering town; providing synchronized traffic signals to reduce the ‘stop and go’ traffic flow and consequently eliminating acceleration noise; and prohibiting the blowing of horns by proper signage and enforcement strategies. In addition to standard silent zones, the Delhi Traffic Police in 2002 banned honking at all signalized junctions too.

The CMVR require a motor vehicle to be fitted with an electric horn for purposes of warning only. It specifies against the use of any multi-toned horn or other sound producing device giving an unduly harsh, shrill or alarming noise. Ambulances, fire engines, salvage vehicles or those of police and motor vehicles department are permitted the use of such sound signals (sirens) as may be approved by the authority. Every motor vehicle is required to be fitted with a silencer to reduce to the extent practicable the noise that would otherwise escape from exhaust gases. The Rules of the Road Regulations – 1989 further prohibit a driver from sounding the horn needlessly or continuously or violate the silence zone regulations; or drive a vehicle that creates noise when in motion; and against driving a vehicle with a defective muffler causing alarming sounds.

April 07, 2008: copyright (c) Maxwell Pereira