[sustran] noise in Bangkok

[Paul Barter]

The June 16, 1997 on-line edition of the Bangkok Post has an interesting
item on noise pollution in Bangkok. Here are a few excerpts:

"Driven mad by noise" by Marie Lamboray

There's no escaping the roar of traffic but sound barriers are helping to
reduce its impact.  Do you feel stressed, easily irritated and tired? Is
your work productivity declining? Believe it or not, noise may be the
culprit?
.....
Ura Siranoot, 17, arrived in Bangkok three months ago from Surin province.
She spends practically all her time under the expressway in Klong Toey,
working in a bicycle shop and sleeping in a small room in the slum
community.  "This is so different from where I lived," she says.  The noise
is "awful", she says, especially at her workplace where she has to endure
noise from three sources - the main road, the train, and the expressway.
It is so bad her ears hurt. So she tries to escape "by listening to music
with my walkman."

 But noise on highways or expressways can be reduced with noise barriers.
Some of them can be seen along some sections of the Bangkok expressway
system.  Most areas on the first stage of the expressway has been left
unprotected, however. Sonthi Kochawat of the Office of Environmental
Planning and Policy (OEPP) explains that this is because when the
Expressway and Rapid Transit Authority of Thailand (ETA) constructed the
first stage, the 1992 Environment Act was not in effect. The act has a
provision on noise pollution.

 In the second stage, however, the Bangkok Expressway Public Company
Limited (BECL) installed three kilometres of noise barriers, giving
priority to high-density residential areas, temples, and schools.  A reason
why more noise barriers were not installed is they are expensive.  The
least expensive barriers have reflective or dispersive surfaces which help
reduce noise by 15 to and 20 decibels (dB).  Absorbent barriers are most
effective, reducing noise by 30 dB. Their diamond shaped lattice screen
absorbs the traffic noise. They are indispensable in high-rise building
areas.
.....
 Barriers found along the Bangkok expressways are dispersive type which an
expert says is not appropriate in an urban environment. According to Lim
Siak Piang, supervisor of the Acoustic Laboratory at the National
University of Singapore, these barriers reflected noise upward, toward
nearby buildings.

Mr Sonthi, who heads the monitoring section of the Environment Impact
Evaluation Division, explains that two standards are used to control noise
pollution on the expressway - the hearing loss standard or the annoyance
standard.  When the noise level exceeds these standards, the expressway
construction companies have to install noise barriers.  The hearing loss
standard is 70 dB. All of the 14 monitoring stations installed by the OEPP
on the Bangkok Expressway System record noise levels higher than 70dB.
........
 In buildings located next to Expressway, floor levels higher than the
expressway receive direct traffic noise magnified by reflected or dispersed
noise from the barriers.  Tall barriers could minimise the problem, says an
expert. Dr Kohei Yamamoto, director of the Kobayashi Institute of Physical
Research in Tokyo, says the efficiency of noise barriers increases as the
barrier's height increases.  In Japan, extremely tall barriers have been
built along expressways. However, he says they cause secondary problems of
poor sunshine or television broadcast reception. Researchers are studying
how to build low barriers with high efficiency for noise reduction.  To
protect their business against traffic noise, private hospitals, hotels,
and office buildings invest a lot of money to insulate their buildings.
......


A. Rahman Paul Barter
Sustainable Transport Action Network for Asia & the Pacific (SUSTRAN)
Until 15 July I am in Perth, Australia.
During that time please reach me at <barter at central.murdoch.edu.au>