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Assessment of Roadway Noise Level and Potential Mitigation Measures

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Sayeeda Bint Ayaz

Dept. of CE, Dhaka University of Engineering & Technology (DUET), Gazipur, Bangladesh

and

Md. Mafizur Rahman

Dept. of CE, Bangladesh University of Engineering & Technology (BUET), Dhaka, Bangladesh

 

ABSTRACT

 

Noise,  commonly  defined  as  an  unwanted  sound,  is  an  environmental  phenomenon  to  which  human  are  exposed throughout  their  life.  Noise  can  also  be  considered  an  environmental  pollutant,  a  waste  product  generated  in conjunction with various human activities. Noise is not simply an annoyance rather a hazard to one’s physical and mental  well-being.  This  study  attempts  to  assess  the  traffic  induced  noise  and  suggests  some  mitigation  measures which  are  likely  to  reduce  the  level  of  noise.  Maximum,  average  &  minimum  noise  levels  are  measured  at  some severely exposed as well as sensitive locations of Dhaka city. The collected data are analyzed using GIS symbological analysis. Results reveal that level of noise at roadside exceeds the allowable limit to a great extent even in the sensitive locations  like hospital, school,  mosque etc.  The  deviation from standard  limit  is found awfully  high.  There exists a constant  level  of  pollution  resulting  from  unbounded  movement  of  traffic  throughout  the  city  due  to  commercial, social,  educational,  recreational  and  other  activities  at  working  as  well  as  holiday.  This  alarming  level  of  noise  is signaling to take immediate measures. Several measures are proposed which include staggered timing of schools and jobs,  flexible  work  schedule,  planned  tree  plantation  along  footpath,  construction  of  noise  barriers  etc.  Along  with these, enhancing mass consciousness and implementation of proper monitoring system may significantly reduce the level of noise.

 

1. INTRODUCTION

 

With    rising    population    growth,    the    urbanization    in Bangladesh is also taking place at a quick pace. The current population  of  the  country  stands  at  140.5  million  out  of which  12.7  million  people  live  in  the  capital  city,  Dhaka. One estimate says by 2050, 57% of people will be living in cities,  compared  to  26%  in  1990.  By  2015,  Dhaka  may become   one   of   the   densest   cities   of   the   world.   The unplanned                         urban        development  coupled  with        urban population growth result in increased demands for transport and in turn vehicle induced noise contributes to problems of high noise levels [1].

 

Noise  is  any  sound  –  independent  of  loudness  –  that  may produce an undesired physiological or psychological effect in an individual and that may interfere with the social ends of an individual or group.

 

Noise  pollution  can  be  defined  as  unwanted  or  offensive sounds that unreasonably intrude into our daily activities. It has many sources, most of which are associated with urban development: road,  air  and  rail  transport;  industrial  noise; neighborhood  and  recreational  noise.  A  number  of  factors contribute to problems of high noise levels, including:

i.  Increasing   population,   particularly   where   it   leads   to increasing   urbanization   and   urban   consolidation   and activities  associated  with  urban  living  generally  lead  to increased noise levels.

ii. Increasing volumes of road, rail and air traffic.

Community awareness of environmental noise  has increased and there is a higher expectation for commonwealth, state and local government to reduce noise levels.

 

Although noise is a significant environmental problem, it is often   difficult  to   quantify   associated  costs.  An  OECD report  on  the  social  costs  of  land  transport  identified  four categories of impact from transport noise (OECD 1995) as

i.   Productivity   losses   due   to   poor   concentration, communication   difficulties   or   fatigue   due   to insufficient rest

i.    Health  care  costs  to  rectify  loss  of  sleep, hearing problems or stress

ii. Lowered property values

iii. Loss of psychological well-being

 

1.1 Sources of Roadway Noise

 

Noise  on  roads  is  caused  by  engine  of  the  vehicles,  its exhaust, horn, brakes, friction between   tires   and   road surface.  Noise  from  the  motors and exhaust  systems  of large  trucks  provides  the  major  portion  of  highway  noise impact, and provides a potential noise hazard to the driver as well. In the city, the main sources of traffic noise are the motors and exhaust systems of autos, smaller trucks, buses, and motorcycles. This type of noise can be augmented by narrow streets and tall buildings, which produce a "canyon" in which traffic noise reverberates [2].

 

The noise from locomotive engines, horns and whistles, and switching and shunting operations in rail yards can impact neighboring    communities    and    railroad    workers.    For example,  rail  car  retreads  can  produce  a  high-frequency, high-level screech that can reach peak levels of 120 dB at a distance of 100 feet (EPA, 1974), which translates to levels as high as 138 or 140 dB at the railroad worker's ear [3]. In Dhaka  vehicles  create  95  decibel.  Microphones  about  100 dB(A) , scooters 80-90 dB (A) and trucks or buses 92 to 94 dB (A) [4].

 

1.2 Noise problems in Bangladesh

 

In Bangladesh noise problem is severe due to some special reasons   which   includes,   vehicles   horns   are   abused   by drivers,  horn  is  used  to  get  right  of  way,  strength  of  horn decides the power of vehicles, existence of non motorized vehicle on the same track encourage the use of horn, many vehicles   have   no   side/rear   view   mirror   especially   non motorized  vehicles-  compel  follower  to  use  horn,  use  of hydraulic  horn,  most  drivers  like  horn  signal  than  light indicator signal for lane changing.

 

1.3 Health Effects in Dhaka City

 

The  survey  regarding  noise  pollution  was  performed  by Geography  &  Environment  department  of  Jahangirnagar University.  100  people  were  interviewed  among  different professionals  like  doctor,  traffic  police,  driver,  teacher, student, businessman and service holders. It was found that all  of  them  were  invaded  with  diseases  due  to  excessive exposure of noise pollution [5].

 

The diseases which attacked among 100 people were as bad headache, temporary hear loss = 12.31%, fatigue = 17.58%, insomnia  =14.36%,  irritability  =  27.57%,  hear  diseases=25.80%, others = 2.64%

 

Therefore, if the prevention of environmental pollution and the  preservation  of  the  nature  i.e.  environment  are  to  be achieved,   then   consideration   for   the   environment   must become  an  indispensable  part  of  the  development  of  road plans. Especially for a city like Dhaka which has over the years   grown   into   a   mega   city,   the   roadside   pollution problem   is   severe   and   is   reported   to   be   serious   and damaging to public health.

 

1.4 Acceptable Limits of Noise (Bangladesh Standard)

 

To  combat  the  hazards  of  noise  pollution,  standardization and   fixation   of   tolerance   limits   of   noise   pollution   is essential.  The  acceptable  noise  levels  for  different  areas recommended  by  Bangladesh  Department  of  Environment (DOE) are as shown in Table 1.

 

 

2. OBJECTIVES OF THE STUDY

 

The  objective  of  this  study  is  to  investigate  the  level  of noise pollution produced from traffic vehicle movement for a selected zone in Dhaka city from the perspective of public health and transportation planning. The above objective of the study thus focuses on the following specific objectives as follows:

 

i. Study   of   the   existing   condition,   effects   and mitigation of roadside noise pollution.

ii. To  evaluate  the  maximum,  average  &  minimum noise level at different points for both working and holiday in the study area.

iii. To   determine   whether   the   noise   level   at   a particular  place  is  unacceptable  limit  or  not  with respect  to  maximum,  average  &  minimum  noise level for both working day and holiday in the study area.

 

3. METHODOLOGY

 

The method was designed and conducted in such a way that it  accomplished  the  basic  requirements  for  a  successful research work as follows:

 

i. The first was the attempt of spreading of the data collection  effort  in  different  areas  in  such  a  way that   the   obtained   results   may   be   regarded   as representative of the actual situation.

ii. The   second   was   the   attempt   of   collection   of enough  data  to  allow  conclusions  to  be  drawn regarding   level   of   noise   pollution   in   different areas.

iii. The third was the attempt of making maps of the affected  areas in  various  levels  of noise pollution in the study zone using GIS.

iv. The fourth was the attempt of analyzing the level of noise pollution using GIS.

 

3.1 Field Survey and Data Collection

 

A  preliminary  survey  was  performed  in  order  to  get  an overall idea of the study area and also to prepare a schedule of  the  data  collection  procedure  of  the  entire  area  in  a systematic way.

 

3.2 Site Selection

 

The  site  selection  was  done  in  such  a  way  that  almost  all categories  of  noise  affected  areas  could  be  represented  in this study so that the scenario of noise pollution in Dhaka city  could  be  reflected.  These areas  were  taken  as  per  the recommendation of Bangladesh Department of Environment (DOE).

 

The study location was a part of Dhaka city which included mainly Ramna Thana. Fig. 1 and Fig. 2 show the location map of the study area. Site location points were shown in the map. Data were collected at 48 places.

The data collection places were as follows:

T.S.C,   Charukola   Bhobon,   I.B.A   Building,   Shahabag, BSMMU    (Main    Gate),    BSMMU    (Inside),    Sheraton, Telecommunication   Building,   Padma   Officers'   quarter (Poribag), Opposite Side of Manob Jomin (Bangla Motor), 21/3-Banglamotor  (World  Literature  Centre  Side  Road), Banglamotor intersection, Sonar Tori Building, Janakantha Bhaban,   Holy   Family   Medical   College   &   Hospital, Opposite  Side  of  Judges  Residence  &  Newly  Constructed Building,  Eskaton  Garden  Officers'  Quarter,  Mintu  Road intersection   (Sheraton   End),   Mintu   Road   intersection (Moghbazar  Road  End),  Orunodoe  Gate  (Ramna  Park), Ramna  Botomul,  Ostachol  Gate  (Ramna  Park),  Kakrail Mosque,  Matshaw  Bhobon,  Supreme  Court,  Press  Club, Doel   Chattar,   Three   Leaders'   Mazar,   PWD   Building, Ramna  Lake End  (Near  Ostachol  Gate),  Sishu  Park,  Over Bridge of Ramna Park, High Court intersection, High Court Mazar, Karjon Hall, Arts Faculty (Dhaka University), Holy Family  Medical  College  &  Hospital  Boundary  Corner, Department   of   Women   Affairs,   Eskaton   Garden   High school,  Red  Cresnt  Borak  Tower,  Tenament  House  Gate, State  Guest  House  'Megna',  Baily  Road-Mogbazar  Road intersection,  Kakrail  intersection  (Mogbazar  intersection end), National Monument (Ramna), Mogbazar intersection, Aziz  Super  Market  and  Akbar's  Nakshi  Palace.  The  study area is shown in Fig. 1 and Fig. 2.

 

The  study  area  was  one  of  the  most  important  parts  in Dhaka city which was surrounded by the centre of the city Motijheel,  the  industrial  zone  Tejgaon,  the  residential  as well   as   commercial   area   Dhanmondi,   Khilgaon   area, Lalbagh  and  kotwali  thana.  All  these  areas  constitute  the major  commercial,  social,  educational  and  other  activities in  the city. Therefore, a huge quantity of traffic generated from all  of  these  areas  contributed  to  the  increased  traffic generation  along  the  roads  of  the  Ramna  area,  thus  had greater impact on increasing the traffic induced noise in that zone.

 

 

 

There  were  three  hospitals  viz.  the  Holy  Family  Hospital, the Bangabondhu Sheikh Mujib Medical University (BSMMU)  and   the  BIRDEM  Hospital   which   were  all sensitive areas under the study zone.

 

The biggest Dhaka University area in our country was also included   in   the   study   zone.   The   study   area   included Supreme  Court,  High  Court,  Ramna  Park,  Shisu  Park  and also a five star hotel named Sheraton.

 

There  were  mixed  areas  like  Maghbazar,  residential  areas like  Pori  bag,  and  commercial  areas  like  Banglamotor which  were  also  included  in  the  study  zone.  As  a  result, almost    all    categories    of    noise    affected    areas    were represented in the study zone.

 

3.3 Noise Level Measurement

 

Noise level data were collected from the study zone using noise  meter.  The  data  showed  by  the  noise  meter  was directly in decibel (dB). The instrument for measuring noise is   the   basic   sound   level   meter,   which   consists   of   a microphone  that  converts  the  pattern  of  sound  pressure fluctuations  into  a  similar  pattern  of  electrical  voltage, amplitudes, and a voltage meter that is normally calibrated to   read   in   decibels.   Data   were   collected   for   different specific  locations  in  the  study  zone  in  hourly  interval. These were taken for both working and holiday.

 

Decibels are measured, most commonly, on the A, B, and C weighting scales. There is also a G-weighting scale that is used to measure infrasound [6]. C-frequency-weighting was used during data collection.

 

3.4 Geographical Information Systems (GIS)

 

GIS provides a comparatively new mechanism for capturing  geographic  knowledge.  A  GIS  is  a  system  for management, analysis and display of geographic knowledge,   which   is   represented   using   a   series   of information sets. These information sets include maps and globes, geographic  datasets,  data  models,  processing  and work flow models, metadata, and descriptive attributes.

 

The noise level data were analyzed using GIS. Using these date  several  maps  were  plotted  showing  the  maximum, average  and  minimum  noise  level  of  the  survey  points. Finally, analysis was done to determine whether a particular point  was  at  alarming  level  or  not  with  respect  to  the allowable limit of that specific category of area.

 

4.  DATA ANALYSIS & RESULTS

 

The  noise  data  were  collected  at  forty  eight  points  in  the study zone from 6am to 7pm and the noise level variation was classified into following ranges:  less than45 dB, 45-50 dB, 51-60 dB, 61-70 dB, 71-80 dB and greater than 80 dB for both working day and holiday.

 

4.1 Noise Level for Working Day and Holiday

 

Among  the  noise  level  data  which  were  collected  from various points, the maximum, average & minimum values of noise at the respective points between 6 am to 7 pm were determined for both working day and holiday.

 

Fig. 3 to Fig. 5 shows the maximum, average and minimum noise  level  of  the  survey  points  for  working  day  and holiday.   These   were   obtained   from   GIS   symbological analysis.

 

 

 

4.2 Alarming and Non-alarming Areas with respect to different Noise Level

 

The maximum, average & minimum values of noise level at various   points   were   represented   as   alarming   or   non- alarming with respect to the acceptable limit of that specific category  of  noise  area  from  6am  to  7pm  for  working  day and   holiday.   The   results   were   obtained   using   GIS symbological analysis.

 

Fig. 6 shows that among 48 places Sonar Tori Building was only  within  acceptable  limit  (less  than  70  dB)  in  case  of maximum noise level for both working day and holiday.

 

 

Fig. 7 shows that among 48 places Sonar Tori Building was only  within  acceptable  limit  (<70  dB)  in  case  of  average noise level for working day.

 

However, for holiday, in case of average noise level several areas were within acceptable            noise level which includes:Eskaton garden high School, Department of Women  Affairs, Red  Crescent Borak Tower, Tenament house gate, Matshaw Bhaban and Charukola Bhaban.

 

 

Fig.  8  shows  that  among  48  places  6  points  were  within acceptable  limit  for  working  day,  whereas  11  points  were within  acceptable  limit  for  holiday  in  case  of  minimum noise level.

 

5.  DISCUSSION

 

From analysis it was found that 52% points had maximum noise level   greater than 80dB, 20% points had around 71- 80  dB  and  27%  points  had  around  61-70  dB  for  working day.  On  the  other  hand  for  holiday  40%  had  maximum noise level greater than 80dB, 27% had 71-80 dB and 21% had  61-70  dB.  Analysis  of  these  values  showed  that  12% points were very much affected by commuter traffic as well as  traffic  from  other  commercial,  social  &  educational activities.  The  Holy  Family  Hospital,  BSMMU,  Dhaka University  area,  High  Court  and  Supreme  Court  region which  were  all  silent  zone  had  a  maximum noise  level  of 60-100 dB which indicate high level of noise pollution. In case of average noise level it was observed that 33% points were above 80 dB and 33% had 61-70 dB in working day. For holiday 38% points had average noise level around 71- 80  dB.  For  the  case  of   minimum  noise  level  33%  points had noise level around 51-60 dB at working day and 23% had  around  51-60  dB    at  holiday.  These  values  indicate severe noise pollution scenario because the minimum noise level at all categories of places remained around 51-60 dB whereas the acceptable noise level for a silent zone was 45 dB  at  daytime.  The  analysis  regarding  maximum,  average and  minimum  noise  level  with  respect  to  acceptable  limit showed  that  for  both  working  day  and  holiday  almost  all the places were at alarming noise level.

 

6.  CONCLUSION

 

From  the  present  study  it  was  found  that  the  maximum value of the 48 points ranged from 62-99 dB, the average value ranged from 47-91 dB and the minimum value of the 48 points ranged from 17-84 dB. Analysis showed that 2% places had maximum noise level within acceptable limit for working day and holiday. On the other hand 2% places had average noise level within acceptable limit for working day and 10% places had average noise level within acceptable limit for holiday. However, 10% places had minimum noise level within acceptable limit for working day whereas 20% places had minimum noise level within acceptable limit for holiday.  Therefore,  it  can  be concluded  that the noise pollution level in Dhaka city is signalling to take immediate measures to reduce noise level.

 

There  exists  a  constant  level  of  pollution  resulting  from unbounded movement of traffic throughout the city due to commercial,   social,   educational,   recreational   and   other activities  and  thus  results  the  alarming  level  of  pollution both at working day and holiday.

 

7.  RECOMMENDATION

 

The following conclusion may be drawn based on the present investigation.

 

i.   Planned tree plantation along footpath and road divider will  be  effective  but  proper  care  should  be  taken  so that  these  might  not  create  any  obstruction  to  the traffic as well as to the pedestrian.

ii.   The  exterior  walls,  window  glasses  and  doors  of  the hospitals and other roadside buildings should be thick enough to reduce the intensity of noise. Use of heavy curtains  in  doors  and  windows  can  also  reduce  the intensity of noise.

iii.   In  the  hospitals  the  cabins  of  post  operative  patients, severe ill patients, patients having chronic diseases and also in operation theater, intensive care unit, coronary cardiac  unit,  neonatal  unit  should  be  distant  from roadside.

iv.   Strict      regulations;     particularly     in     Bangladesh- enforcement of laws is very necessary.

v.   Increasing    people    awareness;    mass    media    like television, radio, newspapers may be helpful to a great extent in this purpose.

vi.   Source  control  in  roadway  noise  has  provided  little reduction in vehicle noise, except for the development of hybrid vehicle.

vii.   The most fertile area of roadway noise mitigation is in urban  planning  decisions.  Hospitals  should  not  be placed  adjacent  to  commercial  roads.  Also  roadway design,   noise   barrier   design,   roadway   geometries, surface  pavement  selection  will  be  effective  in  this purpose.

viii.   Therefore,  in  built  up  areas  there  could  be  strategic regulations which would be fruitful to reduce the level of pollution.

ix.   The  roads  beside  residential  buildings  such  as  Red Crescent Borak tower, hospitals such as Holy Family Hospital  should  be  restricted  for  commercial  traffic, particularly   at   office   hour   these   roads   should   be banned for all traffic.

x.   Staggered timing of various activities such as different timing   of   offices   &   schools   may   contribute to a significant reduction. Also job rotation, work scheduling may help to a great extent in this purpose.

xi.   Speed  control  is  effective  since  the  lowest  sound emissions arise from vehicles moving smoothly at 30 to  60  kilometers  per  hour.  Above  that  range  sound emissions  double  with  each  five  miles  per  hour  of speed.

xii.   Noise  barriers  are  probably  the  single  most  effective weapon   in   retrofitting   an   existing   roadway,   and commonly  can  reduce  adjacent  land use  sound  levels by ten decibels.

xiii.   Noise  barrier  may  be  installed  along  the  road  beside BSMMU and Holy Family Hospital.

 

REFERENCES

 

[1]  “Clean  Air  in  Bangladesh:  Summary  of  progress  on improving air quality”-Article of CAI-Asia, November, 2008.

[2] Environmental Pollution Report (1998), Department of Environment   (DOE),   Government   of   Bangladesh, Dhaka.

[3]  Bangladesh State of Environment Report (2000).

[4]   Kafiluddin,   A.K.M.   (2001),   “Population   Research, Environmental         Conservation        &             Economic Development”.

[5]  A  survey  of  Geography  &  Environment  department, Jahangirnagar University, 2001-02.

[6] Alam. M. J. B. Hoque, M. A. Ahmed, (2000), “Traffic Induced Noise. Pollution in Dhaka City,” Proceedings of the ICBEN-2000.

 

 

Source: duet.ac.bd

 


 

 

 

 

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