This presentation describes the importance of trees across the roads .it also discuss about the structures of a road.

1. TREEES ARE SOUND
BUFFERS

2. Presented By :
 Ahmad Umar
 Ahmad Hassan
 Hamood ur Rehman
 Uzair Aslam
 Mian Faisal
 Gulam Qadir
 Abdul Rehman
 Hafiz Waleed
 Arslan Haider
 Rashid Ali

3.  Sound is created by vibrations in air, which cause variations in pressure.
It results in waves which vibrates ear drum.
Impulses transmitted to brain which registers as a Noise
Noise Sound waves
What is noise ?

4.  Citizens of Rome Perish for lack of sleep.
Noise is more irritating or tiring than other disturbance.
Traffic noise is probably become more irritant now days.
Reduction in noise for public is preferable.
Many solid barriers fences or mounds are used
PROBLEMS OF NOISE :

5. NOISE MEASURED :

6.  Sound is greatest near to the source and diminishes with distance from
source
Asphalt and concrete surfaces reflect sound waves.
Soil porosity also decrease sound level by absorbing waves.
Grass surface behave quit different and reduce it to minimum.
REDUCING NOISE :

7.  One obvious way that trees may be useful in reducing human
perception of noise by creating a visual barrier between the source and
hearer.
Screen of trees with gaps in it to be more effective than a dense screen
in making people think they were hearing relatively less noise.
(Aylor - 1972)
REDUCING NOISE :
Reduction in noise
level of 5-10dB for
belts of trees
between 15-30m
wide

8. How trees reduce noise :
sound
Reflection
Scattering or
Aborption
vegetation
Foliage appears
more efficient part
of tree for
scattering of sound
Tanaka : (1979)

9. Broad leaves with small leaves tend to reduce more noise than
conifers(needle like).
Winter broadleaves shed their leaves in winter .
Conifers gives more better year noise reduction .
Broadleaves ever green e.g.(eucalyptus, holly ) are also important.
Leaves of plant do not absorb a great deal of
noise.
Bark appears to be more efficient in absorbing
noise.
Ground with group of trees relatively large
noise absorbing capacity.
Absorption of sound

10. Allowing trees to become to tall , resulting in gaps opening up in the
understory, will lesson their effective
wider belt of trees ∞ noise reduction
10m wide strip of trees planted close to a road gave an attention of about 5dB.
Size of leaves are also matter
Does size matter :
Trees belt with shrubs are increasing noise reduction
capacity

12. Walls ,fencses,earth mounds and other solid barriers have proved
useful as noise barrier
trees and shrubs have often been combined with solid barriers, for
aesthetic purposes
limited research has shown that screen consisting of solid
barriers with trees have not effective results than trees
alone.
Trees and solid barriers :

13. In order to achieve a significant noise reduction of say 6dB consisting of
trees and shrubs needs to be relatively wide (20-30m)
such methods are useful where land or budget is available
Arguments against the use of vegetation for noise barriers is
the length of time taken for the barrier to become
established
Where trees and shrubs are useful?