Railway Noise

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Railway Noise
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Noise sources

• The structure of a railway consists of train,
  track and roadbed.
• Noise sources include
• rolling noise
• engine noise
• body vibration of a train
• the structure on the ground
• The rolling noise
• generated from the interaction between the wheel
  and rail.

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Noise sources

• There is a wide range of parameters affecting the
  noise level of the railway system
• types of locomotive propulsion system
• the auxiliary equipment such as compressors,
  motor generators, brakes etc.
• the interaction of the wheels and rails
• the noise radiated by vibrating structure such as
  steel bridges, the speed of train and its length.
  
• The generated airborne noise radiated into
  community, also ground borne noise and vibration
  which travels through the track, support
  structure and the intervening soil to nearby
  buildings.

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6 steps of prediction for railway noise

• Divide the railway into one or more segments such
  that the variation of noise within the track
  segment is less than 2 dB(A)
• The reference SEL (sound exposure level) at a
  given speed and at a distance of 25 m from the
  near-side railhead of the track segment taking
  into account the length of the train and the type
  of track and track support system.
• Corrections to SEL for distance of the reception
  point from the track, ground and air absorption,
  the effect of screening by barriers, speed of the
  trains and the angle of view at the reception
  point etc.

Calculation of Railway Noise (CRN) is developed
by the U.K. Department of Transport and the
Transportation.
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6 steps of prediction for railway noise

• Corrections to SEL to take account of reflection
  effects at the reception point.
• The SEL at the reception point by applying the
  corrections determined at stage 3 and 4 to the
  SEL ref, and convert the resulting SEL values to
  values of Leq taking into account the time period
  required and the number of trains.
• Combine the Leq for each segment to obtain the
  total Leq 30mins.

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Regulation

• For the noise assessment, the authorities should
  follow Technical memorandum for the assessment
  of noise from places other than domestic
  premises, public places or construction sites".

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How to determine acceptable noise level?
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• the purpose of table, the following definitions
  apply
• Country park means an area that is designed as
  a country park pursuant to section 14 of the
  Country Parks Ordinance
• Directly affected means that the NSR is at such
  a location that noise generated by the IF is
  readily noticeable at the NSR and is a dominant
  feature of the noise climate of the NSR
• Indirectly affected means that the NSR, is not
  a dominant feature of the noise climate of the
  NSR
• not affected means that the NSR is at such a
  location that noise generated by the IF is not
  noticeable at the NSR

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Major railways in Hong Kong

• Kowloon Canton Railway (KCR)
• East Rail
• Ma On Shan Rail
• West Rail
• Mass Transit Railway (MTR)
• Tsuen Wan Line
• Kwun Tong Line
• Island Line
• Tseung Kwan O Line
• Tung Chung Disney Resort Line
• Airport Express Line

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KCRCs present and future railway networks
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MTR Rail network
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Controls

• Skirt (outdated)
• Wheel absorber
• Vibration absorbing rail fastener
• Elastic sleeper pad and rubber boot
• Insulation mat and rail
• Sound and vibration absorptive viaduct
• Noise enclosure at points and crossings
• Floating slab

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(No Transcript)
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Wheel absorber to reduce squeal noise
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Wheel absorber to reduce rolling and squeal noise
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Insulator for Light Rail
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Base Plate Pad
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Elastic sleeper pad and rubber boot
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Insulation mat
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Type of trains in Hong Kong
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Major control measures used in the Rail

• 1.2 m to 4.2 m high noise barriers along viaducts
• Noise enclosures at points and crossings
• Floating track slabs supported by rubber pads
• Vibration absorbing rail fasteners

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Control used in Rail
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Rail Sound Absorptive Viaduct
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Absorptive barrier at Kowloon Tong
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Installation of floating stab at MTRs Airport
Rail Link
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Translucent noise barrier at the MTRs Airport
Rail Link
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Reference

• Calculation of Railway Noise
• Technical memorandum for the assessment of noise
  from places other than domestic premises, public
  places or construction sites, HKEPD