Corus Rail Products Silent Track Railway noise reduction system October 2007.
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Transcript of Corus Rail Products Silent Track Railway noise reduction system October 2007.
2Business Development
Silent Track - Introduction
• Corus Rail’s Silent Track developed out of a E.U. part-funded research project to reduce noise generated by railways. Full scale testing gave 5 to 7dB noise reduction.
• Silent Track reduces noise generated by rails as train wheels pass over them. The system employs patented “tuned dampers” which are attached to either side of the rail.
• The dampers are designed to suit a particular track-form, and are tailored to meet Clients size requirements. They can be attached to track in-situ, either by high-performance glues or by a specifically designed clip.
• We are also developing the product to enable dampers to be attached onto rail at Hayange before the rail is installed onto track.
3Business Development
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Reference Tuned Absorbers
Noise level (dB)
Track with tuned dampers
Reference track
Silent Track – noise reduction
Noise levels produced by the track vary across the frequency spectrum. The damper is “tuned” to absorb vibrations at the frequencies which emit the greatest levels of noise.
Frequency (Hz)
At low frequency (left side of graph) track noise is low – the damper is designed to have no effect on noise level.
As frequency increases, the noise reaches a peak – the damper is tuned to absorb these frequencies and is thus as effective as possible.
At higher frequencies the track noise reduces – the damper is designed to be less effective at these frequencies
The noise spectrum varies for every type of track form, both in position of the peak and the maximum noise level emitted. Silent Track tuned rail dampers are therefore designed specifically for a particular track form – they are NOT an “off the shelf” product.
4Business Development
Rail as a Noise Source
• Vibration energy from wheel rail contact
• 50 to 5000 Hz
• Wheel rail and sleepers all radiate
• Vertical modes dominate
• Vibrating Length of track is important - size of source
• Noise depends on decay of vibration with distance – the lower the decay rate, the greater the vibrating length of rail.
-5.0E+4
-4.0E+4
-3.0E+4
-2.0E+4
-1.0E+4
0.E+0
1.0E+4
Fo
rce (N)
5Business Development
Effect of Damping on Rail Vibration
• Decay rate can be increased by the addition of rail damping
• This reduces the displacement of the vibration waves along the rail, and therefore reduces the vibrating length of the rail, and hence the noise emitted
-5.0E+4
-4.0E+4
-3.0E+4
-2.0E+4
-1.0E+4
0.E+0
1.0E+4
Fo
rce (N)
Vibration waves are diminished if the rail is damped
6Business Development
Effect of Tuned Rail Dampers on Decay Rate
• The red line shows the increased decay rate on a track fitted with Silent Track tuned rail dampers, compared with the undamped track in blue
Decay Rate dB/metre
Frequency Hz
7Business Development
SilentTrack™ - How does it work?
Elastomer “Springs”Steel Masses
Rail vibration causes the masses to oscillate.
The energy of movement is absorbed by the elastomer material.
SILENT TRACK is a unique 2 mass design developed jointly with the University of Southampton
Silent Track reduces the noise generated by the rails as train wheels pass over them. The Tuned Rail Damper System efficiently absorbs the vibrations from the rail –wheel interface and prevents noise from being generated by the rail.
The Tuned Rail Damper is tuned to the frequency band with the highest noise level.
8Business Development
Silent Track – Damper design
The design of a damper is a two stage process. Firstly, the Clients requirements define the shape of the damper and fixing
method Second, the track characteristics enables Corus to design the internal
arrangement (steel size and spacing) of the damper to give the most effective noise reduction
Track measurement to confirm acoustic characteristics of the track. Factors include:
• Fastening type (Pandrol fastclip, Vossloh etc)
• Pad stiffness (expressed as kN per mm deflection)
• Sleeper type (mono or twin bloc concrete, steel, timber)
• Slab or ballasted track
Computor modelling then used to define most effective steel sizes and spacing
Stage 1 - Clients requirements defining the shape of the damper
Rail type
Clearance constraints
• Rail head
• Rail fastening
• Edge of rail foot.
Fixing constraints
• “removable” damper
• “permanent” damper
Profile
height
length
width
Clip-on
Glue-on
Stage 2 – Corus design of internal arrangement to give effective noise reduction
9Business Development
SilentTrack™ - Tuned Absorber - Details
STEEL MASSES
ELASTOMERwith
DAMPING PROPERTIES
Tuned Rail Damper shown with protective covering removed.
Normally the absorber has a complete covering of elastomer to protect against rusting.
The elastomers are very stable and have been successfully used for 20 years – in sub-sea, pipework, above and below ground, under sunlight and in the presence of ozone.
Dampers have been in track for several years now, with no reduction in performance.
10Business Development
Silent Track – Market Development
Approved product
Trial in progress
National Networks – target markets
Urban Network - target markets
• Holland – Product approval of glued damper April 2004. First commercial sales June 2005. Orders for a total of 16km received. New clipped damper being tested, with approval expected by end of 2007
• France – Homologation trial started 2004, approval April 2007
• Sweden – Trial started 2005. Product now approved (Sept 2007)
• Germany – dampers in DB track as part of EU Silence project, installation June 2006
• UK, Network Rail – approval being sponsored by Thameslink project.
• Finland – Trial proposed, details under discussion, dampers in track by end of 2007
• Italy – trial proposed Naples, postponed by client due to re-organisation.
• Czech Republic – trial proposed, Q4 2007
Interest also from • National networks – Austria, Italy, Belgium, Switzerland• Urban networks – London, Paris, Berlin, Dublin, Tiawan,
Hong Kong, Singapore.
Trial proposed
11Business Development
Silent Track – Summary of Test Results
Country Track type Damper Fixing Noise Reduction
UIC test centre
UIC 60, Pandrol E 500mm “continuous” Cast onto rail Up to 6dB overall
HollandUIC 54, Vossloh + hard pad
500mm “continuous” Glued 3.0 – 3.4dB overall
HollandUIC 54, Vossloh + hard pad
360mm between sleepers (600mm c/c)
Single sided clip
2.6 dB overall
Pierrelatte, France
UIC 60, Nabla + hard pad
300mm, between sleepers (600mm c/c)
“U” Clip5.8dB (rail)
3-4dB (overall)
Sweden UIC 60, Pandrol E400mm, between sleepers (650mm c/c), low height
Spring clip2 - 6dB overall (depending on train type)
Germany UIC 60, Vossloh360mm between sleepers (600mm c/c)
Spring clip 3.2 - 4.1dB (overall)
Italy, Denmark, Finland, UK - discussions underway - awaiting confirmation of test sites!
12Business Development
Silent Track – installation in France
As part of efforts by SNCF to reduce the noise generated by rail traffic, Corus dampers have been fitted onto the “classique” line at Pierrelatte near Montelimar.
The damper was designed to meet the needs of SNCF, particularly to ensure compatability with their maintenance operations (tamping, rail grinding) and clearance around the rail.
We expect to receive full product approval in the coming months
15Business Development
Track maintenance activities
Track where Corus dampers have been fitted can be maintained using normal machinery.
Rigorous trials have been carried out by the SNCF as part of the product homologation process. The presence of Corus dampers had no effect on the normal functioning of tamping machines and rail grinders.
16Business Development
Silent Track – installation in Germany
Latest development of clip for in-situ installation
•Easier to install
•Stainless steel = improved durability
•Improved acoustic coupling material used
17Business Development
Recent measurements from German test site with latest damper / clip design
Inter City Train - av 3 pass-by's
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65
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85
315
400
500
640
800
1000
1250
1600
2000
2500
3150
4000
5000
Third Octave Band
dB
Corus Damper
Undamped
Equates to c. 4dB (A)
overall noise reduction
18Business Development
Silent Track in Holland
In Holland, because the track is different to that in France, the design of the damper is different
They pass behind the rail fastening (type Vossloh), and are glued onto the rail using high performance epoxies.
They are certificated to produce a reduction of 3dB (A) on track with the average rail roughness permitted under Dutch standards.
In Holland our product has been approved for use since 2004. To date around 20km of track have been fitted.
19Business Development
Pre-attached dampers
Dampers of 50cm length have been glued to the rail in factory conditions to form a continuous strip either side of the rail. The rails are then loaded onto the long welded rail delivery train, and the track re-railed in the usual manner.
20Business Development
Silent Track - Benefits in urban areas, and with stations & junctions
10 20 30Barriers are less effective for multiple tracks
Tall buildings near to the track see the highest noise level
21Business Development
Silent TrackBenefits in Urban Environments (2)
distance from track
-10 dB
-5 dB
20m 40m 60m 80m
Noise level without reduction measure
2.5m barrier only effective
at distance
Tuned Rail Damper –
effective at source
Significant advantage for Tuned Rail Dampers for 3
storey dwellings and above within 30 metres
of the track
Noise reduction
Where would you put a barrier in this
situation?
22Business Development
SilentTrack™ - Advantages
• The reduction of noise being generated at its source.
• The ability of the system to be “tuned” to absorb vibrations specific to a particular track form, and over a wide frequency range.
• The system has no maintenance requirement, and has no effect on other elements of the rail infrastructure.
• Can be fitted to standard tracks and will not interfere with normal maintenance operations.
• The system has the same life as the rail itself.
• Visually unobtrusive (unlike unsightly noise barriers!).
• High Noise Reduction Capability : Up to 6dB of noise from the track itself.
• Significant performance advantages over barriers, especially in urban environment.