Corus Rail Products Silent Track Railway noise reduction system October 2007

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.


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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.


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.

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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

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Vibration waves are diminished if the rail is damped


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


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.


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


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.


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


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!


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


SNCF – Results of tests

Reduction of 6dB in rail

noise


SNCF – Results of tests


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.


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


Recent measurements from German test site with latest damper / clip design

Inter City Train - av 3 pass-by's

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Third Octave Band

dB

Corus Damper

Undamped

Equates to c. 4dB (A)

overall noise reduction


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.


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.


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


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?


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.

Corus Rail – Silent TrackTuned Rail Dampers

The Best Solution for Reduction of Railway Noise!!!

Documents

Corus Rail Products Silent Track Railway noise reduction system October 2007