Case Study
Long-term Protection from Structureborne Noise in the Centre of Grenoble (FR)Protection from vibration immissions
caused by the tramway

Elastic bearing with full-surface
mass-spring system madeof Sylomer®

Unchanged high performanceafter 15 years of usePermanent protection from vibration
immissions caused by the tramway

The project
To protect the urban environment
from vibrations caused by passing trams, Grenoble relies on massspring systems in the city centre.
Some sections have been
decoupled using Sylomer® solutions
from Getzner for more than 30years without any need for maintenance. Getzner investigatedthe long-term performance of thesystem on the section in Avenue deValmy, which went into operation in2004.

Most of the sections in the city centre are elastically supported on massspring systems to protect the surrounding area from vibrations. In 2004,
SEMITAG started to run trams on thesection in Avenue de Valmy, which
now carries line C. Here too, the plansincluded a vibration-attenuating system in order to reduce structure-borne
noise. The specifications stated an isolation performance of at least 20 dB
at 63 Hz compared to a conventionallybuilt superstructure system.

he tramway in Grenoble, originallybuilt at the end of the 19th century stopped operation in 1952, and wasfinally reintroduced in 1987. Back then,it was the first urban transport systemin the world to operate exclusively with
low-floor trams.
Today, the tram network extends over
47 km and comprises 81 stations. Thelines are built with a standard gaugeof 1435 mm. The operator SEMITAG uses
two Alstom sets of type TFS andCitadis 402.

T… that are reliably attenuated inboth cases by the Getzner mass-spring
system with an average of 23 dB.

Vibration isolation in dBv

9080706045403530252050

15401030

5

Slab TFS

Frequency in Hz
Slab Citadis

315

250

200

125160

100

6380

50

4025

31.5

1620

12.5

8105

6.3

4020
456.3
810
12.5
162025
31.5
40
50
6380
100
125160
200
250
315
400
500
600
800

Vibration velocity in dB re. 5*10^8 m/s

The TFS and Citadis tram types in use
produce significantly different vibration
emissions at 63 Hz …

Frequency in Hz

The structure-borne noise insulation was determined by means of16 measurements using vibration sensors on the on the elastically Sylomer®
supported slab and the isolated pavement.

The Getzner solution
To protect surrounding buildings fromvibrations, a Sylomer® LG28 massspring system from Getzner wasinstalled. After 15 years of operation,
the long-term performance of theGetzner solution in the Avenue de Valmy
was measured using a range of tests.
Its effectiveness was measured underreal-life conditions. The tests took into
account the loads caused by the typesof trains running and correctly record
the non-linear behaviour of the elastomers. The vibration measurements
were carried out simultaneouslyon the elastically mounted track slab
and the isolated pavement.

Required damping efficiency achieved
The degree of structure-borne noise
insulation was evaluated by means of
16 measurements during tram passes
in both directions. The results showed
insulation performance of 23 dB, easily
outperforming the specified insulating
value of 20 dB at a frequency of 63 Hz– even after 15 years of operation.
“In our opinion, the clean design of theside joints is a key factor in the outstanding long-term performance of themass-spring system. A well-maintained
joint prevents the occurrence of structure-borne noise bridges that reducethe insulation effect,” explains HerbertGehrig, Project Manager at Getzner.
Consistent material properties
after 15 years

14h03-Citadis-AT (max)
14h09-Citadis
14h11-Citadis-AT
14h13-TFS-AT
14h16-TFS-AT
14h17-TFS
14h19-Citadis-AT
14h20-Citadis
14h26-Citadis
14h27-Citadis
14h30-TFS (min)14h31-TFS
14h33-TFS
14h36-Citadis
14h42-Citadis
14h44-TFS
Mean

The natural frequency of the massspring system was recorded using impulse excitation in a load-free state.
The results showed a frequency of25.4 Hz – a difference of just 7 % compared to the specified target frequencyof 27.2 Hz. This shows that the Getzner
mass-spring system is delivering top
performance in the isolation of immissions of both tram types in use in
Grenoble, even after a period of 15 years.

Advantages for customers— Criteria for structure-borne
noise insulation continue
to be fulfilled— Natural frequency of thesystem virtually unchanged
after 15 years in use— Reliable, long-lasting elasticity

FeedbackWhat does the client say
about the project?
“Despite the climatically demanding
conditions in Grenoble and the intensive use of the system, the Getzner
solution isolates vibrations just as effectively now as when it was first installed. Thanks to the results, we cango ahead with the planned adjustmentsof the track in the centre with peace ofmind.”
Marc Beaumont
Rail Engineer | Technical Expert
IngéropFacts and figures
Polyurethane joints

Sylomer® – thickness 28 mm

Operating company:
Implemented:
Solution:
Load:
Getzner
Project Manager:
Project support:

Polystyrene – thickness 20 mm

Société d’Economie Mixte des Transports Publics del’Agglomération Grenobloise (SEMITAG), Grenoble, France2004
Sylomer® LG28 full-surface mass-spring system,
Natural frequency 27.2 Hz
Approx. 60 million metric tons in 15 years of use (as of 2019)
Herbert Gehrig
Ingérop, Rueil-Malmaison, France

Founded:1969 (as a subsidiary ofGetzner, Mutter & Cie)
Chief Executive Officer: Jürgen Rainalter
Employees:
490 (of which 360 in Buers)
Turnover in 2020:
EUR 105.5 million
Business areas:
Railway, construction, industry
Headquarters:
Buers (AT)
Locations:
Peking, Kunshan (CN), Munich, Berlin,
Stuttgart (DE), Lyon, Paris (FR),Pune (IN), Amman (JO), Tokyo (JP),Charlotte (US), Melbourne (AU)
Ratio of exports:
91 %Railway references (extract)— Graz tramway (AT)— Paris tramway (FR)— Budapest tramway (HU)
— Luxembourg tramway (LU)
— Warsaw tramway (PL)— Bratislava tramway (SK)— Nottingham tramway (UK)

AUSTRIA — Bürs GERMANY — Berlin — Munich — Stuttgart FRANCE — Paris — Lyon JAPAN — Tokyo INDIA — Pune
JORDAN — Amman CHINA — Beijing USA — Charlotte AUSTRALIA — Melbourne
www.getzner.com

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