RTR

1| 2013
March 2013 | Volume 53
Euro 25,– | 13914
www.eurailpress.de/rtr
ISSN 1869-7801

RAIL TECHNOLOGY REVIEWRAILWAY DEVELOPMENTINFRASTRUCTURE

ROLLING STOCK

System developments in rail-guided
passenger transport
Infrastructure modernisation
in Slovakia

Semi-integral viaducts
Repairing concrete bridges
Concrete slabs, rail pads andballast mats

Knorr-Bremse:a system supplier
Condition monitoring forrunning gearRail Service directly from the manufacturer
The best treatment for your rails.

Rail-Road-Truck SF02-FS-Truck

Before processing

After processing

www.linsinger.com

Long-term behaviour of Sylomer®
ballast mats
Inspection and stiffness tests of a 21-year old Sylomer® D 220 ballast mat lying
on a DB railway bridge within the Hanover-Würzburg high-speed line showed norelevant change in its properties.

Fig. 1: Bartelsgraben Bridge

The bridge where the ballast mats were installed long ago is the Bartelsgraben bridge(Fig. 1). It is located near Würzburg in thesouthern section of the Hanover – Würzburghigh-speed line which was put into service
in June 1988, three years before the restof the line went into service. The bridge is1160 metres long and carries two tracks.
Construction of the pre-stressed concrete
box-girder bridge began in 1984 and wascompleted in 1986. Its longest supported
span between pillars measures 58 metres.
The line initially describes a 10,000 m radius curve before straightening out. The
gradient falls steadily by 12.5 %.

Dipl.-Ing.
Mirko Dold(source: Wikipedia, photograph: Störfix, 01.07.2006)

1 Installation of the mats
The ballast mats were installed in 1987.
They were delivered in rolls and laid out on
the cleaned subsurface. After laying out,
the mats were folded back halfway on one
side. Using a two-component PU adhesive,the mats were spot-bonded on the bridge
according to the DB AG installation instructions for ballast mats. The other half wasbonded during a second work step. Bonding
in this way ensured that the mats did not
move during the later ballasting process.
In terms of noise requirements, bonding to
the subsurface is generally not necessary
to guarantee effectiveness (Fig. 2).
Dipl.-Ing.
Stefan Potocan, MSc

During the installation of the Sylomer®
D 220 ballast mats from Getzner, an examination and research assignment wascarried out for the Bundesbahn Central Office (BZA) in Minden. The focus of the project was to investigate the deflection of therails in subsurfaces of different elasticities
when a train passed overhead. Data wasobtained for deflections in the: Ballasted track directly on the bridge
 Ballasted track on the bridge with ballastmats
 Ballasted track on a subgrade
Trackside tests and measurements weretaken by TU Munich, the testing institute forthe construction of land traffic routes.

2 Application areas ofballast mats
Product Management
Rail Division;
ballast mats,mass-spring systems
Getzner Werkstoffe GmbH,
A-6706 Bürs
mirko.dold@getzner.com

Product Management
Rail Division
Getzner Werkstoffe GmbH,
A-6706 Bürs
stefan.potocan@getzner.com

Ballast mats are used to provide structureborne sound insulation in dense urban
areas where railway lines pass close tobuildings. Other uses include the protectionof structures and buildings sensitive to vibrations, such as concert halls, museums,
RTR 1/2013

39

n   Long-term behaviour of Sylomer® ballast matsFig. 2: Installation of the D 220 ballast mat on the Bartelsgraben
Bridge in 1987hospitals, historic buildings or vibrationsensitive laboratory, testing or measuring
equipment. Ballast mats also reduce thesecondary airborne noise radiation frombridges.
They are an economical and proven methodof increasing the elasticity of the ballasted
track and bring about a long-term improvement in track bed quality and ride comfort.
Extended tamping intervals and higher
track availability has a positive impact onlife cycle costs.

Pressure [N/mm2]

Ballast mats generally have a two-layered
structure. The load distribution layer is on
the side exposed to the ballast and protects the layer below from the sharp-edged
ballast stones. It also ensures an evenload distribution. Embedded ballast stones
increase the load transfer area, prevent thepremature destruction of the ballast andalso protect the track bed. The spring layer
is made of microcellular polyurethane materials. This structure makes the ballast matsFig. 3: Removed ballast mat showing indentations from ballast stones

volume compressible, negating the need forany profiling or cavities to achieve the desired elasticity. The thickness of the microcellular materials is selected to achieve thedesired static and dynamic stiffness.

3 Two decades later
While renewing the ballast on the Bartelsgraben Bridge between Würzburg and Hanover, DB AG removed a test sample of theGetzner D 220 ballast mat. The extract inquestion was taken from a mat installed in
1987. For 21 years it had suffered an operational load of approx. 384 million tonnes.
This tonnage is far in excess of the load
stipulated under fatigue strength testing as
per DB TL 918071 [1]. At the time the matswere supplied a load cycle of 2.5 millionwas required as the prerequisite for installation on railway lines operated by Deutsche
Bahn. Based on an axle load of 22 tonnes,
we can calculate a fatigue stress of 17.50,250,20,15

million load cycles, which corresponds to afigure seven times higher than that definedin DB TL 918071. The static and dynamic stiffness of the removed sample weremeasured and compared against the values when the mat was new. These variables
can be used to show the creep behaviour
and the performance of the ballast mat.

4 Visual inspection
The visual inspection of the ballast mast
reveals some plastic indentations from individual ballast stones in the load distribution
layer of the D 220 ballast mat. Due to theload distribution through the ballast, theseindentations typically occur directly in theloading area of the sleeper and thus meetwith expectations. This effect was also observed following the creep behaviour testingundertaken at the time. The indentations indicate that the ballast stones were properly
embedded in the load distribution layer andload peaks on the ballast/concrete contact
areas had been permanently avoided. Asa result the loading on the superstructure
was lower, which ultimately led to lower
maintenance costs due to the stable track
bed and longer tamping intervals. No signsof damage to or perforations in the load distribution layer could be established (Fig. 3).
We can therefore conclude that the ballast
mat withstood the high mechanical loads
and will continue to satisfy all its functional
requirements for decades to come.

measured 2008
0,1

5 Testing and results

0,05

040

5.1 Static stiffness

measured 1987

0RTR 1/2013

1234

Fig. 4:
Measuring staticstiffness on the D 220ballast mat sample
567 (before installation andDeflection [mm]after removal)

The static stiffness of the removed ballast mat was determined according to DB
TL 918071. The test was conducted on
samples measuring 500 x 500 mm. Secant
stiffness was evaluated between the load
points 0.02 and 0.1 N/mm². A static bedding modulus of 0.0529 N/mm³ was cal-Long-term behaviour of Sylomer® ballast mats   nculated, which met the specification at thetime of 0.06 (+/– 0.01) N/mm³. Comparedwith the value measured on a new ballastmat by TU Munich [2] (0.0571 N/mm³), thisrepresents a change of 7.9 % after 21 years
in-situ (Fig. 4).

Preload0.03 N/mm³
dyn. bedding
modulus Cdynat roomtemperature[N/mm³]
Mat D 220
before installation

5.2 Dynamic stiffness
The dynamic stiffness was measured on
200 x 200 mm samples according to the
dynamic properties measurement specified by the Müller BBM 12506/1 report[3] of January 1986, in which preloads of
0.03 N/mm² and 0.1 N/mm² were applied
at a test frequency of 40 Hz. The removed
ballast mat returned values of 0.092 N/
mm³ (0.03 N/mm² preload) and 0.090 N/
mm³ (0.1 N/mm² preload). Compared with
1986, this corresponds to a deviation of
11.2 % and 9.6 % (Table 1).

6 Summary
The sample tested showed no relevantchange in its properties (less than 15 %)after 21 years under the track and having
withstood 384 million tonnes. During these
21 years, the ballast mat was installed ona bridge and exposed to all the associat-

Mat D 220
21 years
after installation and384 milliontonnes

Change [%]0.083

Preload0.1 N/mm³dyn. bedding
modulus Cdynat room
temperature[N/mm³]

Change [%]Result

9.6

OK

0.082
11.2

0.092

0.090

Table 1: Comparison of ballast mat dynamic data at the time of installation and after removal

ed weathering effects, together with thousands of frost-thaw transitions. Water has
had no negative impact on the propertiesof the ballast mat. The testing, which is in a
way equivalent to a real-life long-term test,
has shown that ballast mats made from
Sylomer® provide sustained effectivenessand do not exhibit any noteworthy signs ofageing or degradation.

the mat can be found even when subjectedto the closest scrutiny. This result showsthat ballast mats made from Sylomer® arelargely unaffected by weathering effects. Itis expected that the ballast mats will continue to remain completely effective for another 30 years at least.

The values measured are still within thetolerances (+/– 15 %) which were valid at
the time of installation and which remain
so to this day. No cracks or perforations inReferences[1] DB TL 918071 – 1978 edition[2] Müller BBM Report 12506/ 1[3] TU Munich Report GÜ 49/ 89Elastic Solutions
for Track Superstructure
Getzner‘s range of elastic components for track
superstructures consists of the following:— Rail pads
— Baseplate pads
— Elastic insert pads
for sleeper boots— Sleeper pads

Getzner Werkstoffe GmbH
Herrenau 56706 Bürs
Austria
T +43-5552-201-0
F +43-5552-201-1899
info.buers@getzner.com— Ballast mats
— Bearings for mass-spring system— Embedded rail
— Continuous rail bearing
5DLOJURRYHoOOHUV

www.getzner.com

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Sifer 2013,Lille (FR)26th – 28th March 2013
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