Optimisation ofTransition Zones

Significant reduction in themaintenance costs of susceptible
track sections

Reduced wear in all superstructurecomponents

Extended service life and thusincreased availability of track

1

Significant Reduction ofPlaceholder
Text
Maintenance
Costs

Transition onto a bridge

Transition zones: Areas ofrailway tracks that require
high levels of maintenance
When changing from one type ofsuperstructure to another, thevariations in stiffness produce agreater stress on the components,
which consequently require more
maintenance. Solutions offered byGetzner help to significantly reducethis stress and the resulting maintenance costs.

Optimisation of the susceptible transition
zones can signiﬁcantly change thecost-beneﬁt ratio of a line.

Transition zones are sections oftrack where the stiffness of thebedding changes considerably overa short distance. When there is anabrupt change in the superstructure
construction, the variations in stiffness and resulting rail deflections cannot be avoided. Sudden changes can,for example, occur in the transition
from a ballasted track to a slab track,from open track to a bridge or whencrossing over a turnout.
Even where the superstructure system
is similar, a change in the substructure or subsoil can cause increased
levels of maintenance. In the case oftransitions to bridges for example, thedifference in subsoil stiffness and uneven settlement can result in increased
dynamic loads on the components.
Schematic showing a transition zone32 Compensating forDeflection Differences

Ballast wear

Counteracting
increased wear
Because of the design, there is a
stepped change in the superstructure
stiffness in transition zones. Highstatic and dynamic loads can causewear of the superstructure components, even after a short period ofoperation. Elastic products byGetzner can provide the necessary
protection for components and makea valuable contribution to reducing
loading levels.

4I

n transition zones where there is no
optimised stiffness graduation, components may be damaged by the highdynamic loads as a train passes over:
Ballast movement and overloading
lead to ballast wear and hollow areas
between the sleeper and ballast.
Ballast wear is often identified by thewhite spots caused by the resulting
abrasion. Increased rail seat forces
produce a high stress on the ten-sion clamp until it eventually breaks.
Tension clamp breakages often occur
around guardrails. Cracks and breaks
in sleepers are also caused by highloads. In addition, irregular settlement
is caused by variations in stiffness andchanges in subsoil properties.

Broken tension clamp

Broken sleeper

Settlements

Longerservicelife

Variations in settlement

Getzner has the answer

The increased load on the superstructure is also caused by the varying
settlement behaviour resulting fromthe different structural designs. The
longer the track is in use, the greater
the unevenness along the line. As aconsequence, the forces being exerted
on the superstructure construction
steadily increase. Furthermore, settlement variations lead to defects in thetrack geometry, which in turn increases the dynamic load.

Installing elastic elements reduces theimpact loads and the vibrations thatare transferred as the train passes.
The defined use of highly elastic
Sylomer® and Sylodyn® components
compensates for the undefined variations in stiffness in the transitionzone. The improved load distribution
ensures that movement within the ballast bed is reduced and has a positive
influence on settlement behaviour. Atargeted graduation of the rail deflection within the transition zone reduces
the impact loading of the wheel/railsystem and superstructure, significantly extending the service life of thetransition zones and thus the availability of the line as a whole.

Dynamic loads
Differences in deflection as the train
passes over result in increased railwheel forces and dynamic loading of
the entire superstructure. This increased loading leads to more maintenance work and reduces passenger
comfort.

Benefits for customers— Optimised graduation oflarge variations in stiffnessand deflection differences— More even load distribution— Reduced ballast loading— Less hollow areas— Reduced impact loads as thetrain passes over
— Less settlement— Less wear of superstructurecomponents— Increased safety and ride
comfort— Less maintenance work
— Increased availability— Longer service life5

3 Optimal Solution thanks to a
Combination of Elastic Components

Interplay of different
elements
Project-specific challenges require
specific solutions. Thus: The ideal
solution often consists of a
combination of different Sylomer®
and Sylodyn® components.

Rail pads

Baseplate pads

Elastic rail pads are placed directly under the rail base. They have a defined
stiffness and increase the elasticity ofthe superstructure. The improved load
distribution protects the superstructure and offers greater ride comfort.
The increased elasticity has a positiveeffect on the wear of superstructurecomponents.

Modern railway lines are increasingly
built as slab track systems. Highly
elastic Getzner baseplate pads, which
are installed underneath the baseplate,provide the elasticity for such systems.

Rail pads are a simple way of achieving
a targeted graduation of deflection
differences without having to carry out
any work on the system underneaththe sleeper. However, due to the maximum permissible rail deflection within
the fastening system, the compensation options are limited. Getzner offersa full range of rail pads for every required stiffness. The rail pads made fromSylodyn® HS in particular impress with
their very long service life in numerous
application areas.

Elastic baseplate pads preserve theload-distributing function of the rails
and reduce vibrations caused by wheel
and track irregularities. Deflection differences are minimised by the targeted
adjustment of the pad stiffness – forexample, across the transition fromslab track to ballasted track. Comparedwith rail pads, baseplate pads provide
the option to add more elasticity inside
the rail seat.

Find out more about Getzner
rail pads and baseplate pads
at: www.getzner.com/
downloads/brochures

Rail pads
6Baseplate pads

Under sleeper pads

Under ballast mats

Mass-spring systems

Under sleeper pads

Under ballast mats

Mass-spring systems

Under sleeper pads provide vibration
isolation and ballast protection. They
increase the size of the contact areaand have a load-distributing effect that
reduces the stress between ballast andsleeper and consequently minimises
settlement. Furthermore, hollow areas
under the sleepers can be avoided by
fixing the top ballast layer.

Under ballast mats are used to achievea high degree of track elasticity. In addition, they also exhibit extremely highdynamic effectiveness. Due to theirballast-protecting effect in the track,
the installation of under ballast matsis the ideal solution in areas with very
high subsoil stiffness, for example on
bridges or in tunnels.

Mass-spring systems from Getzner provide particularly effective protection
against vibrations and noise for people
living next to railway lines. Getzner
offers three types of bearings for such
systems: point, linear and full-surface
support. Which of these types to use
depends on economic as well as technical requirements.

These properties and the functionality
mean that under sleeper pads increase
the service life of the track and ballast.
Under sleeper pads, which are available
in different stiffnesses, permit the targeted graduation of large variations in
stiffness and also reduce settlementin transition zones.

The respective elastic requirements inthe transition zones can be accurately
matched when selecting the appropriate mat type. Getzner under ballast
mats are easy to work with, can beinstalled quickly and can be driven overby heavy construction equipment.

The wide range of materials withvarying degrees of stiffness and theability to adapt to the geometry permit
a very exact and detailed graduationof the stiffness of the superstructure
system. Mass-spring systems can therefore be used to implement very definedtransitions.

Find out more about Getznerunder sleeper pads, underballast mats and mass-spring
systems at: www.getzner.com/
downloads/brochures

74 Every Transition Zone is different,so are our Solutions

Customised design
The optimal stiffness distribution intransition zones is achieved by taking
into consideration the prevailingframework conditions and specificmaterial properties. Getzner therefore
tailors its solutions to each and everytransition zone.

ts being used along with the optimal
combination of individual bearings in
the transition zone, is realised by means of simulations based on the Finite
Element Method (FEM).

IBased on the drawings of the superstructure constructions provided by
the customer, the FEM model permits aproject-specific and realistic calculationof the transition zone. The transitionzone is simulated in the FEM model byutilising the constructional design ofthe superstructure (guardrails, transi-n order to achieve its goal of obtaining an even graduation of the rail
deflection across changing superstructure constructions, Getzner provides components that are tailored to
the respective underlying conditions.
The calculation, which takes accountof the elastic properties of the elemen-Transition from ballasted
track to slab track

8Realistic FEM modeltion slab) and the relevant parameters,such as subsoil stiffness.
Once the FEM model has been prepared and divided into the individual sectors for the respective superstructure
construction, the simulation programis used to determine the verticaldeflections. The rail seat forces, railfoot tensions and stress between ballast and sleeper can also be calculated.
The bending line of the whole trackpanel for each load collective can bepresented and analysed.

Transition from open track intoa tunnel

Individualcalculations

Perfect solutions based on
accurate data
Based on the substantiated calculations of the FEM model, Getzner looks
at the particular demands of a transition zone and offers solutions involving a combination of various elastic
components.

Calculations based on theFinite Element Method (FEM)

1Getzner has used the empirical values
from numerous projects to further
enhance and validate the simulation
program.
2— Consideration of bedding ofdifferent superstructure forms— Simulation of train traffic— Minimisation of deflection
differences— Combination of various elastic
components— Consideration of a number ofstructural factors influencing
the superstructure construction— Adaptation of the solution
whilst taking account of thelogistical conditions on site

Deﬂection in mm

3Benefits for customers

00.5
Non-optimised transition zone
Optimised transition zone

1
1.5
2
2.5
3
3.5
405

10

15

20

25

30
3540
Number of sleepers

1 FEM model subdivided into sectors
2 Calculated static def lection of the rail
3 Optimised transition zone

9

5 References

Tried-and-tested solutions
used around the world
Getzner solutions have stood the testof time all over the world, as evidenced in the success of the Swiss
Federal Railways network (SBB).
Project SBB-Leuk, Switzerland
In Leuk, a new tunnel was opened
along the Lausanne-Brig line. Trains
travel at speed of up to 160 km/h. To
protect the buildings above the tunnel
portal, the SBB and Getzner have retrospectively fitted the concrete sleepers
with under sleeper pads.

Two types of under sleeper pads wereinstalled along a section of the line.
Sleepers over a stretch of 80 m werefitted with SLS 1010 G from Getzner. Inorder to compensate for the anticipateddifference in deflection caused by thisrelatively soft under sleeper pad,which has a static bedding modulus
of 0.10 N/mm3, a transition zone wasprovided at both ends. The stiffer
SLS 1707 G under sleeper pads wereusedin these transition zones.
The deflection differences in the transition zone between the open track andtunnel were able to be smoothly evenedout by using the two different types ofunder sleeper pads. As the measurements of the rail deflection made by theSBB track geometry car illustrate, thisobjective was successfully achieved.

Lausanne-Brig track section
Leuk tunnel
KM 117,300

KM 117,280

KM 117,170

KM 117,200

Rhone bridge

Lausanne

Brig10Type of pad
SLS 1707 G

Type of pad
SLS 1010 G

Type of pad
SLS 1707 G

15 m

80 m

15 m

Installation of under ballast mats on abridge in the USA

Effectivenessconfirmed

Transition zone references (extract)
CUSTOMER/PROJECTCOUNTRYAPPLICATION AREA

TTCI/ Pueblo Heavy Haul Loop

USA

Heavy haul

GETZNER SOLUTION
Under ballast mats

Union Pacific/ Nebraska Oskosh

USA

Heavy haul

Under sleeper pads

Ferrocarriles Suburbanos/ PuenteMexico

Urban transport

Under sleeper pads + rail pads

Canadian National/ Toronto Oakville Bridge

CanadaHeavy haul

Under ballast mats

Cadiz/ Tramo 2Spain

Urban transport

Mass-spring systems

ÖBB/ Lainz tunnel

Austria

Standard-gauge railway

Mass-spring systems + under ballast mats

Rhaetian Railway/ Samedan

SwitzerlandStandard-gauge railway

Mass-spring systems + under ballast mats

SBB/ Leuk

SwitzerlandStandard-gauge railway

Under sleeper pads

Fact box

Deflection in mm

Vertical deflection Lausanne-Brig
0Brig

Lausanne
Ballasted superstructure

0.5
SLS 1707 G1

SLS 1010 G

1.5
22.5117.10

117.12

117.14117.16117.18117.20117.22117.24117.26117.28117.30Length in km— Ballasted superstructure / open
track, rail deflection approx.
0.4 mm— Transition zone, rail deflection
approx. 1.0 mm— Under sleeper pads, type
SLS 1707 G (Cstat = 0.17 N/mm3)— Ballasted superstructure /tunnel, rail deflection approx.
1.7 mm— Under sleeper pads, type
SLS 1010 G (Cstat = 0.10 N/mm3)11

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