BUFFER STOPS
FIXED AND DYNAMIC
voestalpine Railpro BV
www.voestalpine.com/railpro/en
BUFFER STOPS
RAIL TERMINATION SYSTEMS
A buffer stop on a dead-end track – the signal that indicates ‘end of track
construction’. A highly resilient signaling system, which can absorb ‘tight
parking manoeuvres’ just as easily as high impact blows to stop an overshooting
train. A safe idea!
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Avoidance of unnecessary high costs due to damages to the train
Avoidance of danger for both the train driver and possible passengers
High quality product, as demonstrated by train crash tests
INTRODUCTION
The Fixstop and Dynastop are
products for intercepting trains
while causing a minimum of
damage to both the passenger and
freight trains and the buffer stops
themselves. These buffer stops are
unique because of their extremely
robust steal construction containing
specialised brake shoes. Several tests
have shown that the fixed as well as
the dynamic version can absorb an
impact of more than 1,000 kN. This
result is achieved by a clever method
of determining the dimensions of the
buffer stops’ design.
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DEVELOPMENT
FIXED AND DYNAMIC
In developing these products, the focus has specifically been on their basic
function. When a train hits a buffer stop, it means that it has not come to a halt
in time. The buffer is then activated to stop the train in a controlled manner
within a minimum braking distance. Here, minimal damage to the train, the
buffer and the objects in the nearby vicinity are a prerequisite. In this way, the
buffer stops can safely intercept passenger and freight trains.
The steel construction consists of a
tubular steel frame with high quality
welding connections that determine
the robustness of the buffer stop. This
makes it easy to use, also in terms of
weight.
The buffer stop is made from
galvanised steel which is extra
protected by a two-layer powder
coating. This coating guarantees an
operational life of forty years.
For securing the buffer stop to the rail,
two types of fastening are available.
Depending on its location, either
a fixed or a dynamic model can be
placed.
RAILPRO BUFFERSTOPS
Fixed on dead-end track
The fixed buffer stop, the Fixstop,
is mainly suitable for use on the
dead-end tracks of (holding) sidings
and shunting yards. This buffer is
specifically meant for bringing freight
or empty passenger trains to a halt, if
necessary. In these settings, the trains
can be stopped directly because in
most of the cases no passengers are
involved in the collision.
Gradual standstill
The dynamic buffer stop, the
Dynastop, is used at locations where
passenger trains are running, such as
on the dead-end tracks of stations.
The dynamic slowing down of the
train’s speed facilitates a minimal
impact on the passengers. In this way,
the inconvenience for the travellers
is minimised. Note that it takes no
more than a speed of 5 km/hour
and a direct stop by a fixed buffer
to cause an undesirable situation for
passengers. The Dynastop, however,
moves with the train to bring it
gradually to a halt. Depending on the
space behind the buffer, additional
brake block shoes are placed to
ensure a stop within the maximum
braking distance.
Working principle
When a train collides with a buffer
stop, its energy is absorbed and
transferred into power. As a result,
the track bolts in the weld break
while the train pushes the buffer
stop forward, thereby shoving the
entire
construction
backwards.
Next, it encounters friction from the
ballast between the sleepers and is
slowed down. In this way, the danger
for travellers and other persons in
the proximity of dead-end tracks is
significantly decreased. In addition,
damage to the train, the platform,
buildings and other objects nearby
the rail are minimised or even
avoided.
After impact with a train, the buffer
stop must be inspected thoroughly
for damage such as cracks and
bends before it can be placed back.
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TECHNICAL DETAILS + MEASUREMENTS
The buffer stop is made of tubular steel frame accommodated with middle and side
buffers. This design makes it suitable for absorbing the impacts of both passenger
and freight trains. Furthermore, its galvanised high quality steel frame that is covered
by a two-layer powder coating guarantees an operational life of forty years.
The buffer stop is also available in
a ‘light’ version. This type has been
designed to anticipate the demand
for buffer stops to be used in the lightrail sector, which is growing as a result
of the worldwide increase of urban
public transport. In the design of this
model the lower coupling point of the
vehicle has been taken into account.
This coupling point is located at 65 cm
above the top of the rail with a range
of +/- 21 centimetres. The model is
currently prototyped and tested.
All models can in terms of measure­
ments and technical pre­
requisites
be assembled on the basis of the
specific wishes of the client. The
fastening mechanism has been
developed for rail types 60E1, 54E1
and 49E1. A version with a hydraulic
crash buffer is also available. The
models can be obtained in different
colours, at the client’s request. When
the client is satisfied with the solid
framing construction, the fastening
to the rail can be done in two ways
to create either a fixed or a dynamic
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version. It is possible to rebuild the
buffer stop from fixed into dynamic
and vice versa at any moment during
its operational life.
The Dynastop version offers an
adjustment option that makes it
possible to change the number of
brake components. This makes the
Dynastop suitable for intercepting
both lighter and heavier trains, with
either a higher impact speed or a
shorter braking distance. In addition,
the interception always takes place in
a controlled manner.
In order to facilitate the instalment,
two hoisting eyes are attached. These
aiding tools ensure that during lifting
the buffer stop remains in balance
and can be placed safely.
Logistics
The transport of the buffer stops to any desired location
is offered as an additional service. A sea container carries
an average of six complete product items, which can be
delivered to the client in the form of a ’construction kit’. An
(English) installation handbook is available. If desired, Railpro can offer assembly services at your location.
Measurements & configuration
Width
2,350 mm
Weight
910 kg
Colour
variable
Fastening mechanism
fixed or dynamic
Coupling height range
980 – 1065 cm
Measured from the top of the rail
For passenger trains with moveable coupling
Box with mounting feet for Dynastop contains:
» 4 brake shoes
» 2 – 6 brake block shoes,
Depending on the space behind the buffer stop
and the speed of the impact
Box with mounting feet for Fixstop contains:
» 8 fastening plates
» 16 M24 x 170 mm head bolts incl. screws
» 32 sets of M24 Nord-Lock rings
» Weight 129 kg
COLLABORATION
REALISE SAVINGS
The production of the steel frame can be executed locally
in collaboration with external manufacturers. By sharing
our knowledge, a co-operation with a local welding
company can be established on the basis of a partnership.
This company will then be certified via a special license
arrangement. This unique approach facilitates a direct
response to local market conditions, such as the demand
for local engagement. A steel construction combined with
the patented fastening mechanisms delivered by Railpro
is in terms of high performance and quality exactly similar
to a ready-made item. In addition, production costs are
optimised because, for example, the raw materials are
cheaper and the labour costs lower while there are no
costs involved for transportation from the Netherlands.
RAILPRO BUFFERSTOPS
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TESTCASE
MAXIMUM ENERGY ABSORPTION
MINIMAL DAMAGE
Prior to its release, the Fixstop was subjected to a crash test to
determine whether it could absorb forces exceeding the 1,000 kN
without visible damage. If after a collision the visual inspection shows
that the powder coating is intact, the weld has not incurred any
damage and the buffer stop is still in optimum condition.
In addition, some other aspects of the Fixstop were measured and
subsequently used by the Dutch network operator ProRail as standards
in the drafting of their renewed regulations for rail termination
systems. A passenger train was simulated by a number of coupled
wagons with a total weight of 540 tons. Next, the train collided with
the buffer stop at different speeds. There is video footage available
of these tests. With each test, the speed was slowly increased from
0.2 km/hour to eventually 9.2 km/hour.
N.B.: the weight of passenger trains in the Netherlands is between
137-350 ton.
The results of the tests indicate that the Fixstop can endure an impact
force of 1,000 kN without any serious damage. The force absorbed
is linear with the velocity up to a speed of ca. 9 km/hour. This is,
however, in all likelihood strongly dependent on the stiffness of the
coupling between the carriages or wagons.
During the test, the breaking welds placed at approximately 15 metres
from the buffer stop, broke at a force of about 1,100 kN. As a result,
a part of the rail which carried one wagon was moved backwards
over a distance of two sleepers. The use of breaking welds facilitates a
maximum absorption of the energy generated by the extreme forces
released in a collision. The position of a breaking weld is measured in
such a manner that at least 2 axes, or one bogie, of a carriage will
stay put during the reduction of speed caused by the ballast.
The middle buffers attached to the Fixstop are highly effective in
clamping the full automatic coupling of the wagon, which prevents it
from being launched.
A calculation based on the finite element method (FEM) has proven
that in case of a collision with two buffers, the fixed rail termination
system can endure a force of 1,000 kN divided between these two
buffers without the occurrence of plastic deformation. The same
test was conducted for a collision with the middle coupling. In the
calculation a safety factor of 1,1 was used, so that the overloads
would reach 1,100 kN (Source: research H.E.C. Sterkteanalyse
(Strength analysis), 2010).
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REFERENCE
HIGH SAFETY REQUIREMENTS
MIDDLE AND SIDE BUFFERS
Buffer stops have been used on
dead-end tracks for many years now.
A dead-end track is a piece of track
that can be found at a station or a
shunting yard. Here, the train, tram
or metro vehicle can only continue
its journey by rolling back in the opposite direction.
DUTCH
DESIGN
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Extremely solid elegant design
Patented dynamic brake shoes
Forms of collaboration as
business model (‘polder’ model)
Universal solution
Fixed as well as dynamic
installation possible, including
alternate conversion
RAILPRO BUFFERSTOPS
In general, a dead-end track is accommodated with a buffer stop
that enables the train to come to a
halt when it fails to stop at the usual shunting speed due to an emergency. People and buildings in the
area behind the dead-end track are
thereby safeguarded from a collision. In addition, a buffer stop ensures that a train comes to a halt in
a controlled manner. Given the ever
increasing weight of transport vehicles and the high safety requirements, the prerequisites for buffer
stops have changed. Railpro has developed a buffer stop that meets all
of them.
The buffer stop with the fixed brake
shoes is fastened to the rail. This
property has led to the name ‘Fixstop’. This rail termination system is
particularly meant for the dead-end
tracks of sidings and shunting yards.
The model has been included in the
design regulations of the Dutch railway infrastructure operator (in accordance with OVS00056-9 V003).
In addition, an Order and Purchase
regulation (BEA00376 V007) has
been drawn up. This means that if
a fixed rail termination system is
prescribed, the Dutch railway infrastructure regulations dictate the use
of the Fixstop. voestalpine Railpro
is both the manufacturer and the
supplier of the Fixstop.
The buffer stop has been used in the
Dutch railway network since 2011.
The rail contractor is responsible for
its proper installation. The buffer stop
can be accommodated with both
middle and side buffers for passenger as well as for freight trains and is
installed on all types of vignole-rails.
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voestalpine Railpro BV
Nieuwe Crailoseweg 8
Postbus 888
1200 AW Hilversum
The Netherlands
www.voestalpine.com/railpro/en