Rail conquers the Alps

40 January 2015 | Railway Gazette International
TRACK Low-vibration
Gotthard Base Tunnel
completes LVT installation
The successful completion of tracklaying through the world’s longest
railway tunnel reflects the continuous development of low-vibration
ballastless trackforms in Switzerland over half a century, with further
applications now in prospect.
DIPL-ING PETER LABORENZ
Head of Slab Track Division
Vigier Rail AG
President, Sonneville AG
peter.laborenz@vigier-rail.ch
October 31 saw the formal
completion of tracklaying
in the Gotthard Base Tunnel,
with the installation of
the final section of slab track, ahead of
the timetable agreed in 2009. Thanks
to the use of automated tracklaying
Both highattenuation
and
standard LVT
trackforms are used
in the Gotthard Base
Tunnel.
processes, the construction timescale
has been significantly shortened, which
in turn has allowed the start of commissioning
to be brought forward by a year,
ready for commercial operations to begin
in December 2016.
As well as being the world’s longest
railway tunnel, the Gotthard Base Tunnel
is the longest single application of
ballastless slab track in Switzerland to
date. And as such it has benefited from
a continuous programme of research
and development stretching back more
than half a century.
Swiss Federal Railways began research
into the use of slab track in the
early 1960s, with the aim of developing
a durable and low-maintenance
trackform for its long tunnels through
the Alps. Like Japan, where the J-Slab
system was developed around the same
period, Switzerland has many years of
experience in ballastless track technology.
Today, this is becoming increasingly
important as SBB looks to maximise
the availability of its infrastructure in
order to cope with increasing volumes
of traffic.
Early thinking
Given the importance of northsouth
trans-Alpine transit traffic, an
expert committee was established in
November 1963 to examine different
track technologies and the specific requirements
that should be applied in
Switzerland. Very early on it became
clear that non-ballasted track was the
best option for use in the long Alpine
tunnels. A conceptual design was developed
in 1964 based on feedback from
high speed track experience in Japan,
and the philosophy expounded by Albert
Einstein: ‘make everything as simple
as possible, but not simpler’. That
concept has proven its worth right up to
the present day.
Specific requirements were that the
track components should be well proven
in service, with established maintenance
procedures, that provision could
be made to ensure the required elasticity
and vertical track deflection, and
that the interchangeability of all track
DR-ING WALTER STAHL
Head of Projects & Academic Councillor
Institute of Road, Railway &
Airfield Construction
Technische Universität München
walter.stahl@vwb.bv.tum.de
DIPL-ING THOMAS SILBERMANN
Construction Manager
ARGE Fahrbahn Transtec Gotthard
Renaissance Construction AG
thomas.silbermann@afttg.ch
components could be guaranteed. The
construction method needed to allow
for the track position to be checked and
corrected before it was finally embedded
in the base slab.
Around the same time, SNCF and
its then Trackwork Development Engineer,
Roger Sonneville, were developing
a trackform using twin-block sleepers
connected by a metal angle bar, and this
was adopted in Switzerland. The two
concrete sleeper blocks are encased in
rubber boots to isolate them from the
in-situ cast concrete slab, and a flexible
pad is placed inside each boot, below
the blocks, to provide the necessary degree
of elasticity.
Trial installations
SBB found its first opportunity to
test the concept with a short section
of track in the Bötzberg tunnel laid in
1966 1 . This was followed by a large-scale
trial in the 4·8 km twin-track Heitersberg
tunnel which opened in 1975 2,3 .
Detailed measurements could then be
taken with trains passing at speeds of up
to 200 km/h, allowing the track component
specifications to be optimised.
The good results, both in technical
terms and in the detailed cost comparisons
with traditional ballasted track,
led to further newly-built tunnels being
equipped with slab track, including
the Zürich airport tunnels in 1979, the
Zürich S-Bahn station at Museumstrasse
in 1990 and the 5 km Zürichberg
which opened the same year.
The Heitersberg tunnel pilot project
was effectively concluded in 2014,