43
april 2014
international
construction
TUNNELLING
Unique challenges
>
Innovation
This demonstrates some of the dedication and innovation that
is needed to rescue projects when things gowrong – innovation
that is currently in demand on a project in Seattle, US, where
a huge TBM has been stranded underground since December
last year.
It is not uncommon for TBMs to run into unexpected
difficulties during their bores. However, the level of downtime
currently being experienced by the massive, US$ 80 million,
91.4 m long, 17.5 m diameter TBM known as Big Bertha is
unusual.
Bertha started its Journeyboring the2.83km longHighwaySR
99 tunnel underneathSeattle,US, in July2013.But themachine
has been stranded 18.3m underground near SouthMain Street
sinceDecember,with repairs estimated to take six
months ormore.
The developer, the Washington State
Department of Transportation, said contracting
consortium Seattle Tunnel Partners (STP) and
Bertha’s manufacturer, Hitachi Zosen, had
identified apieceof steel pipeprotruding through
an opening inBertha’s cutterhead.
STP – a joint venture betweenDragados USA
andTutor Perini – is considering several options
to remove the steel pipe and identify other
potential obstructions. As the process to clear
the blockage continues, workers are conducting
critical maintenance, inspecting and replacing
damaged cutter tools on the face of themachine.
STPhas estimated that diggingmight not resume
until at least 1 September this year.
>
GTAMaschinensysteme developed a
multifunctional uphill excavator for the
Crossrail metro project in London, UK.
To support
construction
of the Pernau
Subsurface
Tunnel in
Austria, Doka
used its new
cut-and-cover
tunnel formwork
system, Doka CC.
>
