Two
170m
HS2
tunnel
boring
machines

have
created
another
underground
section
of
the
high
speed
line
in
the
Chilterns,
by
reaching
the
ventilation
shaft
at
Great
Missenden.

‘Florence’
and
‘Cecilia’
are
now
three
quarters
of
the
way
through
their
16km
drive
under
the
Chilterns,
having
spent
the
last
two
years
excavating
the
two
bores
between
the
M25
and
South
Heath,
which
is
roughly
2km
east
of
Great
Missenden.

Designed
for
the
geology
of
the
Chilterns,
the
first
TBMs
were
launched
in
the
summer
of
2021
from
a
site
near
the
M25
and
have
already
excavated
2
million
cubic
metres
of
chalk
and
flint.

Engineers
have
also
completed
five
shafts
that
will
provide
ventilation
and
emergency
access
near
Chalfont
St
Peter,
Chalfont
St
Giles,
Amersham
and
Little
Missenden
with
an
‘intervention’
shaft
at
Chesham
Road.

A
‘headhouse’
will
be
built
on
top
of
the
shaft
to
house
ventilation
and
safety
equipment,
designed
to
resemble
local
farm
buildings
with
new
planting
to
help
blend
it
into
the
surrounding
landscape.

The
landmark
comes
just
weeks
after
planning
consent
was
granted
by
Buckinghamshire
Council
for
the
North
Portal
of
the
tunnel
under
Schedule
17
of
the
HS2
Act,
meaning
that
all
major
design
elements
now
have
consent.

The
tunnel
will
form
part
of
Phase
1
between
London
and
Birmingham,
which
has
been
given
a
‘red’
rating
by
the
Infrastructure
Projects
Authority,
meaning
that
the
London
to
Birmingham
and
Birmingham
to
Crewe
sections
are
considered
to
be
‘unachievable’.

Even
so,
HS2
Ltd
pointed
out
that
‘construction
was
now
hitting
a
peak,
with
“work
intensifying
and
huge
civil
engineering
structures
taking
shape”’.

HS2
Ltd’s
project
client
David
Emms
said:
‘HS2
will
transform
rail
journeys
between
London
the
midlands
and
the
north,
and
free
up
space
on
the
existing
network
for
more
freight
and
local
services.
We’re
seeing
great
progress
on
the
tunnel,
which
will
take
our
trains
deep
under
the
Chiltern
hills,
safeguard
the
woodlands
and
wildlife
habits
above
and
significantly
reducing
disruption
to
communities.

‘The
huge
progress
that
Florence
and
Cecilia
have
made
would
not
have
possible
without
a
huge
team
in
support
–
manufacturing
the
tunnel
segments,
excavating
the
vent
shafts
and
I’d
like
to
thank
everyone
involved.’

The
two
TBMs
are
operated
by
Align,
a
joint
venture
formed
of
Bouygues
Travaux
Publics,
Sir
Robert
McAlpine
and
VolkerFitzpatrick.