The Future - Signalling
Princes Risborough North Signal Box
At
present
our
heritage
trains
run
in
and
out
of
Princes
Risborough
over
the
Network
Rail
siding
between
Thame
Junction
and
the
outskirts
of
Princes
Risborough
(see
picture
alongside)
under
a
Track
Access
Contract
and
an
agreed
‘Method
of
Working’
(MoW).
That
present
day
siding
was
once
the
single
line
that
went
via
Thame
to
Oxford.
Decaying
alongside
it
and
covered
in
undergrowth
was
the
disused
Watlington
branch
track,
which
has
now
been
lifted.
An
appeal
has
been
launched
to
relay
new
track
so
that
the
Chinnor
&
Princes
Risborough
Railway
can
use
it
as
an
independent
line
removing
the
need
for
a
complicated
and
at
times,
restrictive
sharing
of
the
siding.
With
the
introduction
of
the
Chinnor
Independent
Line
will
come
the
need
to
expand
the
signalling
and
pointwork
controlled
by
our
signal
box
and
work
is
well
underway
to
make
the
southern
end
of
the
box
nearest
the
station the operational end.
A
signal
post
has
been
erected
at
the
exit
of
Risborough
Platform
4
and
a
branch
signal
now
stands
proudly
to
the
rear
of
the
signal
box.
A
further
post
is
round
the
curve
towards
Thame
Junction.
These
will
be
needed
to
signal
trains
when
the
pointwork
to
change
tracks
onto
the
Chinnor
Independent
Line
is
installed.
They
won’t
all
be
fitted
with
signal
arms
until
the
whole
system
is
ready
to
be
commissioned,
but
the first ones should go up after the 2022 Santa season has finished.
On
the
sub
floor
beneath
the
signal
levers
is
a
mechanical
interlocking
frame,
shown
below.
This
frame
is
basically
a
mechanical
computer,
invented
decades
before
the
first
electronic
computers,
that
prevented
the
signalman
from
accidentally
setting
signals
and
points that would lead to conflicting train paths and potential collisions or derailments.
As
mentioned
previously,
the
signal
box
operating
level
has
been
partitioned,
splitting
the
box
into
two
separate
areas,
north
and
south.
The
operating
area
will
be
in
the
south
end,
nearest
to
the
platform,
whilst
the
north
end
of
the
box
is
anticipated
to
be
a
demonstration
area
of
railway
signalling
and
operating
practices.
There
will be separate interlocking frames under each section.
With
the
addition
of
new
signals
and
points,
we
had
to
redesign
the
interlocking
to
ensure
the
necessary
protections
were
put
back
in
place
so
the
safety
of
our
passengers
and
trains
is
assured.
We
have
now
completed
the
mechanical
part
in
the
south
end
and
have
added
electrical controls and indicators for additional safety.
For
those
who
would
like
further
reading
on
railway
signalling
in
general,
here
are
a
couple
of
good
websites
that will provide more information:
https://en.wikipedia.org/wiki/Railway_signalling
and
https://www.signalbox.org
NR Thame Branch Siding
Chinnor Independent Line
