Controlling Trains - Network Rail engineering education (3 of 15)
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[train passing]
♪ pizzicato background music ♪
(Narrator) Britain's rail network transports
3 million passengers and
400,000 tonnes of freight a day.
With hundreds of trains using it
at any one time.
All this traffic presents us
with a safety challenge.
Trains are guided by rails,
so it's impossible for them to swerve
or pull over.
Trains are heavy, can't stop quickly
and frequently operate at speeds
which do not enable them to halt
within sighting distance of the driver.
Under these circumstances,
one might assume that
trains are prone to collision.
In fact, rail is the
safest mode of transport in Britain.
And that's because trains are
carefully controlled.
Hence our responsibility
at Network Rail to control them.
Signalling is the control process
Network Rail uses to operate trains
safely, over the correct route
and to the proper time-table.
The two key features of this process
are line-side signals and
the block system.
Trains can't collide if they're not
permitted to occupy the
same section of track at the same time.
So the network is divided into sections
known as "blocks".
Normally, only one train is permitted
in each block at any one time.
The British rail network uses
line-side signals to advise the driver
of the status of the
section of track ahead.
Most line-side signals are in
colour light form,
but a significant number of
semaphore signals remain
on secondary lines.
The semaphore consists of a
mechanical arm that raises
to signify go
or lowers into the horizontal
to signify stop.
The most modern signals have
4 colour aspects.
A green light indicates clear.
A double yellow indicates that
the next signal will be a caution.
The yellow signal indicates caution,
and that the next signal will be red.
And a red means stop,
otherwise known as danger.
It's prohibited
to pass a signal at danger.
The British rail network
was originally controlled
by thousands of manned signal boxes
located at regular intervals
along the lines.
♪ guitar background music ♪
(Stewart) My name's Stewart Sentence,
I'm the signaller at
Uttoxeter signal box.
This is the most traditional form
of system on the railway
as it is at the moment.
A lot of this, as you see, goes back to
when the original railway started.
As far as we're concerned
the universe begins at Caverswall
over to the right and Sudbury there
and we're in the middle.
This set of blocks tells me
where the train is between myself
and Caverswall,
and this set of blocks
tell me where the train is
between Sudbury and myself.
These levers here will operate
the points for the crossings into the
loops and sidings. They'll also work
the semaphore signals.
(Narrator) To prevent a collision
caused by human error,
the safety system called "interlocking"
protects the railway network.
Interlocking is a series of
mechanical devices that prevents
the signaller operating appliances
in an unsafe sequence.
(Stewart) What you have here is what looks like
a simple lever system but is actually,
if you looked underneath the box,
is quite a complicated
interlocking system.
The interlocking system prevents me
giving a green signal
to an approaching train unless I set
that route in that interlocking system
safely first.
It sounds simple
and it basically works simple but
the action what it does is very good.
(Narrator) Level frame signal boxes,
while effective, aren't efficient.
They only cover a short section of line
and manning them with skilled operators
is expensive.
(Stewart) Now I can pull the signals off No. 2.
[loud click]
Some of these you'll see me pulling
quite 'ard; that's because
there's a lot of gape on these.
Some people can't actually pull 'em
at all.
Well a lot of it's fairly hands on.
You see the trains, you've got control
over the trains and the job itself.
It's a good job; a better job
as I've ever 'ad.
Without a doubt.
[clank]
[train passes rapidly]
(Narrator) The next big leap in
rail signalling control came with
the electronic age and the advent of
Power Signal control Boxes
like this one in Derby.
♪ 60s electronic background music ♪
(Signaller) This location opened in 1969,
and when it did open it represented
a massive step forward to the railways
in the way that trains are signalled.
Well, these lines represent mainly the
Derby to Birmingham main lines.
This signal box actually took over
84 mechanical signal boxes,
making it a far more efficient way
of carrying out signalling.
(Narrator) Routes are set by pressing buttons
on a large control panel.
Each section between buttons represents
a stretch of line formerly controlled
by a lever framed signal box.
(Signaller) It's very easy to work around.
The signalling system is
very user friendly and very easy to see
the layout of the trains and where
they're coming from and going to.
The presence of a train is indicated
by these red lights on the panel.
They're activated by the completion
of an electrical circuit
when the train's wheels pass over
the track circuit.
The operation of the
signalling equipment is carried out by
pulling and pushing the actual buttons
that are set in the panel.
To set a route you press
the entrance button,
you press the exit button
and the signalling system between
detects all equipment that's located
between the two signals.
Once that's in the correct position,
the signal will clear
for the train to proceed.
To take the route out,
we simply pull the exit button
and the route will drop out.
(Narrator) Power Signal Boxes are regulated
by a relay room, a little like
a giant mechanical computer.
(Signaller) This is the interlocking room,
underneath the operating floor
of the Power Signal Box.
And in 'ere are all the
banks of relays.
And these relays
relay all of the information
from the touches of the buttons
upstairs from the signaller
outside
to the points and the track circuits
and the level crossings.
(Narrator) Relays are interlocking
electro-mechanical switches.
When the signaller sets a route in the
upstairs control room, you can hear
the switches clicking, working out how
to set the signals and
switches and crossings and whether the
set route is safe.
[clicking]
(Signaller) These cabinets are where the equipment
in Derby PSB reach the modern era.
These allow transmission of the
train head code,
the four-digit running number
that we saw on the panels upstairs
to be transmitted to
adjacent signal boxes to give them
advanced notification of
that train coming so that train
can be routed further down the line.
(Narrator) Powered Signal Boxes are
effective and safe.
But at Network Rail we're now
introducing an even more efficient form
of signalling control.
♪ rapid piano background music ♪
(Jason) Compared to the oldest
lever box signal boxes,
this is a world apart.
It's like an Air Traffic Control Centre
basically, but controlling trains
instead of aeroplanes.
My name's Jason Jones, I'm a signaller
and I work at Ashford IECC in Kent.
The IECC stands for "Integrated
Electronic Control Centre". All the
signalling in this signalling centre
is controlled by computers.
A timetable is downloaded every day
and any alterations etc. are all
programmed into the computer.
When everything's running on-time
and all the trains are
in their correct place and there's
nothing else going on, the computers are
all running the job and I am literally
just sitting here monitoring.
Hello John, yeah it's sitting on
area 83 Ashford, over.
At any time there could be an emergency
of any description and that's when
I will then step in
and take over from the computer.
I will turn the computer off and then
run the trains manually using the
keyboard or the tracker-ball system
that we've got.
On this screen here I can see
the exact layout of the stations
and the tracks.
I can see where the trains are -
where the red line is.
Each red line indicates the location of
the train.
I can see where the trains
are heading for
(what route they're taking)
by the white line.
That's what the computer has set up for
that train to use.
We can also see the signals
what the driver sees out on the track.
The red dots indicate
a signal that's red,
we've got a single yellow,
we've also got a double yellow.
And obviously we've got
the green signals which means
then he can proceed at line speed.
♪ slower piano background music ♪
The computers that Network Rail uses in
this type of location
are specifically designed
for this type of system.
They use various safety protocols,
various fail-safes.
You get three computers working
in tandem with one another and before
any decisions are made,
two of the computers
have to agree with one another.
Ashford covers a huge area,
right from the Kent coast at Folkstone
right the way into Central London.
That is the equivalent, yeah,
of hundreds of the old style
lever frame signal boxes.
[train horn]
We don't just deal with
standard trains here. As well as
the commuter trains that we run
we also run the high-speed trains
into St. Pancras and the
Eurostar trains that come from
Paris and Brussels.
The high speed trains are run
using a totally different way
of signalling trains than the
old-style and conventional signals.
The high-speed line is signalled using
cab-signalling where the driver gets
a display in the cab and that tells him
when to stop his train, start his train
and what speed he must run at.
The trains travel up to 186 mph,
and that's just too fast
for the driver to be able to see
signals out on the track.
All the systems, whether you're
in a lever box or you're in
this type of modern technology
it's all designed to fail safe
and that is any failures,
the signals go back to red.
This job carries
a lot of responsibility.
You are responsible for people's lives
on the trains, the public, drivers,
track workers. You do have a fair bit
of responsibility.
No matter how much the technology
changes, the one thing that
remains the same is
the safety and the security
of the trains out on the track.
