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This is the Severn Valley Railway,
which runs alongside a stretch of the Severn River,
between Kidderminster and Bridgnorth, in the West Midlands of England.
There are only a few preserved steam railways like this operating in Britain,
and all of them are privately run,
relying heavily on the help of enthusiasts, who drive the train,
operate the signal and draw up the timetable.
A timetable has to suit passenger demand,
but it has another very important function, to ensure safety,
which is especially important on single-track sections of line,
like those on the Severn Valley Railway.
If two trains collide, the consequences can be disastrous.
Five people have died in a train crash in Kent.
Two trains collided in thick fog on a single track line.
Collisions on a single track are rare but, nevertheless, a very real danger.
Even in the 90s, trains have come to grief,
despite what are thought to be failsafe precautions.
The two trains collided head-on in thick fog
while travelling on the single track line.
It's thought that both were running late, and there's evidence that one,
at least, skidded, as it tried to brake before the impact.
The collision shattered the front diesel units.
The two drivers are understood to be amongst the fatalities.
In common with other railway lines,
the Severn Valley Railway has to maintain strict safety rules.
There are speed limits.
Here, it's 10 miles per hour,
and the signals indicate whether or not it's safe to proceed.
There would be no problem in running just one train on one line,
but as soon as there are two or more trains running at a time,
they have to be able to pass.
So, you need make use of locations such as stations
where the line becomes double-track.
Bridgnorth and Kidderminster both lie on the valley of the River Severn,
and the two are connected by 24.5 kilometres of railway line.
The line starts on one side of the river,
before crossing over a bridge to the other side.
The line also goes through a tunnel outside Kidderminster.
Trains are able to pass one another at a number of intermediate stations
along the largely single-track line.
A train not only waits for the station platform,
to allow passengers to get on and off,
it may also have to wait for the line ahead to be clear.
This train is having to wait for a train travelling from the other direction
to arrive at the station before it can proceed.
Efficient timetabling should ensure that no train is held up unduly.
In order to investigate this further,
I went to Bridgnorth and boarded a train to Kidderminster with Keith Shaw,
who has responsibility for timetabling the service.
The first stop was to be at Hampton Loade,
one of several stations and potential passing places on the way.
Like all good railway supervisors, Keith is armed with a stopwatch.
Oh, nine o'clock, right on time.
Slowly but surely the train gets up steam,
but its departure time is being noted for a reason.
Can you tell us about what you're doing today?
We're just checking the times of the trains in order to compose the timetable.
We've just left Bridgnorth now pretty well on time.
We've had some difficulties starting, you'll notice,
but that's something that maybe we have to take into account
in the timetable.
Do you have problems with trains being late?
No, not too bad.
On the other hand, it is important that we don’t just sit back
and look at the timetable and say, "well, that's it, forever."
So, let's look at some of the local landmarks
and key places that affect the journey time.
The train has reached a place called Sterns,
just over halfway to Hampton Loade,
where there's a danger of the line slipping into the river.
And so there's a speed restriction, or slack, at 5 miles per hour.
It's 9.15, and we've just passed the slack at Sterns,
and as this is only a one coach train, of course,
it doesn't take us long to pass it, but if you've got eight or nine coaches,
the whole of the train would have to pass the shore section.
I'll just make a note of that.
The particular train on which we're travelling only needs to have one coach,
because it's the early morning taxi for railway personnel.
Right, we're approaching Hampton Loade now.
At Hampton Loade, there's a very interesting ferry,
and there's a ferry across the river which has no power, no motor power,
it's driven by the current of the river.
And it's two very elderly ladies operate it, and if you want to cross,
you go and push a button on a pole,
and they come out of their house and get in the boat.
And it's anchored to a wire which runs across the river,
and by manipulating the rudder,
they can use the current to drive the boat across or back.
It's quite fun.
And, occasionally,
when I'm the signal man at Hampton Loade,
I use the ferry,
park the car on the other side of the river and come across,
which is quite nice, it's quite a nice feature.
Just approaching Hampton Loade Station now,
so we need to check the time. It's just 9.20.
So, that's the journey as far as Hampton Loade,
a distance of 7.2 kilometres.
And we arrived at 9.20.
A useful way to represent a journey is to draw a position time graph,
marking positions on the vertical axis, with BN for Bridgnorth,
and HL for Hampton Loade.
The horizontal time axis is divided into equal time intervals,
starting at 9 o'clock when the journey began,
up to 9.20 when we reached Hampton Loade.
The graph of the trip from Bridgnorth to Hampton Loade looks like this.
Up until 9 o'clock, the train was stationary at Bridgnorth,
and so the graph is horizontal.
As it's speeded up, the graph gets steeper.
At about 6 minutes past 9,
the train had settled to a constant speed for a period of 5 to 6 minutes,
but then it slowed down to enter the cutting at Sterns,
where there's a speed limit.
Let's mark the position of Sterns on the vertical axis.
At 9.16, once the train had passed through Sterns,
the graph gets steeper again as the train speeded up,
until it finally slowed down as it approached Hampton Loade Station,
where it stopped, at 9.20.
The next part of the journey took us beyond Hampton Loade
to Highley Station,
along another 3.3 kilometres of single-track railway.
There were a number of factors which affected our speed.
So, where are we now, Keith?
Well, we're just past Arley Sidings, we're approaching Highley.
We've come over Highley Bank, which is quite a steep gradient,
and it's reverse curves,
that's curves in one direction and then the other,
which makes for increased friction,
which makes it more difficult for the driver.
And so we shall be approaching Highley, soon.
Of course, in the opposite direction,
the gradient works in the driver's favour,
so he has –
it's important he keeps to the speed restriction in that direction, as well.
Slowing now for Highley.
I'll check the time. And 9.27.
After Highley, there's Arley Station,
a further 3.5 kilometres up the line, which we reached at 9.36.
One kilometre beyond Arley,
the line crosses over to the other bank of the river.
Well, that's 9.40, we're just crossing Victoria Bridge,
which, when it was built, in 1861,
was the largest single-span iron structure ever built at that time,
by a firm called John Fowler, and it's 200 feet single-span.
Now, the faster section of the line,
it doesn't have as many slacks on as the earlier part,
and also, of course, by now the engine's warmed up
and things are running much more as they should be.
There's one more stop before Kidderminster,
and that's in the town of Bewdley.
To get to Bewdley Station,
we've travelled a total of 20 kilometres from Bridgnorth and arrived at 9.50.
The next landmark was the tunnel.
We're just approaching Bewdley Tunnel now,
this is another timing point. 9.56.
Trains will, of course, whistle when they go in,
to warn anyone who's inside that there's a train coming,
because there's no way you could –
maintenance staff might be on the ground in the tunnel
or doing some work, to let them know, you know.
To get out of the way.
There are little niches in the side of the tunnel in which you can stand on
if a train comes by, but then you still need to know all of them.
The tunnel was the last timing Keith made
before we reached our final destination, Kidderminster Town.
On the outskirts of Kidderminster, the single-track becomes double again.
Our final arrival time, 10.10.