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Linklater's Scotland:
Maintaining the Forth Bridge
Magnus Linklater
Columnist, Scotland on Sunday
Filed 10 May 06
©Magnus Linklater
This article,
which was originally published in the Spectrum Magazine
of Scotland on Sunday on 7th May 2006, is reproduced on Land-Care
with the kind permission of the author and the newspaper
I STOOD atop the First Wonder of Scotland, and
marvelled. Right up there, on the very summit of one of the three
great double cantilevers of the Forth Bridge, I looked north to
the sweep of the Lomond Hills and south to Arthur's Seat. Then I
looked down.
It was a mistake. I am not, in general, afraid
of heights, but when there is nothing but a thin piece of scaffolding
between you and the swirling green waters of the Firth of Forth,
100m below you, a strange quirk of the imagination says, "Go
on, jump. Just think of it, a couple of reverse flips and then a
clean dive into the sea. What a way to go!" Your knees go weak.
Your grip on the scaffolding tightens.
And then it begins to vibrate. Way down below, a miniature Hornby
Dublo-sized train is approaching the centre of the bridge. It lets
off a double hoot and, in a well-rehearsed safety drill, the men
in orange jackets standing by the track acknowledge its arrival
with a wave, then turn their backs on it and grip the hand-rail
as it passes. The bridge shivers slightly, then relaxes.
These trains are lightweight compared to the thundering
monsters the bridge was used to carrying in its heyday. There may
be 180 or so of them every day, passing every 15 minutes, but they
cannot compare to the massive locomotives, with their 50 wagons,
weighing 900 tons, which rolled across the bridge on January 21,
1890, to test the stability of this revolutionary structure. They
passed over safely, and so has every one of the billion and a half
tons of trains and freight that have thundered across it ever since.
"This bridge is as strong and solid and resilient as the day
it was built," says Ian Heigh, the project manager for Network
Rail, which owns and manages it today. "They used good steel,
they were first-class engineers, they built it to last, and it has."
He glances briefly over at its neighbour, the road bridge, a teenager
in comparison, but already feeling its age. He says nothing.
There are things you see from this magnificent
vantage-point that you would never guess at otherwise. The struts
of the high girders, which plunge down from the top like the tracks
of a rollercoaster, are not absolutely straight. Over the years
they have sagged a little, so that the sight-line is endearingly
bendy. So long as you don't look down, however, you feel supremely
safe in the hoists that lift you smoothly to the top and along the
walkways, protected by balustrades.
The bridge is surprisingly elegant, tapering from
the top to a slim waist at track-level, more maiden than matron
(Heigh always refers to it as "she"). And later, when
we take a launch out to view it from sea height, its arches soar
as gracefully as the Ponte Vecchio.
Heigh, who is 49 and from Bathgate, talks of the
pride he feels in this, the biggest job he has had in his career
as a civil engineer. "It's my bridge - at least, that's the
way I feel. I'm responsible for it, and I aim to restore it to the
very best state it has ever been in."
This is a big ambition. Ten years ago, when Railtrack,
Network Rail's predecessor, inherited the bridge, it was in a sorry
state. Large sections appeared to be rusting away, leaving its famous
dark red blistered and peeling and looking as if it had contracted
a virulent disease. That impression was reinforced when parts of
the bridge were swathed in what looks, from a distance, like bandages.
In fact, these are large plastic sheets, made of something called
Enviro-wrap, which cocoons the lattice-work of steel and prevents
the air around it being polluted as the old paint is blasted off
and the new paint sprayed on.
Inside the encapsulation, as it is known, and
protected by helmets supplied with clean air, up to 150 painters
and blasters are at work on any one day. Once they were suspended
on ropes in the open air. Now, safety is paramount. Workers wear
special harnesses and stand on carefully constructed platforms,
supported by a scaffolding system that is almost as complex and
labyrinthine as the bridge itself. Whereas, 120 years ago, as many
as 57 men are thought to have died in the construction of the original
bridge, there has been not one fatality in the last three years
of the present contract, and no one has had to take more than three
days off because of injury - a remarkable safety record.
The old myth that painting the Forth Bridge is
a never-ending process has not been true for some time. For years,
parts of it were not touched at all. But what is happening now is
perhaps the best and most effective treatment it has had in the
116 years of its existence. First, the peeling layers of old paint
are removed by blasting, which takes it back to the raw steel, a
process known as scabbing and scarring. Then - and it happens within
hours, because exposed steel rusts quickly in the humid sea atmosphere
- the first of four layers of paint is sprayed on. (Over the seven
years of Network Rail's contract, an estimated 400,000 litres of
paint will be used.) To get right into the nooks and crannies of
its corners, and round the 6.5 million rivets that hold the bridge
together, using an old-fashioned paintbrush is still the basic technique.
I asked Heigh if he had ever had to tell his workers to go back
and do some bits again. "Oh, yes," he says. "If it's
not up to scratch, that's just what I do. But I have to say, they're
pretty good at the job these days."
For a century the paint was supplied by the Edinburgh
firm Craig & Rose, but these days it is made in Derby, and is
a state-of-the-art glass-flake epoxy resin, which binds into the
steel and gives it a hard, enamel-like surface. This should, explains
Heigh, last for at least 25 years without having to be redone. "The
paint excludes moisture and is about as impervious as you can get,"
he says. "It is a type that was used on the North Sea oil rigs,
and has been developed since. I describe it as being like the platelets
of an armadillo."
So, how bad a condition was the bridge in ten
years ago? "The basic steel was fine, but if the corrosion
had not been arrested then it might have been serious. It's not
an issue now. The damage is only skin-deep - at worst a millimetre."
So when will it be finished, and how much is it
costing? Network Rail subcontracts the work to several companies,
of which the main one is Balfour Beattie. The firm has a seven-year
contract, which runs out in three years' time. By then the bulk
of the work will have been done.
Depending on the funding available, a decision
will then be taken on whether to carry on and finish those areas
that were painted a decade or so ago. Heigh's best estimate of a
completion date is some time in 2012. The speed of work depends
very much on the weather. There are still only 80 to 90 days a year
when work is possible - you cannot paint in high winds and driving
rain.
The job is costing £13 million a year at
present, and by the time Network Rail has finished, more than £100
million will have been invested. It is money well spent. When, finally,
the last of the scaffolding is removed and the 'bandages' unpeeled,
a proud new bridge will be revealed - a tribute to the sound engineering
and groundbreaking design that confirm it not only as the First
Wonder of Scotland, but as a triumph of modern civilisation.
http://news.scotsman.com/topics.cfm?tid=1119&id=677742006
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