Twice over the Forth: Bridges span two eras

Each time I drive over this bridge, I feel a decided lifting of the heart. A touch childish, perhaps, but I think it's the next-best thing to take-off.

Of course, it may also be that what I feel is a tingle of mock trepidation. A stirring of some vague folk memory that crossing a bridge, for all the reassuring sophistication of modern engineering, remains, at root, a sort of dodgy high-wire act.

The very idea of a bridge, in its apparent defiance of gravity, in its triumph over an impassable gap, contains a kind of daring. It's difficult to be indifferent to bridges, however familiar particular ones become. Ancient bridges – Roman or medieval – often inspire as much admiring affection as today's astounding achievements elicit wonder.

The best bridges, to me, even if they are as safe as houses, do at least have a slight lookof danger about them. They remember their primitive and experimental origins. This one, the Forth Road Bridge in Scotland, suspended on its cables and wires, has that look. And the "look" of a bridge is definitely part of what makes it more than an unremarkable link between two banks.

The Forth Road Bridge, now more familiar to me since I found out you can also walk over it, is a 1960s suspension bridge. To stroll over it and feel the judder from heavy trucks and gaze far and wide, to discover that you can put your hand around one of the cables – they are that slender – is to reintroduce yourself to the bridge's scale and bravado. It is an impressive structure, however much it may have been preempted, then upstaged, by other ambitious suspension bridges worldwide. With a lightweight elegance that was progressive for its time, it spans 1-1/2 miles of river just as it starts to widen out into the North Sea.

But driving over the bridge is still exciting. I love the anticipation as you head toward it. Miles before you reach it, you get sporadic glimpses of its simple towers. They grow successively larger, like snatches of an overture that is building up to the final, decisive flourish just as the stage curtain swings open.

On the final approach to the Forth Road Bridge from the south, you glide down the suddenly expansive road. Then, after paying for the experience (a toll I never begrudge), you are perceptibly lifted by a gentle gradient and funneled into the narrow sweep over open water.

I have a friend who drives to work over this bridge twice a week. He claims to be blasé about it. Probably he encounters it in a too-early morning or weary end-of-day daze. However, I suspect he'd subtly miss it if he took a bridgeless route.

And besides, how can he ignore the other bridge?

Half a mile away, this other bridge (known by devotees as "The Forth Bridge") struts its stuff. From the Road Bridge, it looks smaller than it is. In fact, it is higher than St. Paul's Cathedral in London and at least one of the pyramids. What betrays its scale is the sight of a train creeping across it. The train looks like a toy.

Walking over the Road Bridge meant I could, for the first time, look at this triumph of Victorian engineering properly and slowly. It is the most extraordinary fabrication, this steel cantilever bridge. Looking at it straight across, it has an unexpected airiness. But to look airy could not have been further from the minds of its designers. It was designed not only to look, but also to be so massively strong that no one going over it, even in the hefty steam trains for which it was built in the 1880s, could have the slightest qualm. This was not (and still is not) a bridge to tremor or cause tremors.

One of the supervisors in charge of its construction sought to instill confidence in a public still worried about the recent collapse of another Victorian Scottish rail bridge, over the River Tay. He wrote: "... by its freedom from vibration [it will] ... enjoy the reputation of being not only the biggest and strongest, but also the stiffest bridge in the world."

The cantilever design and steel were comparatively new ways of building bridges at that time. But they had been proved reliable. This bridge, however, was to outdo any other bridge in its "stiffness." Something about this word suggests the nature of Victorian determination. The architects were determined to amaze people by the sheer statistics involved, including the 58,000 tons of steel. Overkill was the order of the day. The Prince of Wales, when he officially opened it, called it "stupendous," and no one felt inclined to disagree.

One of its designers, Benjamin Baker, tried to soften the possible shock of its radical appearance by describing it as "a romantic chapter from a fairy tale of science." The medievalist craftsman/writer William Morris, however, dismissed it as "the supremest specimen of all ugliness." He had a way with words.

The bridge was greatly admired from the start. It is one of those unfathomable anomalies that the Victorians generally could embrace almost anything in the way of industrial design so long as it signified "progress," while dressing their womenfolk in crinolines and bustles and their armchairs and windows in lace and antimacassers.

Even today, a great many Britons would find an abstract steel sculpture in an art gallery baffling while they coo about the blatant, yet functional, abstraction of the Forth Bridge with pride and nostalgia.

As I gaze at it from my footway on the later bridge (which itself may one day be companioned by a third Forth Bridge and even – who knows?– a fourth Forth Bridge), I relish the utter contrast between this bridge and that. And I am forced to conclude that, after all, over there is one great bridge that – as long as they keep painting it – looks as if it will never, ever fall down.

Magnificently stiff, magnificently safe. And yet bounding across the water like some kittenish and jubilant dinosaur.