The Forth Bridges

A to Z Blogging Challenge

The Firth of Forth is a Scottish estuary that divides Fife on the north from Lothian on the south. Firth is probably derived from the Norse word Fjord, meaning narrow inlet. And it’s fortunate that it narrows sufficiently at the town of Queensferry to allow not one or two bridges but three.

The Three Forth Bridges

Bridge number one is the oldest, and is a railway bridge, because cars didn’t exist when it was constructed between 1883 and 1890. Remarkably it still holds the record for being the world’s longest cantilever bridge. A Cantilever works something like this:

The Forth Bridge engineers’ explanation of how the cantilever would work.

The Forth Bridge was also the world’s first major steel structure and is 2467 meters long, used 53000 tonnes of steel and 615 million rivets. During its construction 57 workers lost their lives. The first design for the bridge was by Thomas Bouch, but it was abandoned. The reason why was due to the collapse of another railway bridge in 1879 – an iron bridge that failed during a storm. Bouch’s reputation was destroyed with the bridge. The new designers John Fowler and Benjamin Baker submitted the cantilever design. Both men were involved in the construction of the London Underground, and Baker designed a vessel to carry Cleopatra’s Needle (an obelisk) from Egypt to London.

4600 men were employed, many left with crippling injuries. Caissons were sunk to create the piers and building them requires using compressed air to keep the water out. It was dangerous and uncomfortable work. The towers on top of the piers were completed, then the cantilevers stretched out to fill the gaps in a magical anti-gravity way. The completed bridge allows an uninterrupted train service from London to Aberdeen to this day.

The second bridge, the Forth Road Bridge, opened in 1964 and is a long span suspension bridge. At 2.5km it was the largest outside USA at the time. The first proposals for a road bridge were discussed in 1923. As well as bridge options, there were tunnel ideas too. The Great Depression and WW2 delayed the start. Whereas the Forth Bridge was designed by individual engineers, this newer bridge, like most large scale constructions these days, is the product of a consortium of engineers and designers.

One tower was constructed on a whinstone outcrop – Mackintosh Rock, while the southern tower was situated as far as way from the shore as possible. The cables, nearly 12,000 of them, are steel wires bundled together and the total length of them could go around the world one and half times.

The most recent bridge is the Queensferry Crossing and was opened in 2017. It is a cable stayed bridge, which looks similar to a suspension, but according to this neat little diagram, the forces work differently, so the deck isn’t suspended.

At 2.7km long, it is the longest, 3 tower, cable stayed bridge in the world. The record broken during its construction is the largest continuous underwater cement pouring. For 15 days, 16869 cubic metres of concrete were poured into the south tower caisson non-stop.

So they we have it. Three bridges, yet it has to be said, the Forth Bridge is the most iconic and recognisable. For who hasn’t heard of the saying it’s like ‘Painting the Forth Bridge’. (The idiom is used to indicate a job or task that is never completed.) As soon as the painting job is finished, it needs to be started again. The paint is required to protect the steel from the harsh elements. First a primer was applied, then an epoxy paint by hand to each of the rivets, then the famous red topcoat. But the truth is, the painting was completed in 2011, and should last 20-25 years. Regardless, we’ll stick to the idiom, it does have a great history.

Painting the Forth Bridge

25 comments

  1. I didn’t know about the third bridge! A long time ago (in blogging terms) I mentioned the Firth of Forth in a post. https://suesconsideredtrifles.wordpress.com/2012/11/15/to-the-nth-degree/

    Liked by 1 person

    1. I have to admit, nor did I. But it’s been some years since I last travelled that way.

      Liked by 1 person

  2. Great to know the Scottish history of estuary
    That engineers demo is so cool…..it’s scary to know how risky the construction work was and that quote sums it up…last one

    All the best

    Visiting from a to z http://afshan-shaik.blogspot.com/

    Liked by 1 person

    1. I’m still not sure I get how cantilevers work but the demo is a wonderful way to show it.

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  3. see now that was interesting to me.. I stil get super nervous on bridges but… neat 🙂

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    1. I don’t like heights, so some of these bridges are a little too scary for me!

      Liked by 1 person

  4. These bridges looks awesome!
    Unbelievable how old they are, and how much time, money, work and even lives it took to build them. Thank you for telling us about them.

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    1. It can take decades for a bridge to completed given the planning and costs. Being an island, we have a lot of estuaries to cross, which makes it much more complicated.

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  5. Mummy loves bridges. She’s been over two of yours, but hasn’t been to Scotland for a long time. It’s too far for us to drive now. She was looking into taking us to Wales next year. It might go over a bridge she hasn’t been over before. Maybe that’s why she wants to go. That and a garden…
    George would have loved bridges too.
    Ludo

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    1. I hope you get to Wales; it’s a lovely country.

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  6. I rode a train across the Forth Bridge at night and it was quite awe-inspiring to see parts of the bridge illuminated by lights and parts shrouded in dark fog.

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    1. I’ve never been across it on a train – I didn’t know they illuminated it at night.

      Liked by 1 person

      1. I crossed just the once in 1998. There were big floodlights on the towers. It may have been for maintenance or maybe the famous painting. All I recall is the alternation of bright light and darkness being quite stunning.

        Liked by 1 person

  7. I think I remember Blue Peter doing a segment on the painting of the Fourth Bridge. It’s amazing to think that the railway bridge that was built so long ago still holds such a record.
    Tasha
    Tasha’s Thinkings: YouTube – What They Don’t Tell You (and free fiction)

    Liked by 1 person

    1. I think I remember Peter Purves walking across it?

      Like

  8. Fun the see the recent history of bridges so neatly encapsulated by these three. Now they just need a fourth forth bridge. (Ha ha, I’m sure I’m not the first to have come up with that joke. Or even the fourth.)

    Liked by 1 person

    1. I’m sure there will be a fourth forth bridge one day!

      Like

  9. G’day Rae,
    WOW! What a large amount of cable for the second bridge.

    We also used to be told that Sydney Harbour Bridge was a continuous paint job.

    Liked by 1 person

    1. There’s probably a bridge in every country thata continously paint job.

      Like

  10. Love the pic of the engineers explaining how it works… classic example

    Liked by 1 person

    1. It’s a great illustration. Easier than a diagram.

      Liked by 1 person

  11. Four bridges int eh same place! That’s so strange! 🙂

    @JazzFeathers
    The Old Shelter – Enter the New Woman

    Liked by 1 person

    1. The bridges connect Edinburgh to Aberdeen, without them, it’s an extra hour travel time. The location is ideal because the estuary narrows.

      Like

  12. joyweesemoll · · Reply

    I love the photograph illustrating how a cantilevered bridge works — very convincing.

    The most recent major bridge in our area is a cable-stay bridge, the Clark Bridge at Alton, Illinois. Cable-stay bridges are very impressive in the landscape.

    Liked by 1 person

  13. debscarey · · Reply

    What a wonderful photograph of the engineers demonstrating how cantilevers would work. Fascinating stuff.

    Debs visiting this year from
    Making Yourself Relationship Ready

    Liked by 1 person

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