Author Topic: Forth Bridges  (Read 7242 times)

Offline sbwhart

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3530
  • Country: gb
  • Smile, Be Happy, Have Fun and Rock Until you Drop
Forth Bridges
« on: August 28, 2009, 02:48:55 AM »
Hi Chaps

Our son lives near Endinburgh close to the Forth Bridges, we were visiting over the weekend and as the weather was good on Monday we decided it would be nice to walk across the road bridge.

These are a few shots we took off the road bridge of the old rail bridge.





As you can see from the scaffolding they are still painting it, apparently this time they are shot blasting it down to bare metal and painting it with some modern paint that will last 50 years, I wonder how many tones of the old red lead paint they will have to remove.

This is a ground level shot of the road bridge.



My sons father in law is a civil engineer who worked on the bridge when it was being built, he's actual walked over on the cables, he was telling us that they have a problem with corrosion in the cables they've got microphones attached and they can hear the wires breaking apparently its a world wide design fault with this type of bridge, and if they don't stop it at the current rate they will run out of wires in about 15 years time.

There was a couple of crews working on the bridge when we went over, one crew were working on one of the cables sitting across it roped on goodness how high off the ground they were, no way would you get me doing that. I got chatting to the other crew, they'd got a compressor hooked up to a hydraulic intensifyer, and they were tightening up the bolts that hold the tower cross brasing a job they have to do every 6 months, and because of fatigue the bolts are replaced every 5 years. The bridge moves due to wind and traffic, you can actually feel it move when a big truck passes over.

Have fun

Stew
A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline Stilldrillin

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 4972
  • Country: gb
  • Staveley, Derbyshire. England.
Re: Forth Bridges
« Reply #1 on: August 28, 2009, 03:17:47 AM »
Nice pics Stew,

Enjoyed the interesting faqs too!  :thumbup:

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline ProficientBumbler

  • Jr. Member
  • **
  • Posts: 11
  • Wichita, KS.
Re: Forth Bridges
« Reply #2 on: August 28, 2009, 11:48:06 PM »
Great pics! But I really love the history you shared with it! Can't hardly beat some 1st hand knowledge from someone that was there & in the know! Thanks for a little history & engineering lesson!  :thumbup:
Thanks,
Brian

Offline Brass_Machine

  • Administrator
  • Hero Member
  • *****
  • Posts: 5504
  • Country: us
Re: Forth Bridges
« Reply #3 on: August 31, 2009, 03:05:03 PM »
Great pics.

Loved the extra info Stew!

Eric
Science is fun.

We're all mad here. I'm mad. You're mad.

Offline Rog02

  • Madmodder Committee
  • Full Member
  • *****
  • Posts: 138
Re: Forth Bridges
« Reply #4 on: September 08, 2009, 01:52:43 PM »
Ah, Yes!  The memories those pictures revive.   

Did you ever get to the South Queensferry pub?  It is one of our favorite spots to cruise too.  It is located just beneath the southern approach to the rail bridge.  Good pub grub, and not too many tourists.  The tour buses all stop at the ancient pub down the road.  The view of the bridge structure from the parking lot is great and don't forget to take a few shots of the wife/girlfriend/kiddies riding the bronze seal sculptures at the head of the old ferry ramps!

As, I stay in Fife whenever I am in Scotland (Glenrothes to be exact), I have had the opportunity to commute to Edinburgh via the coastal rail route several times.  The view from the Forth Rail Bridge is truly inspiring and never fails to leave me "gobsmacked".  The fact that the bridge was constructed in the 19th. century and is still in unrestricted use today gives further credence to the design and craftsmanship that went into such a structure.

A bit of the history and an excellent explanation of the force distribution concept can be found here.
http://www.forthbridges.org.uk/railbridgemain.htm

These photos are from The Forth Bridges Visitor Centre Trust http://www.forthbridges.org.uk/index.htm and give a good representation of the view from the South Queensferry landing.


A copyrighted photo by kreidphotography taken from the top of the southern support tower.


The blasting and painting process for a bridge of this size is an ongoing, progressive endeavor and there is always something scaffolded out and enclosed in containment.  Several years ago I spent considerable time fabricating specialty rigging for a coatings company that did similar work.  The complexity of rigging out a structure of this size is mind boggling to say the least and the reblast containment is daunting even to think about.  Reblast is the shot and paint chips following the blasting process, as someone else mentioned the paint contains red lead and must be contained for safe disposal so as to not pollute the River Forth and the nearby area of the North Sea.

As for the corrosion concerns about the support cables on the road bridge here are a couple of good links to news articles.
http://www.ask.com/bar?q=Forth+Rail+Bridge&page=1&qsrc=121&ab=0&u=http%3A%2F%2Fwww.forthbridges.org.uk%2F

http://news.bbc.co.uk/2/hi/uk_news/scotland/3965643.stm

Roger
I'm OLD, I'm TIRED, and I'M GRUMPY!

Offline sbwhart

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3530
  • Country: gb
  • Smile, Be Happy, Have Fun and Rock Until you Drop
Re: Forth Bridges
« Reply #5 on: September 08, 2009, 02:54:27 PM »
Hi Rog

We missed the pub  :( had lunch in a not very good place in the village, next time the pub will get the vote.

Thanks for showing the pics, the one looking down the span makes me feel dizey even from the safety of my computer chair.

Cheers

Stew
A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Offline Darren

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 3795
  • N/Wales
Re: Forth Bridges
« Reply #6 on: September 08, 2009, 03:00:10 PM »
That last image is a cracker.....
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)