Wednesday, 22 October 2014

A visit to bridge 2 at Childswickham road today proved to be very interesting, with the steel fabricators hard at work dealing with the rust and, yes, even here, collision damage.

Once the ballast at the ends has been dug away, the degree of rust attack becomes all too apparent. The picture above shows the Broadway end of one of the main beams, with the end cover almost completely eaten away.
A little further along a 1ft hole in the deck plate, with paper thin material around it. It is just breath taking how water can be so aggressive to steel that is half an inch thick!
Note that the bridge has had its first shot blasting, to clean the steel and reveal the damage that needs fixing. It's the same MO as for bridge 1 at Broadway.
Luckily the cavalry is here... in this picture, showing the downside deck from Broadway, one of the fabricators is welding in a replacement plate that has been made off site to fit precisely into an area that has been cut out, back to strong metal.
Below decks, a damaged piece is being cut out with a large angle grinder. We are 10ft above the road surface here. Note the new piece that has been part bolted in on the right.
Here is a close up of the piece on which work has started. Not all of the bolts are in yet, so there is a bit of distortion on the new plate. New supports for the web have also been made, and trial positioned.
Here is the area where the fabricator was cutting off the rivet heads. (brown marks). It's the flange that is damaged by rust. The brown marks in the centre are traces of the heat generated by the angle grinder. Talking to the fabricator made me realise something that I hadn't noticed at first:
Once again, a lorry carrying something tall and narrow has struck this bridge really hard. And it's right in the middle, underneath. If you zoom in, you can see that something akin to an RSJ has struck this bearer, with two quite distinct sharp points of contact. How did he miss the outside edge?
The answer was of course, he didn't. The initial contact was even harder, and was repaired with an earlier patch, also as at Broadway. You can see both contacts in this picture above - the bent flange at the rear, and a new combination of plates bolted to the beam in the front. Original steel work is riveted in the picture, patched areas are bolted, you can see them clearly.This is an old repair.
In this picture, we are looking at the southern end of the deck. Water/rust damage appears on the end plates of the main beams, and on the deck itself, where the damaged areas have been cut out.
At the up line, a trial hole has been dug to check the condition of the abutment.

Finally, a last look at the down side deck from the southern side. Patch welding continues, and work is progressing well. We are in good hands here.



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