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Author Topic: Network Rail plan to close Tan Hill crossing and replace it with a footbridge  (Read 8853 times)
GBM
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« Reply #15 on: February 26, 2024, 08:21:59 »


There was a guy with a drone doing video too.

Justin?
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« Reply #16 on: February 26, 2024, 11:32:36 »


There was a guy with a drone doing video too.
Justin?

No - he trades as Wokingham Aerial Photography. They have some photos and a video (with very annoying music) on his Facebook/Reels. There's a top view of the Ikea self-assembly junction kit too. I thought I found more videos on Instagram earlier, but can't find that now (or it may have been just photos).
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stuving
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« Reply #17 on: February 27, 2024, 00:35:11 »

Saturday was quite a spectacle, in the sense that it's not every decade you get a socking great mobile crane working at the corner of the street. It was also frustrating, with long waits with nothing happening except huddles of orange rainsuits debating (presumably) how to proceed. Then with no warning, something happens - often quickly. And as it was by then after dusk it was hard to see upwards, into a barrage of bright lights, or at the installation site, under limited site lighting, from the car park.

But I have a backlog of pictures. I'll start with the dramatis machinae:
A bridge of two halves
A toy train to take it down to where you can see one of the piers by the line
A Big Crane (Liebherr LTM1300 6.2)
... and a couple of these things (AC-55, I think). This one is going on-track, which makes a loud clunk noise.
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stuving
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« Reply #18 on: February 27, 2024, 00:40:27 »

Act one was setting up the crane for the lift (also in the first video above). This involves building pads for the outriggers, out of a combination of sandbags, planks, expanded polystyrene sheets, and a steel plate on top (better seen in the video at 8:40). This stuff comes on three artics (plus a trailer), together with the sections of the counterweight and the big spreader beam (p1).

This crane stacks its own ballast weights on a fixed platform in the middle of the vehicle body (p2). Two big lumps are slotted onto each side of this - 10t each bit. It picks up this stack, 96t of steel, with jacks on the back of the crane cab that lock into the ballast baseplate (p3). Only then can it fully extend the jib.
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« Reply #19 on: February 27, 2024, 00:42:47 »

Act two was assembling the sling. In this case it has a massive beam to spread the strops in length, and two smaller ones to spread again in width. The big one was bolted together in the road (p1), I guess because that is flatter and stronger than the crossing. (p2)

Act three was attaching the sling to a bridge span. This took ages, as the plan was changed for some reason. The steel I-beams fixed under each end crosswise had had small extensions bolted to them on arrival, and the strops attached to the ends. This was tried (p3), but in the end the strops ran round the main tube at each side of the deck instead. This involved a rigger splitting the strop at the top so it could be fed along its new path.
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« Reply #20 on: February 27, 2024, 00:46:43 »

And then, finally, the main event: the lift. The highest obstruction was the Vodafone mast by the station wall, so when lifted the span went round away from that, also avoiding the public footbridge (by then closed). It was lowered beside the signal box, onto the train of engineers' trailers (p1). For the second lift, onto the piers, two rail cranes operated in tandem (p2). One was on the tongue of land the centre span of the bridge crosses, the other on the track.

For the second span that crane moved to the other end, perhaps in the siding (I missed that - dinner time!). Obviously attaching the second span was much quicker, and in any case overlapped the work at the bridge site. This time the train of trailers didn't move into place until the span was in place (p3).

And by Sunday Morning, there is a new view up the line from the footbridge by the level crossing (p4).
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paul7575
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« Reply #21 on: February 27, 2024, 10:20:29 »

Great set of photos thanks. 

Always useful to explain how complex these sort of jobs are, I think there were suggestions ‘elsewhere’ it should have been done at the same time as the resignalling and junction relaying, but that was clearly impossible...

Paul
« Last Edit: February 27, 2024, 11:04:11 by paul7575 » Logged
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« Reply #22 on: February 27, 2024, 14:20:43 »

Great set of photos thanks. 
I agree


Always useful to explain how complex these sort of jobs are, I think there were suggestions ‘elsewhere’ it should have been done at the same time as the resignalling and junction relaying, but that was clearly impossible...

Paul

Only by armchair engineers  Grin
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stuving
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« Reply #23 on: February 27, 2024, 23:06:53 »

Now that bit is in place,. what about the bridge itself? The design of the bridge itself got little attention at planning, what with all the shouting about (the lack of) ramps. But it is a bit odd, compared with what we are used to.

The width is quite generous, at 4m overall and 3.1m for the footway. The sloping sides are really quite high, as struck me when I saw a rigger using a stepladder to reach the top. The plans say 1.878m vertically, and it's faced internally with a "brushed stainless steel perforated panel". The centre span does not have this panel now, but I think it will be fitted. The drawing suggests, and the photo agrees, that the panel is more perforated at the top.

So it looks as if the views I was recording from the old bridges will not be coming back - not as clearly, and perhaps not at all. Now, is there a good reason for that obstruction? Even if this is meant as a standard design for all railways, including those with OLE (Overhead Line Equipment, more often "OHLE"), it does seem excessive. And as for the small kids who like to look at the trains ...

The stays preventing a "pack of cards" collapse look temporary, so I guess the stairs will be expected to hold it rigid finally.
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paul7575
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« Reply #24 on: February 28, 2024, 08:19:09 »

The nearest concrete plinth looks odd, you’d expect it to be parallel to the legs? I suppose they had a reason to build it at an angle, but it looks weird…

Paul
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Mark A
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« Reply #25 on: February 28, 2024, 08:56:02 »

Good lord. They've taken a perfectly good bridge and given it anxiety.

Mark
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« Reply #26 on: February 28, 2024, 12:14:50 »

The nearest concrete plinth looks odd, you’d expect it to be parallel to the legs? I suppose they had a reason to build it at an angle, but it looks weird…

Paul

Yes, while the staircase at the far side is in line with the bridge, this one has to be angled to avoid the car park (from which the picture was taken). Before the car park was built, there was a vague aspiration to continue the route from the footbridge on the level to, and through or around, the car park and on a walkway to the new Carnival Hub [sic]. That never made it into concrete, or even into a concrete plan.
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