Reading Station improvements

[whole diary]

[stuving]

"What have you got there?"
"It's only 33 tons of concrete."
"Well, you can't come through the barrier without a ticket. Where are you going?"
"Platform 7."
"Sorry, we don't do platform tickets any more."

The concrete pump's out again - there's a length of trench towards the west end of P7 to fill.

[paul7575]

Crane is in action again tonight Camera 2/02.  Will this be the roof sections on the London end of the canopy for P10/11?

No apparently not they are still in the stack by the North entrance this morning.  Have to wait to see what has appeared on P10/11 this morning.

It might have just been lifting the longitudinal girders for bolting into position?   I'll have a check tomorrow if no-one reports back in the meantime...

Paul

[ironstone11]

Crane is in action again tonight Camera 2/02.  Will this be the roof sections on the London end of the canopy for P10/11?

Judging by the lift for the installation of the existing canopy panels on P10/11, the very large Ainscough crane will be required. See Cam01/1&3 Feb 24, 2013 at around 11.00am.

[stuving]

Judging by the lift for the installation of the existing canopy panels on P10/11, the very large Ainscough crane will be required. See Cam01/1&3 Feb 24, 2013 at around 11.00am.

Not just a big one either -  there's a long lattice-work jib extension too. It's out of camera view most of the time, but you can see it being assembled on camera 01/3 the night before, and see part of it in use on camera 02/1.

[Jason]

There were a few parts for the P1/2 canopy in a fenced off area at the country end but I was too busy running this morning to see what else had appeared.

[paul7575]

The longitudinal girders are now fitted along the whole remaining length of the P10/11 canopy.  I gatherered the information that they expect the canopy sections themselves to be fitted over about 4 or 5 weekends, given the short period available between end of traffic on Saturday evening and the normal Sunday morning startup.

The P10/11 platform wall seems complete to the level of the oversail blocks, except for the far country end where the foundations are yet to be poured.

Over on the P7 side, the gap in the foundation strip under the transfer deck that stuving mentioned has been poured, the block work generally seems to be proceeding quite well.

There don't seem to have been any significant alterations to the track layout west of Caversham Rd bridge over the weekend, so it may be that nothing more is planned for a while, given that the weekend diversions are relaxed on forthcoming Saturdays...

Paul

[Oxman]

The first longitudinal beams were lifted into place on the viaduct today. Visible on camera 06/2.

[paul7575]

The first longitudinal beams were lifted into place on the viaduct today. Visible on camera 06/2.

Does anyone know for sure how the viaduct sections integrate with the 'fixed piers'?   I'm thinking that the fixed ends of the beams must have reinforcement bars that somehow interlock across the pier with their opposite number, and also interlock with with the rebars visible at the top of those piers, and so there'll probably be a concrete pour to finish off each pier top?

Then at the free ends, presumably there are steel pad pieces on the pier top to allow the beam to expand and contract, and they'll have to be fixed securely to the pier.  If anyone knows any detail about how that's usually done I'd be interested, because it isn't too clear in the webcams.   Probably not just big 'Rawlplugs'...   

Paul

[Jason]

Over on the P7 side, the gap in the foundation strip under the transfer deck that stuving mentioned has been poured, the block work generally seems to be proceeding quite well.

A significant amount of blockwork was laid overnight on the fresh P7 foundations at the country end.

[paul7575]

The viaduct sections are proceeding well, (webcam 06/2) - there are now ten beams in position as of 1545 today 22/10, seven on the first span started yesterday, and three on the next one towards the station. 

You can also now see that the outer beams of the set of seven have a different cross section, to give a flat profile to the outside faces.

Paul

[stuving]

Does anyone know for sure how the viaduct sections integrate with the 'fixed piers'?   I'm thinking that the fixed ends of the beams must have reinforcement bars that somehow interlock across the pier with their opposite number, and also interlock with with the rebars visible at the top of those piers, and so there'll probably be a concrete pour to finish off each pier top?

Then at the free ends, presumably there are steel pad pieces on the pier top to allow the beam to expand and contract, and they'll have to be fixed securely to the pier.  If anyone knows any detail about how that's usually done I'd be interested, because it isn't too clear in the webcams.   Probably not just big 'Rawlplugs'...   

Paul

No I don't know, but I'm sure the free end of each span sits on a unidirectional bearing, i.e. it provides vertical support and lateral restraint while permitting longitudinal movement. This was the original idea:

Each deck is fixed longitudinally at one end (proposed as the east end) and is free to slide longitudinally at other supports; guided bearings are required at the free end. Bearings are envisaged as being proprietary POT^▸ (Post Office Telecommunications) type.

Evidently this was written before these details of the design were worked out - it has been changed to halve the number of expansion joints and fixed pier tops.

Assuming it still uses a similar merchant bearing, it could be fixed to the beam and pier in several ways: adhesive, grout, or bolts are commonest. If you look at camera 06/2 on October 17th at about 17:00, you can see work on the top of the two nearest free-end piers (i.e. the nearest and the third away). I can't see any bearings as such, but what looks like seven formwork frames on each pier, suggesting something is to be cast or poured into them. My best guess is that the bearing is built into the beam end, and the base goes into the box and gets grouted in place. But that's only a guess.

[paul7575]

Assuming it still uses a similar merchant bearing, it could be fixed to the beam and pier in several ways: adhesive, grout, or bolts are commonest. If you look at camera 06/2 on October 17th at about 17:00, you can see work on the top of the two nearest free-end piers (i.e. the nearest and the third away). I can't see any bearings as such, but what looks like seven formwork frames on each pier, suggesting something is to be cast or poured into them. My best guess is that the bearing are built into the beam end, and the base goes into the box and gets grouted in place. But that's only a guess.

Thanks to your quoted paragraph from the planning docs I googled 'POT^▸ (Post Office Telecommunications) bearing' and found more than a few articles that broaden my knowledge of the subject!  It does seem possible that the rectangular cast sections visible on the distant pier tops are more cosmetic than structural. With a bit of luck something will become visible when the covers are removed from the nearest pier...

Thanks again.

Paul

[John R]

Out of curiosity, does anyone know what is the maximum gradient that would be permissible for the ramps?

[stuving]

Out of curiosity, does anyone know what is the maximum gradient that would be permissible for the ramps?

On what grounds? For running trains, or to make sure the bridge doesn't slide off its piers? Or did you have something else in mind?

[stuving]

The new Up Westbury will be close to the Down, and I wondered if the short section leading towards it would be taken any further now. However, peering into the distance, there's a big height difference to be made up first. Are the Westburies being lifted to match the Mains heading towards the viaduct, which need to be built up starting right next to the Caversham Road bridge? If so, some of the track renewals here will have to include a fair bit of earth-moving.