GWML Electification

[PenrithBeacon]

...I suspect 'tweaking' means putting an extended vertical transition over a somewhat greater distance.

?

[Glorious NSE]

?

[Edwin_m]

The rail clips are missing on the vertical curve part so it does look as if someone has got the slab wrong on that section. 

[The Stationmaster]

Noted today catenary is now in place on the 'missing link' section on the Up Relief between Pangbourne sub-station (or whatever its purpose is) and the sewage farm; Down Relief still not wired.

 

A few more fittings have appeared on booms in the vicinity of Tilehurst but no further wiring.

[Peter Kazmierczak]

At Heathrow Airport Jn, the worksite for the new flyover is constricted between the up main (UM) and down relief (DR).

 

To me, the track should follow more like the red line I've roughly drawn. Wonder if the concrete base sunk a little?

 

[PenrithBeacon]

Not so long a go I drove on the flyover at Cricklewood and noticed that at least two of the gantries have been replaced with the new design.

 

Regards

[Edwin_m]

At Heathrow Airport Jn, the worksite for the new flyover is constricted between the up main (UM) and down relief (DR).

 

To me, the track should follow more like the red line I've roughly drawn. Wonder if the concrete base sunk a little?

Certainly looks like it, although it could be some kind of optical illusion. Either it's settled or somebody read the drawing for the vertical curve upside down!

[talisman56]

Certainly looks like it, although it could be some kind of optical illusion. Either it's settled or somebody read the drawing for the vertical curve upside down!

 

...or has got the plans for the new ride at EuroDisney by mistake...

Edited May 7, 2016 by talisman56

[Ron Ron Ron]

Photos of the rail at the bottom of the ramp, at the station end of the new Reading flyover, looked similar when first laid.

That was partly an optical illusion due to the distance and the telephoto lenses used for the shots, but it still looked looked like a sharp vertical kink.

However, that was laid on ballast and appears to have been smoothed out in the tamping and alignment process, whereas this new track is fixed on a concrete slab.

 

 

.

[The Stationmaster]

Photos of the rail at the bottom of the ramp, at the station end of the new Reading flyover, looked similar when first laid.

That was partly an optical illusion due to the distance and the telephoto lenses used for the shots, but it still looked looked like a sharp vertical kink.

However, that was laid on ballast and appears to have been smoothed out in the tamping and alignment process, whereas this new track is fixed on a concrete slab.

 

 

.

 

The tamping machines spent a lot of time at the foot of the flyover - over several days.  There was a  similar situation with the Westbury dive under lines where they come back up to original level at the station end and there was a distinct 'hump' there until it was tamped to final profile and that was done over almost the full length of the rising gradient once clear of the flyover with lots of extra ballast added.

[Geoff Endacott]

There is a technical term to describe that type of track profile.

 

Wrong.

 

Geoff Endacott

[corneliuslundie]

It's what comes of using cheap Chinese plywood for the baseboard.

Jonathan

[Ron Ron Ron]

Having looked at the photos again, it appears that the new track is being formed from very short sections of rail.

Almost like Meccano.

As on other new rail infrastructure projects, could it be a temporary arrangement for the purposes of rail access during construction ?

 

 

.

[The Stationmaster]

Having looked at the photos again, it appears that the new track is being formed from very short sections of rail.

Almost like Meccano.

As on other new rail infrastructure projects, could it be a temporary arrangement for the purposes of rail access during construction ?

 

 

.

 

Just for the construction phase I would think - it was cwr on the old flyover and its approaches.

 

Mind you assuming Peter's pic is not distorted in any way - and the surroundings suggest to me that it isn't - I reckon they would have a very interesting time trying to lay cwr through that vertical curve and it would be even more 'interesting' to see the results if they site weld the short rails they have laid so far.

[unravelled]

I wonder if there is a curve to the right coinciding with the change in gradient? With no sleepers to help the eye determine the direction, we are interpreting it as a sudden change in gradient. The track does seem to be angling towards the right and getting closer to the piling on the right.

 

Dave
 

[Arun Sharma]

On another aspect of the OHLE at Didcot..... Passing through the station today, I noted that the headspan girders take several different forms. Some have hexagonal lightening holes, others have simple squares, others have squares backed up by internal diagonal struts and there could well be other variations. Is there some clear rationale regarding the need for these different structures? Given that there is currently very little hanging off the headspans other than the odd register arm I can't yet identify whether some will have signal housings and others just 25kV contact equipment.

[The Stationmaster]

On another aspect of the OHLE at Didcot..... Passing through the station today, I noted that the headspan girders take several different forms. Some have hexagonal lightening holes, others have simple squares, others have squares backed up by internal diagonal struts and there could well be other variations. Is there some clear rationale regarding the need for these different structures? Given that there is currently very little hanging off the headspans other than the odd register arm I can't yet identify whether some will have signal housings and others just 25kV contact equipment.

 

Look at Post 1827 (previous page) to see what the ones with hexagonal holes are used for.  I get the impression the ones with the squares vary in size for reasons of either span or, possibly, the wind loading they will have to take.

 

The big ones at Didcot are presumably that big because of their span although one with a  similar span (to some of them) at Tilehurst has a smaller cross-section but is in a much more sheltered position).

[Titan]

It is all down to the loading. The Hexagonal ones shown in post 1827 are anchor structures, and are both deeper in width as well as height and also have struts to help take the load. On others the section is decided according to the width of the portal and the number of registrations that they will take. There is a reasonable amount of standardisation, For example one of the portal boom sections is identical to that of the two track cantilever, so that the same fittings to attach the registrations can be used for either.

[Arun Sharma]

Thank you Titan and Stationmaster for the explanations.

[aforsyth]

Another bridge is 'fixed' - this time Broad Town Bridge in Royal Wootton Bassett. Good progress, although I liked the look of the original better, as ever.

 

Network Rail video: https://www.youtube.com/watch?v=BpnDFGEelg8

 

Alan

[eastwestdivide]

Another bridge is 'fixed' - this time Broad Town Bridge in Royal Wootton Bassett. Good progress, although I liked the look of the original better, as ever.

 

Network Rail video: https://www.youtube.com/watch?v=BpnDFGEelg8

 

Alan

 

Does anything happen later with those side arches that had previously been infilled with concrete (presumably to stabilise them once the main arch disappeared)?

It looks very odd (if functional) with those rectangular passageways in an arch-shaped mass of concrete under the brick arch.

[Jonboy]

Its looking a bit odd down between Didcot and Milton Park.

 

Different gantry's have over each track:

• a single registry arm off a single mount (vertical pole between the arm and gantry)
• some have two registry arms off a single mount
• some have two registry arms off two mounts - one each side of the gantry (bolted together for stability?)

I will try and get some photos tomorrow.

[PenrithBeacon]

I spent a very pleasant couple of hours this afternoon at Tilehurst Station and found that, in addition to the usual gantries with hexagonal and rectangular holes, there are two which are made of plain I section. This I found very surprising given the emphasis on structural strength.

 

All very odd!

Edited May 12, 2016 by PenrithBeacon

[brian daniels]

I managed to get a better picture of the signal mounted on the overhead on the down main at Moreton from an HST on the relief. Don't worry about the purple strap that's holding up a bit of overhead.

Edited May 12, 2016 by brian daniels

[The Stationmaster]

I spent a very pleasant couple of hours this afternoon at Tilehurst Station and found that, in addition to the usual gantries with hexagonal and rectangular holes, there are two which are made of plain I section. This I found very surprising given the emphasis on structural strength.

 

All very odd!

 

That design is quite common - it seems to be used in some of the less exposed sites but I suspect its use depends on other things as well as they gantries at Tilehurst are quite closely spaced.  However I was surprised by the apparently 'lightweight nature of the full length boom which goes over the whole lot with no intermediate support although the next one to the east of it is pretty  close.  Pictires taken toady at Tilehurst will appear further down this post.

 

Noted also today that the Down Relief 'gap' at Pngbourne station has now been wired but progress at Tilehurst and east thereof seems pretty lackadaisical for a section which allegedly goes live in two weeks time.  as the pics below show there is a distinct lack of register arms on the relief Lines and with one or tow odd exceptions this continues right on through Tilehurst East Jcn where there is little visible progress over the last week apart from adding (only on the Main Lines) some register arms.  the essential fittings for terminating catenary sections are notable by their near total absence.

 

Click on the pictures to enlarge them.

The first picture shows the structures at the western end of Tilehurst station - taken from the Down Main Line platform - note lack of fittings on the Relief Lines side 

 

 

This picture shows the gantry structure which spans all platforms and all four running lines - rather heavier section than the ones further west but much lighter than those of similar span at Didcot

 

 

But here you can see - alas not too clearly, that it is actually quite close to the next structure beyond the footbridge although you can only see the uprights of the latter

 

 

Finally a  couple of views looking eastwards - 37m 67ch is just out of view round the curve in the distance

 

 

Edited May 12, 2016 by The Stationmaster