Great Western Electrification Progress

[ironstone11]

Just wondering...wherever these bridges are being rebuilt, are they being rebuilt wide enough with passive provision for 4 tracks?

Most unlikely. They are usually not completely rebuilt. The deck or arch is usually removed and the abutments taken down to the level of the bottom of the arch.

The abutments are then usually built up with large pre-cast concrete blocks. The new decking is then placed on the new blocks.

There are loads of pictures of bridge rebuilding on the Blackpool - Manchester Electrification thread on this Forum.

 

[Tw99]

Not sure if this has been asked before, but the bridges (at least in west Berks) seem to have had much higher parapets added. Is this something specific about electrification, or just meeting the current standards for bridges ?

 

[edwin_m]

Not sure if this has been asked before, but the bridges (at least in west Berks) seem to have had much higher parapets added. Is this something specific about electrification, or just meeting the current standards for bridges ?

The parapets over an electric railway have to be higher and also have a triangular top, to discourage people from sitting on the edge and dangling ropes down onto the wires. New railway bridges tend to be built to electrification standards anyway, but I read somewhere (possibly on this forum) that the standard had recently increased from 1.6m to 1.8m so this may mean even some fairly modern bridges need modifying.

 

[mr_jrt]

Most unlikely. They are usually not completely rebuilt. The deck or arch is usually removed and the abutments taken down to the level of the bottom of the arch.

The abutments are then usually built up with large pre-cast concrete blocks. The new decking is then placed on the new blocks.

There are loads of pictures of bridge rebuilding on the Blackpool - Manchester Electrification thread on this Forum.

Fair enough. I was just wondering as the GWML is likely to see a lot of growth and more 4-tracking in time (which will hopefully see more of the minor stations closed when some of it was removed reopened). Admittedly that was generally between Swindon and Didcot, but you have to hope they're planning for growth, and that means getting local services out of the way of the expresses.

 

[QueensCurve]

Does anybody know specifically which bridge this effects and when the temporary road is supposed to be constructed?

Think the two bridges are in this view on Google Maps of the Wooton Basset Area:-

https://www.google.co.uk/maps/@51.5353759,-1.9067932,616m/data=!3m1!1e3?hl=en

The temporary road will presumably pass between the 2 bridges to the south of the GWML.
--- old post above --- --- new post below ---

Most unlikely. They are usually not completely rebuilt. The deck or arch is usually removed and the abutments taken down to the level of the bottom of the arch.

The abutments are then usually built up with large pre-cast concrete blocks. The new decking is then placed on the new blocks.

There are loads of pictures of bridge rebuilding on the Blackpool - Manchester Electrification thread on this Forum.

Another passive provision question: is there any intention to remodel the Wooton Basset Junction track layout? This would seem to cry out for a >70mph turnout speed on the Badminton route.

 

[Tio Terry]

The parapets over an electric railway have to be higher and also have a triangular top, to discourage people from sitting on the edge and dangling ropes down onto the wires. New railway bridges tend to be built to electrification standards anyway, but I read somewhere (possibly on this forum) that the standard had recently increased from 1.6m to 1.8m so this may mean even some fairly modern bridges need modifying.

Yes, the Technical Standard for Interoperability for Energy specifies a parapet height of 1.8M. So it's an EU Directive.

 

[Who Cares]

Quite a while since I posted and, more importantly, failed to thank Phillip P for his answer to a technical question....Many apologies, Phillip....

The main reason for the delay was helping put together more information and to get it into the media.....

No preaching from me this time....Please make up your own mind....

http://www.savegoringgap.org.uk/

 

[33Hz]

"Devastating environmental damage"

Riiiight.

 

[Philip Phlopp]

"Devastating environmental damage"

Riiiight.

I've only just stopped laughing, and I read it first last night.

 

[fgwrich]

I've only just stopped laughing, and I read it first last night.

Same from me. What would they like? Better more frequent and greener trains, but not electric powered? Perhaps they'd like the OHLE to stop near Didcot and start again near Reading, so everyone else can reap the benefits until they reach the apparently far too beautiful Goring area where they must go onto Bi mode mode through? Enjoy your 3 car Turbos for the future then!

 

[QueensCurve]

The parapets over an electric railway have to be higher and also have a triangular top, to discourage people from sitting on the edge and dangling ropes down onto the wires. New railway bridges tend to be built to electrification standards anyway, but I read somewhere (possibly on this forum) that the standard had recently increased from 1.6m to 1.8m so this may mean even some fairly modern bridges need modifying.

Is anybody really that stupid?

 

[AM9]

"Devastating environmental damage"

Riiiight.

That's NIMBYspeak for 'spoil my view', or 'affect my house value'.

Looking at their pictures of the AONB. It is already polluted with unnatural beauties like a 180 year old railway, land clearance for farming, plantation trees and houses. The river at 9:12 doesn't look very natural either. Why don't they just call it something like an Area Of Established Beauty?
The project is already delayed enough so getting bogged-down in wrangling about style over function with every parish council along the route would be a recipe for even more delay in which the end result would be no change.
I would say that they have less than a cat in hell's chance of getting headspans because they look prettier (particularly as the gantry steelwork is now largely in place), as the political flack from yet more unreliable electrification infrastructure would invite more kickings for NR.

 

[Henbury Loop]

If I ever become that miserable with nothing better to do in my retirement than join residents association's and complain about pointless issues then I would happily shoot myself.

 

[HowardGWR]

If I ever become that miserable with nothing better to do in my retirement than join residents association's and complain about pointless issues then I would happily shoot myself.

Please don't do that HL. I am looking forward to you keeping us up to date on Bristol area electrification and Metro West news!

 

[swt_passenger]

No preaching from me this time....Please make up your own mind....

Don't expect any sympathy here whatsoever.

 

[po8crg]

I think in the whole North West electrification there are four headspans in total - the four at Rainhill station, which is, well, a bit special for the railway.

 

[Tw99]

Since almost all of the substantial metalwork is already erected in that area, I'm not sure of the point of complaining about it now.

 

[QueensCurve]

Quite a while since I posted and, more importantly, failed to thank Phillip P for his answer to a technical question....Many apologies, Phillip....

The main reason for the delay was helping put together more information and to get it into the media.....

No preaching from me this time....Please make up your own mind....

http://www.savegoringgap.org.uk/

I can see where they are coming from on this, and they offer headspans as an alternative design which, I agree, would be less visually intrusive.

I do wonder if Network rail has been unduly hasty in ruling out headspans as the Germans seem to make them work.

 

[Philip Phlopp]

I can see where they are coming from on this, and they offer headspans as an alternative design which, I agree, would be less visually intrusive.

I do wonder if Network rail has been unduly hasty in ruling out headspans as the Germans seem to make them work.

Network Rail was correct to move to independent registration for each running line with their OLE specifications. We've been over this repeatedly, but a dewirement on one track results in that track being closed with mechanically independent registration. The use of interdependent registration results in all four tracks being closed to electric traction in the event of a dewirement, and the repair of headspans is messy, time consuming and complicated - that would be why the last ECML dewirement took 2 days to repair and why passengers were delayed by tens of thousands of minutes.

It's all a moot point - there isn't a headspan which can work with the new OLE system anyway, Rainhill is essentially a Mk.3b system with a couple of reliability modifications, everything else around it is Series 2 OLE. Series 1 has no headspan design at all, to fit headspans on the GWML, we would have to revert at this stage to an ECML Mk.3b system. That means no 140mph running with two pantographs, and no 110mph/125mph running with three or four pantographs.

The OLE is specifically designed for 140mph operation with multiple pantographs, from the foundation and mast up and outwards, it's designed around 16.5kN tension, as a result it's fitted with 120mm2 cross section contact wire, it weighs more and together with the increased tension, it cannot be accommodated on the Mk.3b OLE system - it can't do 16.5kN tension because it can't support 120mm2 cross section contact wire.

Headspans do have their very limited uses - they're acceptable on lower speed lines (though not welcome) and they're fine for depots, where you don't want masts in between each reception road for drivers to be walking into in the dark. Rainhill is the sort of place where a headspan is begrudgingly acceptable - 125/140mph four track railway is not.

 

[LNW-GW Joint]

Headspans are not "prettier" anyway.
The taller masts are more intrusive than the lower portals.

 

[Henbury Loop]

Sorry to move away from the Goring Gap discussion briefly, I have heard that the Hitachi trains are too long for the curved Bristol Temple Meads platforms.

Is this true and if so how will this problem be overcome?

 

[Philip Phlopp]

Sorry to move away from the Goring Gap discussion briefly, I have heard that the Hitachi trains are too long for the curved Bristol Temple Meads platforms.

Is this true and if so how will this problem be overcome?

Not true specifically. There is a program ongoing at present to deal with gauging issues and allow the Hitachi trains to 'fit' onto the network.

 

[hassaanhc]

Some observations in the original 1990s electrification area:

Installation of new masts is about to start on the platforms at West Ealing and Ealing Broadway, with sections fenced off for storage of tools. Southall has had the ground conditions tested (holes dug and then just filled in again in asphalt) and I'd imagine work will start soon.
Some replacement of headspans in the Old Oak Common area has also been completed, with a number of new portals and twin-track cantilevers.

 

[QueensCurve]

It's all a moot point - there isn't a headspan which can work with the new OLE system anyway, Rainhill is essentially a Mk.3b system with a couple of reliability modifications, everything else around it is Series 2 OLE. Series 1 has no headspan design at all, to fit headspans on the GWML, we would have to revert at this stage to an ECML Mk.3b system. That means no 140mph running with two pantographs, and no 110mph/125mph running with three or four pantographs.

The OLE is specifically designed for 140mph operation with multiple pantographs, from the foundation and mast up and outwards, it's designed around 16.5kN tension, as a result it's fitted with 120mm2 cross section contact wire, it weighs more and together with the increased tension, it cannot be accommodated on the Mk.3b OLE system - it can't do 16.5kN tension because it can't support 120mm2 cross section contact wire.

What is Mk3b contact wire cross section?

 

[Philip Phlopp]

What is Mk3b contact wire cross section?

107mm2 for most of the ECML. Weight difference between 107mm2 and 120mm2 is ~112kg per km, beyond that, the difference between 120mm2 and 150mm2 (high speed specification, effectively) is ~258kg per km.

The additional weight and tension moving from 107mm2 and 12.5kN to 120mm2 and 16kN is well in excess of what the Mk.3b system was designed to accommodate.

 

[Who Cares]

If I ever become that miserable with nothing better to do in my retirement than join residents association's and complain about pointless issues then I would happily shoot myself.

Promise ?

Until retiring, I spent almost all my spare time enjoying my family and friends, good food, nice wine, etc, etc....

I certainly didn't spend my spare time hanging around internet chat forums, getting terribly excited about disused railway lines and old carriages being transported up the motorway....

And at 24 years old, life was one big party....

You really should get out more !!

 

[QueensCurve]

107mm2 for most of the ECML. Weight difference between 107mm2 and 120mm2 is ~112kg per km, beyond that, the difference between 120mm2 and 150mm2 (high speed specification, effectively) is ~258kg per km.

The additional weight and tension moving from 107mm2 and 12.5kN to 120mm2 and 16kN is well in excess of what the Mk.3b system was designed to accommodate.

How much does 112kg of copper cost?

 

[HSTEd]

Then there are always the Mark 3 installations that don't even have copper contact wires.

 

[Domh245]

How much does 112kg of copper cost?

At a scrap price of £3.05/kilo, £341.6

 

[Philip Phlopp]

At a scrap price of £3.05/kilo, £341.6

Contact wire can be Copper, Aluminium or Copper Silver, for the CuAg price, that depends on the ratios of each used. Don't have a current price to hand, will see if I can get something.

The catenary wire and droppers for Series 1 are Bronze Copper Magnesium if memory serves. The different metals used in contact and catenary wire come from various factors, mainly resistance to wear when in contact with the pantograph for the contact wire, and conductance of the catenary wire.