GWML Electification

[phil-b259]

I was only trying to help because you said you didn't know who owned it!

Indeed, and I do apreciate you drawing my attention to the current situation

[The Stationmaster]

Most of the brick arch overbridges on the Baminton Line seem to have had the arches over teh track replaced with precast concrete units in varying styles while the brick built approaches have been retained - quite an elegant solution to do the job fairly quickly and without massive expenditure.  Similarly the same sems to have happened to most arch overbridges between Reading and Didcot.  Some bridges have gained the big galvanised metal covers but mainly it appears where vandalism is a likely risk (although possibly the same might happen with other bridges at a later date?).

 

What is lokely to happen on the Relief Lines at Twyford remains an interesting question - the brick arch there is, I think, the only surviving early brick arch overbridges although it post dates the opening of the railway by some years (but pre-dates the end of the broad gauge and quadrupling).  As such it is probably the closest link of any among surviving overbridges to the Brunellian era;  the much later arch on the Main Lines side is long gone.

 

The overbridges on the Badminton line of course have about as much to do with Brunel as that line itself post-dating his death by a good 40 years.

 

Incidentally I see work has now started on footbridge renewal at Goring (refer the South Oxfordshire link posted by Brian).

[Budgie]

What is this "High Marnham test track"? Where does the test part run from/to, please? And what will be visible testing there?

 

What's wrong with Old Dalby?

I'm surprised NR haven't come up with a continuous test track, similar to Velim in the Czech Republic.

[Fat Controller]

I'm surprised NR haven't come up with a continuous test track, similar to Velim in the Czech Republic.

High Marnham is used to train staff in the use of the High-Output machinery, be it track-renewal, ballast cleaning or electrification. It doesn't need a train-set oval for this, but long parallel sidings where people can rehearse splitting and rejoining the various bits of each train. I believe some of these are a kilometre long when coupled in the full working formation.

Testing of rolling stock is usually carried out at Old Dalby, I believe, which may not be a continuous run, but which does allow trains to reach appreciable speeds.

[brian daniels]

Found a couple more of these very long winded documents but some interesting stuff about the bridges if you have the patience to find it.

 

West Berkshire one

 

http://www.networkrail.co.uk/browse%20documents/projects/great%20western/electrification%20environmental%20statements/england/west%20berkshire/gwml%20electrification%20-%20west%20berkshire%20council%20-%20environmental%20statement%20vol%201b.pdf

 

Gloucestershire

 

http://www.networkrail.co.uk/browse%20documents/projects/great%20western/electrification%20environmental%20statements/england/south%20gloucestershire/gwml%20electrification%20-%20south%20gloucestershire%20-%20environmental%20statement%20vol%202%20appendices%20a-d.pdf

 

Overview with some nice maps showing the bridges and what's intended to do to them.

 

http://www.networkrail.co.uk/browse%20documents/projects/great%20western/electrification%20environmental%20statements/england/gwml%20electrification%20%20mhead%20bristol%20severn%20tunnel%20-%20es%20vol%202%20appendix%20e%20flood%20risk%20assessment.pdf

 

Bath and Box area, scroll down to page 27 to see about Box Tunnel.

 

http://www.networkrail.co.uk/browse%20documents/projects/great%20western/electrification%20environmental%20statements/england/wiltshire/gwml%20electrification%20-%20wiltshire%20council%20-%20environmental%20statement%20vol%202%20appendices%20a-d.pdf

[Downendian]

Interesting and very helpful documents Brian. By the look of the S. Glos bridges my fears that their spans will be replaced by ugly concrete spans are unfounded. Most are to be raised by 5 brick courses. I must get and out get some photos in the coming weeks.

Neil

[RJS1977]

High Marnham is used to train staff in the use of the High-Output machinery, be it track-renewal, ballast cleaning or electrification. It doesn't need a train-set oval for this, but long parallel sidings where people can rehearse splitting and rejoining the various bits of each train. I believe some of these are a kilometre long when coupled in the full working formation.

Testing of rolling stock is usually carried out at Old Dalby, I believe, which may not be a continuous run, but which does allow trains to reach appreciable speeds.

 

At least 100mph on one notable occasion IIRC....

[RJS1977]

Interesting and very helpful documents Brian. By the look of the S. Glos bridges my fears that their spans will be replaced by ugly concrete spans are unfounded. Most are to be raised by 5 brick courses. I must get and out get some photos in the coming weeks.

Neil

 

I think a lot will depend on the specific requirements of the bridge. Obviously in some places the road is too low for the arches to be raised, so a horizontal span has to go in (which obviously can't be brick).

 

Of course,other arch bridges (like the one just east of Cholsey) will be high enough not to need anything doing to them at all.

[Titan]

At least 100mph on one notable occasion IIRC....

 

But I think these days they prefer to be able to use the train again...

[Oakydoke]

https://mobile.twitter.com/NoelDolphin/status/558563209838608384/photo/1

[Xerces Fobe2]

There is an amazing new signal gantry (for a singe signal) June's west of Burnham (Bucks) Station on the down relief line. Basically a tube that must be at @ 300mm wide the is anchored at one end only next to the down main line that goes over the other lines with a few interstimg twists an turns and is probably the longest reach signal I have ever seen!

 

I was on a train earlier this week when I saw this, however I will try and get a photo of this strange looking structure and post it here!

[The Stationmaster]

The structures in the vicinity of Tilehurst - Pangbourne, but particularly around Purley where that picture was clearly taken, are the most advanced of the lot (outside the Reading station - Kennet Bridge area) and some of the portals along there have been in place for a few weeks.  Reading - Didcot was originally (?still?) suposed to be the first section to be energised - in September this year - for IEP test running; it will be interesting to see when that happens.

 

https://mobile.twitter.com/NoelDolphin/status/558563209838608384/photo/1

[Xerces Fobe2]

The West Coast mainline electrification in the 1960's appeared to go go logically, smoothly and timely than the GWML scheme now!

 

I guess there were no boxes to tick etc, years ago - progress?

[Downendian]

As it's such a beautiful day I decided to go and take a few photos for old times sake of the overbridges that I used to spot at, or the GWML engineering works at their sites.

Edit - I stress I poked my camera lens through the barrier fencing, so I was completely legit!

 

First was "Pearce's bridge", 1st overbridge East of Bristol Parkway. This was the vantage point for many photos in publications over the years and was a fine brick arch bridge built in the late 1890s. It's no more- completely demolished and obviously won't be replaced like for like.

Concrete buttresses 1

Concrete buttresses from other side of bridge

 

Temporary bridge for footpath in place

 

Obligatory train - Voyager heading North, I was hoping for a class 70 or 66 but no such luck.

 

2nd bridge from the distance - I was unable to access this bridge due to a huge amount of spoil tipped at the end of the bridge (Curtis lane in Stoke Gifford) it's a clear fly tipping venue and not very pleasant- I photographed D1015 there a few years ago, huge deterioration since. Termed "2nd bridge" by us Parkway spotters in the 1970s. Glad to see it still intact- but for how much longer?

 

Neil

Edited January 24, 2015 by Downendian

[Hobby]

 

for IEP test running; it will be interesting to see when that happens.

 

 

They'll clutter up the line and cause delays, that's what'll happen... 

[phil-b259]

The West Coast mainline electrification in the 1960's appeared to go go logically, smoothly and timely than the GWML scheme now!

 

I guess there were no boxes to tick etc, years ago - progress?

 

Thats rather an assumption and one poster on the forum has already said that they had some inside knowledge about the scheme and it was far from plain sailing.

 

Its already known from official archives that the original WCML budget was revised upwards several times and that the Government of the day seriously considered forcing BR to dump the scheme. The retention of mechanical signal boxes along the Trent valley and at the likes of Stockport being obvious examples of how not everything was done according to the original plan.

 

We also have at least one poster on the forum who has some first hand knowledge of the WCML scheme and they confirmed things were not as rosy as the passage of time may make you believe.

 

You also have to remember that as it was the first large scale overhead electrification project in the UK, skilled OHLE engineers weren't available and it would take time to build up the engineering skills. Why do I mention this - well NR is again struggling with training up enough OHLE engineers thanks to the total dis-interest in large scale electrification by UK Governments since 1989 when the ECML was done

 

What is true of the WCML scheme however is that it was done in an age where the UK population was much more respectful / subservient to authority and as such details of cost overruns, etc would not have been publicised as much as such things are today.

 

Ultimately its only when the GWML scheme is done will we be able to compare the execution of the two schemes. I bet when ALL factors are compared then actually they will come out as fairly similar as the fundamental basics (lack of OHLE skills, lots of resignalling needed, Infrastructure changes at key bottlenecks - i.e. Reading / Birmingham NS)

[Fat Controller]

The West Coast mainline electrification in the 1960's appeared to go go logically, smoothly and timely than the GWML scheme now!

 

I guess there were no boxes to tick etc, years ago - progress?

 

Thats rather an assumption and one poster on the forum has already said that they had some inside knowledge about the scheme and it was far from plain sailing.

 

Its already known from official archives that the original WCML budget was revised upwards several times and that the Government of the day seriously considered forcing BR to dump the scheme. The retention of mechanical signal boxes along the Trent valley and at the likes of Stockport being obvious examples of how not everything was done according to the original plan.

 

We also have at least one poster on the forum who has some first hand knowledge of the WCML scheme and they confirmed things were not as rosy as the passage of time may make you believe.

 

You also have to remember that as it was the first large scale overhead electrification project in the UK, skilled OHLE engineers weren't available and it would take time to build up the engineering skills. Why do I mention this - well NR is again struggling with training up enough OHLE engineers thanks to the total dis-interest in large scale electrification by UK Governments since 1989 when the ECML was done

 

What is true of the WCML scheme however is that it was done in an age where the UK population was much more respectful / subservient to authority and as such details of cost overruns, etc would not have been publicised as much as such things are today.

 

Ultimately its only when the GWML scheme is done will we be able to compare the execution of the two schemes. I bet when ALL factors are compared then actually they will come out as fairly similar as the fundamental basics (lack of OHLE skills, lots of resignalling needed, Infrastructure changes at key bottlenecks - i.e. Reading / Birmingham NS)

 

Hang on, let's not confuse matters: electrification DOES NOT require a full resignalling! It was chosen that as electrification took place, a signalling upgrade would make sense (probably as it was long overdue) to increase capacity and minimise disruption. Sensible decision, but not ultimately related!

It depends whether you are considering it as stand-alone electrification, or a complete route upgrade. If the former, then on a route like the WCML or GWML, you will find that in very short order, the gains from improved reliability (given events I've been involved in this week, that was said tongue-in-cheek..) would be quickly negated by problems associated with ageing signalling and track-layouts that aren't adapted to changing traffic flows. It costs a heck of a lot more, and involves a lot of inconvenience, to go back and sort these things afterwards.

In the original WCML scheme, money was wasted on wiring sidings and yards which seldom or never saw electrically-hauled trains (the one at Bushbury, Wolverhampton, comes to mind), yet skimped on a proper track upgrade, which might have got rid of the pumping clay at every rail-end of the original (1840s) route.

[phil-b259]

Hang on, let's not confuse matters: electrification DOES NOT require a full resignalling! It was chosen that as electrification took place, a signalling upgrade would make sense (probably as it was long overdue) to increase capacity and minimise disruption. Sensible decision, but not ultimately related!

 

I beg to differ - In MOST cases, YES IT DOES.

 

Many bits of signalling equipment installed on lines such as the GWML are NOT IMMUNE TO AC traction. In laymans terms that means the return currents from electric trains have the ability to false clear track circuits and cause Clapham Junction style crashes. (The same basic problem occurs with diesel lines that are then subsequently fitted with conductor rail by the way).

 

Please note that a "Full resignalling" does not automatically mean that the track layout itself is changed (though I accept in many cases this does happen).

 

While modern signalling installations tend to be traction immune by default - this is most definitely not the case of anything installed up to the mid 90s. Thus on the GWML the entire signalling from the Slough area (where the early 90s resignalling of the GWML to accommodate the OHLE installed for the Heathrow Express stops) NEEDS replacement as part of the electrification process with the possible exception of the Didcot area (which is early 90s in date and had signal structures compliment with OHLE installed).

 

Certainly Swindon and Bristol require complete renewal and on the Newbury / Oxford routes most of the track circuits will need changing to a AC immune type. Reading of course is subject to a rebuild so new signalling has been installed here but it should be noted that NONE of the old installation was compliment with electrification.

[Xerces Fobe2]

Harking back to the WCML electrification even the DC Lines signals to be fitted with mesh screens to protect from from possible AC imterference.

[The Stationmaster]

Hang on, let's not confuse matters: electrification DOES NOT require a full resignalling! It was chosen that as electrification took place, a signalling upgrade would make sense (probably as it was long overdue) to increase capacity and minimise disruption. Sensible decision, but not ultimately related!

To amplify what Phil has said - on the GWML full resignalling, albeit with some existing signal structures (other than brackets and gantries) retained is unavoidable.  The existing signalling is 1960s/70s with no ac immunisation although there was some dc traction current immunisation, many of the relay rooms at remote interlockinhgs are already suffering wire degradation plus we are talking about 50 year old cable routes.

 

Signalling out to Airport Jcn was renewed as part of the Heathrow electirification project along with considerable layout changes at various places - further layout changes are now taking place.  The Slough panel area from West Drayton East to Maidenhead West mainly dates from 1963 (some bits are earlier), Maidenhead West to Sonning Sidings dates from 1961, while Reading to Didcot dated from 1965 (and still does between Tilehurst and Cholsey).  Some bits - such as Reading Mainline East - were immunised against dc traction currents while of course Reading panel and several local interlockings had to be demolished as part of teh station rebuilding. 

 

Moreton Cutting - west of Challow was resignalled during the various layout changes I required for the Avonmouth - Didcot coal flow in the early 1990s and we specifically asked for structures with ac electrificatipon clearances and sold state controls were a given then anyway.  But north of Appleford, to Kemmington Jcn, is still mainly 1965 kit and the Oxford control area is 1973.  Swindon control area is - without checking - 1967 while Bristol is very early 1970s.  In other words not only is it all without ac immunisation but it is using cables 40 -50 years old with relay interlockings of a similar age.

 

Simple fact is the GWML was due resignalling anyway - the only bit which has been done already is in South wales and even in that case some of the fairly new signal structures need to be replaced with structures to ac clearances.

 

And in any case the signalling work - as I've already said - seems to be going ahead fairly well but a lot would in any case have to have been done for electrification.

[tomparryharry]

There is an amazing new signal gantry (for a singe signal) June's west of Burnham (Bucks) Station on the down relief line. Basically a tube that must be at @ 300mm wide the is anchored at one end only next to the down main line that goes over the other lines with a few interstimg twists an turns and is probably the longest reach signal I have ever seen!

 

I was on a train earlier this week when I saw this, however I will try and get a photo of this strange looking structure and post it here!

 

Down side approach, just north of Clapham Junction (old B signal box) there has to be the longest single reach display I've ever seen. I've never been able to take a photo- going fairly fast. Quite an incredible structure, and I don't know how it stays out of the dirt!

 

Ian

[tomparryharry]

Does the Severn Tunnel have a good height clearance?

 

Ian

[96701]

Does the Severn Tunnel have a good height clearance?

 

Ian

If you mean for 25kV, then yes either conductor beam or contenary apparently.

[RJS1977]

Harking back to the WCML electrification even the DC Lines signals to be fitted with mesh screens to protect from from possible AC imterference.

 

I may be wrong,but isn't the mesh there to act as a Faraday cage round any technicians working on the signals, rather than to protect the signals themselves?

 

It certainly wouldn't have any effect on the AC return current impacting on the track circuits as per a previous post.

[Titan]

It is really more of a physical barrier to ensure that technicians can work safely rather than intended as a Faraday cage - although it may well act like it if something did go wrong!.  Without any barrier, you are not allowed to work within 2.75m of any live OLE, which would mean an isolation every time a bulb needed changing. With an earthed mesh between you and the OLE, you can work up to that mesh with no restriction, and the mesh itself can be as close as 600mm to live equipment, and even closer to the edge of a momentary passing pantograph.