Great Western Main Line electrification - ongoing discussion

[whole diary]

[stuving]

This seems to apply to DC^▸ (Direct Current) traction systems... are AC systems the same?

Its probably part 1 then, I normally just work off of in house standards

BS EN50122-2 is "BS EN 50122-2:2010. Railway applications. Fixed installations. Electrical safety, earthing and the return circuit. Provisions against the effects of stray currents caused by d.c. traction systems". That's about currents flowing through the ground that destroy pipes, structural steel, and rebar etc. Not likely to mention parapet heights.

BS EN50122-1 is "BS EN 50122-1:2011 Railway applications. Fixed installations. Electrical safety, earthing and the return circuit. Protective provisions against electric shock". That'll be the one, and presumably it covers AC and DC.

There is also BS EN 50122-3: "BS EN 50122-3:2010. Railway applications. Fixed installations. Electrical safety, earthing and the return circuit. Mutual Interaction of a.c. and d.c. traction systems". That sounds like it's all about the electrical system design. Note the other two had earlier versions with different titles.

I've often wondered why, if DC causes such enormous problems of stray currents, is wasn't replaced by AC ages ago. It's not particularly difficult to make a DC motor and its supporting systems to work on both. If you took the decision and waited 20 years, there would not be too much to convert for a changeover. You could even pick a frequency below 50 Hz to make the motor design easier - after all, it's what the Germans did, I think in the 1920s.

[Red Squirrel]

Hey ho. When I googled BS EN50122-2 I found this http://orr.gov.uk/__data/assets/pdf_file/0012/5070/TTGN3.pdf , which is about overhead dc (essentially tramway systems) and which therefore is concerned with parapet heights. Not a standard, but gives some idea of what's what.

As an aside, am I the only one who finds it shocking (pun intended) that British Standards are all made so expensive that they are realistically only available to businesses? Shouldn't they be freely available to anyone with an interest?

[DidcotPunter]

I have just accessed the Network Rail/Murphy plans for the reconstruction of Challow Bridge from the Vale of White Horse District Council's planning website. These show that the top of the parapet on the west side of the rebuilt bridge will be 1800mm above pavement level. There is no pavement on the east side, just a kerb, so this will be slightly higher. So, if you're not taller than 6 foot, you'll have to tiptoe 

You can find the plans here: http://www.whitehorsedc.gov.uk/java/support/Main.jsp?MODULE=ApplicationDetails&REF=P14/V1672/P11

[Red Squirrel]

Oh well - I'll look forward to resubmitted plans for Pearson's Brickyard, with 'pent roof detail' added to the top of the parapet.

Memo to self: must dig out those old platform boots...

[stuving]

Hey ho. When I googled BS EN50122-2 I found this http://orr.gov.uk/__data/assets/pdf_file/0012/5070/TTGN3.pdf , which is about overhead dc (essentially tramway systems) and which therefore is concerned with parapet heights. Not a standard, but gives some idea of what's what.

As an aside, am I the only one who finds it shocking (pun intended) that British Standards are all made so expensive that they are realistically only available to businesses? Shouldn't they be freely available to anyone with an interest?

That guidance document is primarily about stray direct currents (as per its title), whether the feed is overhead or third rail. There is however quite a lot about safety; essentially because safety requires a lot of good earth connections, but that makes stray currents worse.  For safety, it refers to BS EN50122-1, as you would expect. And I can't see any mention of parapets or bridges per se.

BSI^▸ (British Standards Institute) is not unusual in getting most of its income from selling standards; I think most national standards bodies are the same. The reason is obvious enough - so that commercial users of standards should bear the costs not just of publication but of the secretariat. Technical committees are made up of volunteers, and it seems unfair to charge only member companies since they provide these volunteers.

It does get a bit odd where (as is often the case) the standard is written and negotiated and voted on by another organisation, which these days is usually European or international. For electrical/electronic ones this is usually CEN/CENELEC (which operate pretty much as a single body), unless communications is involved when it is ETSI. ETSI is the one I am familiar with - it has both companies (including individuals) and countries (for radio and telecoms regulations) as members. In this case the member companies do pay most of the costs.

Drafts are nowadays made public, and there is a public consultation stage in the approval process. Then the final step before publication is the national vote, where only national standards bodies are involved and most of the people who wrote it are not involved at all. Published standards do cost money.

I certainly came across several people (e.g. government employees) who were offended by the cost (or in some cases the secrecy) of some standards and even regulations. The same is the case in aeronautical standards, a lot of which come from ARINC, apparently an American private company. That's now a bit less obscure, in that it's part of SAE, an engineering institution - though you need to dig to find out.

[Red Squirrel]

That guidance document is primarily about stray direct currents (as per its title), whether the feed is overhead or third rail. There is however quite a lot about safety; essentially because safety requires a lot of good earth connections, but that makes stray currents worse.  For safety, it refers to BS EN50122-1, as you would expect. And I can't see any mention of parapets or bridges per se.

I'm beginning to get the impression that there is some confusion at NR^» (Network Rail - home page) as to what the height should be for parapets - as DidcotPunter points out, the plans for Challow bridge include an 1800mm parapet, whereas the current (sic!) plans for Pearson's Brickyard have a 1525mm parapet - and at Pearson's Brickyard, the OHLE is starting to rise to give the extra clearance required at Bristol Porkway.

Does it depend on how long a stick FT,N!'s 'bloody idiot' would require to poke the wires?

It does get a bit odd where (as is often the case) the standard is written and negotiated and voted on by another organisation, which these days is usually European or international. For electrical/electronic ones this is usually CEN/CENELEC (which operate pretty much as a single body), unless communications is involved when it is ETSI. ETSI is the one I am familiar with - it has both companies (including individuals) and countries (for radio and telecoms regulations) as members. In this case the member companies do pay most of the costs.

Drafts are nowadays made public, and there is a public consultation stage in the approval process. Then the final step before publication is the national vote, where only national standards bodies are involved and most of the people who wrote it are not involved at all. Published standards do cost money.

I certainly came across several people (e.g. government employees) who were offended by the cost (or in some cases the secrecy) of some standards and even regulations. The same is the case in aeronautical standards, a lot of which come from ARINC, apparently an American private company. That's now a bit less obscure, in that it's part of SAE, an engineering institution - though you need to dig to find out.

Hmm... Doesn't cost much to publish online though, does it? I guess I've just got used to the wonderful open-source world of IT, where standards are freely-available and anyone can contribute.

[ChrisB]

All tge work to produce has to be paid for! They don't work for free on Standard development

[TonyK]

Does it depend on how long a stick FT,N!'s 'bloody idiot' would require to poke the wires?

For a Grade 1, yes, and in the case of a Grade 7, the state of the prostate gland.

[Electric train]

I've often wondered why, if DC^▸ (Direct Current) causes such enormous problems of stray currents, is wasn't replaced by AC ages ago. It's not particularly difficult to make a DC motor and its supporting systems to work on both. If you took the decision and waited 20 years, there would not be too much to convert for a changeover. You could even pick a frequency below 50 Hz to make the motor design easier - after all, it's what the Germans did, I think in the 1920s.

We have so much DC electrification to convert it to AC is very expensive and will take decades.  The scheme to convert Basingstoke / Southampton is being questioned on cost even taking into account that the Dc traction equipment and its associated HV network is obsolescent.

I'm beginning to get the impression that there is some confusion at NR^» (Network Rail - home page) as to what the height should be for parapets - as DidcotPunter points out, the plans for Challow bridge include an 1800mm parapet, whereas the current (sic!) plans for Pearson's Brickyard have a 1525mm parapet - and at Pearson's Brickyard, the OHLE is starting to rise to give the extra clearance required at Bristol Porkway.

The confusion is the parapet height is stated in BS EN 50122 for bridges over electrified railways which Civil Engineer regarded as an electrical standard but it is not stated in the Euro Codes Civil Engineers normally work to; often its not until an Electrification Engineer starts to check their design that they find the Civil Engineer has already signed their off, most of the time it get captured before it get expensive.

[SandTEngineer]

The confusion is the parapet height is stated in BS EN 50122 for bridges over electrified railways which Civil Engineer regarded as an electrical standard but it is not stated in the Euro Codes Civil Engineers normally work to; often its not until an Electrification Engineer starts to check their design that they find the Civil Engineer has already signed their off, most of the time it get captured before it get expensive.

ET I'm very surprised at that.  Don't you have IDR (Inter Disciplinary Reviews) and IDCs (Inter Disciplinary Checks) before the design is ultimately approved

[Electric train]

The confusion is the parapet height is stated in BS EN 50122 for bridges over electrified railways which Civil Engineer regarded as an electrical standard but it is not stated in the Euro Codes Civil Engineers normally work to; often its not until an Electrification Engineer starts to check their design that they find the Civil Engineer has already signed their off, most of the time it get captured before it get expensive.

ET I'm very surprised at that.  Don't you have IDR (Inter Disciplinary Reviews) and IDCs (Inter Disciplinary Checks) before the design is ultimately approved

Yes we do which works great when it a whole project, occasionally projects are split and independent of each other and if the Route Asset Team do not pick up on it at AIP (Acceptance in Principle) dummies get spat out latter on .... mainly by the project manager cost, delay being the 2 largest dummies they spit out 

[BBM]

I've just followed a link on Rail UK^▸ (United Kingdom) Forums to a set of recent photos on Flickr which shows the HOPS train undergoing commissioning trials on the High Marnham Test Track in Nottinghamshire as well as the Series 1 OHLE which will be installed on the GWML^▸ (Great Western Main Line). The equipment looks very robust but rather more visually intrusive than I was expecting, certainly compared to the Series 2 OHLE in use on the Liverpool to Manchester line. Here's the link:

HOPS electrification train - Flickr album

[stuving]

I've just followed a link on Rail UK^▸ (United Kingdom) Forums to a set of recent photos on Flickr which shows the HOPS train undergoing commissioning trials on the High Marnham Test Track in Nottinghamshire as well as the Series 1 OHLE which will be installed on the GWML^▸ (Great Western Main Line). The equipment looks very robust but rather more visually intrusive than I was expecting, certainly compared to the Series 2 OHLE in use on the Liverpool to Manchester line. Here's the link:

HOPS electrification train - Flickr album

But the structures in place around Reading are not the same as those - not much lighter, but certainly different.

One thing the test track ones do have is diagonal stays. I was expecting these, and/or guys, to appear at Reading too. The GEML^▸ (Great Eastern Main Line) pictures in the Furrer and Frey presentation that was posted here a while back show such features, in particular on the two-barred portals where we expect tensioners to be mounted. There are suitable extra piled foundations near most portals, not just those two-barred ones, but none is yet used for anything.

[ray951]

But the structures in place around Reading are not the same as those - not much lighter, but certainly different.

From memory and from a distance the posts I have seen between Cholsey and Moreton look very similar to the posts in those photographs. Unfortunately I don't have a picture to prove whether that is the case or not and they also hadn't added any of the horizontal elements of the structure.

[stuving]

But the structures in place around Reading are not the same as those - not much lighter, but certainly different.

From memory and from a distance the posts I have seen between Cholsey and Moreton look very similar to the posts in those photographs. Unfortunately I don't have a picture to prove whether that is the case or not and they also hadn't added any of the horizontal elements of the structure.

A post is pretty much a post - they are all square section. But most of the "plain" supports on either side of Reading are ladder-braced portals (three or four tracks) or diagonally-braced cantilevers (two tracks). I though there were recent pictures posted, but the most recent I can find is http://www.firstgreatwestern.info/coffeeshop/index.php?topic=6405.msg147472#msg147472. That shows both, though the portals look a bit narrower than most. There are a number of variations on the basic themes.