St Pancras electrification

[skyhigh]

Hi all,

I was at St Pancras lower level station last night, and noticed that as far as I could remember, the overhead electrified cable had been changed to a metal bar type. Have I simply remembered wrongly and it always used to be like that, or has it been changed? I don't travel there very often, so it might have been modified a while back!

 

[TheNewNo2]

I'm looking at photos, and in 2010 it looks like normal catenary to me.

 

[RichmondCommu]

Hi all,

I was at St Pancras lower level station last night, and noticed that as far as I could remember, the overhead electrified cable had been changed to a metal bar type. Have I simply remembered wrongly and it always used to be like that, or has it been changed? I don't travel there very often, so it might have been modified a while back!

Deleted.

 

[Philip Phlopp]

Hi all,

I was at St Pancras lower level station last night, and noticed that as far as I could remember, the overhead electrified cable had been changed to a metal bar type. Have I simply remembered wrongly and it always used to be like that, or has it been changed? I don't travel there very often, so it might have been modified a while back!

Bald Rick explains all.

http://www.railforums.co.uk/showpost.php?p=1424992&postcount=5

It's basically regular contact wire held in a special formed metal section, removing the need to tension the contact wire and as a result, allowing a more bespoke stagger as necessary in areas of limited clearance and tight curves.

It's been in use across the UK for a few years but the continental railway systems have been using it for a while, I think it was originally developed to allow previously electrified tunnels with limited clearances to run double deck stock.

 

[DarloRich]

it is a fairly new addition i think - have they gone for the rigid conductor rail?

 

[skyhigh]

Ah, thank you very much - I thought someone would have posted something somewhere, not that I could find it though!

I noticed as last time I was there I saw brackets on the roof that didn't seem to be doing much and wondered why they were there, this time they were being used to hold up the beam. I didn't know if something had actually changed or if I was just going mad!

 

[RichardN]

St Pancras LL used to be part traditional catenary (Northen section) and part solid bar (Southern section) It was mentioned before that they were putting the bar in through the tunnel to the ECML. It sounds like this has happened.

 

[450.emu]

Any pictures of this new conductor bar?

 

[Haywain]

It's been changed very recently at the north end of the platforms. I first noticed just under 24 hours ago, and I use the station on a daily basis. The south end was done a year or two ago.

 

[skyhigh]

I was right at the north end when I noticed it, so that fits.

 

[lincolnshire]

I was right at the north end when I noticed it, so that fits.

The station when it opened was normal overhead line set up when it opened and was converted to a overhead beam style a while later round about the time of the alterations for the new tunnel set up onto the East Coast Mainline.
There looks to be a lot of metalwork up there now as to what was there.

 

[westcoaster]

Some good pictures on this good Twitter account
https://twitter.com/13milepost/status/628544458053783552

 

[AM9]

Some good pictures on this good Twitter account
https://twitter.com/13milepost/status/628544458053783552

Interesting picture, - not sure about the question asking whether "the aluminium section holds a wire in place & provides electrical insulation?" is correct as the aluminium would not provide anything like adequate insulation at 25kV. In an undergound installation, that isolation may be provided by simple glass fibre bars as the benign weather conditions would not dictate conventional ribbed insulators.

 

[jamesontheroad]

It's been in use across the UK for a few years but the continental railway systems have been using it for a while, I think it was originally developed to allow previously electrified tunnels with limited clearances to run double deck stock.

That rings a bell. Is it used in RER tunnels through central Paris?

 

[edwin_m]

Much of the Madrid Metro has solid bar (overhead) electrification of some sort.

 

[nlogax]

That rings a bell. Is it used in RER tunnels through central Paris?

And in the open air at some points too, it seems.

 

[glbotu]

Does anyone know whether it's significantly more expensive. Surely not having to tension the contact wire has some engineering advantages (you only have to worry about the cantilever), so could it have more widespread applications?

 

[AM9]

And in the open air at some points too, it seems.

View attachment 23792

Although that picture looks like it was taken at a point not far from a tunneled section. Just like the Thameslink core section between St Pancras and Farringdon dives in and out of the Clerkenwell tunnels but AFAIK, the rigid conductor structure is continuous until the Farringdon dive-under.
The glass fibre register arms are used extensively on the MML electrified sections, mainly under bridges and in sheltered areas.

 

[jopsuk]

Does anyone know whether it's significantly more expensive. Surely not having to tension the contact wire has some engineering advantages (you only have to worry about the cantilever), so could it have more widespread applications?

I'd have thought it'll be quite a lot heavier, despite using lightweight aluminium section, making it suitable primarily for tunnels where conductor weight is much less of a consideration

 

[edwin_m]

As it's heavier and not under tension, it will tend to sag so will need a lot more supports. Less of a problem in a tunnel where they can just be fixed to the roof.

 

[swt_passenger]

As it's heavier and not under tension, it will tend to sag so will need a lot more supports. Less of a problem in a tunnel where they can just be fixed to the roof.

Furrer and Frey reckon support every 7m - 15m, dependent on speed, so a vastly increased number of cantilevers or portals is required, probably in the order of 10x?

 

[Philip Phlopp]

I'd have thought it'll be quite a lot heavier, despite using lightweight aluminium section, making it suitable primarily for tunnels where conductor weight is much less of a consideration

6kg per metre, compared with an average of 1kg per metre for contact wire (plus the same for catenary wire), and a little extra weight for droppers, probably 2kg per metre is a fair indication of OLE catenary weight, a little more if they've used a thicker cross section contact wire for wear.

The total weight for an installation like this is probably about the same regardless of method, as you've removed the requirement for a tensioner in the system, and provided less complicated mounting brackets which don't have to support both contact wire and catenary wire (removing an insulator in the process).

The main cost is the expense and there's some other issues that need to be taken into account - much larger cross section when exposed to crosswinds, has a fairly large cumulative affect on insulators and cantilevers and it's a bit awkward to work with over longer lengths.

It can need to be pre-formed into shape depending on layout, and it's less convenient over switches and crossovers too, but it's super for tunnels, some bridges and for more architecturally sensitive station installations.
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Furrer and Frey reckon support every 7m - 15m, dependent on speed, so a vastly increased number of cantilevers or portals is required, probably in the order of 10x?

Maybe on straight line, but less of an issue on fairly tight radius curves where you would have a large number of conventional cantilevers anyway to maintain registration and stagger as necessary.

 

[snowball]

Is this event relevant in any way?

https://www.gov.uk/raib-reports/overhead-line-failure-at-st-pancras-international

 

[Peter Mugridge]

Although that picture looks like it was taken at a point not far from a tunneled section. Just like the Thameslink core section between St Pancras and Farringdon dives in and out of the Clerkenwell tunnels but AFAIK, the rigid conductor structure is continuous until the Farringdon dive-under.
The glass fibre register arms are used extensively on the MML electrified sections, mainly under bridges and in sheltered areas.

That picture looks like the section between Gare d'Austerlitz and St Michel on Line C, it's about 50% open / 50% in tunnel between those stations.

 

[ironstone11]

Is this event relevant in any way?

https://www.gov.uk/raib-reports/overhead-line-failure-at-st-pancras-international

Not really. This incident was on the Eurostar platforms which are wired as conventional catenary.

The contact wire was burned through due primarily to the incorrect setting of a spark gap on the train.