Weird electrification at St Pancras?!?

[jscz]

I'm sure someone has already asked this, so feel free to direct me towards there if possible

I was at St Pancras Low Level yesterday for the first time in a while, and noticed that rather than having overhead wires, the pantograph was getting its current from some kind of bar suspended from the ceiling. I'm not sure how new this is, but I can say it was changed from usual methods some time between 2007 and 2017.

---

Here are some images:

Figure 1: St Pancras Low Level in 2007. We can see here that the OHLE is the same as the rest of the 25kV network - copper wires suspended from the celling of the station box.



Figure 2: The platforms in 2013. It's quite difficult to make out what is going on from this photo as the angle makes it hard to discern from the equipment from each of the tracks.



Figure 3: This was taken in 2017 but is identical to how it was yesterday, so interpret it as the modern design. Now there is the bar and almost no other wiring.

---

I was wondering why the (copper?) wires were replaced with a (steel?) bar? I can't think why it's worth it, although I was wondering if the more stable climate underground means the wires don't have to be kept taught by the catenaries, so that could be a factor. It also reminded me of some metro systems where they have a DC 3rd rail suspended in the air rather than as a third rail, which looks quite similar to this but could be a co-incidence.

Anyone that knows why it's like this or could direct me to an already-existent answer would be a star!

 

[SynthD]

It is an overhead conductor rail, for tight spaces where regular OHLE isn’t preferable. You can also see it on the Elizabeth Line.

 

[Whistler40145]

Fixed conductor bars are common in Tunnels and areas of limited clearance

 

[jscz]

I wonder why they added it later rather than including it originally though. And why isn't it present at Farringdon and City Thameslink?

 

[Edvid]

Here's a past explanation (by Bald Rick), from a previous thread on the topic:

Installed over Easter [2013]. Known as conductor beam. The contact wire is fixed to the underside. Much more robust than regular OLE, and practically zero maintenance.

It has replaced a tricky tension length of OLE between approx half way along St Pancras LL platforms* and the middle of the old KX Thameslink platforms. The curvature, cant and gradient change through this section made the OLE pretty difficult to keep in the right place and had high wear rates.

[* Extended through the Canal Tunnels and to just north of StP LL along the Moorgate lines since then]

 

[Dr Hoo]

I wonder why they added it later rather than including it originally though. And why isn't it present at Farringdon and City Thameslink?

The construction of the Thameslink 'box' at St Pancras was quite complicated. It was built 'round' he pre-existing brick arch tunnel and only needed simple catenary when it re-opened. The Canal Tunnels and junction with the link to the line out of KIng's Cross came later and the whole set-up had to be beefed up for very intensive operation and 12-car trains.

 

[Magdalia]

And why isn't it present at Farringdon and City Thameslink?

Possibly because that's where trains change from A/C to D/C and vice versa?

Raising a pantograph onto a conductor beam involves different forces to raising a pantograph onto a flexible wire.

 

[Class 170101]

It is an overhead conductor rail, for tight spaces where regular OHLE isn’t preferable. You can also see it on the Elizabeth Line.

and entering / leaving Glasgow Queen Street on the train.

 

[norbitonflyer]

I believe one of the first applications was at Trowse swing bridge, where having a continuous tensioned wire would obviously be difficult.

 

[Bald Rick]

I believe one of the first applications was at Trowse swing bridge, where having a continuous tensioned wire would obviously be difficult.

Trowse was the first application I’m aware of in this country, and for precisely the reason you hint at, ie the opening of the bridge. You only get to understsnd the detsil when seeingit from the cab, and you can see it as three seperate conductor beams - one on the bridge and one each side, with a decent gap (side to side) to prevent arcing, but allowing the pantographs always to be in contact.

Back to the OP. The St Pancras Station page on Wikipedia states that the low level station opened in December 2007. I don’t think that is right. Not least because self and Mrs BR had a trip on the eurostar just before Christmas 2007, and we definitely changed via KX Thameslink.

My memory is that the Low Level opened in December 2009, on the Monday of the timetable change, a day after the Southeastern Javelin domestic services started. I well remember running for a train on the first Monday evening, having had, ahem, a pre-Christmas sharpener with some colleagues, and nearly taking a tumble as the brand new floor sufrace (laid that weekend!) hadn’t yet had the micro-etching done to give them some grip for people wearing shoes with a lower than optimal friction coefficient. Obviously the Christmas drinks had nothing to do with it.

Perhaps someone can confirm the opening date.

 

[plugwash]

I did a google search for st pancras thameslink opening with a date range restriction of 2007 to 2010 and found a number of contemporary sources that seem to match the date on wikipedia. I did not see anyting that suggests 2009

Goodbye Kings Cross Thameslink…

...hello to the new St Pancras International replacement.

www.ianvisits.co.uk

The King's Cross St. Pancras nexus - a novelty tube map

Just in time for the closure of King's Cross Thameslink and the opening of the Thameslink platforms at St Pancras this weekend, here is a co...

londonconnections.blogspot.com

Kings Cross Thameslink

NEW STATION WITHIN ST PANCRAS INTERNATIONAL BRINGS BETTER JOURNEYS AND EUROPEAN CONNECTIONS

Information for journalists, press, bloggers and the media about Network Rail. Contact the press office to receive news, updates, press releases, videos, pictures, and factsheets, and to arrange interviews, filming and photography

www.networkrailmediacentre.co.uk

 

[bnc2018]

I appreciate it's nearly 20 years ago but the the Thameslink station construction costs in that press release seem amazingly low compared to the costs of things now. According the Bank of England's inflation calculator, £70m in 2007 is £115m now - I'd be pretty amazed if something so ambitious cost anything near that nowadays

 

[Warrior2852]

Back to the OP. The St Pancras Station page on Wikipedia states that the low level station opened in December 2007. I don’t think that is right. Not least because self and Mrs BR had a trip on the eurostar just before Christmas 2007, and we definitely changed via KX Thameslink.

My memory is that the Low Level opened in December 2009, on the Monday of the timetable change, a day after the Southeastern Javelin domestic services started. I well remember running for a train on the first Monday evening, having had, ahem, a pre-Christmas sharpener with some colleagues, and nearly taking a tumble as the brand new floor sufrace (laid that weekend!) hadn’t yet had the micro-etching done to give them some grip for people wearing shoes with a lower than optimal friction coefficient. Obviously the Christmas drinks had nothing to do with it.

Perhaps someone can confirm the opening date.

Network Rail's own history page on St Pancras says December 2007 for Thameslink, a month after upstairs.

The history of London St Pancras International station - Network Rail

St Pancras is a 19th century station that delivers a 21st century regional, intercity, continental and high speed railway to London. Discover its history.

www.networkrail.co.uk

The new St Pancras International station was officially opened on in November 2007 with Eurostar and East Midland services, and with Thameslink services joining that December.

 

[Magdalia]

Network Rail's own history page on St Pancras says December 2007

My records say that too.

My last arrival at Kings Cross Thameslink was on 7 December 2007 and my first departure from St Pancras International Low Level was on 10 December 2007.

 

[themiller]

I'm sure someone has already asked this, so feel free to direct me towards there if possible

I was at St Pancras Low Level yesterday for the first time in a while, and noticed that rather than having overhead wires, the pantograph was getting its current from some kind of bar suspended from the ceiling. I'm not sure how new this is, but I can say it was changed from usual methods some time between 2007 and 2017.

---

Here are some images:

Figure 1: St Pancras Low Level in 2007. We can see here that the OHLE is the same as the rest of the 25kV network - copper wires suspended from the celling of the station box.


View attachment 168433
Figure 2: The platforms in 2013. It's quite difficult to make out what is going on from this photo as the angle makes it hard to discern from the equipment from each of the tracks.


View attachment 168434
Figure 3: This was taken in 2017 but is identical to how it was yesterday, so interpret it as the modern design. Now there is the bar and almost no other wiring.

---

I was wondering why the (copper?) wires were replaced with a (steel?) bar? I can't think why it's worth it, although I was wondering if the more stable climate underground means the wires don't have to be kept taught by the catenaries, so that could be a factor. It also reminded me of some metro systems where they have a DC 3rd rail suspended in the air rather than as a third rail, which looks quite similar to this but could be a co-incidence.

Anyone that knows why it's like this or could direct me to an already-existent answer would be a star!

Garry Keenor’s book, Overhead Line Electrification for Railways describes this arrangement in 12.16.2 on page 165 as ‘a grooved bar designed to accept a conventional contact wire’ so it’s not a rigid contact bar but a contact wire which is supported along its length.

Download the 6th Edition PDF – Overhead Line Electrification for Railways

ocs4rail.com

 

[Western 52]

Doesn't the Severn Tunnel also have conductor rails rather than wires?

 

[themiller]

I think that the Severn tunnel was also fitted with conventional contact wire supported along its length.

 

[JordR]

Is it considerably more expensive than standard OHLE? Is it only capable of accommodating lower speeds?

 

[jfollows]

Is it only capable of accommodating lower speeds?

No, certified safe up to 275kph per the book linked in post 15 above.

 

[oglord]

I think that the Severn tunnel was also fitted with conventional contact wire supported along its length.

It is conductor rail, as per https://www.amcogiffen.co.uk/projects/severn-tunnel-ole

 

[Bald Rick]

Network Rail's own history page on St Pancras says December 2007 for Thameslink, a month after upstairs.

The history of London St Pancras International station - Network Rail

St Pancras is a 19th century station that delivers a 21st century regional, intercity, continental and high speed railway to London. Discover its history.

www.networkrail.co.uk

My records say that too.

My last arrival at Kings Cross Thameslink was on 7 December 2007 and my first departure from St Pancras International Low Level was on 10 December 2007.

Well that just shows how memory fails. Thanks both (and others).

Is it considerably more expensive than standard OHLE? Is it only capable of accommodating lower speeds?

Yes, considerably more expensive.


For the avoidance of doubt, the conductor rail is not in contact with the pantograph. Contact wire is bonded to the rail for the pantograph to, er, contact.

 

[edwin_m]

Is it considerably more expensive than standard OHLE? Is it only capable of accommodating lower speeds?

Also I believe it needs supporting at much shorter intervals than standard OLE. That's not so important in tunnels where it's just bolted to the roof (and wire would also need a similar number of supports unless there was enough height to permit a catenary and droppers). But if it was used in the open air it would need many more supports.

 

[themiller]

It is conductor rail, as per https://www.amcogiffen.co.uk/projects/severn-tunnel-ole

In this reference, it says ‘Unlike the standard open route OLE, the contact wire is held in a “conductor rail” suspended from the small parts steelwork…..’ which is the description of the arrangement in the reference (above in post 15).

 

[Beebman]

Also I believe it needs supporting at much shorter intervals than standard OLE. That's not so important in tunnels where it's just bolted to the roof (and wire would also need a similar number of supports unless there was enough height to permit a catenary and droppers). But if it was used in the open air it would need many more supports.

It's used in the open air at the Patchway Tunnels near Bristol as the gap between the two is only 160m which is too short for a length of tensioned cable:

https://x.com/NoelDolphin/status/1084861500248997888

 

[Whistler40145]

Presumably a conductor bar is used to eliminate sagging and damage to the OHLE?

 

[edwin_m]

Presumably a conductor bar is used to eliminate sagging and damage to the OHLE?

A contact wire is prevented from sagging because it's under tension, and also because there is a curved "catenary" wire above it which holds it up via vertical "droppers". The conductor bar is rigid but also much heavier and not under tension, so if the spacing between supports was as long as it is for a normal wire, then it would probably sag much more.

 

[BRX]

Is it more expensive than 3rd rail? If so why not just extend 3rd rail to St Pancras and have the changeover there?

 

[jfollows]

Is it more expensive than 3rd rail? If so why not just extend 3rd rail to St Pancras and have the changeover there?

“extend 3rd rail”
not going to happen!

Headbolt Lane to Kirkby not electrified due to "safety concerns" ?

Apologies if this has been asked before but I put the subject into the and a thread on this subject did not come up ! I was reading article on the new class 777s in both the current Railway Magazine and the current Milepost (the journal of the Railway Performance Society) and they both stated...

www.railforums.co.uk

 

[plugwash]

Is it more expensive than 3rd rail? If so why not just extend 3rd rail to St Pancras and have the changeover there?

Even if you extended the third rail the changeover at St pancras you would still need an area of overlap that was sufficient to provide for contingencies such as failed power changeovers. So you would probablly still end up needing OHLE out of both ends of St pancras.

 

[Warrior2852]

Is it more expensive than 3rd rail? If so why not just extend 3rd rail to St Pancras and have the changeover there?

They don't do third rail extensions anymore, even small ones - Merseyrail had to buy battery trains just for a one station extension because they couldn't do more third rail.