Connington ECML OHLE Headspan conversions

[jyte]

Just noticed (by fluke) that NR converted (or is in the process of converting) by the looks of things 6 headpans on the ECML at Connington into Portals like the trial boom at Potters Bar.

https://twitter.com/networkrail/status/946395340940308480

#DailyPick Old next to new portal conversion at Connington, Cambridgeshire.

Does anyone 'in the know' have any idea how many headspans NR is planning to replace in this area and if this is the start of a wider replacement programme or just an isolated thing?

 

[furnessvale]

Just noticed (by fluke) that NR converted (or is in the process of converting) by the looks of things 6 headpans on the ECML at Connington into Portals like the trial boom at Potters Bar.

https://twitter.com/networkrail/status/946395340940308480

Does anyone 'in the know' have any idea how many headspans NR is planning to replace in this area and if this is the start of a wider replacement programme or just an isolated thing?

Excellent idea. Hopefully they will start at known trouble spots and work until all the pesky things are eliminated.

 

[jyte]

Yes, the OHLE in this area (south of Peterborough, North of Hitchin) is notoriously unreliable, probably second only to the wiring around Retford.

 

[GRALISTAIR]

Excellent idea. Hopefully they will start at known trouble spots and work until all the pesky things are eliminated.

Yes, the OHLE in this area (south of Peterborough, North of Hitchin) is notoriously unreliable, probably second only to the wiring around Retford.

Not OT but on my favorite topic of electrification - I assumed that the branch to Middlesborough would get done as in electrified -so it made sense to me that -while they were at it, they would convert the headpsans on the ECML in the area of the junction to portals while they were at it - or strengthen and inspect the OHLE while they were at it. Long story short - no need to go to vast expanse and convert the entire ECML to portals - but do it at selected areas , junctions etc.

 

[jyte]

Not OT but on my favorite topic of electrification - I assumed that the branch to Middlesborough would get done as in electrified -so it made sense to me that -while they were at it, they would convert the headpsans on the ECML in the area of the junction to portals while they were at it - or strengthen and inspect the OHLE while they were at it. Long story short - no need to go to vast expanse and convert the entire ECML to portals - but do it at selected areas , junctions etc.

If middlesborough gets done then yes. I suspect NR will want to replace OHLE in the areas where 140mph is possible alignment wise for the new trains, as well as in areas where the wires come down regularly. I highly doubt (because as other projects have proven) that NR is going to replace every head-span on the line however - that would effectively be the cost of electrifying an already electrified railway, unless it's done over a long time period (like 20-30 years).

 

[GRALISTAIR]

If middlesborough gets done then yes. I suspect NR will want to replace OHLE in the areas where 140mph is possible alignment wise for the new trains, as well as in areas where the wires come down regularly. I highly doubt (because as other projects have proven) that NR is going to replace every head-span on the line however - that would effectively be the cost of electrifying an already electrified railway, unless it's done over a long time period (like 20-30 years).

Yes - definitely trying not to get OT - but I assume only because Crossrail justified it, that portals have mainly/all ? replaced headspans Paddington - Airport Jct on the GWML? Long story short - there has to be a strong justification/Business case to replace them anywhere.

 

[jyte]

Loads of headspans left on the GWML.

My understanding from posts on the GWEP page is that NR is only replacing the headspans where the IEPs will be doing 125mph on the fasts, so between Southall and Airport Junction. The 'troublesome' ones near Paddington have also gone as well to improve reliability.

 

[GRALISTAIR]

Back on topic, it is of course the ECML that has hit the headlines for the unreliability of the OHL kit so glad that some measures are being taken.

 

[Elecman]

Loads of headspans left on the GWML.

My understanding from posts on the GWEP page is that NR is only replacing the headspans where the IEPs will be doing 125mph on the fasts, so between Southall and Airport Junction. The 'troublesome' ones near Paddington have also gone as well to improve reliability.

And on the WCML between Warrington and Preston

 

[GRALISTAIR]

And on the WCML between Warrington and Preston

And north of Preston. I can see some from my bedroom window in my UK home - if I get a chance I may even post a photo.

 

[snowball]

However there must be relatively little between Preston and the approaches to Glasgow, as it's mostly only two tracks.

 

[Elecman]

Some around Carlisle

 

[jyte]

Wow it seems like NR's headspan replacement program is actually a much larger scale than I thought - makes me feel much better haha.

 

[Tio Terry]

My understanding of the ECML problem - and this goes way back to BR day's so may be different today - is that the track floats of a bed of reed matting across a bog around Connington and that the track moves vertically relative to the OHEL because the mast foundations don't move at the same rate as a passing train and that this can lead to the pan loosing contact with the contact wire, arching and causing additional wear. Also, the movement of track and OHEL can lead to whipping of the overheads and more contact/arching problems. Now I'm not a Civil Engineer or an M&EE OHEL Engineer, but somebody on here will be, so can you please explain to me what improvement full portals make over head spans in this situation?

 

[jyte]

My understanding of the ECML problem - and this goes way back to BR day's so may be different today - is that the track floats of a bed of reed matting across a bog around Connington and that the track moves vertically relative to the OHEL because the mast foundations don't move at the same rate as a passing train and that this can lead to the pan loosing contact with the contact wire, arching and causing additional wear. Also, the movement of track and OHEL can lead to whipping of the overheads and more contact/arching problems. Now I'm not a Civil Engineer or an M&EE OHEL Engineer, but somebody on here will be, so can you please explain to me what improvement full portals make over head spans in this situation?

Well!

In the event a pan looses proper contact and whips or pulls down a wire, the wires are now (or are becoming) independently mechanically registered, which means the chances of ALL the overhead lines coming down when one is damaged are much lower, which means the system is more reliable.

Interestingly, there's a lot of portals (and sort of portals) in this area already. Between 39:30 and 40:00 on this 2013 shot video you can see that quite a lot of portals in the Connington area. The ones at 39:45 look really similar to some of the ones on the North East Corridor in the US.

 

[Tio Terry]

Well!

In the event a pan looses proper contact and whips or pulls down a wire, the wires are now (or are becoming) independently mechanically registered, which means the chances of ALL the overhead lines coming down when one is damaged are much lower, which means the system is more reliable.

Thanks, but that does not explain to me how this works. The track will still be moving vertically (and possibly laterally?) in respect to the OHEL. So how has a goal post improved the situation? Or have I got this totally wrong?

 

[jyte]

Thanks, but that does not explain to me how this works. The track will still be moving vertically (and possibly laterally?) in respect to the OHEL. So how has a goal post improved the situation? Or have I got this totally wrong?

I wouldn't say you've got it wrong. The chances a train pulls down a wire and closes that single line will be the same if the track moves vertically. The chance a train pulls down a wire, which in turns pulls down all the other wires and closes all the lines there for a day (as has happened many times in the past) in this area should be much lower now.

 

[Tio Terry]

I wouldn't say you've got it wrong. The chances a train pulls down a wire and closes that single line will be the same if the track moves vertically. The chance a train pulls down a wire, which in turns pulls down all the other wires and closes all the lines there for a day (as has happened many times in the past) in this area should be much lower now.

Thanks. So what we are saying is that the probability of a single track dewirement causing a total route closure is greatly reduced. But that this work is not likely to result in a line speed increase from 100 to 125 or even 140 MPH?

 

[jyte]

Thanks. So what we are saying is that the probability of a single track dewirement causing a total route closure is greatly reduced. But that this work is not likely to result in a line speed increase from 100 to 125 or even 140 MPH?

The area where the portals have been installed is a 125mph line-speed I believe, but I can check the sectional appendix. I don't think NR is proposing any 140mph running south of Peterborough...not yet at least, I think that'll mostly be where BR proposed it - Peterborough to the Stoke Tunnel.

140mph south of P-Bro doesn't really work when you've got 100/110mph trains on the fast lines.

 

[Tio Terry]

ETCS/ERTMS is, I believe, being designed around higher speed running in this area.

 

[jyte]

ETCS/ERTMS is, I believe, being designed around higher speed running in this area.

It certainly makes sense to push for 140mph wherever it's possible. If the new OHLE permits 140mph and everything else lines up, i don't see why not.

 

[edwin_m]

If the ground conditions cause one or both columns supporting a headspan to tilt towards the track, then the headspan will go slack and the wires will be out of position and more prone to move as a pantograph passes. If the same ground condition occurs at a portal then the rigid horizontal will resist the inward movement of the vertical and everything is much more likely to stay in position.

 

[GRALISTAIR]

If the ground conditions cause one or both columns supporting a headspan to tilt towards the track, then the headspan will go slack and the wires will be out of position and more prone to move as a pantograph passes. If the same ground condition occurs at a portal then the rigid horizontal will resist the inward movement of the vertical and everything is much more likely to stay in position.

The electrification of Chat Moss- there are loads of pictures on the Manchester-Liverpool electrification thread - illustrated this nicely. The moss moves and was an interesting challenge -no headspans on that route AFAIK. Portals give horizontal brace which headspans do not as pointed out by edwin_m . An interesting applied maths/mechanics question actually.

 

[Domh245]

In the event a pan looses proper contact and whips or pulls down a wire, the wires are now (or are becoming) independently mechanically registered, which means the chances of ALL the overhead lines coming down when one is damaged are much lower, which means the system is more reliable.

I'm not convinced that they are independently mechanically registered, as they still seem to be held in place by wires - indeed all that seems to have happened in that photo is the very top wire of the headspan being replaced by a cross beam - everything below that is still identical. Obviously, this may still be changing and they'll put in parts that fix directly and entirely to the portal, but a dewirement as they are now would still result in the contact wire on the other lines moving out of registration.

 

[jyte]

I'm not convinced that they are independently mechanically registered, as they still seem to be held in place by wires - indeed all that seems to have happened in that photo is the very top wire of the headspan being replaced by a cross beam - everything below that is still identical. Obviously, this may still be changing and they'll put in parts that fix directly and entirely to the portal, but a dewirement as they are now would still result in the contact wire on the other lines moving out of registration.

This is just a temporary phase in as I understand.

They'll end up looking like this trial boom at Potters Bar.

 

[Domh245]

This is just a temporary phase in as I understand.

They'll end up looking like this trial boom at Potters Bar.

Ah, fair enough. That's good to see.

 

[jyte]

You can see the intermediary stage

here,

the diagram about how the process works

here,

and the end result

here.

 

[snowball]

Wow it seems like NR's headspan replacement program is actually a much larger scale than I thought - makes me feel much better haha.

I think some of the people who posted above were only talking about places where there are headspans, not necessarily places where there's known to be replacement programme.

 

[deltic08]

Not OT but on my favorite topic of electrification - I assumed that the branch to Middlesborough would get done as in electrified -so it made sense to me that -while they were at it, they would convert the headpsans on the ECML in the area of the junction to portals while they were at it - or strengthen and inspect the OHLE while they were at it. Long story short - no need to go to vast expanse and convert the entire ECML to portals - but do it at selected areas , junctions etc.

Can someone please tell me where Middlesborough is please? If you mean Middlesbrough, then it is unlikely to be electrified in the current climate with only one passenger train an hour each way. I can't see it being wired until Doncaster-Lincoln-Peterborough is wired as all freight to/from Teesside along the ECML is diverted this way. Additionally, the junction at Northallerton is on double track only so not wired with long headspans.

 

[GRALISTAIR]

Sorry for the incorrect spelling. Middlesbrough was fairly high on Northern Sparks priority list iirc