Limitations of British OLE

[HSTEd]

Well as I understand it the Mark 3 OLE used above Weaver Junction on the WCML and on the entirity of the ECML was originally designed for speeds in the region of 100mph.

However as the OLE wasnt totally replaced (only upgraded to UK1, whatever that is) during the WCML rebuild even though 140mph speeds were expected at the time and that 140mph running was conducted on parts of both the WCML and ECML at varying times for testing purposes (APT and Cl91 trials) I would have to assume that it is capable of 140mph running fairly reliably.

So then, what is "UK1" that has apparently be installed as part of the WCML upgrade and how fast can you practically run trains on the Mark 3/3A/3B OLE without massive replacement?
By which I mean work more extensive than rewiring the line with stronger wire and possibly fitting heavier tension weights, Im talking about work on the cantilevers/headspans themselves and possibly even the support posts.

 

[Old Timer]

In a nutshell

Mk 1, 2, and 3 series OHL was designed and developed by Balfour Beatty, each version being an incremental improvement on the previous one. Mk 1 Equipment was (is) constructed with imperial nuts, bolts, etc, whereas Mk 2 onwards utilises metric components.

In the case of Mk 3 Equipment, the variations (eg a/b/c/d/e/f) all indicate different detail changes, for example "a" series equipment was originally installed with steel Headpsan wires whereas the "b" series Headspans were aluminium. The suffixes also assist to indicate what the composition of the Contact Wire is, eg copper, phosphor bronze, etc.

Mk 4 Equipment was specifically designed for 140mph running and has a much thicker wire cross-section. It is not in any way compatible with Mk 3 Equipment. The WCRM Upgrade was thus the installation of a completely new system not an upgrade to the existing Mk 1 and Mk 3.

Mk 4 also has a higher working tension.

The OHL structures are galvanised steel and are not necessarily Equipment specific, thus they can be used throughout the range. The design of the Structure is based solely upon the various loadings imposed by the Equipment being supported, and part of this will be related to the tensioning of the OHL Equipment.

 

[Wyvern]

Just found an interesting page. I dont know what you think of it.

http://caltrain-hsr.blogspot.com/2008/12/headspans-and-poles-oh-my.html

 

[LNW-GW Joint]

Another difficult question:

Why were class 373 Eurostar sets limited to 110mph when they ran on the ECML?
Was it because of the OLE or some other constraint?

I suppose if Eurostars ran today on the WCML they would still be limited to 110mph because they don't tilt, but is there any OLE reason they could not do 125/140 where permitted?

I was just thinking about the day when new continental-gauge Siemens Channel Tunnel stock is delivered, resulting in some of the UK-gauge 373 fleet becoming spare.
Any mileage in recycling these 373s on domestic routes?
If this was possible, the anti-IEP brigade might be quite keen to get their hands on a few for EC/GW operation.

 

[Old Timer]

1) Power and OHL constraints.

2) No, other than a check to see if the tensioning is adequate.

3) Noty a question I feel competent to answer but there is no reason why they could not run at 125 on the WCML on a limited stop service to Glasgow aka BR-style Preston, Lancaster, Carlisle. Motherwell, Glasgow/

4) I doubt they would be any use on the GW becasue it is too short. The same reasons why it is ludicrous to electrify when a suitable 125 diesel service is perfectly adequate. Outside of a high intensity suburban service electrification needs much longer diatances to be able to recover the costs against diesel operation.

 

[WatcherZero]

They would drain the line section dry and other trains would be stalling.

 

[HSTEd]

Another related point: Are all electrification structures on the ECML Headspans or simple cantilevers?

I ask because gantry type structures would likely be reusable in some sort of future reelectrification work with heavier weight contact wiring while the headspans and possibly cantilevers' support posts would be limited to something similar to the original weight/tension of equipment.

 

[ole man]

On 4 track sections of the ECML they mostly consist of Headspans, with the odd place having Cantilevers.
Most 2 track sections are Cantilevers, such as Grantham, Newark, and Going into Scotland.
Did you mean re-using the OLE structures? I've never known any Old structure to be re-used, unless NR want to keep it for training purposes as they did at Bletchley.
I really can't see Headspans being used again in this country as they cause to much trouble and limits the work you can do on them.

 

[HSTEd]

I meant reusing the OLE structures, simply because I imagine replacing every single OLE mast on the ECML could get very expensive very quickly.
Is the headspan's limitation related to the inability to register lines individually or somesuch?

 

[ole man]

Like i said ive never known any structure to be re-used, how would you get it out of the ground?.Some structures go quite deep into ground.
Starting to become expensive now.
Also the old structures will have been subject to a certain degree of tension already that would be the main reason
I was out last night working on a Headspans and had 2 lines open and 2 lines closed and was limited at most headspans to work i could.
You cant adjust the headspan's to much as you might throw out the open roads, and have to maintain the 9ft rule at all times.

 

[HSTEd]

Like i said ive never known any structure to be re-used, how would you get it out of the ground?.Some structures go quite

I was suggesting leaving them in place and just change the cantilevers or whatever to fit newer, heavier wire, but I presume the supports were sized for the wiring that was being placed on them when they were built to keep the cost down.

 

[Old Timer]

Whilst the re-use of the Structures is perfectly possible, has been done in the past, and is a cheaper means of installing, under the way that Network Rail operates, there arises a liability question which a Contractor simply will not take on by re-using used Equipment. Remember however the Headspan Structures were grouted directly into their foundations so making it near on impossible to re-use them. They were designed to stay in situ !

Another issue is the need under todays CDM Regulations to "prove" that a re-used Structure can bear the stresses and again this is harder to do than simply buying in a new one and sending the old for recycling.

With regards to the running of the Eurostar trains on the ECML. During the mid-1990's the North of London Eurostar sets were being trialled on the WCML and ECML. Part of the problem running with the Faiveley pantograph in the UK was that it was designed for running at high speed on the French equipment and not on the Mk3 lightweight OHLE in UK.

In an attempt to 'tune' the pantograph such that it did not exert such a large uplift in the UK aerodynamic trials were undertaken during the week commencing 8th December 1996 by SNCF using a Eurostar running between Nantes, Angers and Tours in the Loire Valley. Some limited success was achieved however the adjustment needed to run successfully on BR's OHLE was detrimental to running on SNCF's LGV lines
but the Eurostars were subsequently limited to 110 mile/h in the UK for the duration of their use by GNER.

The power consumption was not that much of an issue.

I was suggesting leaving them in place and just change the cantilevers or whatever to fit newer, heavier wire, but I presume the supports were sized for the wiring that was being placed on them when they were built to keep the cost down.

As I said above in my reply, the issue is the need to "prove" that the Structure can withstand the additional forces placed upon it. If we are talking about original Structures then this can and does mean the requirement for new anchor Structures at terminal ends, or the installation of new back-ties to hold the Structure against the wire.

Generally the old Mk 1 gantry Structures were constructed to a very high safety margin, which has allowed the extra stresses caused by Mk 4 Equipment to absorbed without bringing the Structure to its design tolerances. Not all Structures however passed this and had to be replaced or re-inforced.

 

[Bald Rick]

Another difficult question:

I was just thinking about the day when new continental-gauge Siemens Channel Tunnel stock is delivered, resulting in some of the UK-gauge 373 fleet becoming spare.
Any mileage in recycling these 373s on domestic routes?
If this was possible, the anti-IEP brigade might be quite keen to get their hands on a few for EC/GW operation.

Would be surprised if they were going spare. Expect Eurostar to start running direct to Lyon, Geneva, maybe even Strasbourg and Bordeaux. All will be within 5 hrs from London. They may even compete with DB to Amsterdam, Dusseldorf, Koln etc.. That and a few extra services to Paris and the fleet will be well used.

OT now, I've never understood why Eurostar haven't attempted to compete with air on the ski market to Lyon, Grenoble and Geneva, unless it's lack of paths on the LGV PSE. The current ski train is just a in fraction of the potential market.

 

[telstarbox]

On 4 track sections of the ECML they mostly consist of Headspans, with the odd place having Cantilevers.
Most 2 track sections are Cantilevers, such as Grantham, Newark, and Going into Scotland.
Did you mean re-using the OLE structures? I've never known any Old structure to be re-used, unless NR want to keep it for training purposes as they did at Bletchley.
I really can't see Headspans being used again in this country as they cause to much trouble and limits the work you can do on them.

For the 2-track sections, is there any reason why both overhead wires couldn't have been supported centrally rather than on cantilevers from either side? (i.e. picture B rather than A...) This would require much less structural steel over hundreds of miles and wouldn't require much extra space between the roads.

 

[Mike C]

I can't answer the infrastructure questions with respect to current draw being a limitation on 373 running, however let me point out a few facts:

- Our nominal static pantograph uplift force is 70N. This is comparible with common UK practice as I understand. It is also the requirement for CTRL running albeit, the catenary there is 150sq mm vs 107sq mm for MKIII and at nearly double the tension (20kN vs 11kN).

- There is an aerodynamic factor to be applied. The uplift increases with speed, up to around 160N at 300km/h. At 200km/h, the force will be in the region of 105-115N.

- The first few years of running 373/2 on ECML they were limited to 110MPH due to concerns as mentioned above. We ran tests at some point in 2003/2004, and proved that 125mph was indeed possible with no increased risk to OLE.

I believe this was implemented in the latter couple of years of GNER use of the sets, but only between Woolmer Green and an area south of Grantham. North of Grantham, 110mph was maintained until the end of their service.

 

[paulb1973]

For the 2-track sections, is there any reason why both overhead wires couldn't have been supported centrally rather than on cantilevers from either side? (i.e. picture B rather than A...) This would require much less structural steel over hundreds of miles and wouldn't require much extra space between the roads.

There are instances where 'central supports' exist when there are very limited clearances - between Platforms 4 & 5 at the re-built Rugby station for example. The original WCML electrification saw OHLE of this type, on both the southern and northern sections - but this/was not used generally due to the very limited space between both 2 & 4 track sections, presumably.

 

[O L Leigh]

Anecdotal evidence at least supports the notion that the Eurostar was a hungry bugger.

I have already reported once the tale that my traction instructor related about a brake handling trip with a bunch of trainees in a Cl317 that appeared to be down on power coming up from PBO. They were overtaken on the fast by a Eurostar and, as soon as it had cleared the next neutral section, all the power miraculously returned.

O L Leigh

 

[Old Timer]

For the 2-track sections, is there any reason why both overhead wires couldn't have been supported centrally rather than on cantilevers from either side? (i.e. picture B rather than A...) This would require much less structural steel over hundreds of miles and wouldn't require much extra space between the roads.

The normal six foot is inadequate for the installation of OHL Structures as a result of clearance issues.

There would obviously also be issues with the electrical clearance form the live parts of the adjoining line when staff were required to work on one line.

Placing anything in the six foot is also not desirable from a P. Way point of view for all sorts of reasons, one for example being track drainage as we need the track to drain to the sides optimally. Another reason is the constraints that would be placed on maintenance and reneals work, for example you could not drop LWR onto the adjoining line.

Anecdotal evidence at least supports the notion that the Eurostar was a hungry bugger.

I have already reported once the tale that my traction instructor related about a brake handling trip with a bunch of trainees in a Cl317 that appeared to be down on power coming up from PBO. They were overtaken on the fast by a Eurostar and, as soon as it had cleared the next neutral section, all the power miraculously returned.

O L Leigh

The 373 sets as I understand it can draw up to 12MW of power which equates to 16,000hp.

The issue with the GN main line was that it was not designed for the amount of power that is now drawn by trains.

This is not a unique situation as when the first double headed Class 86s started to operate on Freightliner trains on the WCML they would bring out the breakers every time a Driver notched up too quickly. It was also not unusual for us to have to start trains in a progressive manner when we had a lot of trains standing following an incident, as when they all started to draw power, the voltage just simply fell through the floor to the point where there was insufficient even to run the traction motor blowers.

I remember one evening after a major OHL failure that it took over an hour to clear trains out and get back to a situation whereby we could get sufficient power back into the OHL to allow normal operation. We were holding trains back as far as Euston, Coventry and Nuneaton whilst we sorted things out at one point.

It is very easy for those without the knowledge (yourself excluded) to criticise the GN main line electrification but at the same time it is quite wrong to do so with the benefit of hindsight and without the recognition that it was always meant to have been a temporary arrangement to enable the route electrfication to be undertaken. The plan was always to return and resolve the power and catenary system issues however Railtrack deferred the work and Network Rail have tried hard to ignore the problem on the basis that if you bury your head in the sand it might just go away.

Network Rail only belatedly started to replace the Mk3 Headspans on the GN Inner Suburban and Midland simply because they Headspans had physically started to fail.

 

[O L Leigh]

Indeed. I have said before that it was not a fault of the GN electrification if, 25 years ago, it was electrified to a certain standard to permit certain traffic, particularly around the corner from Hitchin all the way up to Kings Lynn. At the time this was considered adequate for the envisaged traffic, as was the case with other railway infrastructure projects of the same era (e.g. the Stansted Airport rail link).

I merely cited this anecdote again as evidence that the power draw of Eurostars on the GN could have been a contributory factor in their 110mph restriction as they were indeed very power hungry. Granted had the power supply been more robust this would never have been an issue, but this cannot ever be considered a shortcoming given that this would have required the power supply to have been "over-specced" for the regular permanent traffic.

O L Leigh

 

[HSTEd]

Did the Thameslink programme related upgrade of Mark 3 equipment on the Midland Main Line to Autotransformer-feeding go ahead?

If so how much work was required to achieve this in terms of replacing structures.

 

[Old Timer]

I cannot say as I spend a lot of time outside the UK but in simplicity there would be no need to alter Structures, as all that happens is that the AT conductor is routed along former Return Conductor route with changes to the insulator pots. Obviously where the feed is applied to the Catenary there will be bare feeders and drapes which will be supported from additional insulator pots, but nothing normally that requires a whole new Structure along the section.

 

[ole man]

There is quite a few structures up and down the WCML and Midland Main line for AT, though i havent had any involvement it looks like new switches and new termination structures

 

[HSTEd]

The article I found on the Midland project suggested new supports for the transformers and some tiebars on some of the existing structures but not wholesael replacement.

On another related matter, in some photos of railways in Japan Ive noticed that they seem to use something half way between a headspan and a gantry, ie. a gantry that has wires supporting it in the middle, presumably turning it into a rigid headspan assembly of some sort.

Has anything like that ever been done in the UK?

 

[ole man]

The article I found on the Midland project suggested new supports for the transformers and some tiebars on some of the existing structures but not wholesael replacement.

On another related matter, in some photos of railways in Japan Ive noticed that they seem to use something half way between a headspan and a gantry, ie. a gantry that has wires supporting it in the middle, presumably turning it into a rigid headspan assembly of some sort.

Has anything like that ever been done in the UK?

Can you put a picture up here, failing that PM me with it?

 

[HSTEd]

Something like that, although I now realise that is only a two track line.

 

[ole man]

They use them on Metro's in this country, there is loads of them on the Birmingham Metro, i know this personally because one snapped whilst we was working there and knocked my friend out.
Never seem them on heavy rail though a TTC does the same thing, and they are everywhere, quite a lot where the M1 follow's the WCML

 

[HSTEd]

Alright, so if headspans are out for future electrification projects on account of all the problems they seem to cause, what is the choice for future four track sections like bits of the GWML and potential southern conversions? Or for six track sections on the southern network.

A mix of TTCs and Gantries?

 

[ole man]

That to me would be the only option, as previously said by many on here Headspans are not capable of high speed, and hinder maintainance.
TTC's and 4/6 track Gantries are going to be used in my opinion.
They will enable easier maintainance, last longer, and more importantly withstand conditions that Headspans cannot

 

[HSTEd]

I am aware that Network Claims that its "Factory Trains" will be capable of wiring an entire tension length with a standard night time possesion, however the literature supplied with this claim suggests that is for a twin track line using single track cantilevers, would the process be much slower using gantries or TTCs on a four track line?

Additionally: if one was going to replace the headspan assemblies used on a route with gantries, could the gantries be posistioned while the headspans remained in service if the wires were to be raised to a greater height above the rails after the conversion?

 

[ole man]

I've never had anything to do with the wiring train( which is stored at Crewe IEMD), though it would be a bit slower, but quite capable of still doing a wire run in a night shift.

Most new OHLE structures are put up before the removal of the old ones, on gantries and TTC's the SPS would be raised up until the old structures are taken down.
Then dropped into position on the night.