Should the ECML OHLE be upgraded

[andylloyd]

Hi all,
do you think the OHLE should be upgraded on the ECML to prevent any further incidents?
Is patching it up a proper repair?

Many Thanks

Andy

[dan4291]

It always seems to be somewhere near Peterborough where it fails. Surely Network Rail has noticed this.

[enotayokel]

There was serious talk of Dewiring a few years ago.

The main problem around Peterbough in the boggyness. The piling of a mast is undermined, moves out of alignment and next unit/91 brings it down

[ajax103]

There was serious talk of Dewiring a few years ago.

The main problem around Peterbough in the boggyness. The piling of a mast is undermined, moves out of alignment and next unit/91 brings it down

What they need to do but it will cost about as much as the "WCML Upgrade" which is to dewire the ECML at Stilton Fen up to Huntingdon and reinstall the old Up Slow as the layout used to be, then when the wires go back, have them much closer together which is another reason why we get OHL problems is because the OHL was done on the cheap and as far apart as possible.

I know this won't happen but it should because then the only bottleneck would be the short Holme Fen area and would greatly decrease future OHL problems.

NXEC could be diverted via Cambridge along with Hull Trains and Grand Central with First Capital Connect using St Neots as the GN terminating station.

[charlierc]

Upgrade it. If NXEC are to get near their supreme punctuality planning, then wire reliability has to improve.

[danielw2599]

An OHL replacement scheme is already underway on the ECML as is on the GEML.

[andylloyd]

An OHL replacement scheme is already underway on the ECML as is on the GEML.

Is this on the troublesome areas then or the southern section?

Cheers

Andy

[danielw2599]

An OHL replacement scheme is already underway on the ECML as is on the GEML.

Is this on the troublesome areas then or the southern section?

Cheers

Andy

Southern at the moment, but these schemes usually run for at least a couple of years so will slowly work north (On both routes) and cover all areas.

[arabiandisco]

The GE re-wiring is to replace the ex-DC stuff, which means Liverpool St - Shenfield - Southend, and the ECML is probably limited to the southern end, as the initial KX suburban electrification in 197x was KX to Royston, so the furthest up the ECML it will get is probably Hitchin.

There's not actually anything wrong with the design of the ECML OLE. The wiring from Weaver Jn to Glasgow is the same design as the KX - Royston stuff, and just about everything done since then is a similar design (HS1 is entirely different, being basically a copy of French practise). It's not as outrageously over-engineered as the southern WCML though, but that was designed to cope with steam engines running under it regularly...

[chriscooper]

Kings Cross to Royston and Weaver Junction to Glasgow were not so bad though, as with other electrification at the time. The problem was the extension northwards on the ECML, where the same basic design was used, but with longer spacing between the masts or headspans. As has been said, it's particularly a problem in the fens where the ground is soft and masts tend to move. Also, the Mk3B (ECML extension, GEML Norwich extension, Bed-Pan etc) masts do have some differences to the Mk3A which might make them more prone to trouble (the As look more substantial in places). Then again, Cambridge to Kings Lynn was done around the same time and in the same sort of area, yet rarely seems to get problems, although oviously it gets less use and lower speeds (1 EMU per hour most of the day, at 100mph, compared to a lot more electric traction on the ECML at up to 125mph) which might help. The Mk1 overhead used in the 60s is based on French practice, and very similar overhead can be seen on classic lines in France. It was very overengineered. The catenary itself was heavier, so required more substantial masts to hold it up, insulators were bigger and heavier aswell, so the whole structure was far heavier and also visually obtrusive. It did last a lot better though and has been much more reliable.
It is arguable though if it was ever a good idea to electrify north of Newcastle on the ECML, due to the nature of the area the line passes through, with subsidence, high winds etc all causing problems. Even connecting to the Grid for electric supply was more difficult and expensive due to the low population density of the area, and required feeder stations at maximum spacing, and also one feeder station which comes directly from the 400kV Supergrid, which was much more expensive than the usual feeders from the 132kV grid. The route, being slower than further south, probably benefits much less from electric traction aswell, and of cource most of the trains (local and Cross Country, aswell as the ECML services beyond Edinburgh) are diesels anyway.

[rfletcher72]

The main problem around Peterbough in the boggyness. The piling of a mast is undermined, moves out of alignment and next unit/91 brings it down

I am intrigued by this very valid point. However, unstable ground conditions are nothing new where OHLE is concerned. Not too far from here, a certain 1500v DC operation ran through an area extremely vulnerable to mining subsidence. As would be expected, this was anticipated from the offset and the OHLE was designed for such areas whereby the whole gantry could be adjusted up or down to lower or increase pantograph clearence, dependant on local conditions.

They don't make them like they used to

Richard

[mattvince]

The Stilton Fen masts are, in fact, portal gantry structures with a horizontal bar between the two masts (Dutch-style), which gives added rigidity. Some of the problems with the BR OHLE are the poor foundations - just bored straight into embankments (of which some are widenings of older embankments, when the ECML was widened to four tracks) - as a result, some of the masts are subsiding, which can have an effect on all running lines. Wind-throw effects are more dramatic with greater mast separation - using headspans might compound the issue of wind-throw, especially on corners (greater vertical and horizontal play). Sometimes an OHLE failure can be a human error - there has been at least one incident in the last 18 months where the 'droppers' (the short wire connecting the catenary wire to the contact wire) were attached to the underside of the contact wire, damaging the pantographs of all trains passing under those wires.

Part of the problem is an inability to manage the issue - such as the non-existence of Bi-Directional Signalling on the south end of the East Coast - having four tracks solves everything - except where you have a broken headspan (the Midland Main Line has split headspans with a third mast between the two pairs of lines, which solves this). Even if the damage to the overheads permitted running on the furthest pair of tracks, there aren't the crossovers to permit such Bi-Di working, nor the staffing to provide enough pilotmen. Fortunately for the West Coast, the TV4 project is installing both full bi-directional signalling on the inner pair of tracks, and the crossovers to enable trains to use that capability.

Of course, in Europe they simply drop the pantograph and coast through the broken section - somehow I can't see HMRI permitting that...

As to Huntingdon - there is a committed plan to put in a high-speed point from the Up Main/Fast to the Up Slow at Huntingdon, thus the need to reinstate the Up Slow back to Holme is significantly less. Them Networkers are not slow - in fact, a 365 will get from Kings Cross to Stevenage in the same time as a '225'...

[rfletcher72]

Some of the problems with the BR OHLE are the poor foundations - just bored straight into embankments (of which some are widenings of older embankments, when the ECML was widened to four tracks) - as a result, some of the masts are subsiding, which can have an effect on all running lines.

At the time it was novel and saved time and money, but maybe the practice of mounting masts on pile driven supports was not such a good idea in hindsight

Richard

[mattvince]

Some of the problems with the BR OHLE are the poor foundations - just bored straight into embankments (of which some are widenings of older embankments, when the ECML was widened to four tracks) - as a result, some of the masts are subsiding, which can have an effect on all running lines.

At the time it was novel and saved time and money, but maybe the practice of mounting masts on pile driven supports was not such a good idea in hindsight

Pile-Driven concrete bases are pretty much universal for OHLE - how else do you support the mast and all the forces which are applied on it? Naturally OHLE can be supported on suitable lineside/overline structures (retaining walls, tunnels), but there aren't too many of them around Stilton Fen. What BR should have done was to reinforce the embankments with additional material (as Railtrack/Network Rail have done in some places - which is why you will see piles of exposed stones, often in Gabion Cages, on certain sections of the lineside), and using 'soil nails' and 'rock-bolts', and perhaps careful use of 'geotextiles' to reduce subsidence. That kind of subsidence doesn't just affect the OHLE masts, it can mean the adjacent line being undermined. And, just perhaps, BR should have put the masts in the 10-foot (between Slow and Fast lines), with support arms off either side. This might have required slewing the Slow lines - although that might be no bad thing for other reasons.

Perhaps someone else can clarify, but it seems to me that, uniquely for Germany, their new OLE masts (cylindrical-shaped units used on 'Neubaustreke') are driven into the soil directly (latticework and I-beam masts still use concrete pile bases).

[chriscooper]

I don't know of anywhere on the MML where there are split headspans with a mast between the pairs of tracks. In places where the track pairs are further apart, they have masts for each line, and in some places they are close enough together that the centre pair of tracks has a single mast supporting the arm for each track. Most of the electrification is done with standard, 4 track headspans.