Reliability of electrified lines

[RGM654]

In the Another day, another overhead line failure near Paddington thread

It is often stated that one of the benefits of electrification is better reliability. Are there any “real world” stats for the UK comparing across electrified and unelectrified lines? Or before-and-after electrification?

This seems a subject worthy of discussion in its own thread, so here you are. In the last few weeks there have been many disruptions caused by damage to overhead wires.

 

[zwk500]

To kick things off, here's the post-opening report of the GWML: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://assets.publishing.service.gov.uk/media/649c5957bb13dc000cb2e2cb/great-western-route-modernisation-first-post-opening-evaluation-final-report.pdf

Page 54 is the start of the relevant section, although COVID coming so hot on the heels of completion leads to a slightly distorted figures.

 

[QueensCurve]

To kick things off, here's the post-opening report of the GWML: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://assets.publishing.service.gov.uk/media/649c5957bb13dc000cb2e2cb/great-western-route-modernisation-first-post-opening-evaluation-final-report.pdf

Page 54 is the start of the relevant section, although COVID coming so hot on the heels of completion leads to a slightly distorted figures.

Broken link in the above, should be:

https://assets.publishing.service.gov.uk/media/649c5957bb13dc000cb2e2cb/great-western-route-modernisation-first-post-opening-evaluation-final-report.pdf

 

[Evolution]

It’s an interesting debate, however, as someone who signs plenty of electrified lines across the North West and Yorkshire, I can honestly say I’ve never had an OLE related issue (this could now be the equivalent of the commentators curse ). I’ve been asked to examine the OLE after a train ahead experienced an ADD but that’s it. In my parts it’s fairly reliable, in general.

It does seem to be heavily location specific, with the ECML and GWML suffering more so than other areas.

I experience more issues usually track circuit related on non-electrified lines. But that’s another discussion in itself.

 

[zwk500]

I experience more issues usually track circuit related on non-electrified lines. But that’s another discussion in itself.

It's related to the topic though - does electrification require closer attention to track circuits and therefore reduce delays by association, or is it just that electrification triggers upgrades that would have happened anyway (such as axle counters).

 

[Evolution]

I’d guess it been the latter. The routes where I have issues with track circuits and need to be talked passed signals the most are either Absolute Block or older colourlight areas with lesser traffic than the OLE areas. You can tell the line side equipment isn’t as modern, but some of these are smaller branch lines, subsequently there’s a “if it ain’t broke, don’t fix it” mentality, especially with this current governments plan to reduce costs.

I’ve been driving several years now and I’ve never seen as many ESR/TSR’s on my routes, some staying on for months. Lots of rough riding track as well. You can’t help but feel this governments pound foolish penny wise attitude to rail investment will come back to bite them in the proverbial.

 

[Horizon22]

It's probably not a simple comparison due to the intensity of services being worked and the amount of traffic and stock that can be utilised for electrified line.

Most OLE issues on the GWML are on the older 90s electrification between Hayes and Paddington which was in place for the new line to Heathrow Airport

 

[norbitonflyer]

I suspect the answer is that an electric train is more reliable as there is less to go wrong, as much of the power generation equipment has been moved off the train. But the infrastructure is more vulnerable for precisely the same reason.

 

[Adrian1980uk]

I suspect the answer is that an electric train is more reliable as there is less to go wrong, as much of the power generation equipment has been moved off the train. But the infrastructure is more vulnerable for precisely the same reason.

I don't think that's the whole story though, the ohle lines are some of the most intensive used lines. The GEML was notorious for failure but I'm guessing now it's been through a renewal process it's one of the most reliable.

 

[6Gman]

There do seem to be particular issues in specific areas - the first few miles out of Paddington, the southern part of the WCML for example.

So is someone investigating why?

 

[PeterC]

I don't think that's the whole story though, the ohle lines are some of the most intensive used lines. The GEML was notorious for failure but I'm guessing now it's been through a renewal process it's one of the most reliable.

I would assume that a lot is down to the age of the infrastructure. I commuted on the GEML in the 70s and 80s and my memory of delays is all in the latter part of that period.

 

[Meerkat]

There do seem to be particular issues in specific areas - the first few miles out of Paddington, the southern part of the WCML for example.

So is someone investigating why?

Not just because they are the busiest bits?

 

[800301]

Wire damage at Didcot, currently using IET’s to do the stopper shuttle between Reading and Didcot where staff allows

 

[mike57]

There do seem to be particular issues in specific areas - the first few miles out of Paddington, the southern part of the WCML for example.

So is someone investigating why?

Also ECML between Grantham and Retford seems to crop up with depressing regularity, so is it installation, environment, or the fact that this section is mainly 2 track and any issues probably result in a total blockage and so have a more serious impact.

 

[Bald Rick]

It does seem curious that the lines most susceptible seem to be those mostly used by Class 800 family trains.

 

[Trainbike46]

It does seem curious that the lines most susceptible seem to be those mostly used by Class 800 family trains.

Could that not be because there aren't that many busy OHLE lines where there's no 80x? Currently, the WCML and the MML are the main ones where they don't come, but there's orders for 80x for those lines as well!

 

[jayah]

I suspect the answer is that an electric train is more reliable as there is less to go wrong, as much of the power generation equipment has been moved off the train. But the infrastructure is more vulnerable for precisely the same reason.

The infrastructure doesn't have built in redundancy like a multiple unit, nor does someone come and helpfully park the OLE inside a depot building most nights.

 

[Bald Rick]

Could that not be because there aren't that many busy OHLE lines where there's no 80x? Currently, the WCML and the MML are the main ones where they don't come, but there's orders for 80x for those lines as well!

GEML, WAML and various suburban lines in the north west and Scotland beg to differ.

 

[Annetts key]

In terms of track circuit reliability, the track circuit equipment itself is often very reliable (except the ASTER / SF15 types which are obsolete and hence there is a lack of spares). A significant number of track circuit failures are either cable problems or just as, if not more likely, problems with the track.

For a track circuit to work correctly and be reliable, the ballast has to be in good condition (no muddy wet beds), if concrete or steel sleepers are in use, the insulations for the chairs (pads and "biscuits") need to be in good condition, the Insulated Rail Joints (IRJs) need to be in good condition, and if point work is involved, the insulations for all the stretchers and point operating equipment needs to be in good condition.

Unfortunately, poor or a lack of proper preventative maintenance means that many of these get left until a failure occurs...

It's really difficult to compare track circuits to axle counters in terms of reliability and the reasons for why the failures occur, because they are completely different systems and work very differently.

Under BR, Western Region at one time found some money to fund a programme to improve track circuit reliability. This worked very well. Most importantly, because old cables, connections were renewed with a better rail fixing method plus "doubling up" the cables to the rails (two independent cables, so if one was damaged, the second would allow the track circuit to continue to operate normally). But also because other defects were reported and fixed.

Poor ballast / track conditions can cause axle counters to fail. The rail mounted head can fall off the rail if the vibration causes the nuts and bolts to work loose.

Being far more complex, means the electronics that form a large part of the axle counter system can fail in many more ways compared to conventional track circuit equipment. One single equipment failure can cause two or many axle counter sections to fail.

So, I hope I have given you a flavour of the differences. And why (apart from simple statistics), it's not easy to say which is better overall...

 

[Wivenswold]

Greater Anglia topping the reliability charts even though a significant proportion of their services are electrified. Having a new fleet and a recent OHL replacement program helps though.

 

[Nicholas Lewis]

Greater Anglia topping the reliability charts even though a significant proportion of their services are electrified. Having a new fleet and a recent OHL replacement program helps though.

Only Liv St-Shenfield-Southend Vic modernised from fixed tension the rest of it as it was built some of it over 60 years old now.

 

[Western Sunset]

I know it's completely different in terms of line speed and frequency, but did the 1500Vdc overhead of the Woodhead route ever have problems?

 

[Nicholas Lewis]

I know it's completely different in terms of line speed and frequency, but did the 1500Vdc overhead of the Woodhead route ever have problems?

Not sure but 1500V DC was battleship engineering you won't find any headspans for starters.

 

[snookertam]

GEML, WAML and various suburban lines in the north west and Scotland beg to differ.

Equally, many lines in the Central Belt of Scotland use other hitachi units, which without having too much technical knowledge may well have common equipment in and around the pantograph areas. Very few problems with overheads in Scotland these days I find. Those that do occur are more often than not weather related.

Been a while since I could recall a major dewirement here. The age of the equipment across Scotland vary from early 60s to mid-2010s. We have hitachi IETs running using the wires as far as Edinburgh and twice per day Stirling. We have very intensely used sections and quite fast sections too. Yet none of the problems we are seeing down in Western England.

 

[Verulamius]

Does the amount of force exerted on the wire by the pantograph vary by class of train? Could that be a factor?

 

[Bald Rick]

I know it's completely different in terms of line speed and frequency, but did the 1500Vdc overhead of the Woodhead route ever have problems?

Not sure but 1500V DC was battleship engineering you won't find any headspans for starters.

The Woodhead design was near identical to that of the GEML from Liverpool St to Shenfield. However it was used much less, and (obviously) never reached the age that the GEML kit did which started to fail regularly 20 or so years ago.

Equally, many lines in the Central Belt of Scotland use other hitachi units, which without having too much technical knowledge may well have common equipment in and around the pantograph areas.

The pantographs are different, which is the key point. As is the linepseed.

Only Liv St-Shenfield-Southend Vic modernised from fixed tension the rest of it as it was built some of it over 60 years old now.

Shenfield - Chelmsford was fixed tension DC as well, and that has long since all been upgraded.

 

[Taunton]

The Woodhead design was near identical to that of the GEML from Liverpool St to Shenfield. However it was used much less, and (obviously) never reached the age that the GEML kit did which started to fail regularly 20 or so years ago.

Looks to me that the electrification infrastructure out to Glossop/Hadfield is still there unchanged. Different voltage now, of course.

 

[Yindee8191]

There do seem to be particular issues in specific areas - the first few miles out of Paddington, the southern part of the WCML for example.

So is someone investigating why?

WCML is because it’s ageing and extremely intensively used.

The first few miles from Paddington were built on a shoestring in the 90s and are pretty shoddily thrown together. Plus they now see 20+ electric trains an hour in each direction instead of the 4ish they were designed for.

 

[snowball]

Perhaps over time virtually all headspans in the country, such as Paddington to Airport Junction, will be converted to portals. They are normally only used where the number of tracks is at least 3, so they are not much found on lines that aren't busy. It's already happening on the south end of the MML.

 

[Benjwri]

Perhaps over time virtually all headspans in the country, such as Paddington to Airport Junction, will be converted to portals. They are normally only used where the number of tracks is at least 3, so they are not much found on lines that aren't busy. It's already happening on the south end of the MML.

There are more conversions to portals planned for the OHLE, in the same way some already has been back when the rest of the line was wired. A fairly decent amount of money has already been spent on design.