Track/ride quality

[stuu]

I was in Milan last week and travelled on the Malpensa Express to the airport. The ride was exceptionally good most of the way, there were times where if you had closed your eyes you wouldn't have been able to tell you were moving. Even my wife noticed and she has never shown the slightest interest in anything to do with trains.

This was on the Milan suburban network with normal ballasted track - what do they do differently to make it so much smoother? Is it just frequency of maintenance?

 

[D6130]

As someone who has travelled extensively by rail in Europe over the past forty years or more, it has always struck me how much better the ride is generally on most Western European railways, compared with equivalent British lines....even in pre-privatisation days. OK, so our lines are much more intensively trafficked than say cross-country long disatance lines in France and Spain, But most German, Dutch, Belgian, Swiss, Austrian and Italian lines operate at close to - or even above - British traffic frequency levels. Apologies to any current or former British permanent way engineers on here, but I've always had the impression that the former Southern Region lines had/have the worst ride quality. Whether this is because of the wet clay subsoil in the Thames basin causing drainage difficulties, or the hammering that the track suffered for years by old EMUs with heavy axle-slung traction motors, I am not certain, but I have heard anecdotally that the lateral motion of the bogies on the Desiro units is causing problems on the South Western main lines. I also remember the Southern section of the WCML having an appalling ride back in the late 70s/early 80s with mile after mile of deep wet patches and numerous temporary speed restrictions as a result. Perhaps the quality of the ballast used also has some bearing on the ride quality....I recall that some of the best-riding track that I have experienced in Britain being on those sections of the former Scottish Region which were/are ballasted with the distinctive red granite from Cloburn Quarry near Carstairs. I think, when it comes down to it, most Western European countries invest far more money into their railways than we do and as a result, their budgets for track and ballast renewal and maintenance are much higher, enabling renewals and tamping, etc. to take place much more frequently. That has certainly been my experience in Italy, where heavily-used main lines seem to have their permanent way renewed at least every ten years....and sometimes more frequently than that.

 

[Annetts key]

Please note that I’m not an expert on the permanent way. But I do know that the ride quality does depend on the following all being good:

• The underlying track formation, including the membranes that are used to keep the underlying soil from being pushed up into the ballast formation. This also includes embankments.
• The ballast being in good condition. Granite is very hardwearing but more expensive than the limestone from the West county quarries that is often used.
• Proper drainage, including good maintenance of drains, culverts and cess ditches is also essential.
• Renewal of pads, biscuits (rail/sleeper insulations) and fixings (clips) before they get too badly worn and then the concrete sleeper starts getting damaged.
• Keeping the ballast well packed under the sleepers. Especially at and near rail joints.
• Prompt repairs to rails before they become damaged (be it weld repairs, grinding, replacement).

Unfortunately doing it ‘right’ costs lots of money. So everything gets risk assessed. If it’s not a safety issue, the remedial work often gets deferred. So often the problem grows…

For example, if the drainage is poor, and the ballast is not kept packed under concrete sleepers, soon, the motion of trains passing will cause the sleepers to repeatedly hammer the ballast. Then limestone ballast will turn gradually to mud. Which causes even more drainage problems. That in turn causes more track and sleeper movement. So the length of the ‘wet beds’ grows and grows.

And if the track is bouncing, it can also result in fixings, bolts, nuts etc. working loose. Sometimes it gets so bad that signalling equipment (axle counter heads, treadles, point equipment) can literally fall off the rails…

I’m sure a permanent way member will be along soon to correct me, and/or expand on what I have written.

 

[Bald Rick]

One thing to remember is that a fair bit of the Malpensa express is relatively new railway, opened in 1999, and some in 2016. Track quality on new railways here is usually very good too.

The broader point is valid though. I think it is simply because the track engineers on the continent accept lower tolerances for alignment defects. On some lines they also have lower axle load limits.

comparisons on high speed lines are less variant though - I find the French LGV network to be rather more lively than HS1 for example.

 

[D6130]

comparisons on high speed lines are less variant though - I find the French LGV network to be rather more lively than HS1 for example.

Especially the LGV Nord Europe between Calais and Lille, which passes through some fairly marshy countryside. There are some seriously scary bumps - especially on the 'voie pair' (up line towards Paris) - just on the Lille side of Quilleval crossovers, where the line crosses the canal, river and Lille-Calais classic line in quick succession. It's also a wee bit lumpy in places between Lille and TGV Haute Picardie....caused by the presence of former coal mines nearer to Lille and also by uncharted WW1 trenches, the collapse of one of which caused the Eurostar derailment at Croisilles, near Arras, in June 2000. Generally though, I find the ride on most French, Belgian, German and Italian high speed lines to be exemplary.

 

[satisnek]

I can recall travelling on an Intercity cross-country service all the way from Birmingham to Folkestone back in the 1990s, and noticing how the ride quality got much worse once on Southern Region metals. Back then of course the track was being beaten up by all the old slammers with axle-hung motors. I don't know how different it is today.

 

[thirdraildrive]

Worth noting a lot of their trains seem to have a lot more suspension equipment too; additional yaw dampers etc. Most of the smooth ride certainly is a well maintained track but the suspension overkill probably highly contributes. I'm sure if I ran my networker down the same strech it'll be a bit bumpy still

 

[Irascible]

Please note that I’m not an expert on the permanent way. But I do know that the ride quality does depend on the following all being good:

• The underlying track formation, including the membranes that are used to keep the underlying soil from being pushed up into the ballast formation. This also includes embankments.

I wonder how much of our network is particularily bad in that respect, given the basic infrastructure was often done a) in a hurry, b) on the cheap, and c) by people who'd only really done canals before. Although there's much later sections ( looking at you, bits of the B&H ) which have been pretty awful for ride over the years, so c) isn't much of an explanation...

 

[Annetts key]

For embankments, often the railway used whatever material was available. So if there were cuttings or tunnels needed on the same line, or nearby, the spoil from these was used to form embankments.

Some embankments apparently ended up with ash and coke mixed in…

Relaying of track can range from the simple provision of new rail only, new sleepers and new rail, new ballast laid on top of the existing, then compacted by using ‘tamper’ on track machines, ‘ballast cleaning’ where a on track machine removes the top layer (all ballast from the top of the sleepers to about one foot below the base of the sleeper) and then fresh ballast is laid down and ‘tamped’, and finally, all the track and ballast is removed and everything including the membrane is replaced.

Although the ignorant politicians like to harp on about our Victorian railway infrastructure, apart from maybe sidings and infrequently used branch lines, all the rails and sleepers are far more modern, as will be the top layer of ballast at least. Rail on main lines often does not last longer than 30 to 40 years for example.

British Rail in my area in the 1980s to 1990s had an extensive and continuous programme of track renewals for example, with at least several miles worth of ballast cleaning and retailing taking place across the area.

But to do this kind of work, generally you need the relevant section of line closed all weekend.

 

[Bald Rick]

Relaying of track can range from the simple provision of new rail only, new sleepers and new rail, new ballast laid on top of the existing, then compacted by using ‘tamper’ on track machines, ‘ballast cleaning’ where a on track machine removes the top layer (all ballast from the top of the sleepers to about one foot below the base of the sleeper) and then fresh ballast is laid down and ‘tamped’, and finally, all the track and ballast is removed and everything including the membrane is replaced.

Although the ignorant politicians like to harp on about our Victorian railway infrastructure, apart from maybe sidings and infrequently used branch lines, all the rails and sleepers are far more modern, as will be the top layer of ballast at least. Rail on main lines often does not last longer than 30 to 40 years for example.

British Rail in my area in the 1980s to 1990s had an extensive and continuous programme of track renewals for example, with at least several miles worth of ballast cleaning and retailing taking place across the area.

But to do this kind of work, generally you need the relevant section of line closed all weekend.

There’s quite a lot more to track renewals than that.

Tampers don’t ‘compact’ the ballast, they effectively reposition track (the sleepers and rails) by moving ballast around. The only things that compact ballast are 1) ‘Wacker’ vibrating plates, 2) the Dynamic Track Stabiliser (DTS) and 3) passing trains.

The ‘top’ ballast is that which is above the bottom of the sleepers. The ‘bottom’ ballast is that which is below the bottom of the sleepers. There is usually 300mm of bottom ballast (more on high speed lines), and beneath that is often , but not always, a geo textile membrane or 100mm of sand. And beneath that, in places is drainage.

To replace the full track system (rail, sleepers, ballast) you do not need to close the line all weekend. A majority of such work is done overnight with high output plant, or in possessions of around 27-30 hours, usually on Sundays. Some is done in longer weekend possessions of 51-54 hours, and this is the most efficient way of doing the work from a pure construction cost. But, obviously, it disrupts passengers on Saturdays, and on most routes there’s around twice as many passengers on Saturdays as on Sundays.

 

[Annetts key]

Some relevant videos on You Tube

(describes tamping)

(describes tamping in even more detail)

My comment relating to it takes all weekend was intended to make the point that it’s not something that can generally be done on a midweek night. Typically in my area, services end early on Saturday evening/night and can’t start again until Sunday late afternoon/evening/night. The exact times depending on how much work is taking place.

 

[Bald Rick]

My comment relating to it takes all weekend was intended to make the point that it’s not something that can generally be done on a midweek night.

If done conventionally, it tends not to be done mid week nights, although it has been done.

However the High Output plant was specifically bought for midweek work, and is usually deployed then. But typically ballast and track is done on separate visits.

 

[mcmad]

If done conventionally, it tends not to be done mid week nights, although it has been done.

However the High Output plant was specifically bought for midweek work, and is usually deployed then. But typically ballast and track is done on separate visits.

Even High Output kit need a decent overnight white period, due to the time to set up and dismantle the machine each night. Using it the way Network Rail do is not how the continent use it and even the NR teams themselves admit that the kit performs far more reliably when used in long disruptive possessions at the weekend rather than doing half an hours actual work a night.

 

[warwickshire]

Try riding Leamington Spa to Banbury both directions on the up and down around Fenny Compton Junction area.
Notably on the Chiltern units when riding them the track ride quality is like a hard bump to the side and quite a hard one. Especially at Clattercote crossing on the up.
And on the down on the bend just after Fenny Compton and around Bishops Itchington. Track quality around there is a real something.

 

[contrex]

especially on the 'voie pair' (up line towards Paris)

La voie paire, un train pair.

 

[stuu]

Thanks for the detailed replies

One thing to remember is that a fair bit of the Malpensa express is relatively new railway, opened in 1999, and some in 2016. Track quality on new railways here is usually very good too.

Actually the best bit was the oldest segment out of the city, which is ~150 years old, although obviously heavily rebuilt at least twice.

 

[Ploughman]

lt helps if tamper crews use the onboard computer systems to get the best out of the systems and not just to record another basic maintenance tamp.

 

[melon68]

Try riding Leamington Spa to Banbury both directions on the up and down around Fenny Compton Junction area.
Notably on the Chiltern units when riding them the track ride quality is like a hard bump to the side and quite a hard one. Especially at Clattercote crossing on the up.
And on the down on the bend just after Fenny Compton and around Bishops Itchington. Track quality around there is a real something.

I recall back in the early 80s lots of temporary speed restrictions of around 50-60mph on that stretch, which were due to exactly that, terrible condition of the track... I last travelled down to Oxford around 1997 and the Mark 2 rolling stock was still bumping around quite a bit at anything above about 70mph

 

[td97]

Network Rail have a database of track quality recordings, which are standard deviation results from the New Measurement Train. The data is broken down into ⅛th mile (200m) increments for virtually every line in the country.
Even better, the database contains all the historical readings, well in excess of 20 years, so it's possible to detect trends of gradually decreasing track quality followed by remediation work, or consistently poor quality, etc.
So in short, Network Rail are fully aware of every single area of poor track quality across the UK network, down to a 200m section.

 

[Bald Rick]

So in short, Network Rail are fully aware of every single area of poor track quality across the UK network, down to a 200m section.

subject to measurement train frequency on any given section.

The Down Fast of the MML in the old favourite section from Hendon to Elstree has gone ’off’ in a matter of days.

 

[GS250]

Guess it also depends on the state of the rolling stock too. I had some real mixed journeys on the last few years of the HST's on the ECML. Most were pretty smooth and definitely less bumpy than an Azuma. However a couple were pretty lively to say the least. Hunting both sideways and back and forth.

 

[alistairlees]

Redhill to Tonbridge can be particularly exciting, especially from the redhill end to about Penshurst.

 

[DoubleO]

lt helps if tamper crews use the onboard computer systems to get the best out of the systems and not just to record another basic maintenance tamp.

Tamper crews don't make that decision. They work to the instruction of the NR engineer in charge on the shift. Track quality should indeed be better if the track is measured in advance and specific design values are entered, however this involves more shifts and probably more possessions for the tech staff to undertake the measurements. The software used to smooth track automatically can still achieve very good SD values.