Slab Track in the UK

[HSTEd]

Well Ive heard and read a lot about Slab track of various types, especially "Rheda 2000", and how it is widely used in Japan and to a far lesser degree in Germany.

Supposedly it allows drastically reduced maintenance with some lower speed layouts requiring now maintenance other than rail grinding for decades.

I am also aware of some ballastless track having been laid for testing on the Grantham-nottingham line with some of the bed still visible on some sections of the route, and that it is used in St Pancras station and the channel tunnel.

Has it ever been seriously considered for main line use in the UK (both in tunnels, on bridges and in the open) and what conclusion did the test sections I mentioned lead to with regards maintenance and track ride quality?

 

[swt_passenger]

Rheda 2000 is used in at least two places I know of for definite, Southampton and Hampstead tunnels. I'm fairly sure there are some stretches of the ELL that use it, just north of Whitechapel seems to ring a bell?

I'm sure there'll be many more examples of use on NR once a few more replies appear...

Southampton: http://www.lesmac.co.uk/pdf/case-study-southampton.pdf

 

[142094]

There are a few places on the Metro system up here that use it (and to my knowledge they have been in place since the system opened 31 years ago with no problems). Mainly found in some of the tunnels and also on the Ouseburn Viaduct.

 

[stockport1]

falkirk high tunnel and mersey rail?

 

[RichmondCommu]

There are also the remains of concrete slab track at Duffield on the long disused up slow.

 

[Hydro]

There's a fair bit of slab track around the place. Mainly in tunnels, but there's a section alongside Crewe LNWR on the Alsager line. The Glasgow sub tunnels are full of the stuff.

 

[90019]

I believe it's used in the Haymarket tunnels.

 

[HSTEd]

So it would appear it has been relatively widely deployed..... now for the big question, are the apparent drastic savings in maintenance illusory or actually demonstratable in britain? Because these projects mostly seem tobe in relation to increasing clearence in tunnels.

 

[stockport1]

So it would appear it has been relatively widely deployed..... now for the big question, are the apparent drastic savings in maintenance illusory or actually demonstratable in britain? Because these projects mostly seem tobe in relation to increasing clearence in tunnels.

The advantages in tunnels are that clearance is increased not only by the fact the track is lower but but the fact that the track wont wander like ballasted track will. Also it is less of a fire risk due to contamination.

The major drawback in tunnels is that water ingress can damage the concrete especially if no extra drainage is installed.

Also the interface between slab track and ballasted track can be a weak point due to the slab track not moving and ballasted track wandering.

Over time i would expect to start to see appear in all tunnels,viaducts ,stations and high residential areas where noise may be an issue?? (last point is debatable)

I do also wonder if HS2 will be slab track due to the 250mph top speed.

It is supposedly only around 20% more expensive than ballasted track to install but i believe it requires longer possession times.

 

[Pumbaa]

Also used in Macclesfield tunnel on the Cheadle Hulme - Colwich branch of the WCML.

 

[Wyvern]

There are also the remains of concrete slab track at Duffield on the long disused up slow.

This along with the stretch mentioned at Nottingham above were part of the investigation by the Research Division in the early seventies. THere are drivers on these forums who remember going over it.

An asphalt base was also considered at Nottingham.

It was patented by BR under the acronym PACT which still shows up in Google.

http://www.agrri.org.uk/BRR/Track.htm

 

[Hydro]

The major drawback in tunnels is that water ingress can damage the concrete especially if no extra drainage is installed.

Also the interface between slab track and ballasted track can be a weak point due to the slab track not moving and ballasted track wandering.

Over time i would expect to start to see appear in all tunnels,viaducts ,stations and high residential areas where noise may be an issue?? (last point is debatable)

Slab track is essentially low maintenance, precisely due to the point of being "fixed" rather than "floating" geometry. It can be quieter, especially when noise reducing fastenings that the likes of Pandrol and Vossloh produce. The advantage in tunnels is that once installed, it most certainly is *fixed* and will maintain the required clearances. It won't develop problems, mainly due to water contaminating ballast and creating voiding wet spots, that require the geometry to be potentially changed.

The interface between slab and ballasted track is no different to any other floating/fixed geometry interface; for example, longitudinal timbered bridges. If the lifting and lining is correctly run out on the approaches when tamping, it should not be much of a problem.

Disadvantages include installation cost. It is expensive, I couldn't tell you exactly how much, but if you've researched 20% that's still a not inconsiderable figure to pay on top of your renewal costs. The nature of ballasted track means that it's self draining if maintained correctly, slab track requires drainage concerns to be built into the design as water doesn't find it's own way to the catchpit.

It is low maintenance, but be prepared for an incredible headache if something does go wrong, because it WILL cost a lot and be very time consuming to fix. This shouldn't happen if installed correctly; however, I have seen with my own eyes moderate cyclic top on old slab track due to poor installation that just cannot be fixed without tearing out the concrete base (consideration was given to double padding the rail in the low points but over time this would damage and break the fastenings). As such, it had been left - it wasn't dangerous and won't get worse like ballasted track will over time but of course a geometry defect will induce more wear into the track. Water ingress onto slab track again should only be a problem if the concrete starts cracking (which it shouldn't do!)

On the Soton on the W10 project, only Soton tunnel itself was ever slab tracked, every other tunnel was traditionally lowered. Previously the tunnel was ballasted, and was notoriously wet in there - one cab ride I did I noticed water literally gushing down the walls at one point. This encouraged geometry defects to build up in the tunnel itself, and most notoriously, at the tunnel mouth at the Soton end.I worked in Maintenance down there, the tunnel mouth area was just full of wet beds, twist and top defects (and to top it off, was a red zone working prohibited area, so rarely could sit in there for a good days digging). The tunnel got slabbed, the S&C at the mouth relaid and it's as good as gold now.

 

[trentside]

I was watching a DVD of the Hastings to Tonbridge line yesterday, which mentioned that concrete slab track was apparently used to strengthen some of the tunnels along the route during electrification. Is this the case?

 

[Hydro]

http://www.agrri.org.uk/BRR/Track.htm

What a link, that BRR folder is full of great stuff. Some familiar names on the papers under "Condition Monitoring". Shame that the papers can't be read in full, though I suspect I've seen a lot of R Lewis' papers already, being quite familiar with his track geometry system.

Trentside: Certainly was used between Tonbridge and Redhill (Penshurst tunnel has it IIRC), so I can't see why it wasn't continued down to Hastings.

 

[Wyvern]

Ray Lewis was my boss earlier on.

 

[Hydro]

We've had a few lectures/presentations from him, a very clever man indeed. We still use the Serco-Lewis Digital Track Geometry System, a system that's only now being considered for replacement. Some say it's still better than the NMT's measurement kit (controversy there, good thing there are no NMTies here to attempt to shoot that down).

 

[Scotrail84]

I believe it's used in the Haymarket tunnels.

Only Haymarket South tunnel is slab track and it suffers from poor drainage several areas within the tunnel are constantly full of water, this is partly due the the fact the tunnel retains its open shaft about halfway through.

When Haymarket North tunnel was wired last year the old wooden sleepers and rails were replaced with new wooden sleepers and rails the north tunnel however does not have an open shaft (not sure if it ever had one) and does not suffer from poor drainage or flooding.

 

[90019]

Only Haymarket South tunnel is slab track and it suffers from poor drainage several areas within the tunnel are constantly full of water, this is partly due the the fact the tunnel retains its open shaft about halfway through.

Fair enough, I thought it was both of them.

Actually, that's something that's been bugging me for a while.
Where is the shaft opening on the surface?
I wonder if it's this?

 

[Scotrail84]

Fair enough, I thought it was both of them.

Actually, that's something that's been bugging me for a while.
Where is the shaft opening on the surface?
I wonder if it's this?[/QUOTE]

I think it could be the shaft. That's the sub station beside the western approach road. I have wondered where it is also

 

[90019]

I think it could be the shaft. That's the sub station beside the western approach road. I have wondered where it is also

It's the only thing I can see on Google Maps that looks like it could be it, and it does look to be in about the right place.
Next time I'm up that way, I'll see if I can see anything.

 

[KBD1]

Fair enough, I thought it was both of them.

Actually, that's something that's been bugging me for a while.
Where is the shaft opening on the surface?
I wonder if it's this?

I think it could be the shaft. That's the sub station beside the western approach road. I have wondered where it is also[/QUOTE]

There was talk of putting in track slab in the North tunnel when they started to electrify between Waverley & Newbridge Jn. There were some clearance problems for the OHLE in the North tunnel, but found it cheaper to reprofile part of the tunnel masonry instead.

The google image is correct, the second is located behind the Police Station in Torphican St Lane.

No shafts in the North tunnel, but still gets wet when there is a burst main in the roads above, in which causes problems for the OHLE. Drip trays are fitted to the tunnel at parts, but usually the burst drains / water seepage are outwith these trays.

 

[90019]

The google image is correct, the second is located behind the Police Station in Torphican St Lane.

Do you mean Dewar Place Lane?

Is that the same tunnel or the other one?

 

[KBD1]

Water ingress used to be a major problem in Haymarket South tunnel, not just from the shafts themselves, they are now partially covered over, but from the defective pointing to masonry of the tunnel itself. Played havoc with the track circuits.
A few areas have been repaired over the years, but still gets wet, not as much though.
The North tunnel was certainly the driest.
--- old post above --- --- new post below ---

Do you mean Dewar Place Lane?

Is that the same tunnel or the other one?

Dewar Place is the road that passes the Scottish Power Sub Station, where one of the shafts is located, no public access obviously.
The image is in the the sub station.
I am sure there is only one lane between Torphican St & Dewar Place.
If you google map image, go slightly to the left / West, you may see it, it's not more than 250mtrs from there.
You can pass shaft cover, but most people wouldn't bat an eye lid as it now sort off blended in to the surroundings.

 

[HSTEd]

So, has there been any serious proposals to replace large amounts of existing track in the open on main lines with slab track?
It would seem the maintenance arguments are compelling, assuming quality control problems in the laying can be overcome, especially with the introduction of High Speed Grinding technology to the scene.

Doesn't this offer the possibility of a truly 24 hour railway?

 

[KBD1]

Do you mean Dewar Place Lane?

Is that the same tunnel or the other one?

Yep.
Just had a look myself, thought it was called Torphican St Lane
It's located between the sort of large white buildings at the East end of the lane, looking at google map.
Dewar Place Lane is the first shaft from Haymarket Station. Sub Station the second or vice versa from Waverley

 

[90019]

You can pass shaft cover, but most people wouldn't bat an eye lid as it now sort off blended in to the surroundings.

Yep.
Just had a look myself, thought it was called Torphican St Lane
It's located between the sort of large white buildings at the East end of the lane, looking at google map.

Is it at all obvious when you pass it?

 

[Wyvern]

So, has there been any serious proposals to replace large amounts of existing track in the open on main lines with slab track?
It would seem the maintenance arguments are compelling, assuming quality control problems in the laying can be overcome, especially with the introduction of High Speed Grinding technology to the scene.

Doesn't this offer the possibility of a truly 24 hour railway?

Two problems I can think of are the length of possession required to install it and being really sure that the substrate is stable. Any problems that might occur with the concrete slab would be in no way as easy to fix as with conventional ballast.

 

[swt_passenger]

So, has there been any serious proposals to replace large amounts of existing track in the open on main lines with slab track?

From the points raised I'd suggest there hasn't. The installation costs are too high for general use, despite the longevity - so it will only be seen where there are other imperatives such as gauge clearance or noise reduction.

 

[Old Timer]

Building a slab track is more expensive than building traditional ballasted track, which has slowed its introduction outside of high-speed rail lines.

There are also a number of disbenefits which can affect the decision as to whether to install or not.

Slab track layouts are not easy to modify after they are installed, and the curing time of the concrete makes it difficult to convert an existing, busy railway line to ballastless track – one only has to look at the time it took on the Manchester lines at Crewe.

Slab track can also be significantly louder and cause more vibration than traditional ballasted track. While this is in some part attributable to slab track's decreased sound absorption qualities, a more significant factor is that slab track typically uses softer rail fasteners to provide vertical compliance similar to ballasted track; these can lead to more noise, as they permit the rail to vibrate over a greater length.

Issues have also been experienced when the fastenings have been incorrectly torqued leading to a failure of the fitting bolts. In one case these had to be removed by the use of liquid oxygen which broke down the retaining resin.

Where it is critical to reduce noise and vibration, such as in Urban areas, the concrete slab can be supported upon soft resilient bearings. This configuration is called "floating slab track" but is expensive and requires more depth or height. The benefit is that it can reduce noise and vibration by a significant amount.

Alternatively, the rail can be supported along its length by an elastic material; when combined with a smaller rail section, this can provide a significant noise reduction over traditional ballasted track, however this is not suitable for high speed or heavy haul lines where the trend is now to move to even larger rail size.

 

[Bald Rick]

So, has there been any serious proposals to replace large amounts of existing track in the open on main lines with slab track?
It would seem the maintenance arguments are compelling, assuming quality control problems in the laying can be overcome, especially with the introduction of High Speed Grinding technology to the scene.

Doesn't this offer the possibility of a truly 24 hour railway?

Considered - yes, considered seriously - no. It was looked at for West Coast Modernisation, but was quite a lot more expensive and VERY disruptive to install. It is also inflexible (if you pardon the pun) in that if what's underneath moves, it is pretty difficult to get the slab back in the right place.

The only track maintenance it actually eliminates is tamping - perhaps one possession a year, and it does offer reduced patrolling and inspections (gauging etc). However patrolling and other inspections will most likely to be automated in the coming years. In any event there is still other maintenance that requires possessions, eg overhead line.