Mixed-Gauge Sleepers on the Tarka Line?

[DLT]

Stopped at Portsmouth Arms on the Exeter to Barnstaple "Tarka" line on Sunday, to admire the smart new track with steel sleepers.

 

 

 

Attention was drawn to an apparent extra set of fastenings on a line of sleepers.

Closer photographs seemed to show that these sleepers belong/belonged to a mixed gauge line, with the narrow gauge at approximately metre-gauge.

 

 

 

 

Have I got this completely wrong?  

Are they secondhand from Europe?  Or is the Tarka line being converted to narrow gauge ? ? ? 

A question for the Good Captain perhaps...

 

Tahnks, Dave.

 

 

[PatB]

There's a distinct air of West Australian mixed 3'6" and standard gauge about those, although why anyone would ship heavy, low value things like sleepers halfway round the world defeats me.

[Dunsignalling]

My guess is that they may be a dual purpose product as much as a dual gauge one and the maker may have supplied them either to clear surplus stock or top-up an order for which he didn't have enough purely SG ones on hand for immediate delivery.

 

John

[rockershovel]

Truly a "prototype for everything"!

[Nearholmer]

A quick look at Tata steel europe's steel sleeper brochure confirms that they make and supply pretty much every conceivable variant, so maybe, as was said above, they made-up a shortfall with the next nearest.

 

But, why all together in the track? They aren't to take a load-spreader beam of some sort, are they?

 

K

[BG John]

Or is the Tarka line being converted to narrow gauge ? ? ?

The line has been narrow gauge since 1877, when the LSWR got their hands on it and banished the broad gauge .

[RFS]

In some areas on the Southern Region 3rd-rail system, an extra rail is added to assist with current return.  Perhaps these sleepers are to that spec and have simply been used as they were surplus.  See here -

 

http://railphotoprints.uk/p775480951/h59712d8b#h59712d8b

[Trog]

Or it could just be so an extra rail can be added to stiffen the track on a tight curve to reduce the risk of buckling.

[DLT]

My guess is that they may be a dual purpose product as much as a dual gauge one and the maker may have supplied them either to clear surplus stock or top-up an order for which he didn't have enough purely SG ones on hand for immediate delivery.

John

 

That sounds like a plausible explanation John

 

A quick look at Tata steel europe's steel sleeper brochure confirms that they make and supply pretty much every conceivable variant, so maybe, as was said above, they made-up a shortfall with the next nearest.

But, why all together in the track? They aren't to take a load-spreader beam of some sort, are they?   K

 

My guess is that sleepers would be supplied in a pack of however-many, so when delivered to site you would find a number similar ones together, rather than randomly distributed.

 

I've no idea what the track looks like elsewhere though.

 

Many thanks for your thoughts,

Dave.

[Oldddudders]

Or it could just be so an extra rail can be added to stiffen the track on a tight curve to reduce the risk of buckling.

 

No. It was common in that area, although more so on the oddly-named Mid-Kent line - which only went to Hayes, Addiscombe and Sanderstead. The area around New Beckenham and Clock House was best known for it - as well as being famous in them thar days for flooding, with water above the juice rail, at which point operations by electricity stopped. Evidently earth return was iffy even on dry days. 

[Edwin_m]

In some areas on the Southern Region 3rd-rail system, an extra rail is added to assist with current return.  Perhaps these sleepers are to that spec and have simply been used as they were surplus.  See here -

 

http://railphotoprints.uk/p775480951/h59712d8b#h59712d8b

Steel sleepers aren't allowed on third rail lines.

[Trog]

Also used for a single guard rail, or dual guard rails if you put alternate sleepers the other way round.

[Trog]

In some areas on the Southern Region 3rd-rail system, an extra rail is added to assist with current return.  Perhaps these sleepers are to that spec and have simply been used as they were surplus.  See here -

 

http://railphotoprints.uk/p775480951/h59712d8b#h59712d8b

You could do that with old running rail and I have seen it done, but conductor rail as shown in your picture would be better as the steel is optimised for electrical conduction over strength and wear. Which is why it cripples so easily and hence needs careful handling.

[Zomboid]

Where I've seen an additional rail in the 3rd rail negative it's been con rail. Aside from Euston-Watford north of Harrow (where it was previously used for tube trains) it's been on single track sections. Multiple tracks have loads of running rails in parallel anyhow, so the improvement is less marked.

[Trog]

There is or was scrap 113A CWR ex Kilsby Tunnel laid in the 4' north of Carpenders Park on the DC for traction return. It has been there since the 1980's when the Electrical Engineers objected to the P-Way scrapping the disused Neggie Rail.

[Zomboid]

That system would have depended on the rail being there when it was designed, I can imagine the problems removing it would cause.

[Derekstuart]

Although shortened by the telephoto effect, you can clearly see rail twist due to the reducing cant of the left curve and increasing cant of the right curve in the background. It might be that the twist is just at the limit allowed by NR and this is, as others have said, an additional means of keeping the track in place- that would explain why it is only on the curves, but since the spaces haven't been populated by anything it does seem a little odd.

 

Or as Trog wrote (and I think most likely) mountings for a guide rail to stop the train going down the embankment in event of a de-railment into what looks like (from the colour) soft or marshy ground. Again un-populated it isn't going to do much good.

[DLT]

Some photos of this track being laid, on the Cornwall Railway Society Blog, at the bottom of this page:  http://www.cornwallrailwaysociety.org.uk/headlines---latest-reports-and-photographs/previous/39

No explanation about the sleepers though.

Cheers, Dave.

[Mike Bellamy]

DLT, on 29 Sept 2016 - 12:30, said:

 

No explanation about the sleepers though.

 

 

 

Yes there is - did you miss the comment below the photo in the post made 11/11/15 

 

 

These are re-cycled sleepers from the massive Hayle Viaduct refurbishment of a year ago.  Note the additional clip positions for the guard rails.

 

.

 

[dp123]

Although shortened by the telephoto effect, you can clearly see rail twist due to the reducing cant of the left curve and increasing cant of the right curve in the background. It might be that the twist is just at the limit allowed by NR and this is, as others have said, an additional means of keeping the track in place- that would explain why it is only on the curves, but since the spaces haven't been populated by anything it does seem a little odd.

 

Or as Trog wrote (and I think most likely) mountings for a guide rail to stop the train going down the embankment in event of a de-railment into what looks like (from the colour) soft or marshy ground. Again un-populated it isn't going to do much good.

 

 

The curve transitions shouldn't even approach the maximum allowable twist limit (strictly twist is a defect, defined as a change in cross level as measured over 3 metres - the rate of change of cant into, out of and between curves is always gradual enough that it would be outside the parameters to classify as a defect and as such the twisting of the track to gain or lose cant is simply curve geometry rather than twist), - if curve movement is an issue due to tightness of radius, LRPs (Lateral Resistance Plates) would be installed rather than a strengthening rail (which would be akin to the strap rails on breather panels).

[Trog]

That system would have depended on the rail being there when it was designed, I can imagine the problems removing it would cause.

 

As it took the Electrical folk about fifteen years to get round to bonding the extra rails to the traction return rail, presumably rather insignificant problems. They only did it then because I asked if they needed it or could I scrap it to do some relaying, they assured me that it was vital. To which I expressed surprise pointing out that it had never been bonded into the return circuit, the bonds went on almost overnight.

[Zomboid]

The kind of problems that you don't notice immediately, as the trains will get through ok. The resistance is important for the short circuit current, if the resistance is higher than expected, then the current is lower than expected, and you can't be sure that the DC circuit breakers will trip when they're needed.

You can tell how important that is by how quickly it was fixed when the problem was identified.

[Nearholmer]

World of the strange! I think I might have been the very 'electrical folk' that Trog refers to. I moved jobs from SR to a role where I had a view of how electrical safety was being (not) looked after on the Watford DC lines ....... The condition of the bonding and the way circuit breaker settings were being dealt with made my hair stand on end. There was even an incident of a short circuiting device burning to a blob, and the breakers staying firmly closed.

 

K

[Trog]

World of the strange! I think I might have been the very 'electrical folk' that Trog refers to.

K

 

Its a small railway.

 

I remember a story of a train driver putting down an isolating bar, before fishing a bike out from under his train. When he came back for the bar it had melted, I wonder if that is the incident you are thinking of?

[Nearholmer]

Indeed it is.

 

I don't recall what exactly led to it, but it was definitely a driver putting down an SCD, which evaporated. We discovered that a person who shall remain nameless had thoroughly misunderstood how the DC breaker setting arrangement worked, and had issued an instruction as to how to set them up, which rendered them ineffective. Also found the plan to get rid of fourth rail, without understanding the implications, and some con rail and bonding in such poor condition that it limited current flow below breaker settings - the CR in Kilburn tunnel was so corroded that you could see in one side of it, and oh the other.

 

Probably c1987, because I only stayed in that job for a couple of years, before moving underground.

 

K