Expansion joint near end of track

[Tom Burnham]

I'm curious as to what this expansion joint is doing alongside the platform at Marlow.  Are sleepers at expansion joint usually tied together like that?  There's a short section (about 20 sleepers) of flat bottom rail off to the left, and then a similar length of chaired bullhead rail with a rail-built buffer stop attached to it.  I believe quite a lot of the line between Marlow and Bourne End was relaid a year or so ago.

Thanks in anticipation!

[Wickham Green too]

Looks quite normal to me - the joint is 'within' the flat bottom rail so uses standard components ( including bullhead straps ) ..... using an expansion joint there avoids any tendency for the buffer stops to move !

[Peter Kazmierczak]

Yep, as Wickham Green correctly states, quite a common arrangement.

[Miss Prism]

Has the size of ballast bits got smaller in modern times?

[Trog]

Bog standard flat bottom adjustment switch, but in a position like that is a total waste of money as if the stops were just bolted or welded onto the end of the CWR all they would do is perhaps move in and out a bit as the CWR expanded and contracted.

 

Probably just somebody with little or no experience blindly following the standard that says to put an adjustment switch between flat bottom CWR and bull head jointed. Without thinking about why the standard asks for that, and why it is un-necessary where there is too little bull head track to allow a buckle especially as the free ends of the rails will allow for any expansive movement of the rails anyway. I would have just relaid up to two sleepers from the buffer stop joints in concrete sleepered CWR, installed two Pan11 hardwoods, then the FB/BH joint and BH buffer stop, that arrangement would have been just as good need less maintenance and saved a fortune.

 

The ballast looks to be the standard 50mm size normally used, although historically 28mm stone was used in dry tunnels where drainage of rain was not a problem as it is easier to work with. (Hence why 28mm ballast is sometimes called tunnel ballast).

 

About the only recent use of tunnel ballast I am aware of was some of the late 1990's relaying on the Euston - Watford DC line CWJ, as the genius of Railtrack ensured that there was no longer any tampers suitable for 3rd/4th rail electrified track available at the south end of the WCML so all maintenance had to be done by hand. By the year 2000 or so supplying nonstandard sized ballast became too difficult for the supply side, so the poor old trackmen have since just had to lump un-nessessary shovelling of the 50mm ballast.

[Tom Burnham]

Thanks, all!

[Fat Controller]

On the spur between Burrow's Sidings and the former  Fort plant at Danygraig, Swansea, there were two of these joints on the same siding, within 10 paces of one another.

[bécasse]

6 hours ago, Trog said:

I would have just relaid up to two sleepers from the buffer stop joints in concrete sleepered CWR, installed two Pan11 hardwoods, then the FB/BH joint and BH buffer stop, that arrangement would have been just as good need less maintenance and saved a fortune.

At least they saved some money by not gold plating the rail .......

[St. Simon]

10 hours ago, Miss Prism said:

Has the size of ballast bits got smaller in modern times?

Hi.

 

Modern Ballast (or at least it was when I did my P-Way training 8 years ago) is between 25 & 50mm is the preferred size.

 

Simon

[Trog]

17 hours ago, bécasse said:

At least they saved some money by not gold plating the rail .......

Give them time and they will.

[Mike_Walker]

Almost all of the Marlow branch was relaid in November 2019 from a point just before Donkey LC leaving Bourne End through to Marlow.  Most of it is CWR on steel sleepers but there is a short section on concrete at Bourne End and at Marlow plus as mentioned, a short section of BH under the stop block at Marlow.  One of our MDRS members asked the question why at the time but I can't remember the answer now.

 

This past week (half term) the branch was closed to permit relaying from just south of Cookham almost to the river bridge at Bourne End.  Again this is CWR with concrete sleepers as far as approximately the summit between Cookham and Bourne End then steel.  I did ask the question and was informed that the choice is dependant on the stability of the ground structure below the railway.

 

This now means that then entire branch from Maidenhead has been relaid apart from across the river and the Bourne End station area.  The latter may be connected to the long held plans by GWR to remodel the junction to permit trains to pass there but that seems to have gone quiet since the pandemic struck.

[Trog]

The choice between steel and concrete sleepers is like most things in life money driven.

 

If the ballast under the existing track is half way decent and the track radii are not too tight it is cheaper to relay using steel sleepers. As these are only ~1/4" thick and hence rest on top of what was the top ballast so after scarifying the existing top ballast you get about 5" of extra halfway decent new bottom ballast for free, as you do not have to reballast which more than covers the fact that steel sleepers cost more than concrete.

 

If the radii are tight or the existing ballast is in technical terms heavily contaminated with clay sh*t, it will b necessary to reballast the track in which case it is cheaper once you have your bed of new ballast to lay the sleepers on to use concrete sleepers. In the case of tight radii the extra weight of the concretes also helps resist buckling forces in hot weather.

 

On very tight curves the use of CWR is banned, but you could until a few years ago reduce the risk of 60'-0" rails on a tight curve threpenny bitting as the rails straightened, by using 120'-0" rails balancing the extra buckling forces off by increasing the concrete sleeper numbers per length, perhaps using LREPs and the CWR ballast profile on jointed track. However the use of LWR (rails over 60'-0" but not CWR) was banned due to buckles where rail often BH on poor condition softwood sleepers had been welded up into lengths over 60'-0" but no additional precautions had been taken. So once again idiots + H&S = annoyed experienced staff.

Edited October 31, 2022 by Trog
Must learn to spell.

[Ncarter2]

On 30/10/2022 at 14:56, Trog said:

Bog standard flat bottom adjustment switch, but in a position like that is a total waste of money as if the stops were just bolted or welded onto the end of the CWR all they would do is perhaps move in and out a bit as the CWR expanded and contracted.

 

Probably just somebody with little or no experience blindly following the standard that says to put an adjustment switch between flat bottom CWR and bull head jointed. Without thinking about why the standard asks for that, and why it is un-necessary where there is too little bull head track to allow a buckle especially as the free ends of the rails will allow for any expansive movement of the rails anyway. I would have just relaid up to two sleepers from the buffer stop joints in concrete sleepered CWR, installed two Pan11 hardwoods, then the FB/BH joint and BH buffer stop, that arrangement would have been just as good need less maintenance and saved a fortune.

 

The ballast looks to be the standard 50mm size normally used, although historically 28mm stone was used in dry tunnels where drainage of rain was not a problem as it is easier to work with. (Hence why 28mm ballast is sometimes called tunnel ballast).

 

About the only recent use of tunnel ballast I am aware of was some of the late 1990's relaying on the Euston - Watford DC line CWJ, as the genius of Railtrack ensured that there was no longer any tampers suitable for 3rd/4th rail electrified track available at the south end of the WCML so all maintenance had to be done by hand. By the year 2000 or so supplying nonstandard sized ballast became too difficult for the supply side, so the poor old trackmen have since just had to lump un-nessessary shovelling of the 50mm ballast.

Agreed, complete waste of money, however we do ourselves no favours. As we live in a blame culture and common sense does no longer exist, it is hardly a surprise these situations arise. The fact renewals are largely completed by contractors, who will deliver what is set out with no concept of constructive discussion is now a fact of how things work. If that means a renewal adjoins another, but the spec set out inadvertently leaves a gap of say 5 sleepers, you can bet those delivering will leave those 5 sleepers. Again, interpretations on mileage will factor. Gone and forgotten are the days where engineers could be engineers and make decisions. 

[Ncarter2]

On 31/10/2022 at 18:53, Trog said:

 

On very tight curves the use of CWR is banned, but you could until a few years ago reduce the risk of 60'-0" rails on a tight curve threpenny bitting as the rails straightened, by using 120'-0" rails balancing the extra buckling forces off by increasing the concrete sleeper numbers per length, perhaps using LREPs and the CWR ballast profile on jointed track. However the use of LWR (rails over 60'-0" but not CWR) was banned due to buckles where rail often BH on poor condition softwood sleepers had been welded up into lengths over 60'-0" but no additional precautions had been taken. So once again idiots + H&S = annoyed experienced staff.

The problem with 120’s is you struggle to get adequate JCT’s and given the rails are experiencing hot and sustained periods of heat, it still results in problems and speed restrictions. Even with good sleepers, more per length and LERP’s, if the expansion isn’t there, the rail will eventually go. 

[kevinlms]

1 hour ago, Ncarter2 said:

Agreed, complete waste of money, however we do ourselves no favours. As we live in a blame culture and common sense does no longer exist, it is hardly a surprise these situations arise. The fact renewals are largely completed by contractors, who will deliver what is set out with no concept of constructive discussion is now a fact of how things work. If that means a renewal adjoins another, but the spec set out inadvertently leaves a gap of say 5 sleepers, you can bet those delivering will leave those 5 sleepers. Again, interpretations on mileage will factor. Gone and forgotten are the days where engineers could be engineers and make decisions. 

Fact is, if a contractor DOESN'T build to spec, then there is a high risk that they won't get paid! Or at the least will need to argue their case.

[Ncarter2]

31 minutes ago, kevinlms said:

Fact is, if a contractor DOESN'T build to spec, then there is a high risk that they won't get paid! Or at the least will need to argue their case.

Not disagreeing, but the common sense element has gone. During the WCRM there were several sensible decisions made for the greater good. We don’t even entertain that now. Once a spec is issued, that’s it. Want to amend or change, cancel the work and start from scratch. Part of the issue is skill fade and the inability to pick things up and make engineering based recommendations. 

[Trog]

3 hours ago, Ncarter2 said:

Agreed, complete waste of money, however we do ourselves no favours. As we live in a blame culture and common sense does no longer exist, it is hardly a surprise these situations arise. The fact renewals are largely completed by contractors, who will deliver what is set out with no concept of constructive discussion is now a fact of how things work. If that means a renewal adjoins another, but the spec set out inadvertently leaves a gap of say 5 sleepers, you can bet those delivering will leave those 5 sleepers. Again, interpretations on mileage will factor. Gone and forgotten are the days where engineers could be engineers and make decisions. 

 

I had specified a track relaying job through a platform with catch pits and stated that short ended concrete sleepers were to be used to fit the track round them. As I thought the practice of using timber sleepers that cost more, lasted half as long and were an un-necessary discontinuity in the track was a bad idea. {3" and 6" short ended concrete sleepers having been a standard catalogue item in BR* days.}  *(Before Railtrack)

 

The contractors came back stating that short ended sleepers were no longer available, so I double checked with the manufacturers engineer that it was still OK with the newer designs of sleeper, and told the contractor to get a diamond cutting saw and chop three or four inches off some normal ones then.

 

The reply was that I would not be able to find anyone from Railtrack willing to sign that off so they would have to use timber. The look on their faces when I asked for a pen and paper and wrote them an instruction to do it on the spot. 

[Trog]

3 hours ago, Ncarter2 said:

Agreed, complete waste of money, however we do ourselves no favours. As we live in a blame culture and common sense does no longer exist, it is hardly a surprise these situations arise. The fact renewals are largely completed by contractors, who will deliver what is set out with no concept of constructive discussion is now a fact of how things work. If that means a renewal adjoins another, but the spec set out inadvertently leaves a gap of say 5 sleepers, you can bet those delivering will leave those 5 sleepers. Again, interpretations on mileage will factor. Gone and forgotten are the days where engineers could be engineers and make decisions. 

 

Back in the early days of Railtrack I worked for a contractor and Railtrack HQ in their wisdom moved us off our traditional patch and gave us a contract elsewhere, it was evident that the local Railtrack engineers did not want us there. Partly because we had displaced their mates and partly because we put in loads of variation requests as their specifications for the work were dreadful. They eventually got so fed up with us that they decreed that we should just do what the specification said and that they would not be issuing any more variations so don't bother asking.

 

A couple of weeks later I am given a specification asking for new concrete CWR plain line to be installed from A miles XX yrds to A miles XXXX yrds. Fair enough you might think except for the fact that this mileage included a double junction. A variation having been refused it was so tempting to just gas axe the lead and diamond and lay in the requested plain line. But I thought Trog someone has to be the adult here, and I also thought that regardless of the stupid orders it would probably still be me that got fired when the s**t hit the fan on the following Monday morning.

 

So I did the sensible thing and curtailed the relaying job at the crossing joint of the lead. As the S&C was bullhead I also finished the relaying with a 30' - 0" length of new bullhead on hardwood sleepers. As you must not change the sleeper material within two sleepers of a joint, and the crossing joint was also an IBJ. Taking the flatbottom right up to the crossing joint and just managing the sleeper transition with a couple of flatbottom pan11 baseplated hardwoods would have been slightly nearer the letter of the specification. If that mattered much compared with me cutting 150 odd yards off the length of the job. But would have gifted the local maintainer with two pairs of worn bullhead to new flat bottom lift and junction insulated plates. A potential nightmare for the maintainer as finding a pair of them when they inevitably decide to break on a snowy February night would not be fun.

 

Sure enough a couple of weeks later one of the Railtrack Engineers was complaining about the unauthorised changes to the specification and also wanting to know why I had done some of the relaying in timber sleepered bullhead, when my betters had specified flatbottom concrete.