Labels on sleepers: what do they mean?

[Jim Martin]

I was waiting for a train at Merseyrail's Waterloo Station this morning  when I noticed a number of labels fixed to the sleepers on the Liverpool-bound platform.  Can anyone explain what these mean, please?

 

The first labelled sleeper looks like this:

 

 

successive sleepers are labelled as follows (number of sleepers is the number from the previous label):

7 sleepers: "10"

3 sleepers: "00"

5 sleepers: "05"

8 sleepers: this...

 

Then at intervals of 7 or (usually) 8 sleepers, they are labelled 05, 10, 15, 20 etc. up to 45, then another 7 sleepers, then this...

 

and that's the last one.

 

if these are relevant: the direction of travel is from left to right in all the photos; there's a signal at the platform end (15-20m beyond the last labelled sleeper); and immediately beyond that is a curve severe enough to have a lubricator installed. 

 

Jim

[St. Simon]

Hi,

 

The outer labels are the applied Cant to the track (i.e., what height the rail next to the label is at)

 

The centre labels identify the curve in the track, so R = Radius and I think the TL = Transition Length between two constant radius curves (at least I assume that what it means based on my limited P-Way design knowledge!)

 

They are installed to help maintenance with maintaining the curvature / cant as well as just for info. I think it is a relatively new thing done when track is installed / renewed. No need for them on straight track as you just maintain it straight and level.

 

Simon

[Jim Martin]

Hi Simon

That's really interesting,  so all this means that there's a curve of 2330m radius, then a transition of 15m, then another of 50m (there's a funny little kink in the platform, so maybe that's why there are two successive transitions?)  then a curve of 660m radius?

 

I assume that the numbers on the labels are heights in mm?

 

Jim

[Jeremy Cumberland]

3 minutes ago, Jim Martin said:

Hi Simon

That's really interesting,  so all this means that there's a curve of 2330m radius, then a transition of 15m, then another of 50m (there's a funny little kink in the platform, so maybe that's why there are two successive transitions?)  then a curve of 660m radius?

 

I assume that the numbers on the labels are heights in mm?

 

Jim

 

The two curves are in opposite directions. To the left of your first sleeper is a constant radius right hand curve of 2300 metres radius, with a 15 metre long transition. The constant radius curve has a 15 mm cant, and this reduces over the transition to zero at a rate of 5 mm every 8 or so sleepers (I don't know what the 00 is in the middle of this transition). Then comes the 50 metre long transition for a left hand curve, with the cant increasing by 5 mm every 8 sleepers or so till the last sleeper you've photographed begins the 660 m constant radius curve with its 50 mm cant.

 

Transitions are needed for two reasons:

• They mean there isn't a sudden jerk into the curve at its beginning (and out of the curve at its end).
• They keep track twist (changes of cant) within acceptable limits. If you have too much track twist, then you risk unloading one of the outer wheels of long-wheelbase vehicles, leading to the risk of derailment.

[Southernman46]

Yep - that's about the size of it 👍

 

The transition lengths are linespeed dependant - rate of change - so many mm in so many m - there are two level of this - up to 100mph & above 100mph if my track design memory is correct. Always a pain even with TD software to get two transitions to line up - was often a best fit and hope the rails end actually line up within reason on-site 🤦‍♂️

I see the local boys are already covering the plate in ballast !

IMHO you can't beat the info painted in yellow on a black patch on the sleeper - always made me feel that someone had actually measured it rather than just glued a label on.

 

There are also vertical transitions for vertical curves but these aren't recorded trackside. 

[Jeremy Cumberland]

24 minutes ago, Southernman46 said:

IMHO you can't beat the info painted in yellow on a black patch on the sleeper - always made me feel that someone had actually measured it rather than just glued a label on.

The numbers, whether on a fancy plate or chalked in yellow crayon, represent what the cant should be, not what it actually is.

[Southernman46]

Just a personal preference from an old dinosaur 😁

 

It's when taking random measurements during a TME's walk and finding they don't match the actual cant life gets interesting 🤦‍♂️

Edited November 9, 2023 by Southernman46

[Jim Martin]

39 minutes ago, Jeremy Cumberland said:

The two curves are in opposite directions. To the left of your first sleeper is a constant radius right hand curve of 2300 metres radius, with a 15 metre long transition

The right hand curve must be where the track adjusts to the island platform, because in the big scheme of things there's what appears to be a left-hand curve at both ends of the station. Would a short 2km radius curve be visible to the naked eye?

[Jeremy Cumberland]

12 minutes ago, Jim Martin said:

Would a short 2km radius curve be visible to the naked eye?

Certainly, but perhaps not to someone stood on a platform and who is not used to looking at track alignment. If you sight along the rail, it will be obvious. On Google maps, you can see the right hand curve clearly: https://www.google.com/maps/place/Waterloo/@53.4749624,-3.0245545,299m/data=!3m1!1e3!4m6!3m5!1s0x487b24669c20b375:0x3d372efe6af9d68f!8m2!3d53.4749484!4d-3.0254987!16zL20vMGJ4cTA3?entry=ttu

[90136]

On 09/11/2023 at 11:30, Jeremy Cumberland said:

 

The two curves are in opposite directions. To the left of your first sleeper is a constant radius right hand curve of 2300 metres radius, with a 15 metre long transition. The constant radius curve has a 15 mm cant, and this reduces over the transition to zero at a rate of 5 mm every 8 or so sleepers (I don't know what the 00 is in the middle of this transition). Then comes the 50 metre long transition for a left hand curve, with the cant increasing by 5 mm every 8 sleepers or so till the last sleeper you've photographed begins the 660 m constant radius curve with its 50 mm cant.

 

Transitions are needed for two reasons:

• They mean there isn't a sudden jerk into the curve at its beginning (and out of the curve at its end).
• They keep track twist (changes of cant) within acceptable limits. If you have too much track twist, then you risk unloading one of the outer wheels of long-wheelbase vehicles, leading to the risk of derailment.

The 00 is another way of denoting the point of reverse in the curve. 

[Buhar]

1 hour ago, 90136 said:

The 00 is another way of denoting the point of reverse in the curve. 

So nothing to do with a change of gauge then?

 

Alan

[90136]

2 hours ago, Buhar said:

So nothing to do with a change of gauge then?

 

Alan

Not on this train set 😆

[Mol_PMB]

The track position must be more tightly controlled alongside platforms, where the trains need to just clear the platform edge under worst-case conditions, but be as close to it as practical when passengers are boarding/alighting. Curved platforms are especially sensitive because of the overthrows, which may vary at different door positions, and the effect of cant (excess or deficiency) which can roll the vehicle in different directions. 

Traditionally train door stepboards have been higher than platforms so that they can 'oversail' the platform edge on curves. This means a step up but helps to minimise the horizontal gap. However, modern trends are for level stepping (train floor and platform at the same height) which is challenging to implement on an existing system with curved platforms, without having excessive horizontal gaps.

With the 777s, Merseyrail now has level stepping and this has required some modifications to platform edge positions and track position. I expect the copious labels on the sleepers at this location are to help control the track position and hence the vehicle position relative to the platform.

[Southernman46]

1 hour ago, Mol_PMB said:

I expect the copious labels on the sleepers at this location are to help control the track position and hence the vehicle position relative to the platform.

This might be old hat .......................

They are purely to do with top & line of the track and are no more than should be present at any transition etc. - the track position relative to the platform is recorded on entirely separate Datum plates affixed to the platform structure which record distance to running edge and the level of the nearest rail (as well as Cant). The top surface of the block matches this position and ISTR green is for a "installed design" of the track (i.e. a renewal) and red blocks represent measured position during the annual / 3 yearly gauging survey carried out by the Maintainer - I may be out-of-date now.

The last platform I gauged was Castle Cary many years ago whilst it was raining and had to endure water running off the platform edge during the process 🤦‍♂️

 

[90136]

9 hours ago, Southernman46 said:

The top surface of the block matches this position and ISTR green is for a "installed design" of the track (i.e. a renewal) and red blocks represent measured position during the annual / 3 yearly gauging survey carried out by the Maintainer

The only point that I can add to this, is on the WCML during my time and post ATG implementation, all lines cleared for Tilt were Green blocked irrespective. We had the Emsat’s that were always running about and we had to maintain geometry much more stringently. Any line not cleared for Tilt would be Red block at first survey post renewal. 
How I miss the nuances of the WCML.