Running Gauge Dimension

[Luis Marin]

Hello everyone,

I need a bit of help looking for a Network Rail Standard, a British Standard o any standard applicable to UK which specifies the Running Gauge Dimension.

I know the standard dimension is 1,435 mm (4 ft  8 1⁄2 in). But where is this write, apart of Wikipedia?

Many Thanks,

Luis.

 

[swt_passenger]

Hello everyone,

I need a bit of help looking for a Network Rail Standard, a British Standard o any standard applicable to UK which specifies the Running Gauge Dimension.

I know the standard dimension is 1,435 mm (4 ft  8 1⁄2 in). But where is this write, apart of Wikipedia?

Welcome to the forum. Here's a Railway Group Standard, GC/RT5021 page 16.

2.9 Track gauge
2.9.1 Nominal track gauge
2.9.1.1 New and re-laid track shall be designed to give a nominal track gauge of 1435 mm.
2.9.1.2 Maintenance limits for nominal track gauge are set out in 2.11.3 and 2.11.4.

https://www.rssb.co.uk/rgs/standards/GCRT5021 Iss 5.pdf

 

[Luis Marin]

Thank you very much!!

 

[philthetube]

I was once playing a quiz machine in a pub with three other drivers and the question came up, what is the standard british rail gauge, great we thought until we saw that the answers were in Metric, we failed.

 

[mcmad]

Also specifued un Networkrail track construction standard nr/l2/trk/2102

 

[swt_passenger]

Also specifued un Networkrail track construction standard nr/l2/trk/2102

That's not publicly available though?

 

[edwin_m]

BR changed the track gauge to 1432mm for a while in the early 80s. I believe the civil engineers thought it would be a good idea but the rolling stock people had optimised the wheel profile for 1435 so the narrowing made the ride much worse. It was restored later but I think there is still some 1432mm out there.

 

[najaB]

BR changed the track gauge to 1432mm for a while in the early 80s. I believe the civil engineers thought it would be a good idea but the rolling stock people had optimised the wheel profile for 1435 so the narrowing made the ride much worse.

It boggles the mind that a 3mm difference in gauge (less than an eighth of an inch in old money) made that much of a difference.

 

[coppercapped]

It boggles the mind that a 3mm difference in gauge (less than an eighth of an inch in old money) made that much of a difference.

The eighth of an inch should be considered in respect of the normal clearance between flange and rail, where it is a large proportion, rather than an eighth of an inch with respect to the gauge. It's the flange - rail clearance which is important in the steering of the wheelset.

People go on nowadays about the problems caused by the 'fragmentation' of the industry but this gauge change happened when BR was 'monolithic' and under one management. But still the civil engineers didn't talk to the mechanicals...

 

[AngusH]

BR changed the track gauge to 1432mm for a while in the early 80s. I believe the civil engineers thought it would be a good idea ...

I'd be curious to know why they thought it might be better (?)

 

[edwin_m]

I'd be curious to know why they thought it might be better (?)

At a guess they were concerned about the lateral oscilation known as hunting, which was a particular feature of older bogies at 100mph. On the face of it, it's logical to expect that putting the rails a bit closer together will reduce this oscillation.

However, in the 60s and 70s a lot of research was being done into vehicle ride, feeding into such things as the APT programme and long-wheelbase freight wagons. Part of this was to produce a "worn wheel profile" for application to new wheels, the important feature being that its shape didn't change significantly as it wore down in service.

The angle of contact between the wheel and the rail is a key contributor to how the vehicle rides and in particular whether a small disturbance such as a curve is likely to trigger a period of hunting. With the worn rail profile it was possible to optimise the suspension for a reasonably constant wheel-rail contact angle over the wheel's life. However moving the rails a few millimetres changes the position of the point of contact, and since the worn profile is a continuous curve across the tread this also changes the contact angle. The result is a sub-optimal ride, probably exacerbating the hunting they were trying to prevent.

 

[AngusH]

A most interesting explanation. Thank you!

It sounds like it was certainly worth a try, even if it didn't work out in the end.

 

[edwin_m]

A most interesting explanation. Thank you!

It sounds like it was certainly worth a try, even if it didn't work out in the end.

It would have been saved a lot of time and money if they'd had a conversation with their M&E or Research colleagues first.

 

[The Lad]

How is FB rail Inclined, by the shape of the sleeper bearing area?

 

[Darbs]

It's inclined except at vertical S and C!

 

[Darbs]

How is FB rail Inclined, by the shape of the sleeper bearing area?

Base plates are cast at the inclination, if I remember it's 1 in 20 and likewise concrete/steel sleepers are cast with the inclination

 

[Ploughman]

Normally, just off the switches or the back of the nose, what is called a twist rail is located. These are installed in pairs 1 left and 1 righthand according to position.
The rail itself can be anything over 4.5m in length but at some point it will have a twist formed into it at an S+C fabricators works.
Commonly it would be towards one end of the rail but the position can vary according to designs.
Visually they are not easy to locate until you get close.
Indicators as to location can be taken from a change in Sleeper type Inc to Vertical types or by a change in Baseplate types again Inc to Vertical types.
Looking along the foot edge of the rail sometimes shows the twist position.

There are markings stamped in the rail indicating position but when caked in crap these can be had to make out. New rails usually have paint markings to indicate location.

However it has been known that to get trains running after an incident or a Twist rail was missing on installation, a piece of normal rail has been forced into place, with the intention of rectifying it later. However sometimes later never comes.

 

[edwin_m]

Normally, just off the switches or the back of the nose, what is called a twist rail is located. These are installed in pairs 1 left and 1 righthand according to position.
The rail itself can be anything over 4.5m in length but at some point it will have a twist formed into it at an S+C fabricators works.
Commonly it would be towards one end of the rail but the position can vary according to designs.
Visually they are not easy to locate until you get close.
Indicators as to location can be taken from a change in Sleeper type Inc to Vertical types or by a change in Baseplate types again Inc to Vertical types.
Looking along the foot edge of the rail sometimes shows the twist position.

There are markings stamped in the rail indicating position but when caked in crap these can be had to make out. New rails usually have paint markings to indicate location.

However it has been known that to get trains running after an incident or a Twist rail was missing on installation, a piece of normal rail has been forced into place, with the intention of rectifying it later. However sometimes later never comes.

Interesting thanks. Do you have to have a set of transitional sleepers or baseplates as well to accommodate the twist?

 

[themiller]

BR changed the track gauge to 1432mm for a while in the early 80s. I believe the civil engineers thought it would be a good idea but the rolling stock people had optimised the wheel profile for 1435 so the narrowing made the ride much worse. It was restored later but I think there is still some 1432mm out there.

I may be wrong but I see to remember that it was a high speed straight section of the ECML in England that was changed but never heard any more about it. It was either from an article in the railway press or a news article on BBC television at the time.

 

[edwin_m]

I may be wrong but I see to remember that it was a high speed straight section of the ECML in England that was changed but never heard any more about it. It was either from an article in the railway press or a news article on BBC television at the time.

I read it in Modern Railways in connection with the Selby Diversion so I'm inclined to agree.

 

[furnessvale]

Interesting thanks. Do you have to have a set of transitional sleepers or baseplates as well to accommodate the twist?

No. The twist occurs at a single point in the space between two sleepers.

 

[The Lad]

Does that not slightly tighten the gauge going from vertical to inclined?

 

[furnessvale]

Does that not slightly tighten the gauge going from vertical to inclined?

Not necessarily. If the gauge corner of the rail is a fixed point, twist can be made by rotating the foot of the rail and adjusting the spacing of the baseplates or other rail fastening.

 

[Joseph_Locke]

Not necessarily. If the gauge corner of the rail is a fixed point, twist can be made by rotating the foot of the rail and adjusting the spacing of the baseplates or other rail fastening.

a manufactured twist is twisted around the running edge

 

[furnessvale]

a manufactured twist is twisted around the running edge

What I said, or maybe what I THOUGHT I said which is probably very different!

 

[The Lad]

So by putting in a wider nylon on the 4 foot side the gauge would be kept the same by pushing the base of the rail further out?

 

[furnessvale]

So by putting in a wider nylon on the 4 foot side the gauge would be kept the same by pushing the base of the rail further out?

Many years since I was actively involved in PerWay design but I believe it is done rather differently.

Vertical rail was introduced to simplify points and crossings. Plain line is still inclined. The twist rail is introduced at the interface between P & C and plain line. Thus P & C components (eg baseplates) are set to gauge based on a vertical rail and plain line components are set to gauge based on an inclined rail. Therefore there is no need for specialised minor components.

HTH

 

[edwin_m]

More recent S&C is now inclined anyway.

 

[furnessvale]

More recent S&C is now inclined anyway.

You learn something every day! Have the alleged benefits of vertical evaporated, or have they decided to use inclined at a simple crossover, keeping vertical for major layouts eg Euston or Birmingham New St etc?

 

[Joseph_Locke]

You learn something every day! Have the alleged benefits of vertical evaporated, or have they decided to use inclined at a simple crossover, keeping vertical for major layouts eg Euston or Birmingham New St etc?

The eternal trade-off: vertical S&C is easy because all the baseplate seats are flat, so you only need a relatively small number of standard "bits" to make any layout you like. Inclined S&C means that you need special baseplates everywhere (the switch rails themselves are still vertical though). However, Inclined S&C generally rides better and doesn't twists, whereas vertical S&C can have ride issues and does need twists.

However, the "designs" for RT60 were so complicated that inclined stock rails were the least of its problems.

That said, there is (Hopefully) an NR60V suite an its way, combining the efficient RT/NR60 geometries, 60kg/m rail and vertical rails. NR56V is still standard for some track categories.