Standard units for railway installs?

[dbrb2]

Out of interest, does anyone know whether there is an official position from NR on the use or imperial vs metric units? I have seen both used very widely in documents, but nothing that seems to mandate one or the other

I was curious, since you wouldn't want to think (as a basic example) you were doing 100kph only to find out you were actually doing 100mph...and given how prescriptive NR standards generally are, it seems likely it is defined somewhere...?

 

[pdeaves]

Broadly, operating speed/distance is imperial. Engineers use metric. There are some exceptions (of course). A rule wouldn't be a rule without exceptions!

 

[ComUtoR]

I was curious, since you wouldn't want to think (as a basic example) you were doing 100kph only to find out you were actually doing 100mph...

The signage is different for a 100mph PSR and a 100kmph PSR. It would be down to the Driver to know which unit their speedo was measured in. Everything I currently drive is measured in MPH only.

 

[driver9000]

Speed boards showing KPH have black backgrounds. Speedometers are either marked MPH/KPH or you will know from your traction knowledge how it is scaled.

I would also hope Drivers can tell the difference between 100kph (62mph) and 100mph.

 

[dbrb2]

Point taken - I just recall the NASA mars mission that was lost when two different groups of engineers used imperial and metric without telling each other:

https://en.wikipedia.org/wiki/Mars_Climate_Orbiter

So wondered if there was some NR standard that laid out in excruciating detail when, where, and how different units should be used

 

[ComUtoR]

ROGS guidance | Office of Rail and Road

orr.gov.uk

Start there.

Have a quick look here next :

ROGS | Office of Rail and Road

This page provides an overview of the regulatory requirements for managing safety on the railways, tramways and other guided transport systems.

orr.gov.uk

Take a shovel, a flask, sleeping bag and a decent tent; then go....

RSSB home page

The Rail Safety and Standards Board (RSSB) is the independent safety, standards, and research body for Great Britain’s rail network. We help to make an evolving railway safer, more efficient, and more sustainable.

www.rssb.co.uk

 

[alxndr]

Generally speaking speeds and distances are imperial and equipment is metric, but there are exceptions.

Some equipment in use is old enough to have imperial fittings. I carry two tool bags, one with metric kit and one with imperial kit.

 

[furnessvale]

Generally speaking speeds and distances are imperial and equipment is metric, but there are exceptions.

Some equipment in use is old enough to have imperial fittings. I carry two tool bags, one with metric kit and one with imperial kit.

As long as you have an adjustable spanner and screwdrivers of the correct type in each bag you will be OK.

 

[alxndr]

As long as you have an adjustable spanner and screwdrivers of the correct type in each bag you will be OK.

Not always space for an adjustable and you're more likely to end up rounding off a nut with an adjustable. Adjustables can get you out the mire but a properly sized spanner is always superior.

I know which kit I need for each job, so it's a case of picking the right bag (or at least until I discover someone's managed to get the wrong nut on the wrong thread anyway).

 

[furnessvale]

Not always space for an adjustable and you're more likely to end up rounding off a nut with an adjustable. Adjustables can get you out the mire but a properly sized spanner is always superior.

I know which kit I need for each job, so it's a case of picking the right bag (or at least until I discover someone's managed to get the wrong nut on the wrong thread anyway).

Woosh!

Perhaps I didn't make myself clear. As long as you have a metric adjustable spanner and a set of metric screwdrivers in your metric bag, and an imperial adjustable spanner and a set of imperial screwdrivers in your imperial bag, you should cover all eventualities!

 

[alxndr]

My

Woosh!

Perhaps I didn't make myself clear. As long as you have a metric adjustable spanner and a set of metric screwdrivers in your metric bag, and an imperial adjustable spanner and a set of imperial screwdrivers in your imperial bag, you should cover all eventualities!

Apologies, my mistake! I missed the "in each bag" part.

 

[Dr_Intoxicated]

Woosh!

Perhaps I didn't make myself clear. As long as you have a metric adjustable spanner and a set of metric screwdrivers in your metric bag, and an imperial adjustable spanner and a set of imperial screwdrivers in your imperial bag, you should cover all eventualities!

Very droll

 

[squizzler]

I'm surprised nobody here has mentioned chains as a unit of distance yet. What's all that about, eh? Would I be correct in thinking they are used as a unit of measurement in infrastructure even today?

 

[driver9000]

I'm surprised nobody here has mentioned chains as a unit of distance yet. What's all that about, eh? Would I be correct in thinking they are used as a unit of measurement in infrastructure even today?

80 chains to 1 mile. The Sectional Appendix still shows chains but the Scottish appendix uses yards.

 

[Ashley Hill]

It seems the SLU (21ft) has been abandoned. All loops are shown in metres.

 

[alxndr]

I'm surprised nobody here has mentioned chains as a unit of distance yet. What's all that about, eh? Would I be correct in thinking they are used as a unit of measurement in infrastructure even today?

They're a perfectly good unit of measurement, thank you very much!

Depending on the document I'm reading measurements are in one of four things:

• Miles and chain (perfect!)
• Miles and yards (acceptable)
• Miles, quarters, and yards (awkward)
• Miles and meters (utterly barbaric (albeit mathematically simpler for the accuracy I need))

Regardless of what the measurement is given in, I convert back to miles and chain to be able to make sense of it.

Some bits are now measured in kilometers but nothing that I get involved in.

It seems the SLU (21ft) has been abandoned. All loops are shown in metres.

The Western Sectional Appendix shows loops in meters and also in feet.

 

[philthetube]

I was in a pub playing a quiz machine with three other drivers and a question came up, waht is the distance between the rails on a british railway track?

Great we thought until we looked at the answers, they were in Metric, Doh.

 

[Mojo]

Great we thought until we looked at the answers, they were in Metric, Doh.

I always forget how many inches and feet it is, but can quite easily remember that it's 1,435mm.

 

[pdeaves]

The Western Sectional Appendix shows loops in meters and also in feet.

The last time I looked at such things, the 'feet' measurement was in convenient multiples of 21 so it was easy to see places that used to have SLUs marked.

 

[alxndr]

The last time I looked at such things, the 'feet' measurement was in convenient multiples of 21 so it was easy to see places that used to have SLUs marked.

So they are! That's an interesting little fact to know. Not using it for that purpose, or being up on my 21 times table, I'd never spotted it myself.

 

[Taunton]

I'm surprised nobody here has mentioned chains as a unit of distance yet. What's all that about, eh? Would I be correct in thinking they are used as a unit of measurement in infrastructure even today?

The good thing about chains was, at 66 feet, they were just the same as a standard BR carriage. So whereas 10 chains may not give much of a mental image, 10 carriage lengths did.

 

[eMeS]

Why then is it called the "four foot"? I assume this refers to standard gauge, which is 4'8½" - so "five foot" would be closer. Historical reason? Sloppiness?

 

[pdeaves]

Why then is it called the "four foot"? I assume this refers to standard gauge, which is 4'8½" - so "five foot" would be closer. Historical reason? Sloppiness?

Simply because 'the four foot' is easier than 'the four foot eight and a half inches'. It's derived more from a slang way of saying it than the mathematical precision of how you should round a fraction (of a foot) over 1/2.

'Right away' is, I understand, linguistically derived from 'you have the right of way'. Again, a simple way of saying it.

 

[Ashley Hill]

IIRC (I may be wrong) isn't flat bottom rail four foot eight and three eighths?

 

[Chris Hamilton]

Most signalling kit (nuts, bolts, screws etc) is Metric these days, though there are a few outliers, such as the prolific use of 0BA and 2BA nuts (2BA nut spinner is an S&T mans best friend), even on brand new kit (usually to be found on anything still using a BR reference design). Almost anything electrical is measured in Metric, such as distances and cable core sizes.

Plenty of Imperial fittings used where we interact with the Pway, such as carriage bolts for holding equipment to wooden sleepers and a declining number of stretcher bar bolts (We are progressively replacing all Mainline stretcher bars with a new design).

One thing that has bugged me however, is in a recent Resignalling design in my old area, the locs were renumbered to a new format of “ELR/mileage from datum/chains”, when all old locs were “km from Euston/loc number in sequence” or “km from datum.m from km start”. Seems like a backward step, especially as it was very handy that our locs were numbered the same as the OHL, so turning up at a gate and looking at the OHL structure number would tell you if you were in the right place. Also, most S&T folks in my area don’t know mileages, as assets are our guide. I couldn’t tell you where the 89MP is, but I know where signal such and such is.

 

[furnessvale]

IIRC (I may be wrong) isn't flat bottom rail four foot eight and three eighths?

For a time, 4' 8.5" (1435mm) gauge was reduced to four foot eight and three eighths (1432mm) to assist in controlling hunting. However, I believe other problems occurred around the gauge corner so gauge is now back to 1435mm.

 

[alxndr]

Most signalling kit (nuts, bolts, screws etc) is Metric these days, though there are a few outliers, such as the prolific use of 0BA and 2BA nuts (2BA nut spinner is an S&T mans best friend), even on brand new kit (usually to be found on anything still using a BR reference design). Almost anything electrical is measured in Metric, such as distances and cable core sizes.

2BA nuts are going out of favour, sadly. Almost everything has gone to WAGO connections on my patch now with a resignalling, which are truly awful. The few remaining 2BA links have been fitted with a little perspex cover in case someone, somehow, manages to zap themselves on the exposed terminals.

They haven't managed to fit WAGOs into point machines though, so 0BAs are fighting on there, and there's still 2BAs hiding in supp detectors.

One thing that has bugged me however, is in a recent Resignalling design in my old area, the locs were renumbered to a new format of “ELR/mileage from datum/chains”, when all old locs were “km from Euston/loc number in sequence” or “km from datum.m from km start”. Seems like a backward step, especially as it was very handy that our locs were numbered the same as the OHL, so turning up at a gate and looking at the OHL structure number would tell you if you were in the right place.

Prior to resignalling our numbering method was a letter and a number. The letter would change each time you passed an interlocking. Not the most intuitive, but it's a lot easier to happen to remember where "E7" is, rather than "ELR088D042" is. The latter is the current method they've chosen here, consisting of the ELR - miles - up or down side - meters divided by 10. It works, if you halve the end number you more or less get the chainage (a chain being near enough 20m) but it drives me up the wall as a matter of principle mixing imperial and metric like that.

Also, most S&T folks in my area don’t know mileages, as assets are our guide. I couldn’t tell you where the 89MP is, but I know where signal such and such is.

I only work that way because of the new loc numbering, all the signals having changed their numbers, and my operative being ex-p-way. Give him a mileage and he'll know exactly where it is and the distance to the nearest access off the top of his head. Give him a signal and I might as well have asked him to head to Timbuktu. Turns out the more I've used mileages, the more I've found it useful.

 

[Hellzapoppin]

So E7 is either Avonmouth Station, Windsor branch or my own personal preference is a couple of miles short of Brinkworth?? Wooton Bassett West is E1.

 

[alxndr]

So E7 is either Avonmouth Station, Windsor branch or my own personal preference is a couple of miles short of Brinkworth?? Wooton Bassett West is E1.

A few years ago you'd have been right, but all the old locs on the Badminton line were lost a couple of years ago to the SASR resignalling. There's now nothing where E7 was and E1 has been demolished to nothing more than a concrete base.

 

[mcmad]

2BA nuts are going out of favour, sadly. Almost everything has gone to WAGO connections on my patch now with a resignalling, which are truly awful. The few remaining 2BA links have been fitted with a little perspex cover in case someone, somehow, manages to zap themselves on the exposed terminals.

Not North of the border they aren't. WAGOs are all but banned and every spec has a clause that 2BA are to be used, I think after a previous bad experience with them.