Chains as a measurement.

[Flying Phil]

I'm fairly sure and I stand to be corrected when the railways were first built they had chain gangs. They used the chain as a set messured distance when the routes were being layed.

I always had thought that "Working in a chain gang" referred to convicts being chained together or is that an American convention?

 

[najaB]

I always had thought that "Working in a chain gang" referred to convicts being chained together or is that an American convention?

I suspect it's a case where the same term refers to two different things, depending on context.

 

[Class 170101]

And the battery cannot fail on a page of the latest notice on paper.

Correct but water would make it un-readable.

 

[Class 170101]

London Underground use Kilometres as well and I believe the zero point for the entire Underground Network is of all places Ongar.

Bizzarely it still is some 20 years after closure of the line between Epping and Ongar (as far as the Underground were concerned).

 

[Railsigns]

Bizzarely it still is some 20 years after closure of the line between Epping and Ongar (as far as the Underground were concerned).

The alternative being to re-mileage the whole network for negligible benefit.

 

[alxndr]

And of course the sponge recipe of another poster is in ratios. Just the same in metric. Just don't mix up the systems.

Not quite, it refers to ounces and eggs. You could find a metric amount and stick to the ratio for flour/butter/sugar, but you can't get metric eggs.

 

[Bevan Price]

"It's interesting that in terms of weight, the basic metric unit of one kilogram is by definition a thousand of another unit" I thought that the Kilogram was a unit of mass equal to a very precise lump of metal kept in Paris? Weight is a force measured in Newtons (SI).(Pedant Alert!)

The kilogram was originally defined as the weight of one litre of water at its temperature of maximum density (just under 4 degrees Celsius). However, that was difficult to use as an international standard because the weight varies with temperature, and "weight" (as opposed to "mass") depends on the gravitational forces exerted by earth - which decreases with increasing altitude. Hence the (initial) change to the weight of a lump of platinum.

 

[InOban]

But you can't get imperial eggs either. The weight range for different sizes is given in g. However 2oz. is in the middle of the range specified for a medium egg.

 

[edwin_m]

It wouldn't be impossible. It wouldn't be easy, but 1mm is a small enough measurement that any imperial measurement could be changed to mm. That said, I probably wouldn't bother.

New signalling plans, for example, will be prepared in metres. Ones I have seen recently show the "chainage" of each feature in metres from the same zero point as the route's mileposts. But older plans may be in miles/chains, miles/yards and I think I've even seen some in miles/metres. These are unlikely to be re-dimensioned (any minor changes will use the same measurements as the rest of the plan) until they are superseded by new plans which probably only happens with re-signalling. Similar probably applies to other types of plan.

GPS is only one of the technologies which modern train control systems use to determine exact location. They could automatically slow the train for a TSR...

This is a safety-related function (consider the consequences of failing to slow down) so would need a system with a high safety integrity to prevent it failing to alert for a TSR, and also a high reliability so it doesn't give false alarms or shut down completely. GPS wasn't really designed with that sort of integrity, and there have been worrying stories that the Russians are now able to "spoof" the system into giving an incorrect location - not to mention the risk that a space collision could create enough junk to disable the satellites.

ERTMS includes features to impose and enforce TSRs with adequate safety integrity, relying on balises and wheel rotation to confirm position, so as this gradually spreads across the network it should bring improved methods with it.

 

[pdeaves]

I note that, in this discussion of old-but-still-in-use measurements, no one has mentioned the SLU for measuring freight trains and loops. The SLU is a standard length unit equal to 21 feet (7 yards), to all intents and purposes the length of an 'old fashioned' four wheel wagon (so a train of 10 of these wagons would be 10 SLU, as would five double length wagons). Although there are no (or very, very few) wagons this length now, SLU is still used on occasion.

 

[snowball]

The kilogram was originally defined as the weight of one litre of water at its temperature of maximum density (just under 4 degrees Celsius). However, that was difficult to use as an international standard because the weight varies with temperature, and "weight" (as opposed to "mass") depends on the gravitational forces exerted by earth - which decreases with increasing altitude. Hence the (initial) change to the weight of a lump of platinum.

The kilogram is the last SI standard unit still defined in terms of an artefact. Unfortuntely there seems to be an unexplained drift (of the order of a few tens of micrograms over a century) between the mass of the primary kilogram lump and the copies which serve as secondary standards. Several groups are working on ways to redefine the kilogram so it doesn't depend on an artefact, and a decision is set to be taken in 2019.

 

[Mojo]

Not quite, it refers to ounces and eggs. You could find a metric amount and stick to the ratio for flour/butter/sugar, but you can't get metric eggs.

You’re not weighing the eggs though so it’s irrelevant; the 2 in the 4-4-4-2 method relates to two eggs and not the weight of them.

 

[philthetube]

Back to chains, though not strictly on topic, (though more so than the size of eggs), and provided for information and to give a useless fact to discuss at dinner parties.

An Acre is a chain x a furlong.

 

[InOban]

Which is why we use the hectare, which is 100m x100m.

 

[TwistedMentat]

I note that, in this discussion of old-but-still-in-use measurements, no one has mentioned the SLU for measuring freight trains and loops. The SLU is a standard length unit equal to 21 feet (7 yards), to all intents and purposes the length of an 'old fashioned' four wheel wagon (so a train of 10 of these wagons would be 10 SLU, as would five double length wagons). Although there are no (or very, very few) wagons this length now, SLU is still used on occasion.

Another kinda rail related one is containers. 20 foot, 40 foot, Hi-cube (9ft 6in), etc. are all referred to in Imperial/US measures though the standard international measurement definitions are in mm. And in the case of container ships they're measured in TEUs, or Twenty Foot Equivalents.

Lots of specialised industries use seemingly out of date measurements due to historic reasons. Though when you dig down you'll generally find the definition of the Imperial/US measurement is in relation to metric. So it still ends up as metric/SI in the end.

 

[Maurice3000]

As the USA is the last bastion of the Imperial system of weights and measures (with some modifications such as the short ton of 2,000lbs and a smaller gallon) changing to SI units to bring alignment to the USA would have been highly unlikely back in 1963.

It may have had something to do with the Americans already investigating a switch to metric in the 1960s and ultimately deciding to make the switch (although abandoning the transition again under Reagan). I can imagine people on this side of the pond being spurred on to do the same (not knowing that the American progress would stall two decades later).

The UK hasn't exactly been that quick either. While in the UK parliament had approved the introduction of the Metric system in the 19th century, it took until 1965 for the UK to officially switch to being a metric country. Most UK industries had converted by the 1970s. In typical fashion, though, Imperial still limps along and rears it head from time to time.

Obviously, all of this happened long before the UK joined the European Community (as the EU was then called) and it was more driven by trade and industry than politics. Ironically I can see Brexit leading to the UK becoming more serious about getting rid of the Imperial hangovers as the UK will need to get better at international trade. The rest of the world doesn't use Imperial...

 

[snowball]

The UK hasn't exactly been that quick either. While in the UK parliament had approved the introduction of the Metric system in the 19th century, it took until 1965 for the UK to officially switch to being a metric country. Most UK industries had converted by the 1970s. In typical fashion, though, Imperial still limps along and rears it head from time to time.

From Wikipedia's page on the Metrication Board (created 1969):

Following the 1979 general election and another change of government, Sally Oppenheim, described by the last director of the Metrication Board, Jim Humble, as having "been almost the lone but persistent critic of the metric programme"[1] was appointed Minister of State for Consumer Affairs. On 14 November 1979, six months after her appointment, she announced that no more statutory orders would be made regarding metrication – continued progress would be on a voluntary basis. The following year the Metrication Board was wound up, one of the 457 Quangos that were wound up in the "Quango bonfire" of 1979–81.

 

[Joseph_Locke]

SLU and TEU aren't and never were in UK law, any BS or the SI system. They're just handy (if potentially anachronistic) measurements that are an adopted norm, a bit like barleycorns (shoe sizes) or smoots (bridge spans).

 

[Maurice3000]

From Wikipedia's page on the Metrication Board (created 1969):

In hindsight you could argue that it fits in with the whole 'market, not the state' thinking of those times. Letting the companies decide instead of the state deciding for them. By 1979 the market had already long decided that metric was the way to go anyway.

Unfortunately it has kept some dubious practices in place. Buying a house for instance. Houses are designed in metric, planned for land surveyed and sold in metric, built in metric with metric materials and regulated using metric building codes and laws. Then an estate agent comes and often sells it in square feet (even though that is a breach of trading standards). Once you've bought it, it's back to metric to buy your carpets and curtains. I understand why they do it, of course, as a 861 square feet flat sounds much bigger than the 80 square metres as it was designed. A dubious practice nonetheless and something a Metrication Board could have prevented.

Meanwhile the state kept metricating too as since then the government, emergency services, military, NHS, Ordnance Survey, Land Registry etc. have all gone metric. My partner works for the NHS and it would be a potentially life threatening breach of protocol if she decided to measure people in feet, inches and stones or medication in anything other than milligrammes and millilitres.

 

[Dr_Paul]

Maybe we should convert it back to miles and chains post Brexit.

I recently told a group of young kids that when Britain leaves the Common Market, all measurements will be in imperial, and currency will go back to pounds, shillings and pence. I managed to keep a straight face whilst telling them, and the look of horror on their faces was a treat!

 

[philthetube]

Which is why we use the hectare, which is 100m x100m.

which is , to within 0.5% a furlong x a furlong. Simples

 

[birchesgreen]

I recently told a group of young kids that when Britain leaves the Common Market, all measurements will be in imperial, and currency will go back to pounds, shillings and pence. I managed to keep a straight face whilst telling them, and the look of horror on their faces was a treat!

Quite a lot of people actually want that, politicians included so maybe their horror is not totally unfounded.

 

[InOban]

which is , to within 0.5% a furlong x a furlong. Simples

So you're happy to work to 5% errors?

Just a question. When these enthusiasts built Tornado, did they get specially made imperial nuts and bolts? I seem to remember that the boiler had to be made in Germany, so presumably that was metric...

 

[najaB]

So you're happy to work to 5% errors?

For most everyday uses, 0.5% is 'close enough'.

 

[furnessvale]

For most everyday uses, 0.5% is 'close enough'.

It's good enough for the pump dispensing your petrol!

 

[4069]

which is , to within 0.5% a furlong x a furlong. Simples

No, it's close to half a furlong x half a furlong.

 

[InOban]

Actually the error is 1.01156%.

 

[najaB]

Actually the error is 1.01156%.

Either way on a piece of land 0.5 furlongs square compared to 1ha you're talking about a 2.5cm border. So for most real-world applications it's 'close enough'.

 

[Maurice3000]

Back on the topic of chains. I recall that a few years ago (probably as a result of the Grayrigg derailment when it became clear that Network Rail hadn't been very good at managing its track assets) there was uproar over the detail that Network Rail did not have a proper inventory of its assets. Apparently nobody in Network Rail could adequately provide an account of the total assets it was responsible for.

It was pointed out that this was partially due to the fact that over the years NR had used a whole range of different units to manage its tracks (probably a mixture of miles, kilometres, chains, metres and yards) which made it hard to keep track of things. The solution was to standardise on metric, the land the tracks are on is surveyed in metric and the trains that ride on them are designed in metric so it makes sense to use the same units.

I don't expect people with tape measures to walk the entire length of all tracks and do an entire stock take in metric. I do expect that any major maintenance (electrification? tamping? sleeper replacement? remodelling?) will involve measuring everything up in metric once and for all and stop depending on many decades old records. Especially with the advent of modern Geographic Information Systems (GIS) that should be fairly straightforward and more precise than ever. Imagine having a computer system that can tell you that the distance between an outer rail and the column of a particular bridge is precisely 2241 millimetres.

 

[SpacePhoenix]

Whenever (if it's actually used on the railways) LIDAR is used, do all distances that it measures get recorded in metric?