Imaginary Locomotives

[jjb1970]

Indeed, it is one of the great myths that boilers are inefficient. Boilers can achieve incredibly high efficiency, but the figures for boiler efficiency can be highly misleading if people think the figure represents locomotive/power package efficiency. Another aspect which is often lost is that boiler and steam engine power is largely a function of evaporation rate, but people tend to focus on pressure. If you shut the steam valves on a boiler it's very easy to raise pressure to lift the safety valves or rupture tubes and the drum if you disable the safety valves and boiler protection but there would be no power output. Conversely, even quite low-pressure boilers can operate at high power with a high evaporation rate if the cylinders or turbine are designed for LP operation. Why high superheat and pressure does is give much better thermal efficiency. Ultimately to consider steam plant performance you need to consider the boiler, air heaters and any other heat recovery, steam pipework, cylinders/turbine, condenser and feed pumps as an integrated system.

[rodent279]

What element of the test data from the Rugby tests was wrong?

I have difficulty believing that the ability of a steam loco to produce a short term power output considerably in excess of its sustainable power output was not understood-that would have been known by enginemen for decades, since almost the birth of steam power.

 

Testing done by Rugby was not limited to the test plant, either. Testing on the road was also done by the Rugby programme, using the ex-LMS load banks to simulate loads, and the dynamometer cars from Darlington, Derby & Swindon. I can't believe that together, those test results would not have shown that under some conditions, a steam locomotive was producing a power output that could not be maintained indefinitely, because the steam demands were in excess of the maximum evaporation rate of the boiler.

 

The implications are that the difference between short term power output & continous power output, as applied to railway locomotives, was not understood, & that the difference between the maximum installed BHP of a diesel engine, and the maximum power at rail produced, after transmission losses have been taken into account, was not understood.

 

I can understand that to the lay-man, the difference might be difficult to follow at first, but it's not exactly rocket science, I seriously doubt that professional test engineers would have difficulty grasping the concept. I can believe the higher echelons of the railway management (& government?) did not want to hear this, as it would not allow steam to be eliminated as quickly as they would have liked.

 

[Compound2632]

19 minutes ago, rodent279 said:

What element of the test data from the Rugby tests was wrong?

 

I have been told that E.S. Cox manipulated or fabricated Rugby test data to produce results more favourable to particular ideas of which he was a proponent. Unfortunately I don't know the details but I understand there is good documentary evidence of this at the NRM.

[DenysW]

44 minutes ago, Compound2632 said:

E.S. Cox manipulated or fabricated Rugby test data

I had also read that he looked for reasons to discard test runs that did not fit his preconceptions/biases. This then changes the averaged results. Also an assertion that he retained his pro-L&Y (thus anti LNWR, MR, etc.) stance throughout his working life.

 

I used to work in a discipline that generated very large amounts of very noisy data, and it is extremely tempting to study intensively the 'bad' data points and accept unchallenged the 'good' ones. Some colleagues were more prone to this than others. How much more tempting to do this on fairly sparse, very expensive to duplicate, noisy data.

[Compound2632]

13 minutes ago, DenysW said:

I used to work in a discipline that generated very large amounts of very noisy data, and it is extremely tempting to study intensively the 'bad' data points and accept unchallenged the 'good' ones. Some colleagues were more prone to this than others. How much more tempting to do this on fairly sparse, very expensive to duplicate, noisy data.

 

Indeed, and perhaps I am equally guilty in examining Cox's career? Because of the ...

 

13 minutes ago, DenysW said:

assertion that he retained his pro-L&Y (thus anti LNWR, MR, etc.) stance throughout his working life.

 

There were many interesting things going on at Horwich in the early 1920s which unfortunately never fully came to fruition.

Edited November 1, 2022 by Compound2632

[DenysW]

1 hour ago, rodent279 said:

What element of the test data from the Rugby tests was wrong?

A summary of the case for the prosecution, a single block of text selectively extracted from the SteamIndex article on him:

 

"Criticism of Cox's work

 

Tester, Adrian, Centre bearings, weak frames and all that. Backtrack, 2013, 27, 125. and Tester page (in SteamIndex)

Nothing E.S. Cox wrote can be taken on trust unless it can be verified elsewhere and ideally from original sources. Examples of where he has been economical with the truth or deliberately misleading include the following:
(i) When large lap valves were an advantage and when their presence served no useful purpose.
(ii) Axlebox performance – that of inside cylinder engines misrepresented.
(iii) Frame performance of other older classes but no mention of the worse track record of more modern classes, some of which he was responsible for designing.
(iv) Misquoting dynamometer test result figures – the erroneous numbers always support his case.
(v) Locomotive test results falsified at Rugby.

 

To conclude, the machinations of this very fluid writer in promoting his own biased views on locomotive engineering have, for half a century, misled a great number of enthusiasts. It is time his opinions are treated with scepticism – if nothing else, one is likely to be nearer the truth!"

 

I haven't tried to find the equivalent case for the defense, or to validate the Adrian Tester's accusations.

[Ohmisterporter]

There must have been something the L&Y were doing or planning surely? Having a bias towards the company culture you were trained in is not in itself a bad thing but it can become so when anything better from another company is ignored. Anyone who has worked for a firm that has amalgamated/taken over another can testify to this. 

[rockershovel]

I don't know anything about dynamometer, but I DO know about what has been referred to already as "noisy data". I should think that the problems inherent in producing good quality data models of long, loose-coupled freight trains on a network as heavily used and geographically variable as the British one, suitable for manipulation and interpretation by 1950s and 1960s techniques are beyond anyone. 

 

That's without accounting for the problems resulting from top-down management by people with no actual understanding of either the specific subject, or good management practice (which is pretty much what our political system produces, and has always produced). 

[JimC]

Its by no means unknown for a management that is faced with evidence that a grand plan is not financially viable, to hurtle along regardless and make sure there is little evidence of its problems to be found.

A cynic might consider that a management which considered dieselisation inevitable/unavoidable, but knew that the cost would be unacceptable to their political masters, might decide to head down the road regardless, carefully avoiding the sort of extended evaluation and testing which might demonstrate the financial problems to come, and rely on sunk costs and propaganda to get them through. Not, perhaps, realising that the financial problems might result in the political masters imposing a even worse result a few years later.

[john new]

2 hours ago, rodent279 said:

What element of the test data from the Rugby tests was wrong?

...snipped...

 

As I wrote above, there is a lot of published, written, controversy over interpretation of the L116 report (IIRC issued from Rugby) and the conflicts between that and other reports (from memory one's produced at Derby).  The performance society journal would be a good starting point to research the debate if you really want to find out.

[rodent279]

34 minutes ago, JimC said:

Its by no means unknown for a management that is faced with evidence that a grand plan is not financially viable, to hurtle along regardless and make sure there is little evidence of its problems to be found.

A cynic might consider that a management which considered dieselisation inevitable/unavoidable, but knew that the cost would be unacceptable to their political masters, might decide to head down the road regardless, carefully avoiding the sort of extended evaluation and testing which might demonstrate the financial problems to come, and rely on sunk costs and propaganda to get them through. Not, perhaps, realising that the financial problems might result in the political masters imposing a even worse result a few years later.

So if you are looking to replace your fleet of 8P Pacifics with diesels, and the only thing available over 2-2500 hp that is both homegrown and fits within the UK loading gauge, is a high cost, high maintenance locomotive that is the railway equivalent of a Bentley marrying a supermodel, you probably don't want to hear that you need 3000+ installed hp to do the job.

So you misinterpret, manipulate & fiddle the figures to support the idea that a fleet of locomotives with less installed power, that is available, and you can afford now, can do the job.

 

Bending the facts to fit the agenda-nothing new under the sun is there?

Edited November 1, 2022 by rodent279

[The Johnster]

If Cox’s machinations compromised the Rugby data, and the Rugby data was relied upon to find specifications for new diesel locos to replace steam despite the purpose of Rugby being to evaluate alterations/improvements to steam to see of they were worth the outlay, and then the top-down management that had replaced or sidelined the Riddles team (so far as locos were concerned) in the coup of 1954 when the Railway Executive of the BTC was replaced by the BRB with a brief to modernise at all costs, on top of which the received wisdom regarding dieselisation was based on US practice (to be fair the only game in town then) not best suited to British operation, then we have a perfect storm of misinformation and policy imposition when the 1955 Modernisation Plan was formulated, and the poor performance of the 1st generation diesels become almost inevitable.  
 

The perfect storm was made even more perfect by the tendering process of the 1955 plan.  It was politically necessary, given that large amounts of public money were involved, and politically desirable to spread the joy and be seen to be protecting jobs

among the struggling private sector loco builders, to invite tenders for untested designs in large numbers, and hardly surprising that some of them turned out to be liabilities.  What is surprising is that a few of them were at least adequate, but none particularly covered themselves in glory.  

 

14 minutes ago, rodent279 said:

So if you are looking to replace your fleet of 8P Pacifics with diesels, and the only thing available over 2-2500 hp that is both homegrown and fits within the UK loading gauge, is a high cost, high maintenance locomotive that is the railway equivalent of a Bentley, you probably don't want to hear that you need 3000+ installed hp to do the job.

So you misinterpret, manipulate & fiddle the figures to support the idea that a fleet of locomotives with less installed power, that is available, and you can afford now, can do the job.

 

Bending the facts to fit the agenda-nothing new under the sun is there?

If we are talking strictly about the 1955 Plan Type 4s, none managed above a nominal 2,000hp.  We are only talking about two classes, the 40s (which were effectively Type 3s in practice because of the deadweight) and early 42s, from the original plan.  But you’re right, it was all about the King’s New Clothes but there was no little boy who hadn’t heard about the magic tailors to speak up; they’d all been got rid of in 1954 and the King was in the altogether.  The road hauliers must have thought it was xmas!

[rogerzilla]

Cox (whose memoirs are worth reading) also reckoned 4-cylinder locos were unnecessary, assuming 2 cylinders could be fitted within the loading gauge.  The Horwich Crab was one result, as were most of the BR Standards.  His argument was that the hammer-blow issue that plagued 2-cylinder engines at high speed was a red herring and could be solved by reducing the balance weights and adjusting drawbar springing to damp out the surging motion.  This doesn't make much sense as, even if you isolate the train from the surging, you make it worse for the crew.  Hawksworth must have had the same idea for his County, which is basically a Castle-size and Castle-power loco with two cylinders.

[toby_tl10]

7 hours ago, JimC said:

Not, perhaps, realising that the financial problems might result in the political masters imposing a even worse result a few years later.

The keyword is at the end. Who cares about a few years later? There could be 3 governments and 12 prime ministers in that period of time, and your boss is changed for the 20th time. When that even worse result eventually emerges, those who caused it have all moved to new positions, retired or deceased! And it keeps happening again and again

[The Johnster]

Multi-cyldinered steam locos, those with 4 or 3, developed mostly in the early years of the 20th century as part of the response to an increase in speeds and loads at that time and by the late 40s and early 50s were being thought of as a bit of a luxury.  The default passenger loco prior to thier introduction had been an inside cyldiner 4-4-0 and the default goods loco, also used for general mixed traffic work, was an inside cylinder 0-6-0, with a smaller wheeled variant for mineral work.  The CMEs and the crews liked them, they worked, were robust and easy to maintain, and adequate for nearly all 19th century traffic, and the 4-4-0s rode well at 19th century speeds and were kind to the track.

 

The turn of the century brought a demand for bigger locomotives to handle the increased loads that resulted from the introduction of heavy bogie coaches and increased mineral traffic to the capital, which was growing exponentially in population, mostly in the form of new suburban houses that were owned by one familty, coal heated, a trend repeated to a lesser extent in other cities.  Many of the CMEs of the time struggled a bit with the new bigger engines, I'll mention Drummond on the LSWR and Webb on the LNW but they weren't the only ones.  New problems were manifesting themselves, not all of the new big boilers steamed particularly well, fireboxes had to be rethought (Atlantics were a response to this) and cylinder capacity increased.  Where it increased to a point beyond which the loading gauge could handle it, multiple and outside cylinders were resorted to, and at the same time compounding became popular, another method that demanded a multi-cylinder approach, usually 3 with the smaller hp outside and the bigger lp inside the frames.

 

Now, this is all old ground, and I've gone over it because it is during this exact period that that the CMEs of the post-war world cut their teeth, and where their various enthusiasms and dislikes formed.  Post WW2, the preference was for the simplicity of outside motion and valve gear and the bulk of designs featured 2 outside cylinders.  All the BR standards were built to this specification (I would discount 71000 as a standard, it was very much an opportunist one-off built to replace 46202).  But the 2-cylinder outside motion locomotive, especially a big powerful one, is the worst possible option when it comes to hammer-blow; not only are the reciprocal forces large, but they are situated in the worst possible place, outside the frames and at the end of the loco, where they will assist the weight of the big outside cylinders in disrupting the ride of the loco and punishing the track.  A big selling point of the early diesels is that they didn't do this!

 

The cutting edge of steam design in those days was focussed, fairly successfully, on increasing the power and steam raising capacity available from the boilers and making the steam and exhuast passages as efficient as possible (this is what Chapelon and Porta were about), and is seen in retrospect as a doomed fight-back against inevitable modernisation, but I'm not sure that's how their proponents saw it at the time.  A modern steam loco in the late 40s and early 50 has some big advantages when you take a holistic view; it is about a third the cost to build of a diesel of equivalent ability, easier to maintain, the infrastructure to support it already exists and everybody knows how to fire it and drive it, not insignificant factors in a post-war austerity situation.  The later British boilers, especially Thompson's, Bullied's, and Riddles' (except 71000 in it's original form as built), were very efficient steam raisers, though the wide fireboxes on the Britannias terrified WR firemen until the Canton crews learned how to deal with them!  Ivatt and Ell at Crewe and Swindon respectively greatly improved the steam and exhuast passages of older 8P 4-6-0s, Manors, and some of the smaller BR standards, and, while they accused it of everything else including attempted murder of firemen, nobody accused the Leader of poor steaming.

 

All of which is in line with my view that a lot of work was being done at the end of steam development to bring steaming and power output into line, but hammer-blow seems not to have been being addressed except with Leader; perhaps it was generally thought of (and not particuarly expressed much in print or conversation, in the way that elephants in rooms are often taken as given and understood by all involved in the discourse) as a) too difficult to solve without a major rethink away from the Stephensionian reciprocal model, not really going to go down well with the beancounters and politicos during austerity and anyway a poisonous concept to sell to them in the wake of the Leader debacle, and b) the Per Way Dept's problem, in a lack of holistic thinking typical of the period.  If Cox was propounding locos with 2 big outside cylinders like fattened up Crabs, some of this sort of thinking may have influenced him.  Not that this is an excuse to use his position to tinker with data to promote his own agenda, of course.

 

My personal and rather uninformed (I'm not a trained engineer) view is that the standards should have all been 3-cylinder machines with outside motion and the best access between frames possible from ground level, in which I find myself in rather disturbing agreement with Tuplin, whose views I find highly entertaining but do not much respect as a rule.  I can see why Riddles chose not to go down this path, though; any gubbins between the frames was anathema in those days.  Riddles' original concept, a range of standard engines to replace older types and hold the fort until the main routes were all electrified by about 1980, was a good one and might have served the railway better than what actually happened to it (actually, almost anything might have done that!), but it was dead in the water and holed below the waterline (or the fusible plug) doing a very effective Titanic impression after 1954, and was perhaps naive in the light of the Treasury's reluctance to properly fund big electrification projects, still an issue now.

 

It wasn't steam or even Cox's compromised Rugby data that caused the failure of the 1955 plan's loco policy, and it is worth pointing out at this stage of the discussion that the 1955 plan was highly effective and successful at modernising the railway despite the adverse economic conditions it was about to face.  The development of Motorways and effective heavy road haulage in the following decade tested the railway's resilience to the extreme, and it's survival is in a large part a result of the Plan's views on fast goods, intermodals, air brakes, electric heating, CWR, and MAS; don't forget that.  It was the loco policy and it's requirements for underpowered and ineffective diesels, some of which were seriously problematic when it came to reliability and availability, and the arguably unpredictable unreliability of Treasury funding for the electrifications that should have had all main lines done by 1980 that was at fault, though I would maintain that the faulted Rugby data can be held at least partially responsible.

[The Johnster]

33 minutes ago, toby_tl10 said:

The keyword is at the end. Who cares about a few years later? There could be 3 governments and 12 prime ministers in that period of time, and your boss is changed for the 20th time. When that even worse result eventually emerges, those who caused it have all moved to new positions, retired or deceased! And it keeps happening again and again

This is the basic problem of capitalist democracy, political short-termism and business profit-taking, also a form of short termism.  And this is what is reckoned to be the best form of government; we're doomed.  Don't care much any more, I'll be dead soon anyway and the water is rising...

[tythatguy1312]

1 hour ago, The Johnster said:

This is the basic problem of capitalist democracy, political short-termism and business profit-taking, also a form of short termism.  And this is what is reckoned to be the best form of government; we're doomed.  Don't care much any more, I'll be dead soon anyway and the water is rising...

I feel like we've all spent enough time debating the innate flaws of capitalism and how society as we know it is slowly going to ****, so can we please get back on track. What would British Rail have looked like had the 1955 scheme's Locomotive plan been scrapped early? I feel like it goes without saying that British rail tried to dieselise too fast, resulting in a lot of ignored & misread warning signs. Would better diesels and more efficient steam locomotives have been built continuing on?

[rogerzilla]

Diesel technology wasn't there in terms of power to weight ratio, that was the problem.  The US had well-developed 2-stroke EMD diesels but we couldn't afford them and GM wouldn't allow them to be built here under licence.

 

The best simple non-condensing steam locomotive, one with a perfect boiler and front end, would still only be about 17% efficient at turning fuel into work.  The only way to improve on that is with much higher pressures and superheat, but (as Cox points out) the practical limit is about 300psi before the loco becomes too heavy for the track, and those locos that did run near 300psi (Bulleid spam cans and Hawksworth Counties) became maintenance liabilities and were set for lower pressures in later service.

 

So steam is a dead end unless you have access to lots of cheap fuel and labour, plus availability is about 1/3 that of diesel, which can work 24 hours a day with less frequent and quicker major overhauls.

 

Electric is best but the payback period on electrification is probably "never", so it has to be seen as a public good.  At a time when most electricity came from paying the CEGB to burn coal at about 30-35%  efficiency, minus transmission losses, it probably wasn't much cheaper per mile than burning coal in the loco itself.  Ironically, the same situation now exists with cars: it is cheaper to burn petrol than to run an electric car from public chargepoints (there is still a modest saving if you can charge at home).

[AlfaZagato]

I think the reliability of early diesels is something not readily approached.   Especially in regards to the high-power designs.   By the time of rampant worldwide diselisation, EMD had already been building engines in the correct size bracket for about 10-15 years.   Even with that experience, the design was only developing 100hp/cylinder, and was heavy to do so.

 

There were designs with better specific outputs, but most of them needed significantly more upkeep.   The Kraus-Maffeis were mentioned earlier?   Part of what kept them from being successful in the US was the fact they needed nightly work in the best of times.    SP was used to diesels that could go weeks or months between services.   My understanding is that Deltics were on a similar interval.    Tolerated probably due to nightly maintainence  being somewhat more normal to a still very steam oriented British Railways.

[rockershovel]

1 hour ago, tythatguy1312 said:

I feel like we've all spent enough time debating the innate flaws of capitalism and how society as we know it is slowly going to ****, so can we please get back on track. What would British Rail have looked like had the 1955 scheme's Locomotive plan been scrapped early? I feel like it goes without saying that British rail tried to dieselise too fast, resulting in a lot of ignored & misread warning signs. Would better diesels and more efficient steam locomotives have been built continuing on?

Continuing on what? 

 

I've always felt that with the notable exception of the HST 125,  the mistake was in dieselising AT ALL, rather than continuing with steam until electrification was carried out. 

 

A propos the political background to railways, they are an inherently political topic. The development of modern European nations is directly linked to its railways, especially Germany and Italy.

 

America is generally regarded as the avatar of unrestrained capitalism, but if you look at the development of railways there you see above all, the creation of a transcontinental railway as an ideologically driven project, driven forwards even during the greatest civil war in history and in the face of multiple financial scandals and failures. Even today the American railroads are one of the very few things supported by the federal government as a public good. 

 

Britain never had that question. Its borders were defined and explored, centuries ago. Its railways grew organically from commercial development which funded them from prosaic motives of moving products and supplies around from producer to market. We have been through successive rounds of state intervention for a century without really solving the problem. 

[rogerzilla]

The other factor often overlooked is that railways and coal had a symbiotic relationship that wasn't necessarily appreciated in the 1950s.  The railways were invented to carry coal and the initial network was influenced by this.  Once you stop moving so much coal about, whether for firing locos or for industry, the nature of the railway changes massively, especially outside the SR, which was already a more passenger-oriented railway.  You need far fewer freight locos, marshalling yards, and branch lines to docks and factories.  And Class 14s.

[rockershovel]

3 hours ago, rogerzilla said:

The other factor often overlooked is that railways and coal had a symbiotic relationship that wasn't necessarily appreciated in the 1950s.  The railways were invented to carry coal and the initial network was influenced by this.  Once you stop moving so much coal about, whether for firing locos or for industry, the nature of the railway changes massively, especially outside the SR, which was already a more passenger-oriented railway.  You need far fewer freight locos, marshalling yards, and branch lines to docks and factories.  And Class 14s.

Indeed. Britain's railways evolved to suit a coal-powered, heavy industrial nation mining its own resources within its borders and transporting products for internal sale or to export ports. 

 

Passenger commuter traffic was really a Southern or Metropolitan Railway speciality until the 1960s, hence the lack of electrification outside that area. 

 

 

[Compound2632]

14 minutes ago, rockershovel said:

Passenger commuter traffic was really a Southern or Metropolitan Railway speciality until the 1960s, hence the lack of electrification outside that area. 

 

There were intensive commuter services in all the large conurbations of the midlands, north, and Scotland by the late 19th century. These led to a number of pioneering electrification schemes in the early 20th century, notably the NER's on Tyneside and the L&YR's Liverpool - Southport and Manchester - Bury routes, at a time when the southern companies were only just starting to experiment with electrification. The NER's Tyneside scheme was operational while there was still steam on the underground! There would have been more were it not for the worsened financial conditions after the Great War.

[The Johnster]

18 hours ago, rogerzilla said:

 

So steam is a dead end unless you have access to lots of cheap fuel and labour, plus availability is about 1/3 that of diesel, which can work 24 hours a day with less frequent and quicker major overhauls.

 

It is now, but was it as dead as it was made out to be in the 1950s or early 60s?  Thermal efficiency is less relevant with steam, as so long as the boiler can raise steam quickly enough to do the work the loco is successful, and in some ways less wasteful of polluting heat than diesel, which continues to waste heat up the exhaust when it is idling and does so at a pretty high rate when it is working hard.  And when it is running at speed it is flat out, while steam is running under an advanced cutoff and not much regulator.  Diesel is dirtier under these circumstances because most of what goes up the chimney of a steam loco is, um, steam, which will condense into harmless water droplets which fall close to the railway.  Of course, when the steam loco is working at a lower cutoff and full regulator, accelerating or climbing, a lot of smoke and sulpher is released into the local environment, and steam is then dirtier than diesel.

 

The idea that diesel locos were 3 times more available than equivalent steam at that time is also questionable in practice; depends what you mean by available.  The figure is not inaccurate when one is describing starting up a diesel for use in traffic cf. lighting up a steam engine from cold, which has to be done slowly to mimimise the effects of expansion on joints and valves.  But steam engines in normal service were not allowed to go cold except for boiler washouts about every 10 service days, which took them out of traffic for about 48 hours.  They were kept in light steam between duties, and preparing them for traffic could be done in about an hour, including the driver's prep routine which is 20 minutes steam or diesel.  I suspect the figure was used as a counter argument to those who pointed out that, by and large, a new diesel loco cost about 3 times as much as an equivalent new steam loco.  The diesel can't work 24 hours a day, because it needs to come in for fuel and coolant, but I'd agree it has a greater 'range' than equivalent steam.

 

The mistake of the 1955 Plan, and the 1954 management that was obsessed with modernisation, was to disrupt the Riddles concept of standardised steam to last until electrification was complete (though I'll accept that, with hindsight they may have had a better understanding than Riddles of the likelihood of prising the money out of the Treasury for that happening by 1980).  Even before the standards were built, there were large numbers of relatively new steam engines in service with 30 or more years of life expectancy in them, and the railway was well provided with reasonably modern motive power in most places. 

 

But the decision was that we had to have diesels because the Americans had diesels and that was the way to go, and it has blighted the railway for nearly 70 years, providing the Treasury with an excuse to not fund electrification schemes.  What, I wonder, would have happened, if the railway had been able to go to the Treasury in 1965, with the success of the Manchester/Liverpool electrification under it's belt, and ask for money to electrify the rest of the network to replace the steam engines that were by now appreciably closer to the ends of their working lives?  It was done abroad.

[rogerzilla]

Efficiency is efficiency!  The diesel certainly has losses, but it's all counted in the numbers.  It's like saying you get lower mpg in a car at 70mph, but it's compensated for by travelling for less time.  Of course it's not.

 

I think the Clean Air Acts would have done for steam in any case.  It was always a fraud to claim that the invention of the brick arch allowed locos to "consume their own smoke" and run on cheap coal rather than coke, but it was politically and financially expedient.