It depends on exactly how you attempt to define "efficient"--but, honestly, none.

Diesels have a far higher thermal efficiency (i.e. BTUs converted to work/movement), a higher availability (less servicing necessary), the ability to be run in multiple from one control, the ability to run with one person running it all, and more.

The only way steam potentially comes ahead is the old adage "a diesel can start a train it can't run at speed; a steamer can run the wheels off a train it can never start."

I must say that the TGB 4 post above is spot on. Once the diesel revolution started in earnest right after WW2 steam didn't have any chance of winning.

Back then the very best steamers achieved a thermal efficiency ( % of fuel turned into pull at the drawbar) of 6-7% on a good day vs. the diesels of 30-35%. No contest. One engineer ( no fireman) could run any number of units coupled together to achieve the horsepower needed for a given assignment, diesel fuel was readily available cheap and produced no ashes.

Most coal mined after WW2 was mined by mines under contract to the national United Mine Workers union led by John L. Lewis. Every two years he would threaten a national strike and frequently pull the men out which put all coal users under fear of running out. Not an issue with diesels.

Also, per service mile the diesel demanded about 60% fewer men in the shops to keep it running reliably.

All in all in was surely a no contest situation.

This is clearly evidenced by what happened. The American railroad locomotive fleet went from 40,000 steamers, 4,000 diesels in 1946 to 35,000 diesels and 400 steamers in 1956.

When you look at it objectively we're lucky as many steamers survived as did.

IMHO-Ross Rowland

One factor that made rapid Dieselification I think was the competion with auto transportation. In Germany (both) steam survived for a much longer time. And Germans (especially West) had invested a lot in trains. Romania, who had less automobiles per capita even compared to East Germany moved faster into Dieselfication (electrification was accelerated more into the '70's).
Not to many U.S. steam locomotives survived. Darn, how jerks could they be and not preserving any of "New York Central" Hudson steam locos... a streamlined Dreyfuss one could ctach the eye even of an automobile maniac. Well, it's a wonder that more then 1 Big Boy locomotives survived.

I think Ross's statistic makes it look more like an equal trade, when it was not. The change was more severe. I believe if you measure it in tractive effort, the replacement was a much lower ratio diesel:steam, because the diesel "units" were replacing individual big steam power like 2-3 to one, but, the diesels had (have) much higher availability, so not as many units were required.

That is, the interesting comparison might be total tractive effort. The total tractive effort of the fleet in steam days would have been much higher than that in diesel days, but much of that steam tractive effort was in the workshop getting boiler washes or whatever. That is why so many locomotive servicing areas could close.

So from Ross's numbers, you have a transition from 44,000 locomotives to 35,400 locomotives, but I believe the total tractive effort decline was more severe.

One of the exchanges I had on the Narrow Gauge forum concerned water service. There were something like 15 water tanks from Alamosa to Durango. The few from Alamosa to Antonito were on city water. Then a couple more had gravity feed from springs or such. But the rest, they had pumps. Many of those pumps were gasoline motors, and a few (like Gato) still had their steam pump plant at least on backup.

Towards the end, when trains ran only every few weeks, every time a train was scheduled, somebody had to go and visit every one of those tanks, and start the motor, and make sure the tank was full of water.

That is just one example of the labor and cost of running steam, which is eliminated when using diesel.

Add to the above the incredible problems with running in territory with highly mineralized, alkaline water at best, or no water at all in a dry season, such as across Arizona and New Mexico--among the first regions in the country to "go diesel" (Santa Fe, Southern Pacific). I've heard it described as the moral equivalent, as far as steam loco maintenance was concerned, as trying to run mainline trains by burning lignite, pulpwood, or old tires.

Both the Santa Fe and SP ran literal trainloads of water to various points on the system, both for their own use and for others. The Grand Canyon Railway still runs water to the South Rim to refill steam tenders on the now-rare steam operating days, adding to the costs. Last I knew, at least two towns in northern Arizona still had water systems that were still maintained by BNSF to recent days.

The end of steam and the steam verse diesel debate will go on for years to come. Time has also added to the debate.

The Nickel Plate Road began an early conversion of their yard power, but hung on to the 700 class until a steel strike put the last fires out and they rented diesel locomotives from the C&O to fill in. The NKP claimed, in test of the 700s against the diesels, that the operating cost margins, were paper thin.

The N&W ran steam for a long time because they hauled what they burned and had put a lot of improvements into their steam locomotives and their servicing. The N&W was also standardized mostly on 3 or 4 models.

The fast and sudden end of the N&W steam came about because of the merger with the Virginian Railroad. The New York stock advisors advised them to get rid of steam, because they were looked at as an antiquated railroad. The stock swap was going to cost the N&W big time, with the rapid dieselization, it cost the Virginian. The ratio in the stock swap, completely flipped in the N&Ws favor.

The N&W also had one of the best 0-8-0 switchers, which was an improvement of a C&O 0-8-0. These were built new in 1953 and they all went to scrap in 1958 with their original boiler tubes in them.

It also must be said, that early diesels had many problems as well. They were not nearly reliable as some make them out to be, in addition, there was a big learning curve for employees to learn the new machines. Alco had a very reliable switcher with the 539 engine and that showed with the large number of Alco S1 and S2 locomotives sold. The early EMD "F" units were drawbar coupled, so when one failed, they all went to the shop. The early EMD engines were bad leakers and power assemblies were hard to change. All makes of cab units suffered from this.

The end of steam was going to come after the war, as many steam locomotives were just plain worn out from the wartime traffic. But many improvements were made to steam shortly after the war that greatly increased their reliability.

"Super Power" steam and roller bearings where a great help, but a little too late.

The water situation in Arizona and California (between Winslow and Barstow) caused the US War Production Board to authorize EMD to produce FT's for ATSF during WWII when the USN needed 2000 12-567's for LST Landing Ships to enable the invasions of Europe and Pacific Islands.

As to steam being more efficient it was very limited and did not include construction of steam infrastructure (coal wharves, water facilities, ash facilities etc.) or shopping of engines. For example PRR did a study of using diesels on the NY&LB in North Jersey. The study showed steam (K4s) cost less until the engine needed a major shopping versus diesel (Baldwin BP20) which could be used elsewhere such as Columbus. PRR ran the K4's there to the end of steam.

Phil Mulligan

It was also said that a problem with a steamer could be diagnosed in 10 minutes and it would take a week to fix. A diesel would take a week to diagnose and 10 minutes to replace the bad component. The idea that no new and different infrastructure was going to be needed for diesels is simply not accurate, but steam era facilities could be altered...... I used to have an engineering textbook from the early 1950s that predicted steam would no longer be manufactures and would be replaced by diesels when the capital investment in the steam was repaid in the mid to late 1970s. I wish it had happened that way.

I would guess that after WWII there were less then 5% of the steam locomotives that were less than 15 years old. The rest were obsolete and warn out. It was opportunity made in heaven for the diesel.

But how fast was diagonozed and repaired an electric locomotive?
"U.P." kept it's big steam locos even after mid '50's. Probably 'Big Boy' and 'Challanger' had some adavantages.
Steam locomotives at night (or allmost all at night): https://www.danzigergallery.com/artists ... thumbnails

One other point not yet brought up is that N&W built their own engines so they had also invested in that part of the infrastructure.
I have heard it said (but have not researched) another part of their dieselization was that component parts from makers such as Elesco, Hancock and The Superheater Company were getting hard to find or being discontinued due to drop in demand. Anyone else have comment on this? ..............mld

The UP, and many railroads, kept steam for traffic surges. They went whole months without any steam operating, and they put the steam in service for short periods when there was a peak demand for transport. When the engines came due for major servicing, they were put on the scrap line. It was purely a matter of using up investment they already had, and when the time came that it was required to invest more money in the steam power, they shut it down.

The SD class diesel locomotives really killed the last steam. They were more reliable, and made a whole fleet of F locomotives available as standby power. Also, because the railroads also had nearly standard, equivalent locomotives, it became much easier to short term lease power for seasonal demands.

The places where steam continued were places where the financial future of the railway was in doubt. Examples include the D&RGW narrow gauge, the Westside Lumber Railroad, or the switcher at Dallas Union Terminal (the railroads were hoping that passenger service would end before a diesel replacement was needed).

This was a problem in the early days of diesel, especially when a railroad had a "buy something from everyone to see what works" policy (see PRR, British Railways, etc.). By the time builders (especially the ones that survived, EMD and GE) were up to second generation diesels, and the railroads developed more first-hand experience, the art of diagnosis and servicing had improved substantially.

Sorry if I do put a stupid question, but I don't know too much about steam locomotives: "N. & W." couldn't keep in working conidtion the J class locomotives for weekend work? Maybe the did looked antiqueted, but people are atracted by steam locomotives and maybe for this they could get more passangers.

On the other hand, where can I find pictures with pre '40's "Great Northen" and "Milwuakee Road" electric locomotives "in action" pulling passanger trains.