The limit is piston & valve speed. The same ideas as a limiting RPM in an ICE/diesel engine.
At 531 RPM the pistons would be making 531 complete fore/aft cycles per minute. or for round numbers, 10/sec or 100 millisec per cycle, and 50 millisec per stroke in either direction.
That’s an awful lot of slamming back and forth for something so large made of 1930s tech.
We’ve got the same issues in the airline biz.
FAA & DOT and local airport authorities try to argue that they don’t need to invest in infrastructure since on-time performance is adequate in the Northeast corridor and has been mostly unchanged for decades.
The airline industry retorts that we’ve slowly but surely added about 40% to the scheduled gate-to-gate times since the 1970s and have made zero progress on better on-time performance. All that 40% does is get fed into the maw of traffic delays caused by, first among many other reasons, inadequate infrastructure investment.
And so it goes.
Yes.
I’m away from my railroad reference material, but in the 1930s several nations were doing experimental work with higher and higher speed locomotives: Britain, the US, and Germany. But I take your question to be about regular scheduled services, and there the US and Britain were way out front.
As I recall, portions of the Pennsylvania Rail Road’s Washington-to-New York corridor, some portions of the Pennsy and New York Central routes through Ohio and Indiana, and some long straightaways on the Santa Fe out West saw daily trains exceeding 100 mph. I’m less familiar with the British routes, but I think both the East Coast and West Coast routes to Scotland had some sections with 100 mph running.
Electrification and diesel-electric locomotives presented the promise of making such service widespread in the US after the war, but aviation had made even greater strides and began siphoning off the business travelers, while railroads began taking a closer look at their accounting and realizing the freight service was what was really paying the bills. After a 1946 train crash near Chicago, federal regulations restricted speeds on nearly all US rail lines to 79 mph.
That would be my answer. There were some attempts at compounding train engines, but the low pressure cylinder mass was a problem.
A couple of corrections/clarifications to my post of yesterday:
Looks like Germany in the 1930s was actually the world leader in scheduled railway speeds (I had misremembered their work as mere demonstrations). The Berlin-Hamburg Flying Hamburger, introduced 1933, ran 160 kph (100 mph) in places, and the end-to-end schedule speed was 124 kph (77 mph). Several other cities had similar high-speed connections to Berlin. Though the Nazis claimed the advances for National Socialism, most of the work predated Hitler.
This piece about American train speeds in the 1930s lacks any obvious source note, but reads like a piece published in a British railway journal. It suggests that the fastest schedule speed for entire runs from one US city to another topped out at 77 mph. That doesn’t completely foreclose my claim that there were sections where 100 mph was regularly achieved, but 90 mph is probably more likely. Late in the decade, as more diesel-electric locomotives were delivered, 100 mph running became much more achievable.
The New York–Washington route we today know as the Northeast Corridor was electrified in 1935 by the Pennsylvania Rail Road, and the GG-1 locomotives ordered for that service were designed for a top speed of 100 mph, though schedule speeds never exceeded 80 mph as far as I can tell.
Thank you, Mr. Downtown. Were my time-traveler to inspire a move toward faster trains in that era, improvements would probably be in rail-beds and perhaps electrification, yes?
Yes, though things changed dramatically during the decade, as diesel-electric locomotives proved themselves beginning in 1934 in the US. That solved the problem of steam power’s reciprocating motion, without the need for costly overhead wiring. Railroad electrification using overhead wires or third rail had been known since the 1890s.
Two other problems present themselves with routine running over 80 mph: grade crossing accidents go up to unacceptable levels, and trackside signaling becomes insufficient. To get close to 100 mph, signals have to be presented on the driver’s in-cab display rather than being glimpsed (perhaps through fog) as they rush past.
The United States is a Great country and our “Train Transport” is just fine! We use trains almost exclusively for hauling freight, not people and it works just great this way. We do this that way because most people ( by far ) would much rather travel by Jet or car than a train. Jets are much faster and cars take us where rails won’t and allow us to have flexible schedule.
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