The trouble with trying to make trains go faster

The trouble with trying to make trains go faster

Since George Stephenson’s Rocket, designers have been trying to make trains go faster and faster. Despite all the innovations, particularly in the last 50 years it’s still a dream that all cities around the world could be connected by high-speed trains that complete journeys in a flash, allowing you to arrive at your destination relaxed and untroubled. Why is this the case?

Going fast on rails brings its own special set of problems. Human bodies are simply not built for rapid acceleration, we experience certain low frequency motions that create discomfort – a feeling of “motion sickness". We also experience rapid acceleration, for example, each time we take off and land in a plane.

Then there is the logistics of trying to send a train faster along a track. Going fast means pushing air out of the way, which also requires a lot of power. A train travelling at 300mph (480km/h) uses roughly 27 times more power than one travelling at 100mph (160km/h). And at ground level the air is a lot denser than it is at 35,000ft (10,600m) where airliners regularly cruise. That means more resistance, and therefore more vibrations.

But train operators and companies are pushing for ever-greater speeds, and they have been trying out a range of innovative designs that they hope will make trains go super-fast and be ultra-comfortable at the same time.

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Top speed is about as useful a metric as megapixels are for digital cameras.

Easy for lazy marketing, completely worthless for determining how good a system actually is.

More resistance means more vibration? Where did that come from?Planes routine fly at 200-400mph at 5000' - 10000'. They must be vibrating a lot that I somehow missed.

RyanS said:

Top speed is about as useful a metric as megapixels are for digital cameras.

Easy for lazy marketing, completely worthless for determining how good a system actually is.

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Absolutely!! My favorite example being the NS line between Atlanta and Birmingham. Maximum speed 79 mph, thanks to curves almost none operable at that seed. Raise the speed limit to 125 mph or more would mean nothing for run time.

More vibrations? That is only one goofy statment of many in a quotation that is near all nonsense.

jis said:

More resistance means more vibration? Where did that come from?Planes routine fly at 200-400mph at 5000' - 10000'. They must be vibrating a lot that I somehow missed.

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They sure do vibrate a lot, if the Chinese plane I flew on in the 1980s is anything to go by... the wall of the fuselage rhythmically moved back and forth about a foot the entire flight.

I think they make fuselages stiffer here in the "West".

George Harris said:

RyanS said:

Top speed is about as useful a metric as megapixels are for digital cameras.

Easy for lazy marketing, completely worthless for determining how good a system actually is.

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Absolutely!! My favorite example being the NS line between Atlanta and Birmingham. Maximum speed 79 mph, thanks to curves almost none operable at that seed. Raise the speed limit to 125 mph or more would mean nothing for run time.
More vibrations? That is only one goofy statment of many in a quotation that is near all nonsense.

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Yeah, it is certainly right up there in the top ten idiotic articles I have read in a while.

Ok, it's a blundery article...but I do wonder about a point that comes up from it:

Xpress West dialed back their planned top speed at least in part because of power consumption issues. The same thing happened in China, though there safety likely also played a non-trivial role. It at least seems to me that there's a limit on what can be cost-effectively managed in terms of top speeds, at least in terms of mass-marketing. Is there likely to be a significant sub-market that would spring for...say, a 250 MPH train as the "express" while the "non-express" caps out at 186 MPH? I'm speaking in terms of top speeds with the understanding that the averages would be similarly affected (i.e. the 186 MPH train might average 110 MPH while the 250 MPH train might average around 150 MPH).

For another way to put it, there's clearly a market to go WAS-NYP in under three hours (witness the relative successes of the Metroliners and Acelas in their respective eras). There's a lot of talk in the medium/long term of getting that closer to two hours. What sort of premium would knocking that back towards 90-minutes-or-less actually command? Yes, I recognize there's a gain in capacity and in equipment utilization, but while it's obvious that a lot of folks (or at least, their expense account managers) will plunk well over $200 for a ticket on the Acela over the Regional (albeit likely having at least something to do with train priority and relative train quality), how many would actually plunk down another $100 to save another 30 minutes?

I know this total is not zero, but it is also not unlimited. I could see a situation emerge on some routes where a line is engineered for some obscenely high speed but very few trains come close to it. On the NEC, for example, it wouldn't shock me to see the Next-Gen project end up with only a handful of trains actually running at the top speed "allowed" due to power constraints; likewise I could see a long-term situation out in CA where a train that can knock an extra 30 minutes off the "regular" LA-SF time commands a premium by way of both faster speeds on some segments and skipped intermediate stops...but you don't actually have a massive number of those trains (you mainly get them as "extra specials" at peak hours).

If the next Gen NEC gets built in my lifetime, I'll eat my shorts.

Green Maned Lion said:

If the next Gen NEC gets built in my lifetime, I'll eat my shorts.

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I was looking at the idea conceptually more than anything; put another way, if anything the above probably argues against such a plan.

Green Maned Lion said:

If the next Gen NEC gets built in my lifetime, I'll eat my shorts.

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Most fortunately you will not need a large collection of shorts to consume in this way.

There are lots of factors concerning how a train is able to reach higher speeds. Power consumption is one, aeronautical drag is another, friction is a third, and there is more. Aeronautical drag is the reason we've started seeing thos odd-looking duck-nose trains in the last few years, apparent their more aerodynamically efficient then just a sharp point.

peter

The Japanese have been doing duck nosed Shinkansen trains now for more than a decade. They actually have some of the most bizarre nose structures that I have seen anywhere.

I was under the impression that the duck noses had more to do with minimizing the noise that comes with entering/exiting a tunnel at high speed.

There seems to be more errors than fact in this article. Seemingly written by a journalist, with a journalist education.