Comment by NamTaf | Hacker News Reader

Comment by NamTaf | Hacker News Reader

I’m not sure if it’s just lost in translation, but Wuhan to Guangzhou isn’t even 1000 km so I don’t know where they get the 2200 km they’re quoting. That’s likely a figure for GZ to Beijing.

I have used the high speed line between Wuhan and GZ (and through to HK) several times. It’s currently a 4.5 hour direct journey (once per day) or a 5 hour journey if you change at GZ or Shenzhen. The HSR is 300ish km/h at the moment and that route stops about 4-5 times along the way, off memory.

Aside, I also don’t know how much benefit 1000 km/h travel would bring. That’s an enormous energy requirement to accelerate up to such a speed only to stop 4-5 times along the way. 600 km/h would likely be much more realistic, because if you shorten the duration too much you run into the wall of needing to accel/decel constantly to make the stops.

Lastly, the HSR there is already capable of 350 km/h at least, but they limited it to 300 km/h after a massive derailment that caused a heap of fatalities years ago and never increased it back up again. It may be reading into it too much, but it may also be telling that they didn’t see the benefit of upping the top speed again even when considering the loss of face.

> only to stop 4-5 times along the way

That's the big one. What HSR needs is not even higher top speed but some control breakthrough that allows much higher train frequencies in order to cut down on stops via more trains that can serve more specialized connections (e.g. the local/through etc). No idea what that breakthrough might be, perhaps something as crazy as rocket-assisted emergency braking.

this for example https://www.youtube.com/watch?v=p9Ig19gYP9o

Why not aero braking? You could install little flaps actuated with hydraulics along the train. This could probably be part of the normal braking system. The amount of drag produced by something like this at 1000kmh would likely be very substantial.

You can't just add things to the outside of a train, as you have a certain "gauge" (Not sure if that's the word for it) on a track/tunnel/etc.

You can when you build new lines for your maglev trains.

To be honest, I think wind resistance would play a lot bigger factor than people give it credit for since its force scales nonlinearly with velocity.

At 1000 or even just 600 km/h, wind resistance would do some damage just by letting off the accelerator.

It really depends where you want to go.

If you go from Shanghai to Suzhou via HSR a train goes roughly every 15 minutes. Most trains going east go through Suzhou (since it is a major hub) and it is roughly 30 minutes away which is a decent distance so worth stopping for. The train only gets to maximum speed for about 15 minutes in the middle.

Would be cool to make a system where the train could drop off tailing cars and redirect them to stops, and pick up new cars which are accelerated to a matched speed and then linked, removing need for the train to fully decelerate at intermediate stops.

A similar system could drop off middle cars...

Good point! You could have engines on the front and back cars, approaching a stop could make trailing cars apply slight breaking to create separation between them when going over 'router' tracks, allowing leave the train and new cars to enter in the gaps, then back engine could accelerate gradually to unify the train before switching main power back to front car.

This would be really fun to watch in action.

Or when it fails.

I think 1000 km/h travel would bring HUGE benefits.

State-of-the-art high-speed trains at 350 km/h tend to waste less time than planes for distances shorter than about 1000 km if you include the time it takes to get to the airport, check-in, go through security, and all that nonsense. Beyond 1000 km journeys, planes tend to be more time-saving.

1000 km/h is about the cruising speed of an aircraft so if it were possible to achieve that with a train, it would no longer make sense to take planes for the same journey -- which would be HUGE plus for comfort for, say, trips between Europe and Asia. Imagine for a 10-hour journey that you could walk around freely, enjoy massive amounts of legroom, enjoy the views of Siberia, sleep in peace and quiet, dine at a dining table, and not have to be strapped into a seat all the time. For high-volume routes it is also likely to be lower-carbon in the long run than air travel, and at the very least, can be powered on something more sustainable and less polluting than jet fuel. The bulk of your environmental impact would come from laying the track itself, so it would have to be a route of extremely high tourism or business importance, e.g. Shenzhen-Shanghai-Beijing-Moscow-Warsaw-Frankfurt-Paris-London or some such. Or Los Angeles to New York.

The problem is any accident at that speed everyone on the train or near vicinity is toast. Even a plane coming in to land is around 300km/h.

As opposed to the countless survivors of most plane crashes.

Not to mention the one critical advantage of the train, run out of fuel or some breakdown, you just stop in the middle of nowhere, on a plane, it's likely a different ending unless flying near Hudson river with an amazing pilot.

I don't think too many survivors are expected if a train derails at 280 km/h?

High speed trains don't derail that often if built well. Modern high speed rail systems have better safety records than planes.

China's high speed rail system has had 1 accident with 40 deaths out of several billion passenger kilometers of trips, and that was involving a slower, older technology. The latest, fastest trains in China have not had any accidents to date.

Japan's Shinkansen has had 2 derailments in half a century of operation, one due to an earthquake and one due to inclement weather. Both incidents had zero injuries.

The European systems have had notably higher accident rates but still surpass the safety records of planes.

The article says that for 1000 km/h they would be using vacumn tubes. With vacumn tubes there's no air resistance and theoretically no need to continue adding power once you're at speed.

Shanghai-Beijing route is 350 kmph again, they think about the ways to increase it up to 400 kmph.

There are currently 61 high-speed trains from Wuhan to Guangzhou on most days (although to different stations in Guangzhou). The fastest one is now just under 4 hours.

That's only if it does stop 4-5 times, though. Japan's HSR has trains where some stop at intermediate stations and some just go between major cities.

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