"Alfa-X, the world’s fastest bullet train"

[longhorn]

https://www.telegraph.co.uk/news/2019/05/10/worlds-fastest-shinkansen-bullet-train-starts-test/

"It is a futuristic shade of silver, has a super long nose stretching 72 feet - and is on track to become the world’s fastest bullet train.

Japan, the birthplace of high-speed rail travel, has unveiled its latest new generation bullet train Alfa-X, which will be able to travel at top speeds of 224 mph."

I think 250 mph is probably the highest speed one would want to go using rail. Any higher, and I would think Hyper Loop or "Maglev" (yeah I know.....) would be the preferred mode.

Interesting using such a long nose for better aero and less noise. Physics doesn't care about aesthics.

 

[urpert]

Quote from the article:

“It will also be - perhaps unsurprisingly - dramatically faster than trains in the UK, ”

I wonder what the Telegraph’s editorial position on HS2 is?

 

[hexagon789]

360km/h is rather unimpressive I must say.

 

[Giugiaro]

Operators are planning to test run the new bullet train at its maximum possible speed of nearly 249 mph, although its top speed when in commercial operation will be capped at 224 mph.

400km/h is far from the 574.8km/h of the French V150.
It seems the Japanese aren't really that keen to do French leg stretches. Either that or there's no section in their railway network where they can go over 400km/h...

 

[HankyuDentetsu]

There are a few mitigating factors which have kept the Shinkansen network from making significant advances in speed over the last 20-30 years.

The biggest problem is that a significant portion of the network runs through narrow tunnels bored through mountainous landscape. This is why almost every new model of high speed train in Japan has an extremely long nose (compared to European HSR at least) to mitigate the enormous pressure changes from entering these narrow tunnels at high speeds. On the Tokaido Shinkansen (Tokyo-Osaka) for example, the line is limited to 285kph in part because the current rolling stock suffers structural damage through pressure changes entering the tunnels any faster than ~300kph. They have also found significant vibration issues in the tunnels themselves when travelling over the 300 mark.

If they had put a little more foresight into future line speeds when building the core of the network, I'd imagine you would see far higher speeds being achieved.

But two other factors are also at play; given the heavily mountainous terrain in Japan (roughly 70% of the landmass is mountainous), it is extremely difficult to build rail in a straight line for prolonged periods of time, meaning that curves are frequent and tilting technologies have to be employed. There are exceptions to this of course; they're currently testing up to 360kph between Kyoto and Maibara on the Tokaido Shinkansen using fairly standard (albeit new) rolling stock.

Finally where there is flat land in Japan, there are people, and often the Shinkansen tracks are surrounded very closely by residential and commercial development - this creates a significant noise issue, and limits line speeds in a significant number of areas.


So the Alfa-X is impressive not for it's proposed maximum speed, but for the extremely advanced aerodynamics, stability control, and noise mitigation techniques at play to allow the train to operate in such difficult conditions.

It's also obviously worth reminding that they're currently building the Chuo Shinkansen - a Maglev system with an operating speed of 500kph will be operational between Tokyo and Nagoya by 2027, completely blowing every other high speed network in the world out of the water.

 

[hexagon789]

There are a few mitigating factors which have kept the Shinkansen network from making significant advances in speed over the last 20-30 years.

The biggest problem is that a significant portion of the network runs through narrow tunnels bored through mountainous landscape. This is why almost every new model of high speed train in Japan has an extremely long nose (compared to European HSR at least) to mitigate the enormous pressure changes from entering these narrow tunnels at high speeds. On the Tokaido Shinkansen (Tokyo-Osaka) for example, the line is limited to 285kph in part because the current rolling stock suffers structural damage through pressure changes entering the tunnels any faster than ~300kph. They have also found significant vibration issues in the tunnels themselves when travelling over the 300 mark.

If they had put a little more foresight into future line speeds when building the core of the network, I'd imagine you would see far higher speeds being achieved.

But two other factors are also at play; given the heavily mountainous terrain in Japan (roughly 70% of the landmass is mountainous), it is extremely difficult to build rail in a straight line for prolonged periods of time, meaning that curves are frequent and tilting technologies have to be employed. There are exceptions to this of course; they're currently testing up to 360kph between Kyoto and Maibara on the Tokaido Shinkansen using fairly standard (albeit new) rolling stock.

Finally where there is flat land in Japan, there are people, and often the Shinkansen tracks are surrounded very closely by residential and commercial development - this creates a significant noise issue, and limits line speeds in a significant number of areas.


So the Alfa-X is impressive not for it's proposed maximum speed, but for the extremely advanced aerodynamics, stability control, and noise mitigation techniques at play to allow the train to operate in such difficult conditions.

It's also obviously worth reminding that they're currently building the Chuo Shinkansen - a Maglev system with an operating speed of 500kph will be operational between Tokyo and Nagoya by 2027, completely blowing every other high speed network in the world out of the water.

Forgive me if I'm wrong, but isn't the Tokaido the original Shinkansen line? If so going from the original 210km/h to 285km/h is quite impressive in itself, so I don't think we should be too hard on the original engineers for not envisaging 300km/h+ running.

Also, thank you for explaining why Japanese high-speed trains have such long noses in many cases, is it route specific because some don't have as pronounced noses as others?

 

[edwin_m]

As well as having lots of straight track, the French have trains with power cars, so a super-powered version for record attempts can be created relatively easily by removing most of the trailers. The Shinkansen has underfloor motors so shortening the train doesn't affect its power to weight ratio much.

 

[HankyuDentetsu]

Forgive me if I'm wrong, but isn't the Tokaido the original Shinkansen line? If so going from the original 210km/h to 285km/h is quite impressive in itself, so I don't think we should be too hard on the original engineers for not envisaging 300km/h+ running.

Also, thank you for explaining why Japanese high-speed trains have such long noses in many cases, is it route specific because some don't have as pronounced noses as others?

No you are quite right, the Tokaido Shinkansen is the original line, so it's rather unfair of me to criticise!!

It really is quite impressive that 285km/h will be achieved on this line, in part because of the challenging terrain but also because of the insane peak time service frequency. From March 2020 there will be 17 services per hour, up from 15ph today. So that's a 16 car, 400m long train running in each direction between Tokyo and Osaka every four minutes at peak times: the frequency and capacity of the Tokaido line is mind boggling.

In terms of nose lengths, serious noise and tunnel compression issues seem to arrive in the high 250km/h+ range, meaning that only the fastest lines sport rolling stock with the long noses. Several of the more rural Shinksansen lines operate in the low-mid 200km/h range or slower still, which use older rolling stock that have much shorter noses (Joetsu Shinkansen - 240km/h, Yamagata Shinkansen - 130km/h, Akita Shinkansen - 130km/h), in addition to older stock that has recently been phased out - the E1 (240km/h).

All new stock; N700S, E5, E6, are 300km/h+ capable and have similar elongated noses. (except the lovely E7 which maxes out at 275km/h and only operates at 260).

Another interesting facet about the Alfa-X prototype, is that currently travel through the Seikan Tunnel - the world's longest undersea tunnel at 53.85km long - is currently limited to 140km/h for Hokkaido Shinkansen services because it shares the tunnel with freight trains which are in danger of being derailed by the pressure wave if the Shinkansen service was to travel any faster. Presumably the Alfa-X's new aerodynamics may allow them to uprate the speed through this section too.

 

[hexagon789]

No you are quite right, the Tokaido Shinkansen is the original line, so it's rather unfair of me to criticise!!

It really is quite impressive that 285km/h will be achieved on this line, in part because of the challenging terrain but also because of the insane peak time service frequency. From March 2020 there will be 17 services per hour, up from 15ph today. So that's a 16 car, 400m long train running in each direction between Tokyo and Osaka every four minutes at peak times: the frequency and capacity of the Tokaido line is mind boggling.

In terms of nose lengths, serious noise and tunnel compression issues seem to arrive in the high 250km/h+ range, meaning that only the fastest lines sport rolling stock with the long noses. Several of the more rural Shinksansen lines operate in the low-mid 200km/h range or slower still, which use older rolling stock that have much shorter noses (Joetsu Shinkansen - 240km/h, Yamagata Shinkansen - 130km/h, Akita Shinkansen - 130km/h), in addition to older stock that has recently been phased out - the E1 (240km/h).

All new stock; N700S, E5, E6, are 300km/h+ capable and have similar elongated noses. (except the lovely E7 which maxes out at 275km/h and only operates at 260).

Another interesting facet about the Alfa-X prototype, is that currently travel through the Seikan Tunnel - the world's longest undersea tunnel at 53.85km long - is currently limited to 140km/h for Hokkaido Shinkansen services because it shares the tunnel with freight trains which are in danger of being derailed by the pressure wave if the Shinkansen service was to travel any faster. Presumably the Alfa-X's new aerodynamics may allow them to uprate the speed through this section too.

Thank you for the detailed reply, even 15 trains an hour is impressive so 17 is quite something.

 

[HankyuDentetsu]

Thank you for the detailed reply, even 15 trains an hour is impressive so 17 is quite something.

You're welcome, and agreed - it is quite something, particularly for services whose delays are measured in seconds, not minutes!

 

[edwin_m]

It's only possible because the delays are measured in seconds. Is this also the route where some of the trains pull into long loops for their station stops, during which a couple of non-stop trains overtake, and they then occupy the timetable path left empty by the next stopping train?

 

[hexagon789]

It's only possible because the delays are measured in seconds. Is this also the route where some of the trains pull into long loops for their station stops, during which a couple of non-stop trains overtake, and they then occupy the timetable path left empty by the next stopping train?

And the system is pretty much seperate to the classic network which I imagine must help compared to European high-speed lines where the first and last segments are often over classic lines into city stations.

 

[HankyuDentetsu]

Yes and yes to both of you - the current set up of 15 tph at peak allows for 10 express, and 5 semi express services. Every station on the line has a minimum of 4 tracks running through it, meaning the 5 semi-express services can stop and wait at intermediate station platforms while the express blaze through on the central lines at full speed. Two express services sometimes pass before the semi-express resumes its journey. Amazingly from March next year that goes up to 12 express services.

This system is common across most of Japan's standard rail networks too - it's extremely efficient and allows an incredible number of express services to be run per hour.

And yes, with the exception of the Hokkaido line - specifically the Seikan Tunnel - Shinkansen services do not share the lines with any other service, even in city sections, making it extremely reliable. Delays are seldom as a result. Shinkansen lines are often run entirely on elevated viaducts (or tunnels) on all but the most rural of land, meaning there is no interference at all from ground level events.

The joys of having an enormous amount of money to spend during the bubble years, and linearly connected hyper dense population centres which are perfectly distant for maximum HSR efficiency! No need to mess around with hubs and spokes here!

 

[Catracho]

And yes, with the exception of the Hokkaido line - specifically the Seikan Tunnel - Shinkansen services do not share the lines with any other service, even in city sections, making it extremely reliable.

Not to be too nit-picky, but the Akita and Yamagata Shinkansen also partially run on conventional lines. Your argument still stands of course - the almost complete separation from the traditional network is a core reason for the Shinkansen's reliability.

 

[edwin_m]

Then again, the traditional networks in Japan are highly reliable too.

 

[HankyuDentetsu]

Not to be too nit-picky, but the Akita and Yamagata Shinkansen also partially run on conventional lines. Your argument still stands of course - the almost complete separation from the traditional network is a core reason for the Shinkansen's reliability.

Ah I was under the impression that both of those lines were reguaged, meaning that standard JR rolling stock could no longer use them? I must admit I don't know much about either and have never used them, so apologies if I'm wrong

 

[WideRanger]

Ah I was under the impression that both of those lines were reguaged, meaning that standard JR rolling stock could no longer use them? I must admit I don't know much about either and have never used them, so apologies if I'm wrong

No, you are correct. Those lines were converted from traditional lines into Shinkasen Lines, and in the process lost connection with the rest of the historic network (whch remains narrow gauge).

 

[Catracho]

No, you are correct. Those lines were converted from traditional lines into Shinkasen Lines, and in the process lost connection with the rest of the historic network (whch remains narrow gauge).

There are still services other than the Shinkansen operating on them though. And the Omagari - Akita section (roughly 32 miles) of the Akita Shinkansen is dual gauge/separate gauge, allowing both 1067mm and 1435mm stock to operate on the line.

 

[HankyuDentetsu]

There are still services other than the Shinkansen operating on them though. And the Omagari - Akita section (roughly 32 miles) of the Akita Shinkansen is dual gauge/separate gauge, allowing both 1067mm and 1435mm stock to operate on the line.

I didn't know that. You learn something new every day, thanks for clarifying Catracho.