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Old August 1st, 2012, 11:53 PM   #81
hmmwv
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I have to say ballastless tracks is certainly better suited for very high speed trains, it allows the tracks to be positioned more precisely and prevent unwanted debris from being thrown when a train passes by. Yes TGV is able to go fast on the ballast tracks but I'd imagine the maintenance requirement is quite strict too. I rode the TGV from Paris to Aix-en-Provence a couple of years ago and in sections it went to above 300km/h but the ride was shockingly uncomfortable.
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Old August 2nd, 2012, 02:12 AM   #82
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Quote:
Originally Posted by foxmulder View Post

1) Chinese network is mostly elevated which has quiete a lot of advantages:

a) Required footprint of the lines decreases. (You can tell from the pictures that Beijing-Shanghai line's foot print is less than half of those in Spain and France)
This is a fair enough point, however it's an extremely inefficient use of resources.

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b) It is inherently safer for people who lives around.
Wenzhou train crash. How close was it to utterly destroying the nearby houses? Because it's falling from a height, it can travel further. Also this is an utterly baseless claim.

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c) It creates a foundation to increase minimum horizontal and vertical curve radius of line since elevation imperfections of the geography becomes less of an issue. This in turn translates into a higher potential maximum speed.
Or you know, elevate the track in the valleys, and tunnel through the mountains. (Which is exactly what every HSL in the world does, btw). Having it on viaducts the entire route is just wasteful when on a large area of flat land.

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2) The minimum curve radius is 7000m without any exceptions: The advantage of this obvious, you can go at top speed all the time. This is why Chinese lines even though they are limited to 300km/h right now still have the highest average speed.
This point has been proven wrong multiple times, stop bringing it up. The highest average speed is because it has the longest distances between stops.

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3) It uses ballastless track:

a) It requires significantly less maintenance. There are many reasons for this, will not go into details. a simple google search gives nice information.
Correct.

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b) It is more stable so do not require solutions to stabilize it like this:
This solution only really exists in Japan, and it is to stabilize the ballast in the event of an earthquake.



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So, again it presents the potential for higher speeds.

Only disadvantages of these standards is the cost. It is more expensive to build.

Moreover, when one considers the sheer scale of the Chinese network build with these standards, it is easy to claim, in high speed rail infrastructure, China is the leader.
I think you'll find that in terms of sheer amount, China is the leader. But remember it was German engineers who planned and designed nearly all of it. China simply has the political will to build these lines, not the technical know-how nor experience, thus it's hard to say that China is truly the leader.
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Last edited by Sopomon; August 2nd, 2012 at 08:16 AM.
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Old August 2nd, 2012, 08:35 AM   #83
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Quote:
Originally Posted by hmmwv View Post
I have to say ballastless tracks is certainly better suited for very high speed trains, it allows the tracks to be positioned more precisely and prevent unwanted debris from being thrown when a train passes by. Yes TGV is able to go fast on the ballast tracks but I'd imagine the maintenance requirement is quite strict too. I rode the TGV from Paris to Aix-en-Provence a couple of years ago and in sections it went to above 300km/h but the ride was shockingly uncomfortable.
The big advantage of traditional ballasted track is that it is much easier to correct it again if for some reason the foundation moves. With ballast less track you are essentially building your whole line on a bridge. Since that is what the Chinese do anyway, it makes sense for them.
However, if you are going to build a line at grade the picture changes.

As to the TGV becoming uncomfortable, that's more due to the fact that SNCF cares somewhat less about passenger comfort than many other railways...
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Old August 2nd, 2012, 08:41 AM   #84
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Originally Posted by aquaticko View Post
Granted, most if not all of these will likely end up operating at the 350kmh threshold due to concerns of economy and efficiency, but what comes after that?
There is still a lot to be gained by further improving network integration. I am going to London from Lausanne soon, and will lose 1 1/2 hours changing stations in Paris. If for example SNCF were to build a TGV tunnel under Paris (an idea that comes up now and then), with a new underground station in the middle trips that now require a change of station in Paris would become more convenient.
France also plans a high speed connection across the south (Bordeaux - Toulouse - Montpellier).
These are just two examples of possible incremental improvements to the system that would reduce trip times for quite a large number of passengers, without having to increase train speed times beyond what is economically practical.
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Old August 2nd, 2012, 09:03 AM   #85
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Track geometry is not really an innovation for HSR. Ballastless tracks are, but they pale compared to what really made HSR feasible: rolling stock and signaling. Without modern in-cab signaling, HSR would be extremely dangerous (e.g., train engineers relying on visual signs to proceed, limit speed, stop, deploy brakes etc).

Ballastless tracks have lower maintenance costs and downtime. They are more noisy though, albeit the mains source of trains travelling 250km/h+ is air displacement, not friction deflection on the ground.

Now I'm curious to know at which average speed Maglevs start being more appealing as they can deal with steeper grades. Given enough power, TGV tracks could host trains travelling at 600km/h on 5000m curve radii without risks of tipping over. But that would be tricky for passengers unless seat belts were deployed on seats. But the wear and tear would be dramatic and the component safety for mechanic parts would be raised to some akin to airlines.

I think higher commercial speeds will be only attainable with maglevs. It is a disgrace Germant ditched their early 1990s plan for a network of maglev tracks there.

TAlking of maglevs, I have a question: what is, at current technology state, the minimum time interval between two trains travelling at maximum power on a same maglev track in the same direction?
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Old August 2nd, 2012, 09:37 AM   #86
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Quote:
Originally Posted by Sopomon View Post
I think you'll find that in terms of sheer amount, China is the leader. But remember it was German engineers who planned and designed nearly all of it. China simply has the political will to build these lines, not the technical know-how nor experience, thus it's hard to say that China is truly the leader.
Also remember that China is where Europe and the US were in the 19th century.

During the early and mid 19th century Europe and the US build railroads at a tremendous pace. That is because both were industrialising rapidly at that time. Also then it was not uncommon for large stations to be built outside cities, just like it is in China now. The cities later expanded to engulf them. One can expect that the same will happen in China.
China has the advantage of being able to do this at a moment where the state of the art has advanced so that 300kph trains are normal. But they have this advantage because they arrived late at the party...
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Old August 2nd, 2012, 09:38 AM   #87
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Originally Posted by Suburbanist View Post
Given enough power, TGV tracks could host trains travelling at 600km/h on 5000m curve radii without risks of tipping over. But that would be tricky for passengers unless seat belts were deployed on seats.
Am I right in assuming that you are in favor of higher speeds because it would provide an excuse for forcing passengers to wear seat belts?

(In fact, if the superelevation is adjusted seat belts wouldn't be needed)
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Old August 2nd, 2012, 10:12 AM   #88
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Originally Posted by foxmulder View Post
LGV Nord has a min turn radius of 4000m so it is not up to standard of Chinese 350km/h network. I am sorry to let you down but it is the hard cold fact.
The LGV Nord is designed for 350km/h - THAT is a cold hard fact.

If you go back a few pages you'll see that I stated that different authorities have different specifications as to what the minimum curve radius is required depending on their own decision as to the maximum lateral force the passengers should experience.

Technically a train is perfectly capable of negotiating a 2km curve at 300km/h, the passengers wouldn't unless strapped to their seats. So, stop holding on the this 7km figure, as it doesn't make your point, whatever it is.

Quote:
Originally Posted by MarcVD"
That's the other way around. It's the Paris-Brussels direction which is
straight, and you need to take a curve to exit the line before you enter
Lille. And yes indeed, the whole high speed line between Paris and Brussels
can be travelled at max speed, without any slow down in between.
Thanks yes I knew this, I just didn't make it clear. I know the speed through Lille is 240km/h, but what is the linespeed of the direct line to Brussels? Is it full speed?
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Old August 2nd, 2012, 12:33 PM   #89
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Quote:
Originally Posted by makita09 View Post
Technically a train is perfectly capable of negotiating a 2km curve at 300km/h, the passengers wouldn't unless strapped to their seats.
Wouldn't that just be a matter of having sufficient super-elevation?

Of course, extreme super-elevation then becomes a problem for slower trains...
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Old August 2nd, 2012, 01:59 PM   #90
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Quote:
Originally Posted by makita09 View Post
Technically a train is perfectly capable of negotiating a 2km curve at 300km/h, the passengers wouldn't unless strapped to their seats. So, stop holding on the this 7km figure, as it doesn't make your point, whatever it is.
Care to show some PROOF to back up your claim?
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Old August 2nd, 2012, 05:43 PM   #91
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Quote:
Originally Posted by Sopomon View Post
This is a fair enough point, however it's an extremely inefficient use of resources.
No it is not. If it is arable land then it is probably better use of the resources. Or if land is too expensive because it is on an urban area. Japan is even planing to build its maglev line in tunnels mostly because of the cost of land acquisition. So it is a choice you should make for better use of the land.

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Wenzhou train crash. How close was it to utterly destroying the nearby houses? Because it's falling from a height, it can travel further. Also this is an utterly baseless claim.
You didn't get my point. I prefer to have a house next to an elevated line if I had livestock for example. There is zero possibility that something can walk on lines. (Germany accident... poor animals )

Quote:
Or you know, elevate the track in the valleys, and tunnel through the mountains. (Which is exactly what every HSL in the world does, btw). Having it on viaducts the entire route is just wasteful when on a large area of flat land.
It is not wasteful. It is better planing, especially for China.

Quote:
This point has been proven wrong multiple times, stop bringing it up. The highest average speed is because it has the longest distances between stops.
huh?? When did that happen? All lines mentioned as having 7000m min curve radius in reality have tighter ones. Sorry


Quote:
This solution only really exists in Japan, and it is to stabilize the ballast in the event of an earthquake.
Earthquake is one of the reasons why a more stable track is better. Overall, if you have resources, there is no excuse not to use ballastless track.

Quote:
I think you'll find that in terms of sheer amount, China is the leader. But remember it was German engineers who planned and designed nearly all of it. China simply has the political will to build these lines, not the technical know-how nor experience, thus it's hard to say that China is truly the leader.
Technology came from Germany but they did not plan or design vast portions of the network. Right now, China is pretty much have the full capability to build the cutting edge high speed lines.






Quote:
Originally Posted by makita09
The LGV Nord is designed for 350km/h - THAT is a cold hard fact.
That does not change its minimum curve radius. It is 4000m on LGV Nord. Trains can go 1000km/h if they can. It is not the point.
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Old August 2nd, 2012, 05:45 PM   #92
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Okay, this discussion is now being rehashed again and again. I think I am going to have to lock this thread as we've reached a bit of an impasse.
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