# MISC | HSR Accelaration



## bluemeansgo (Oct 28, 2008)

Something I think that is often neglected when talking about High speed trains is how long they take to get to their top speed and how long they take to go from top [operating] speed to full stop.

I have been looking for information on the actual acceleration figures and it seems that the information is difficult to find. I could only find the acceleration for the N700 in Japan.

According to wikipedia, it accelerates at 2.6 km/h/s. This gets it up to its maximum speed in about 3 minutes.

How does this compare to:

JR N700 0.72m/s² (based on 2.6km/h/s)
JR E3 Series
Siemen's ICE2/ICE3/Velaro
Alstom's TGV/AGV
Italy's Pendolino
Bombardier Zefiro 0.6m/s² (0.7m/s² for 250km/h trainsets)
Spain's Talgo
Korea's KTX
Other...

How important really IS acceleration and braking? How much time can a trip be shortened by?

For example, if a train running 350km/h has the worst acceleration at what speed will the train with the best acceleration equal it for an average trip?

I know trains often have to slow down in urban areas and stops along the way, so it would be interesting to know for how much time the train is actually traveling at its top speed and what percentage of the trip is spend just speeding up and slowing down.


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## bluemeansgo (Oct 28, 2008)

I have found some information on the Zefiro:

*250 & 300+ km/h trainsets*
Acceleration at start with full load
0.57 m/s² (up to 50 km/h)

Residual acceleration at max operating speed (300km+ version)
*≥ 0.06 m/s2
*Residual acceleration at max operating speed (250km version)
*≥ 0.07 m/s2
*

Service brake
0.6 m/s² 300 km/h – 200 km/h
0.8 m/s² 200 km/h – 0 km/h

Google tells me that 2.6km/h/s = 0.722 m/s² so about 20% faster acceleration. Anyone find data for other trainsets?


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## gincan (Feb 1, 2006)

Unless you can get hold of the actual acceleration graph it's rather useless to compare trains. Anyway Talgo states on their webpage 1.2m/s².


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## yaohua2000 (Dec 26, 2008)

bluemeansgo said:


> For example, if a train running 350km/h has the worst acceleration at what speed will the train with the best acceleration equal it for an average trip?


A train running 350km/h accelerates like this:

One stop (CRH2C): Leave Tianjin at 2008-08-04 06:34:50; Stop at Wuqing for one minute; Arrive Beijing South at 07:11:00
http://img27.imageshack.us/img27/9053/200909100c3a1ecc9d05d03.png









Non-stop (CRH2C): Leave Tianjin at 2008-08-04 08:09:35; Arrive Beijing South at 08:39:25
http://img44.imageshack.us/img44/2433/20090911e31c7f510bc35b8.png


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## LUCAFUSAR (Mar 31, 2009)

gincan said:


> Unless you can get hold of the actual acceleration graph it's rather useless to compare trains. Anyway Talgo states on their webpage 1.2m/s².


:sly: Sorry, but this is the maximum lateral acceleration in curve. It has nothing to do with "speeding up" capability of a high speed train.


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## LUCAFUSAR (Mar 31, 2009)

The Alstom Pendolino ETR600 gets the max speed of 250 kph in about 3 minutes. But i don't know its max acceleration.


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## gramercy (Dec 25, 2008)

wow, thx @yaohua2000 for posting those graphs, i can draw some serious conclusions from it

obviously today (the Wuhan-Guangzhou is not open yet) the only place the chinese can run above 300 kph is Beijing-Tianjin, and you did these tests just before the olympics in 2008

now:
- it is worth noting that they only reached 350 for a SINGLE minute (!)
- 330++ is for 11 minutes
- this graph shows just how important it is to build LONG lines (hundreds and hundreds of kms) and pass-through stations for these kind of speeds: look at the first graph, for the entire lenght it is either accelerating or braking  

based on the second graph, where they only go at 350 for a single minute, i'd say after the olympics they probably abandoned that all together and they are only running at 330 kph


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## makita09 (Sep 8, 2009)

http://www.twoof.freeserve.co.uk/motion1.htm has some useful info on how to work out a train's acceration characteristics.


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## yaohua2000 (Dec 26, 2008)

gramercy said:


> based on the second graph, where they only go at 350 for a single minute, i'd say after the olympics they probably abandoned that all together and they are only running at 330 kph


They abandoned that *before* the end of the Olympics. The last time I recorded 350 km/h of running was on August 11, 2008. It had slowed down to 340 km/h since August 12, and later to 335 km/h, and now at 330 km/h.


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## Oscuro_XS (May 6, 2009)

Speed at full throttle of the Siemens Velero E and the Talgo 350.
Inclination: 2%
IDA-> Departure
Vuelta -> Return


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## gincan (Feb 1, 2006)

LUCAFUSAR said:


> :sly: Sorry, but this is the maximum lateral acceleration in curve. It has nothing to do with "speeding up" capability of a high speed train.


You're absolutely right, I didn't read correct. Anyway, maximum curve acceleration is rather important unless the line is dead straight, for example maximum curve speed for given curve radius between the RENFE S102 and S103 at 1,1 3,9 5,9 and 10km radius.


Serie 102 140 km/h 244 km/h 257 km/h 285 km/h 299 km/h

Serie 103 136 km/h 232 km/h. 241 km/h 271 km/h 285 km/h


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## poshbakerloo (Jan 16, 2007)

It depends on how long the track is...

For shorter routes good acceleration is important...


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## gramercy (Dec 25, 2008)

yaohua2000 said:


> They abandoned that *before* the end of the Olympics. The last time I recorded 350 km/h of running was on August 11, 2008. It had slowed down to 340 km/h since August 12, and later to 335 km/h, and now at 330 km/h.


THANK YOU for confirming this

there is waaaay too much confusion about the actual speed of that line, and i kept arguing that there is no way without ETCS Level 2
so they are only doing 330kph


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## UD2 (Jan 21, 2006)

the bigger impact is done by the space in between stops, the number of stops, and the speed limits surrounding the stops.

the acclelerating capabilities of the moving stock it self should not be place on top of the pirority list.


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## bluemeansgo (Oct 28, 2008)

yaohua2000 said:


> A train running 350km/h accelerates like this:
> 
> Non-stop (CRH2C): Leave Tianjin at 2008-08-04 08:09:35; Arrive Beijing South at 08:39:25
> http://img44.imageshack.us/img44/2433/20090911e31c7f510bc35b8.png


AWESOME! Thanks so much. This really puts things into perspective, doesn't it?

From that graph, it looks like it takes about 9 minutes in "real world" acceleration. I'd imagine this is because trains typically won't go full acceleration.

I believe that CRH-2 is a modified E2-1000 Shinkansen with extra motor cars in the middle ( to increase its speed from 250 to 350 ).

Now... a way to quantify this all.

Of course, stopping patterns matter... however the faster the acceleration and braking the less stopping matters. In essence, you can have stops closer together and maintain the same overall speed. But again, it would depend on how much acceleration really plays a part.

If the fastest accelerating train was played against the slowest one and there were 1 stop every 100km what kind of a time difference are we looking at for a 1000km line?

How about if stops were spaced out every 200km?


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## Ariel74 (Oct 2, 2009)

*more confusions*



gramercy said:


> THANK YOU for confirming this
> 
> there is waaaay too much confusion about the actual speed of that line, and i kept arguing that there is no way without ETCS Level 2
> so they are only doing 330kph


I think you are pretty confused with your argument gramercy yourself. The fact that they lowered the top-speed to 330km/h proves NOTHING about what is or is not possible with or without ETCS level 2. The explanation can be VERY simple: it is not energy efficient to reach the top speed of 350km/m when the short length of the track means one can only maintain that speed for one minute. Maybe you can try your argument again when the wuhan-guangzhou line opens later this year, but it simply does not work with such a short line as Beijing-Tianjin.


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## gincan (Feb 1, 2006)

bluemeansgo said:


> AWESOME! Thanks so much. This really puts things into perspective, doesn't it?
> 
> From that graph, it looks like it takes about 9 minutes in "real world" acceleration. I'd imagine this is because trains typically won't go full acceleration.


The Velaro E, same train but slight lighter (425t) than CRH3 (447t) accelerate 0-320km/h in 380 seconds, that's 6 minutes and 20 seconds. So the 9 min
is definitely not full acceleration.


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## bluemeansgo (Oct 28, 2008)

gincan said:


> The Velaro E, same train but slight lighter (425t) than CRH3 (447t) accelerate 0-320km/h in 380 seconds, that's 6 minutes and 20 seconds. So the 9 min
> is definitely not full acceleration.


True... but I bet those measurements are on an empty train.



Ariel74 said:


> I think you are pretty confused with your argument gramercy yourself. The fact that they lowered the top-speed to 330km/h proves NOTHING about what is or is not possible with or without ETCS level 2. The explanation can be VERY simple: it is not energy efficient to reach the top speed of 350km/m when the short length of the track means one can only maintain that speed for one minute. Maybe you can try your argument again when the wuhan-guangzhou line opens later this year, but it simply does not work with such a short line as Beijing-Tianjin.


Completely agree. This is part of the reason that I brought up this subject. Sometimes we're obsessed with top speed here... but when it comes down it, energy efficiency, noise and acceleration are just as important.

in fact, the faster a train runs, the fewer train one can [safely] run on the tracks because of safety margins.

I know that's one reason that the Tokaido line between Tokyo and Osaka can't run much faster. They wouldn't be able to reliably run as many trains on the line as they do now. And if the *Japanese* can't run more trains on a line, then I don't know who can. Their trains are timed to the second.


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## gramercy (Dec 25, 2008)

Ariel74 said:


> I think you are pretty confused with your argument gramercy yourself. The fact that they lowered the top-speed to 330km/h proves NOTHING about what is or is not possible with or without ETCS level 2. The explanation can be VERY simple: it is not energy efficient to reach the top speed of 350km/m when the short length of the track means one can only maintain that speed for one minute. Maybe you can try your argument again when the wuhan-guangzhou line opens later this year, but it simply does not work with such a short line as Beijing-Tianjin.


really..

so name me ANY train controll system that allowes for 350 kph

and by the way, i know it for a fact that they are using ETCS L1 on the line, so...


and OF COURSE i agree with the efficiency, let me quote myself here


gramercy said:


> And here is why:
> - there is NO train controll system currently that can safely operate trains ABOVE 320 kph, ETCS is the only one that even has a hope and it doesnt even work on the "350" Beijing-Tianjin. i have serious doubts that they actually do this and if they do then they do it without a controll system which means less frequency
> - 380 kph would require +103 % energy (cost) compared to running at 300 kph, +67 % compared to 320 kph and +31 % (almost a third) compared to running at 350 kph. as a result the ticked would be twice, two thirds or one third more expensive
> - not the chinese, nor bombardier have demonstrated their OWN design anywhere near these speeds
> ...


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## pietje01 (Mar 18, 2008)

gramercy said:


> really..
> 
> so name me ANY train controll system that allowes for 350 kph


TVM430?


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## metsfan (Apr 14, 2008)

I know the NJT arrow 3 trains, and their diesel trains, can really accelerate quite fast. The ALP series are more meant for sheer hauling capacity & top speed vs acceleration, though if an ALP-46 wants to go, even with 10 MLV cars, it can do 0-100 (stop to limit, single level cab car first operation limited to 95, MLV cab first is 100) in about 20 seconds or less. Of course, pax may not enjoy this, so it is rarely done. More common is 60 mph to 100 mph, going into and out of restriction zones along the NEC. A talented engineer (of which NJT has several) can really put the throttle out the front window of the cab and ride the dynamic brakes to get maximum traction for HP accelerating. One time said engineer took us from stopped to 100 MLV first, man did those tall cars sway!!! 

- A


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## bluemeansgo (Oct 28, 2008)

So... a few simple calculations on the non-stop graph posted on page 1.

Looks like it travels 2 minutes at 45kph on cruise control.

*1.5km @45kph*

It travels for 11 minutes at an average of about 340kph (between 330 and 355)

*62.5km @ 341kph*

The total trip is 115km.

So, the train spends 51km accelerating and decelerating. This takes 16 minutes, meaning an average speed during this time of *191.25kph.*

So, to recap
01% of dist. on Cruise @ 45kph
46% of dist. accel/decel @ ~191.25
54% of dist. at full speed @ ~341km/h

Put another way, %62 of time is NOT spent at top speed.

( I know, I'm using kph and not km/h... it's easier to type and sounds better. Yes, I live in a metric country )

If we double the time spent at top speed, we're up to 177.5km @ ~266kph in 40 minutes.

If just 1 minute can be cut off the acceleration and deceleration time, with 177km between stops it would set a new scheduled service record of 280kph avg. without even trying.

Of course, that's about a 12% increase in performance, so nothing to sneeze at.

However, even on the current 115km run between Beijing and Tianjin, reducing acceleration time from 16 minutes to 14 minutes, would increase the average speed 7.5% from 238kph to 256kph. That's a pretty big increase which would improve even more for shorter journeys.

I guess the real question is... what is the average/optimal distance between high speed rail stations?

My guess is, with the limits of rail technology and acceleration, stations should be around 150km apart.

Any closer than this and going faster will result in very little actual increased benefit, until acceleration is improved.

Perhaps, this is a good reason Mag-lev is a worthwhile technology. It's not so much the top speed, but the acceleration.

Given that the Shanghai gets up to 430kph in just 4 minutes... if regular rail had THAT kind of acceleration, we'd have an AVERAGE speed of 330kph... or in other words, *a 40% INCREASE in average speed over 115km!!!*. Trip time would be down from 29 to 21 minutes.

And that's running at a maximum speed of 341kph.

Perhaps Mag-lev should be considered for SHORT-distance high-speed... not long-distance.


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## yaohua2000 (Dec 26, 2008)

bluemeansgo said:


> So... a few simple calculations on the non-stop graph posted on page 1.
> 
> Looks like it travels 2 minutes at 45kph on cruise control.
> 
> ...


If you read my previous post carefully, you may notice the graph did not start as the train leaving the station. The roof of the platform blocks GPS signal and it takes a while for a GPS receiver to lock the satellite after that. It is not easy to make the train stop at the center of the city. There's quite a section of speed-limiting track near Tianjin Railway Station with sharp railway curve radius. That is also why most recently built Chinese high-speed train stations are far from the urban area.










green line = lower speed, purple line = higher speed


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## alphorn2 (Oct 31, 2009)

bluemeansgo said:


> How important really IS acceleration and braking? How much time can a trip be shortened by?


The answer is, of course, "it depends". The more stops or slowdowns you have on your way, the more important acceleration gets. Here's the numbers I could find, including in this thread.

0.48 m/s² Alstom ETR 610
0.57 m/s² Bombardier Zefiro(0-50 km/h)
0.72 m/s² JR N700
0.86 m/s² ICE-3
1.20 m/s² Stadler Dosto (max speed 200 km/h)

Not comparable:
0.38 m/s² Siemens Velaro CN (0-200 km/h)
1.20 m/s² Talgo 350 (Locomotive only!)

The Stadler Dosto is an upcoming double decker derived from a regional train, which is why it has high acceleration. Also, the lower max speed helps.

Note that the acceptable lateral acceleration level in curves (for passenger comfort) is 0.85 m/s² on high quality track. Yet I expect that longitudinal acceleration can be higher since it does not come as a sudden surprise.


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## Ariel74 (Oct 2, 2009)

It's annoying to have an argument with someone who has not the least ability to distinguish completely different things: I don't care a straw about what the chinese can or cannot do, I was just pointing out that your purported _argument_ using the fact that the chinese lowered the top-speed for the beijing-tianjin route does not work. You seem to be obsessed with the question of who can do what. Either this obsession or a general lack of ability to read logical argument made it impossible for you to see that I was taking issue with your argument, not your conclusion per se.

try to cure your obsession, or learn some logic. 




gramercy said:


> really..
> 
> so name me ANY train controll system that allowes for 350 kph
> 
> ...


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## LUCAFUSAR (Mar 31, 2009)

edit.


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## LUCAFUSAR (Mar 31, 2009)

alphorn2 said:


> The answer is, of course, "it depends". The more stops or slowdowns you have on your way, the more important acceleration gets. Here's the numbers I could find, including in this thread.
> 
> 0.48 m/s² Alstom ETR 610
> 0.57 m/s² Bombardier Zefiro(0-50 km/h)
> ...


Sorry, but the 1.2 m/s2 value of the Talgo350 is the maximum lateral acceleration in curve. It has nothing to do with the speeding up capability of a train.
About the ICE/3: on the Siemens website I found that the Velaro E (AVE Class 103), that is 800 kw more powerful than the ICE3, reaches 320 kph in 380 seconds. So, the average acceleration is 0.84 km/h/s2, i.e. 0.234 m/s2. I think that the ICE/3 has lower acceleration capabilities, because it's less powerful than the Velaro E.


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## bluemeansgo (Oct 28, 2008)

yaohua2000 said:


> If you read my previous post carefully, you may notice the graph did not start as the train leaving the station. The roof of the platform blocks GPS signal and it takes a while for a GPS receiver to lock the satellite after that. It is not easy to make the train stop at the center of the city. There's quite a section of speed-limiting track near Tianjin Railway Station with sharp railway curve radius. That is also why most recently built Chinese high-speed train stations are far from the urban area.
> 
> 
> 
> ...


Cool! So, that would slightly increase the average speed during accel/decel ever so slightly.

I accounted for the lower initial speed where it is "cruising" and I figured it had to do with the station being "inside" the city.

Ideally, I think it's better for a station to be closer to the centre of the city, though you sacrifice a bit of time. There is time involved in getting to the station as well.

This may mean underground lines in the city, which are more expensive, but in some cases worth the extra cost.

Of course, every country has different needs. It's just nice to see a country so heavily invest in such a potentially clean technology.


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## bluemeansgo (Oct 28, 2008)

Question: In general, is a multiple EMU setup ( like Shinkansen ) able to accelerate faster than a TGV, given similar tracks?

How do newer players (like Pendolino, Talgo and Zefiro ) fare when it comes to acceleration?


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## Tri-ring (Apr 29, 2007)

bluemeansgo said:


> Question: In general, is a multiple EMU setup ( like Shinkansen ) able to accelerate faster than a TGV, given similar tracks?
> 
> How do newer players (like Pendolino, Talgo and Zefiro ) fare when it comes to acceleration?


I believe so since you have less load per powered axle providing more allowance for the wheels to apply torque to the rail without slippage. The down side is that it applies more weight and electro-magnetic resistance to the overall train set and motors requiring more overall power out to obtain faster top speed.


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## sotavento (May 12, 2005)

alphorn2 said:


> The answer is, of course, "it depends". The more stops or slowdowns you have on your way, the more important acceleration gets. Here's the numbers I could find, including in this thread.
> 
> 0.48 m/s² Alstom ETR 610
> 0.57 m/s² Bombardier Zefiro(0-50 km/h)
> ...


Some different ranges apply to those values ... from what I found until now we get the acceleration values taken from:


0->80km/h (only marginal in HST , urually only comuter/urban trains)

0-160km/h (electric locomotive hauled and other intercity trains)

0-200km/h (HST in europe usually refer to this range) 

0-300km/h (until now only the TGV acc. values refer to this)

300-320km/h , 320-330km/h (until now only the TGV acc. values refer to this)

Most HST acc. values only consider the 0-200 so everything should be taken with a grain of salt. hno:


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## sotavento (May 12, 2005)

bluemeansgo said:


> Question: In general, is a multiple EMU setup ( like Shinkansen ) able to accelerate faster than a TGV, given similar tracks?
> 
> How do newer players (like Pendolino, Talgo and Zefiro ) fare when it comes to acceleration?


In short ... NO ... nothing like that _in general_ ... just when trains are built specifically for that same greater acceleration.


Bypassing the usual rants and deaf-ears discussion about what is or isn't a EMU or not ... 

500 series Shinkansen has 18,24MW evenly distributed among 64x 285KW traction motors (64 axles)
N700 series shinkansen has 17MW distributed among 56x 305KW traction motors (64 axles) , 715ton , 1323 pass.
ICE3 (double?) has 
TGV Duplex has 17,6MW (Double consist) distributed among 16x 1100KW powered axles (plus 36 unpowered axles)

What diferentiates the Japanese shinkansen from the european HST's is merely the way they evolved ... from what they evolved from ... and the safety/environmental/service conditions in wich they would need to operate.

- the allowance of passengers in the 1st coach of a HST ir a recent adition to European trains 
- the high-tech inovations put onto the trains is abundant no matter wich train in particular we speak about.
- HST run on aerodinamics and brute force 
- the tecnologies aplied to HS trains prior to 1994 are majorly outdated nowadays (and that means ICE1/2 , Shinkansen 300 and older , etc) 
- HS coaches are usually assigner dedicated purposes (other than carrying passengers) ... some carry traction motors , some carry transformers , etc

^^ The explanation for all of this is very simple ... HST in Japan is developed to run on dedicated tracks ... in europe HST run on _"the"_ national networks and stretch their legs here and there on a stretch of HSR (wich might not even be dedicated exclusively to passenger traffic).

In terms of acceleration it is considered ideal to have roughly only 1/2 the axles motored ... something in the way of a balance between grip and torque on those same axles.


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## LUCAFUSAR (Mar 31, 2009)

sotavento said:


> ...
> ICE3 (double?) has
> ...


ICE3 in double consist has 2*8.0 MW>16.0 MW.


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## ruready1000 (Nov 18, 2008)

*Starting Acceleration*

Shinkansen N700 Series : 2.6 km/h/s (0.72 m/s/s)
Shinkansen 700 Series : 1.6 km/h/s (0.44 m/s/s) or 2.0 km/h/s (0.55 m/s/s)
Shinkansen 300 Series : 1.6 km/h/s (0.44 m/s/s)
source

Korea KTX-II : 1.6 km/h/s (0.45 m/s/s)
source


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## sotavento (May 12, 2005)

LUCAFUSAR said:


> ICE3 in double consist has 2*8.0 MW>16.0 MW.


Thanks ... it seems that I "ate" a couple of lines of text over there somehow. hno:

ICE3 , Talgo350 , HST(diesel) and one or two more. :dunno:


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## Maadeuurija (Nov 14, 2010)

I have a question
In what time a train with N700's acceleration can pass a 44km long line with no stops between and top speed of 350 on the line?


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## k.k.jetcar (Jul 17, 2008)

Maadeuurija said:


> I have a question
> In what time a train with N700's acceleration can pass a 44km long line with no stops between and top speed of 350 on the line?


I don't have the math for such a calculation, but from actual schedules, for example, the stretch of the Tokaido Shinkansen from Kyoto to Shin-Osaka, a distance of 39km, takes 13 min start to stop for a N700 trainset on a Nozomi service (180km/h avg.). Note that this portion of line has some curves. Another example, the stretch of track from Maibara to Kyoto, which has a long stretch of straight track (capable theoretically of 330km/h running), a total of 68km, requires 22 minutes for an older 700 series to traverse start to stop (185km/h avg.). On your imaginary line with no curves, grades, other traffic, and a top speed limit of 350km/h, a N700 will have a higher avg. speed than the real-life examples above.


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## sotavento (May 12, 2005)

Maadeuurija said:


> I have a question
> In what time a train with N700's acceleration can pass a 44km long line with no stops between and top speed of 350 on the line?


first one needs to get the engine rpm , wheel base lenght (2x pi radius) and all other usefull information regarding the mechanical proprieties of the power package. 


Then we can begin to discuss about the acceleration proprieties of the train such as what torque those engines can get onto the rails and calculate the proper acceleration/breaking time in the extremes of the route (0-350 acceleration curve = x km , 350-0 deceleration curve = x km , full 350 = x km) 

Once we break the acceleration and deceleration curves into their various smaller components* one can proceed to try to guess the average** accel/decel distance ... what remains is the full speed lenght.

* a train can have a very long gear ratio and the power available to the motor can(or can't) easily fully accelerate at slower speeds and thus the initial acceleration can be affected from this factor. Two examples:


In portugal the Alfa Pendular(4000 series) runs at 220km/h using the SAME ~500KW siemens electric engines as the urban/comuter 2300 series EMU's ... 
Both have (suposedly) 1950rpm nominal at full speed ... but in reality the AP is using the same gear/transmissions as the Italian ETR and the spanish AVE104 (wich are known for reach above 270/280km/h) and the portuguese speed record (slightly above 250km/h) was achieved without even reaching the 1950rpm on the engines ... 
AP trains are known for being very VERY sluggish in accelerating from standstill to medium/high speeds ... due to the extremelly long gearing ratios 0-250?) 
Another interesting factor is that those same motors in the 2300 class have a "daily use overspeed capacity" up to 3950rpm (units are geared to 120km/h at 1950rpm) ... 

A pair of trains exiting Gare do oriente simultaneously in the up direction (4 tracks with 160/200km/h limit for 20km in all tracks) is something to see ... as the AP is totally humiliated by the sheer acceleration of the comuter units ... wich are able to completely exit the station platforms while the AP is still barely able to jerk and begin to roll ... by the time the AP eventually passes the end of the platform the 2300 is already at the next station with its doors open ... and when the AP reaches that point still strugling to go as much as 60km/h (?) the 2300 is already long gone ... when eventually the AP reaches the operational 120km/h of the other train it has already lost a minute or two in the process ... while the other train in between 1km/2km stops runs for most of the time at that "full speed".
Given the ability of that same 2300 to overspeed so easily if one considers the 320km long Northern Line (Lisboa-Porto 1/2 of it at 200/220km/h) one can guess that for most of the time the 2300 could easily cruise at 140/160 km/h with 8/10 intermediate stops and still manage to achieve BETER start to stop times as a DIRECT AP train ... since every time (and there are plenty) the AP would need to play the reprises game (accel/decel) it would be eventually defeated by KO each and every time along the curveous/hilly route. 
If weren't for the tilting abilities of the AP it would eventually be left further behind even further since the acceleration couldn't possibly cope with the performance required of them ...

On an even harder setting on the Southern Line (Lisboa-south) the AP is evenly matched by the 160km/h intercity trains due to the exact same reasons of sluggish acceleration. 
A 20km long section of 220km/h track is passed uphill(northbound) in a pure reprise of 100-200(yess 200) slow acceleration due to the inability of the train to gain enough speed to get there in time before it runs out of 220km/h trackage. :nuts: 
On the downhill(southbound) direction it just cruises at 227/228km/h (220 + 4km convel + 4km convel tolerance) for the entire lenght ...
Notice: coming from the north the single track 220km/h diverges into a double track and 00km south it merges again into a 80km(110km/h for tilting trains) single track ... so the northbound and train has no chance from the start to the end of the section. :dunno:
The point is that acceleration is a b*tch unless you have enough to spare ... :cheers:



Back to N700 performances ... the N700 is preciselly a JR atempth to have some faster shinkansen in the usuall conditions into wich the 2300 series (above) need to operate. Main fast trains in the middle of a very dense comuter stile operation (12/15 tph in each direction with average 180km/h on these regional/comuter traffic).


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## aquaticko (Mar 15, 2011)

The question I have about all this is how much accelerative and braking force is typically thought to be commercially acceptable. That seems to me to be the real limitation on HSR speed-ups in the future.


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## sotavento (May 12, 2005)

comuter trains usually go as high as 1,2 /2,5 m/s2

HSR trains usually have lower maximum acceleration usually as low as 0,5 /0,7 due to extremelly high gear ratios.


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## Suburbanist (Dec 25, 2009)

In any case, the relatively linear staggered profile of the fourth derivative of movement (eg derivative of acceleration) 0layd a significant role on the fact the average human feels much more comfortable on a train than a bus starting or stopping


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## sotavento (May 12, 2005)

M-NL said:


> Compared to what? Because in reality they aren't: The latest generation TGV power cars as used for the POS and 2N2 models 'only' have a 4640 kW power rating per car, whilst there are several current locomotive models with a 6400 kW power rating.
> 
> In fact realise that on a German Neubaustrecke with a 250 km/h limit an ICE2 would have a hard time beating a Railjet, given that most German cities aren't that far apart. A Railjet would accelerate much faster to it's 230 km/h top speed, helped by it's 6400 kW, whereas the ICE2's 4200 kW will need more distance to get to 250 km/h.


Technically speaking the railjet is just an upgraded ICE2 trainset ... reusing the good old 1216/1116 of course.


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## ArtManDoo (Aug 5, 2008)

M-NL said:


> With the common in Europe 22,5t maximum axle load pretty much any modern electric loco can reach the maximum possible tractive effort of around 75 kN per axle, regardless of it's maximum speed. A German class 101 or a Taurus is just as happy pulling a passenger train at 200+ km/h as it is pulling a 'heavy' freight train at 80 km/h. A German class 145 can be used for passenger trains.


What about the 75kN per axle if to consider max tractive effort vs continuous? It is confusing. For example, for how long time can it be used; for acceleration from 0 to 230km/h Yes? And for hauling a 3000t freight train up from a steep slope for 20 minutes, rather Not?


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## ArtManDoo (Aug 5, 2008)

sotavento said:


> 1.2m/s2 in regular operation could be tolerated in long distance trains
> 2.5m/s2 is the usual value considered acceptable for emergency braking ... wich in urban transit is put into effect in daily basis in many systems (especially in light rail/tramway usage) so I put it there.


Wow 1.2m/s2 seems to be quite rapid for long distance trains. I thought for long distance 0.6m/s2 and suburban 0.8m/s2 :lol:

But which value should be considered for keep the timetable under worst scenario, I mean when the conditions are very bad e.t.c leaves/mist on railhead, 0.5m/s2 or 0.4m/s2 maybe?


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## M-NL (Sep 18, 2012)

ArtManDoo said:


> What about the 75kN per axle if to consider max tractive effort vs continuous? It is confusing. For example, for how long time can it be used; for acceleration from 0 to 230km/h Yes? And for hauling a 3000t freight train up from a steep slope for 20 minutes, rather Not?


Those 75 kN per axle are available up to the point where maximum power is reached. For most modern locos that would be at around 60 km/h. From that point on power would remain constant and therefore tractive effort would drop with the increasing speed. As I calculated earlier to 25 kN per axle @ 230 km/h for a Taurus, for instance.

An electric loco is only limited by a maximum current and its cooling capacity. As long as the transformer oil (for AC locos), electronics and motors don't get to hot they could theoretically keep on going indefinitely. Most published figures are in fact continuous ratings. Some locos can even deliver more than that for shorter period of time. 

Examples: 
Siemens ES64U2: 7 MW for 5 minutes, 6.4 MW continuous.
German class 103: 12 MW for short periods, 7.78 MW hourly and 7.44 MW continuously

You wouldn't want to pull a 3000t train up a steep slope with a single loco. When operating at the edges of the performance envelope any loss of traction would bring the train to a halt very quick. It would also be very slow, which may not be practical if you're running only a few minutes ahead of the next high speed passenger train.


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## ArtManDoo (Aug 5, 2008)

M-NL said:


> Those 75 kN per axle are available up to the point where maximum power is reached. For most modern locos that would be at around 60 km/h. From that point on power would remain constant and therefore tractive effort would drop with the increasing speed. As I calculated earlier to 25 kN per axle @ 230 km/h for a Taurus, for instance.


Yes I got it, expressed myself wrong 

As my education is IT, my physics is not the best...
I wrote a piece of code for calculate acceleration 0-230km/h, some drag is added

Vectron + 6 viaggio-comfort coaches
tare + conventional load 426,1 tons
starting tractive effort 300kN
distance for acceleration it gave: 10,4km

Vectron + 4 viaggio-comfort coaches
tare + conventional load 312,9 tons
starting tractive effort limited to 250,3kN
distance for acceleration it gave: 7,4km


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## sotavento (May 12, 2005)

ArtManDoo said:


> Wow 1.2m/s2 seems to be quite rapid for long distance trains. I thought for long distance 0.6m/s2 and suburban 0.8m/s2 :lol:
> 
> But which value should be considered for keep the timetable under worst scenario, I mean when the conditions are very bad e.t.c leaves/mist on railhead, 0.5m/s2 or 0.4m/s2 maybe?


I'm talking about braking and not acceleration of course. One would need a very different technology to achieve those accelerations all the way up to 320km/h ... nowadays we get sluggish HST trains precisely because they only get one speed/shift ... if they aplied mechanical/hidraulic speed shifting we could have greater (theoretic) accelerations available.


But I prefer another aproach to very high speed ... conventional rails leading onto MAGLEV HSR corridors where the wheels simply lift hidraulically from the floor above a certain speed. And gone be the HSR hardware ...


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