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Old June 5th, 2014, 04:58 AM   #8121
foxmulder
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Quote:
Originally Posted by Sunfuns View Post
Not that it matters, but Europe has some very thinly inhabited areas. Norther Scandinavia and Northern Russia most obviously.
Yeah, but no one really means Russia when they say Europe, do they so as these stats.. they do not include Russia in Europe.
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Old June 5th, 2014, 09:02 AM   #8122
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Lanzhou-Urumqi HSR

CRH2 tests run in Xinjiang,Northwest China.

[IMG]http://i61.************/egbjwx.jpg[/IMG]
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Old June 5th, 2014, 10:23 AM   #8123
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Quote:
Originally Posted by foxmulder View Post
You and keber do not know what exactly railroad capacity means. It means "...maximum number of trains that would be able to operate on a given railway infrastructure, during a specific time interval, given the operational conditions."
Still unclear. Do you mean maximum number of trains that are able to arrive at the end of the line, or maximum number of trains that can be present along the line at one time?
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Originally Posted by foxmulder View Post
Let's say you have a 10km rail line. If you had a single train just sitting in the middle of the line it would have been using the whole capacity.
If you have a single train stalled in the middle of a railway line then it is not "using the whole capacity" because the "capacity" is not exactly a single train either way. In terms of trains getting through, the capacity is zero, because neither the stalled train nor any other train is getting through, not for an hour and not for any time till the stalled train is cleared; in terms of trains present on the line, there can be any number of trains parked behind the stalled train and waiting for the obstruction to clear. Well, not unlimited number, because there will be a finite number of trains and cars that can fit on the half line behind the stalled train.
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Originally Posted by foxmulder View Post
If train is running at 10km/h it will take it 1 hour to "use" that stretch.
Yes, but during that 1 hour the trains queuing behind it also get ahead, so if there are many trains in the 10 km stretch then you can have many of them arriving in next 1 hour.
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Originally Posted by foxmulder View Post
If it is running at 100km/h it will take 6 minutes so you can have 9 more trains.
9 more trips by the same trainset. Again, the headway between the consecutive trains does not directly depend on the time it takes to traverse a section of arbitrarily chosen length.
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Old June 5th, 2014, 05:41 PM   #8124
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Quote:
Originally Posted by Sunfuns View Post
Not that it matters, but Europe has some very thinly inhabited areas. Norther Scandinavia and Northern Russia most obviously.
This is another case where a density map could be useful, in this case population density, e.g. like this:



There are criticisms of this one as well, it is of indeterminable age (not that it matter much for Europe and China, that have much more stable populations than e.g. much of Africa), the projection isn't area-equal (since Europe is further to the north than China it will appear less dense, and China more dense), and most of all the map is too small for the resolution (1 dot/100,000 people, which today would exceed 70,000 dots), ending up with red blobs of dense population, and white blobs of sparse population.
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Old June 5th, 2014, 06:00 PM   #8125
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Quote:
Originally Posted by chornedsnorkack View Post
Still unclear. Do you mean maximum number of trains that are able to arrive at the end of the line, or maximum number of trains that can be present along the line at one time?

If you have a single train stalled in the middle of a railway line then it is not "using the whole capacity" because the "capacity" is not exactly a single train either way. In terms of trains getting through, the capacity is zero, because neither the stalled train nor any other train is getting through, not for an hour and not for any time till the stalled train is cleared; in terms of trains present on the line, there can be any number of trains parked behind the stalled train and waiting for the obstruction to clear. Well, not unlimited number, because there will be a finite number of trains and cars that can fit on the half line behind the stalled train.

Yes, but during that 1 hour the trains queuing behind it also get ahead, so if there are many trains in the 10 km stretch then you can have many of them arriving in next 1 hour.


9 more trips by the same trainset. Again, the headway between the consecutive trains does not directly depend on the time it takes to traverse a section of arbitrarily chosen length.
You are thinking rail lines as conveyor belts. They are not. If they were, in that hypothetical stretch of 10km line you can put 25 400m trains and claim that is the capacity!

Think a 2 lane of 6-lane highway vs a two lane city road. Think the speeds cars can reach and also think about the people may pass in a given time. Now, can you imagine the difference between number of people pass through that 2 lanes of the highway and of that of the city road???

Trains' ability to accelerate, brake and maximum speed are critical parameters.

If you do not believe me, try to find a scientific research article or a railroad engineer.
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Old June 5th, 2014, 06:24 PM   #8126
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Hangzhou-Changsha line test run,now 400+km/h is hard to see compared to several years ago

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Old June 5th, 2014, 09:27 PM   #8127
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Quote:
Originally Posted by foxmulder View Post
You and keber do not know what exactly railroad capacity means. It means "...maximum number of trains that would be able to operate on a given railway infrastructure, during a specific time interval, given the operational conditions."

Let's say you have a 10km rail line. If you had a single train just sitting in the middle of the line it would have been using the whole capacity. If train is running at 10km/h it will take it 1 hour to "use" that stretch. If it is running at 100km/h it will take 6 minutes so you can have 9 more trains.

Something like this:
Oh, God, what a mess... What you wrote is simply craz and has nothing to do with reality.
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Old June 6th, 2014, 04:47 AM   #8128
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Quote:
Originally Posted by flankerjun View Post
Hangzhou-Changsha line test run,now 400+km/h is hard to see compared to several years ago
Still impressive. Tnx for sharing.
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Old June 6th, 2014, 04:51 AM   #8129
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Originally Posted by Attus View Post
Oh, God, what a mess... What you wrote is simply craz and has nothing to do with reality.
Care to explain the relation between speed and capacity, or there is no relation?
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Old June 6th, 2014, 10:12 AM   #8130
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Simple:
1 - a subway train of 500 people, which travels 70 km/h, with a headway of 3 minutes (easily attainable in modern subway systems)
2 - a high speed train of 500 people, which travels 300 km/h, with a headway of 5 minutes (less is too dangerous because of necessary braking distances)

1 - this subway line can theoreticaly deliver 10000 people per hour
2 - this high speed line can theoretically deliver 6000 people per hour

Now, where do you see speed in those equations?
Of course, there are many other important factors for calculating capacity, but achieved top speed isn't one of them.

And talking about dudes - I design new railway lines, what do you do for your living?
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Old June 6th, 2014, 10:40 AM   #8131
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Quote:
Originally Posted by :jax: View Post
This is another case where a density map could be useful, in this case population density, e.g. like this:

Interesting to see the thin line connecting east China and vast empty west (Xinjiang). That's pretty much where the Silk Road and Lanzhou-Xinjiang Railway are located.

People can see how important the Lanzhou-Xinjiang Railway and the opening Lanzhou-Xinjiang HSR are to west area development.
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Old June 6th, 2014, 12:44 PM   #8132
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Quote:
Originally Posted by keber View Post
Simple:
1 - a subway train of 500 people, which travels 70 km/h, with a headway of 3 minutes (easily attainable in modern subway systems)
2 - a high speed train of 500 people, which travels 300 km/h, with a headway of 5 minutes (less is too dangerous because of necessary braking distances)

1 - this subway line can theoreticaly deliver 10000 people per hour
2 - this high speed line can theoretically deliver 6000 people per hour"
True, but in that hour the metro has taken 10,000 people 70 km, while the HSR has taken 6,000 people 300 km. Less people per hour, but more than double the people-km.

Let's slow the metro down to 60 km/h for simpler calculation. You have two cities 300 km apart, how long would it take to move 5000 people, that is 10 trains, from one city to the other?

With the metro train #10 will leave 27 minutes later than train #1, with HSR train #10 will leave 45 minutes later. The metro takes 5 hours for the trip, the HSR 1 hour. Total time for metro: 5 hours 27 minutes. Total time for HSR 1 hour 45 minutes.

For 50,000 peoples the metro train #100 will leave 4 hour 57 minutes later than #1, and HSR#100 8 hours 15 minutes later (the headway has made headway so to speak). Total time metro: 9 hours 57 minutes, total time HSR 9 hours 15 minutes.
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Old June 6th, 2014, 02:08 PM   #8133
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Quote:
Originally Posted by :jax: View Post
True, but in that hour the metro has taken 10,000 people 70 km, while the HSR has taken 6,000 people 300 km. Less people per hour, but more than double the people-km.

Let's slow the metro down to 60 km/h for simpler calculation. You have two cities 300 km apart, how long would it take to move 5000 people, that is 10 trains, from one city to the other?
But travel time and headways are two completely different things.

2 cities 300 km apart? Say Shanghai and Nanjing.
So let´s say the trip time is 60 minutes on CRH (actually it is not quite 300 km/h average now, the best trip time is 67 minutes now...) and 5 hours by the parallel mainline. And suppose both are filled to capacity - 20 number trains each hour, and 12 G trains, each with 500 seats.

In one hour, the number trains would deliver 10 000 passengers to a distance 300 km. In the same hour, the G trains will have delivered 6000 passengers the same distance. So the number trains still have carried more passenger-km.

The difference is that the G train passengers each will have spent 1 hour sitting on the train, while number train passengers each have been there for 5 hours.
Also, at any one time there would be 12 G trains with 6000 people on the 300 km HSR line, and 100 number trains with 50 000 passengers on the main line.
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Old June 6th, 2014, 02:58 PM   #8134
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Quote:
Originally Posted by :jax: View Post
True, but in that hour the metro has taken 10,000 people 70 km, while the HSR has taken 6,000 people 300 km. Less people per hour, but more than double the people-km.
The calculation of railway line capacity is not my field, but i believe the use of passenger-km as a mean for calculating or comparing the capacity of a line or modes of transport is not valid. Based on your example A380s, departing every 10 minutes with 500 passengers on board and covering a distance of 900km in an hour, will have 1.5 times more passenger-kms than the high speed train.

Quote:
Originally Posted by keber View Post
Simple:
1 - a subway train of 500 people, which travels 70 km/h, with a headway of 3 minutes (easily attainable in modern subway systems)
2 - a high speed train of 500 people, which travels 300 km/h, with a headway of 5 minutes (less is too dangerous because of necessary braking distances)

1 - this subway line can theoreticaly deliver 10000 people per hour
2 - this high speed line can theoretically deliver 6000 people per hour

Now, where do you see speed in those equations?
Of course, there are many other important factors for calculating capacity, but achieved top speed isn't one of them.
The term headway depends on speed among other things. In the following graph L2 and L3 are the levels of ETCS.

source : François LACÔTE ERTMS: Boosted performances for High Speed Lines
ALSTOM Transport, France
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Old June 6th, 2014, 04:02 PM   #8135
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Interesting graph. Of course I know that headway depends on speed too, but didn't know that there is such low headway possible at such great speeds with ETSC L3 (or L2). In reality I never heard about such short headways, most studies and practical examples that I saw for higher speed railways have headways around 4 or 5 minutes, some even 3. But none even near 1.5 minutes except some suburban trains and metrolines.

But as you said, passenger-km is not a valid unit for railway capacity as it is not for road capacity.
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Old June 6th, 2014, 04:04 PM   #8136
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It's not my thing either, I jumped in for the fun of it. I've had (data) network analysis way back in the past though, there are some similarities and differences. It comes natural to me to think of a train as a data package for instance.

I agree that the putative passenger-km isn't particularly interesting as a capacity metric, but a comparison with A380 is. Both a train and a plane could be seen as travelling through a virtual tube. Starting in Beijing, which mode of transport can ship the most people to Shanghai Hongqiao, assuming 5 minutes headway for HSR and 2 minutes interval between the A380s due to wake turbulence (could safely be extended to 5 minutes, there still aren't enough of them in existence to do this "air escalator")?
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Old June 6th, 2014, 04:05 PM   #8137
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Wait... a headway distance of 80 seconds at 300km/h?

Hmm...
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Old June 6th, 2014, 04:30 PM   #8138
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An example of capacity is Kowloon-Canton railway. 183 km.

The whole line, and many stations, were built back in 1910... as a single track, unelectrified (steam powered) one.

The Kowloon-Lo Wu section, 34 km, was double tracked and electrified in 1980s. It now has 14 stations.

Trains which make all 14 stops take 45 minutes between Kowloon and Lo Wu. So average speed 45 km/h - top speed something like 110 km/h.

The line is NOT a metro line - there are some tunnels, but as mentioned it is built as a ground, long-distance line. The loading gauge allows trains 3100 mm wide.

The SP1900 trains are 12 cars, and about 280 m long.

Now, from 1998, Automatic Train Protection system allows 24 trains per hour. This should mean headways of 2,5 minutes.

Also, the 2,5 minute headway means that at any time there are 18 trains en route between Kowloon and Lo Wu, and since these are 280 m long each, more than 5 km of the total 34 km track are occupied by trains at any time.

The rest of Kowloon-Canton railway, 149 km from Lo Wu to Guangzhou Station, was also double-tracked in 1980s, electrified in 1998 and quadruple tracked in 2007. It was sped up to 200 km/h in 1998.

How does the number of trains between Lo Wu and Guangzhou, on the high speed section, compare with the number of trains on the low speed section between Lo Wu and Kowloon?
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Old June 6th, 2014, 05:23 PM   #8139
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Quote:
Originally Posted by keber View Post
Simple:
1 - a subway train of 500 people, which travels 70 km/h, with a headway of 3 minutes (easily attainable in modern subway systems)
2 - a high speed train of 500 people, which travels 300 km/h, with a headway of 5 minutes (less is too dangerous because of necessary braking distances)

1 - this subway line can theoreticaly deliver 10000 people per hour
2 - this high speed line can theoretically deliver 6000 people per hour

Now, where do you see speed in those equations?
Of course, there are many other important factors for calculating capacity, but achieved top speed isn't one of them.

And talking about dudes - I design new railway lines, what do you do for your living?
I am a scientist.

If you are a railway engineer, you are not being honest here.

It is well documented that with speed, capacity increases. By comparing a subway line to intercity high speed line you are being insincere. Obviously most of the metro lines carry more people than Beijing-Shanghai High Speed line. But it is comparing apples to oranges. Capacity in its definition has "time" and "distance" parameters in it. At least this is what I read in scientific articles of your field. And it makes perfect sense to me.

Explain me, please. If we decrease max speed from 300km/h to 150km/h on a high speed line (let's say 300km length) what will happen to capacity?
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Old June 6th, 2014, 06:24 PM   #8140
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If it's time between trains rather than distance between signals that governs how many trains can run on a section of track, in a purely theoretical world the capacity of the line won't be affected by speed - it would simply take longer for all trains to clear the line (meaning that you have trains starting and finishing at half way or whatever at the beginning and end of the day)
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