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Old June 6th, 2014, 09:41 PM   #8141
Attus
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Originally Posted by foxmulder View Post
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?
Actually nothing.
More detailed: with a lower speed you may have shorter headways with the very same signalling system so that the capacity can be slightly increased.
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Old June 6th, 2014, 09:58 PM   #8142
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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)
In theory, the length of trains themselves limits the line capacity at low speeds. But these are very low speeds.

If 24 trains leave Kowloon each hour, each of them 280 m long, then these trains take up 6720 m length of track. So a line cannot possibly have space for 24 trains per hour if the speed is much below 7 km/h.

But thatīs a speed applicable to rail yards and stations. So at Kowloon station, these 24 trains per hour need to be distributed to several tracks. But once out of the station, they can spread out on the same track.

24 trains per hour on Kowloon-Shenzhen section of the railway line would take up 45 km at their speed 45 km/h, so they themselves occupy 6720 m and the remaining 38 km is empty track between train. If they accelerate to say 180 km/h on the Shenzhen-Guangzhou section then they spread over 180 km, but their own length is still 6720 m. If they then accelerate to 350 km/h on Guangzhou North-Changsha South high speed section then they spread over 350 km stretch.

But can the signalling and braking of Guangzhou-Changsha-Beijing or Changsha-Hangzhou-Shanghai high speed railway handle 24 trains per hour that Kowloon-Shenzen section can release into them? Or do these high speed lines need longer headways?
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Old June 6th, 2014, 10:14 PM   #8143
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Theoretically the signalling system of the Chinese HSLs can handle a headway of 4 minutes at the speed of 300 km/h.
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Old June 7th, 2014, 02:16 AM   #8144
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Quote:
Originally Posted by Attus View Post
Actually nothing.
More detailed: with a lower speed you may have shorter headways with the very same signalling system so that the capacity can be slightly increased.
That is the thing, you are assuming you can double the frequency of the trains.

Anyhow, enough off-topic on my part....
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Old June 7th, 2014, 03:27 AM   #8145
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As given that is not surprising. You double the speed, you double the distance between them (and then a little, ignored here). At 300 km/h the distance between the trains will be 25 km apart, at 600 km/h they will be 50 km apart, at 60 km/h they will be 5 km apart. The trains are moving faster, but 12 trains an hour, so the size of the trains determine the number of people shipped in that hour.

Given that a 16 car train is about 400 meters long, the utilisation rate is 1.6% at maximum capacity at 300 km/h, 98.4% would be non-train. This too is not a useful metric except for amusement purposes (chornedsnorkack used the slow end of this stick to get 100% utilisation rate in Hong Kong). It would show that a hypothetical "rolling pavement" at 300 km/h would ship 63 times as many people. Since we are at the hypotheticals, a 300 km/h train doing an emergency deceleration at 1g should go to 0 km/h in about half a minute.

In practice, and I'd venture that is the case for train and data networks alike, you don't want to maximise utilisation, you want to maximise throughput. Adding more traffic can reduce throughput. In a data network you get package collisions, that thankfully you don't get very often in a road or rail network, but you do get congestion. The peak traffic is the only reason we think of capacity to begin with. Put in data terms, you have one huge file to be delivered in the morning, and one huge file during the evening, some more traffic during the day, little traffic during the night. Then I think my case is more realistic. You have N people waiting at the gates to be delivered, how long will it take to ship them there?
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Old June 7th, 2014, 07:42 AM   #8146
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Quote:
Originally Posted by foxmulder View Post
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.
Or imagine a hotel vs. a restaurant. How many clients per day ?
For the hotel, it's the actual projected number, you can't take more people than capacity in beds. Same for high speed train.

Wereas in a restaurant you can have more clients, because each of them will stay for 1-2 hours. They will leave and others will come. Everything is so fast, just like in suburban trains.
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Old June 7th, 2014, 09:54 AM   #8147
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Guiyang-Guangzhou HSR,250km/h-300km/h,this is a milestone line for Guizhou Province,it is the first HSR in Guizhou,will cut thetime from 20-22 hours to about 4 hours.






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Old June 7th, 2014, 10:11 AM   #8148
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For the hotel, it's the actual projected number, you can't take more people than capacity in beds. Same for high speed train.

Wereas in a restaurant you can have more clients, because each of them will stay for 1-2 hours. They will leave and others will come. Everything is so fast, just like in suburban trains.
Just how is a high speed train different from a suburban train in that respect?

Train G71 travels from Beijing to Shenzhen North, taking 10:16 total (leaves 8:00, arrives 18:16).

It also makes 15 intermediate stops: Baoding East, Shijiazhuang, Handan East, Hebi East, Zhengzhou East, Zhumadian West, Xiaogan North, Wuhan, Changsha South, Zhuzhou West, Hengyang East, Leiyang West, Shaoguan, Guangzhou South, Humen.

Does G71 carry as many passengers as seats because everybody who gets on in Beijing stays to Shenzhen North and nobody gets off or on in the stations in between? Or does G71 carry 16 times as many passengers as seats, because everyone who got on at Beijing gets off at Baoding, new passengers get on at Baoding but travel just to Shijiazhuang, and so forth till at Humen the train is again completely emptied and then filled with new passengers travelling just from Humen to Shenzhen?

I suspect that the answer is somewhere in between. But does anyone have actual ticket sales records as to exactly how many tickets are on average sold for the same seat from Beijing to Shenzhen?
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Old June 7th, 2014, 12:10 PM   #8149
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Originally Posted by chornedsnorkack View Post
I suspect that the answer is somewhere in between. But does anyone have actual ticket sales records as to exactly how many tickets are on average sold for the same seat from Beijing to Shenzhen?
I don't have statistic, but the number is probably low, I have seen fully sold out G trains with actually plenty of seats on board. So the system isn't very good at assigning multiple passengers to seats once they open up. However, this situation don't happen as often on D trains, since they sell a small portion of standing tickets, and those passenger will hunt down every last open seat available.
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Old June 7th, 2014, 09:51 PM   #8150
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Guiyang-Guangzhou HSR,250km/h-300km/h ... will cut thetime from 20-22 hours to about 4 hours.
250km/h sounds ridiculously slow for G-trains. But anyways, tripping through Guilin,Sanjiang and Kaili is going to be a blast.
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Old June 8th, 2014, 03:12 AM   #8151
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Speaking of high speed trains in China, have they figured out a time for the opening of the Kowloon-Shenzhen line for 2015?
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Old June 8th, 2014, 03:44 AM   #8152
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Speaking of high speed trains in China, have they figured out a time for the opening of the Kowloon-Shenzhen line for 2015?
Is it even going to happen in 2015?
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Old June 8th, 2014, 05:14 AM   #8153
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Is it even going to happen in 2015?
Delayed due to construction issues : http://www.skyscrapercity.com/showth...506990&page=34

Expected opening in 2017.
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Old June 8th, 2014, 08:47 AM   #8154
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Is Shenzhen Longhua-Shenzhen Futian high speed railway also delayed, or does it have a known due date for opening?
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Old June 9th, 2014, 05:48 PM   #8155
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Guiyang-Guangzhou HSR,250km/h-300km/h,this is a milestone line for Guizhou Province,it is the first HSR in Guizhou,will cut thetime from 20-22 hours to about 4 hours.
This is typical in China. All forms of regular transport average 30 to 60 kph. Bus, train, car on highways. The HSR, connecting subways, and aircraft of course, eliminate the massive slowdown in transit speeds.

Once you exit the HSR system your travel speeds will plummet and be much lower than any other country.

Being within 50kms of a HSR line and/or station will reduce much of this.

I recall a trip from Guangzhou to Wuhan in early 2010 that took 3.25 hours and then the trip from Wuhan to Xian took 17 hours by bus.

For those of you who may visit China and want to ride the HSR, you need to prepare for the very slow travel velocities once you disembark.

You will be able to take an HSR trip of 550kms in 2.5 hours and when you get on the connecting bus at the train station you will then consume 90 minutes to travel 50kms.
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Old June 9th, 2014, 06:51 PM   #8156
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This is typical in China. All forms of regular transport average 30 to 60 kph. Bus, train, car on highways. The HSR, connecting subways, and aircraft of course, eliminate the massive slowdown in transit speeds.

Once you exit the HSR system your travel speeds will plummet and be much lower than any other country.

Being within 50kms of a HSR line and/or station will reduce much of this.

I recall a trip from Guangzhou to Wuhan in early 2010 that took 3.25 hours and then the trip from Wuhan to Xian took 17 hours by bus.

For those of you who may visit China and want to ride the HSR, you need to prepare for the very slow travel velocities once you disembark.

You will be able to take an HSR trip of 550kms in 2.5 hours and when you get on the connecting bus at the train station you will then consume 90 minutes to travel 50kms.
But then again why on earth would you go from Guangzhou to Wuhan on a HSR train and then continue on to Xi'an by bus?!
Wouldn't it have made much more sense to go all the way to Xi'an by HSR as there is a direct line? If it wasn't open yet at the time you could still have chosen a conventional train that would've taken you there much quicker...
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Old June 9th, 2014, 06:54 PM   #8157
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Is Shenzhen Longhua-Shenzhen Futian high speed railway also delayed, or does it have a known due date for opening?
The HSR section from Shenzhen North to Futian is reportedly still on target for opening before 2015.
I really hope it can open sooner though as the North railway station in Longhua is just too far away from where I am now (Hong Kong island)!
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Old June 9th, 2014, 10:42 PM   #8158
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If it wasn't open yet at the time you could still have chosen a conventional train that would've taken you there much quicker...
Slightly quicker.

At present, there are 3 T trains Wuhan-Xian, taking 11:08 to 12:01, and 9 K trains, taking 13:26 to 15:23.
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Old June 10th, 2014, 01:55 AM   #8159
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But then again why on earth would you go from Guangzhou to Wuhan on a HSR train and then continue on to Xi'an by bus?!
Wouldn't it have made much more sense to go all the way to Xi'an by HSR as there is a direct line? If it wasn't open yet at the time you could still have chosen a conventional train that would've taken you there much quicker...
Because there was no CRH at that time and the train did not leave until the next day and the train heads north and then west not directly NW.

So many incorrect assumptions. Hong Kong is *slightly* different from the mainland.
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Old June 10th, 2014, 01:56 AM   #8160
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Slightly quicker.

At present, there are 3 T trains Wuhan-Xian, taking 11:08 to 12:01, and 9 K trains, taking 13:26 to 15:23.
Please do not post about something you know nothing about.

You are posting from reading a webpage, and you have never set foot in China.

If I could block your ignorant posts, I would.
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