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Old November 11th, 2013, 11:30 AM   #1641
chornedsnorkack
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Quote:
Originally Posted by Pansori View Post
Hong Kong section is 36km long. Hypothetically if you would run a train on the entire route at an average speed (which would never happen in reality) of 200km/h vs. 350km/h the time it would take would be the following:

200km/h: 10min. 48sec.
350km/h: 6min. 10 sec.

So essentially we would be talking about 10 minutes vs 6 minutes. Not very much of a difference, right?

However we all understand that this is just a hypothetical average speed which would never happen in real life.
My calculations:
Letīs make it acceleration to top speed at 1 m/s2, cruise at top speed, then deceleration at the same rate. 36 km total.
200 km/h - 56 m/s (3,3 km/min)
acceleration and deceleration 56 s each, cover 3,1 km combined
cruise 33 km, slightly under 10 minutes
total slightly under 12 minutes
350 km/h - 97 m/s (5,8 km/min)
acceleration and deceleration 98 s each, cover 9,5 km combined
cruise 26,5 km, about 4 minutes 35 s
total 7 minutes 50 s
430 km/h, which happens to be the top speed of Shanghai Transrapid, very comparable distance of around 35 km - that is 120 m/s or 7,2 km/min
acceleration and deceleration 2 minutes each, cover 14,4 km combined
cruise 21,6 km, takes exactly 3 minutes
Total 7 minutes 0 seconds
In actual practice, Transrapid trip time is quoted at 7 minutes 32 seconds.

The calculated 50 second trip time difference between 430 km/h and 350 km/h is small. The 4 minute trip time difference between 350 km/h and 200 km/h is not so small.
Can anyone check and improve my calculations?
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Old November 11th, 2013, 03:37 PM   #1642
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How can the difference in your calculations be almost identical to my calculations with hypothetical 200 and 350 kmh average speed? There is clearly something wrong in your estimates.

OK I think I got it. With your calculations for 350kmh top speed the average speed is around 270kmh which is impossible. Are you sure you got the acceleration and deceleration numbers right?

Last edited by Pansori; November 11th, 2013 at 03:42 PM.
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Old November 11th, 2013, 03:46 PM   #1643
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Quote:
Originally Posted by Pansori View Post
How can the difference in your calculations be almost identical to my calculations with hypothetical 200 and 350 kmh average speed? There is clearly something wrong in your estimates.

OK I think I got it. With your calculations for 350kmh top speed the average speed is around 270kmh which is impossible.
Break down my calculations:
9,5 km for acceleration and deceleration with average speed 175 km/h
26,5 km cruise with average speed 350 km/h.
Quote:
Originally Posted by Pansori View Post
Are you sure you got the acceleration and deceleration numbers right?
What is your offer for acceleration?
Note how close my computed time 7:00 at 430 km/h is to the observed time 7:32.
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Old November 11th, 2013, 09:08 PM   #1644
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Quote:
Originally Posted by chornedsnorkack View Post
Can anyone check and improve my calculations?
You have an assumption of linear accelaration from standing to maximum. This is a reasonable approximation to the smoothed accelaration that occurs for mechanical reasons, and for passenger comfort. I saw in a sales blurb for CRH380 (sorry, can't find the link right now) a claimed emergency braking distance of 6km from 350km/hr. Assuming it can accelerate at the same rate without blowing fuses everywhere, on a 36km run this gives
2'4" each accelerate and decelerate, with 4'7" at top speed,
total run time 8'15" or 262 km/hr average.

Double the accelerate/decelerate distance for safety and comfort gives
total run time 10'16" or 211km/hr average.

The numbers are pro rata similar to your quoted Transrapid timings. They also show that on short runs it's the starting and stopping that gobble up the time. This is an advantage the maglev has over trains that need to do one or two short runs before getting out on the trunk line.
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Old November 11th, 2013, 10:19 PM   #1645
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Quote:
Originally Posted by xinxingren View Post
You have an assumption of linear accelaration from standing to maximum. This is a reasonable approximation to the smoothed accelaration that occurs for mechanical reasons, and for passenger comfort. I saw in a sales blurb for CRH380 (sorry, can't find the link right now) a claimed emergency braking distance of 6km from 350km/hr. Assuming it can accelerate at the same rate without blowing fuses everywhere, on a 36km run this gives
2'4" each accelerate and decelerate, with 4'7" at top speed,
total run time 8'15" or 262 km/hr average.

Double the accelerate/decelerate distance for safety and comfort gives
total run time 10'16" or 211km/hr average.

The numbers are pro rata similar to your quoted Transrapid timings. They also show that on short runs it's the starting and stopping that gobble up the time. This is an advantage the maglev has over trains that need to do one or two short runs before getting out on the trunk line.

There's a paper below which gives you all the operating details for the ICE design. There's speeds, timings and deceleration/acceleration rates.

http://www.railway-technical.com/Inf...acity%20v3.pdf

They go with a deceleration rate of 0.5 m/s2 for passenger comfort.

The long-distance CRH380 sets seem to have an acceleration rate of around 0.6 m/s2, whilst commuter sets elsewhere in the world have a much higher acceleration rate.
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Old November 11th, 2013, 11:21 PM   #1646
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So what would be a realistic average speed in the Hong Kong territory of the express link?
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Old November 12th, 2013, 04:12 AM   #1647
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Quote:
Originally Posted by Pansori View Post
Yes, if I remember correctly it takes well over 30 minutes from Hung Hom to Lo Wu (should be same to Lok Ma Chau). If they'll be using MTR380 trains to run to Shenzhen it will be essentially world's fanciest short-distance commuter trainsets.
I'm wondering perhaps it's better for MTR to use CRH6A's as short haul service. The trains are more suited towards shorter haul and dwell situations and the MTR380 can't even max out on speed in the HK-SZ tunnels while the CRH6 is just right.
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Old November 13th, 2013, 12:35 AM   #1648
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CRH6's would only limit MTR to running between Kowloon and Futian correct? Do they plan to run short routes like that or take the trains all the way to Guangzhou South and back to Kowloon?
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Old November 13th, 2013, 05:38 AM   #1649
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Having a standard 380 fleet for both CRH and MTR allows for crew/train substitution if required.

It also enables extensions to short haul services should a CRH long haul service be cancelled by ad hoc.

MTR buying the CRH6 would not allow flexibility in operations.
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Old November 13th, 2013, 06:42 AM   #1650
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Quote:
Originally Posted by FM 2258 View Post


CRH6's would only limit MTR to running between Kowloon and Futian correct? Do they plan to run short routes like that or take the trains all the way to Guangzhou South and back to Kowloon?
The MTR plans huge amount of shuttle service to the PRD. There will be a short haul train terminating at Shenzhen North every 15-minutes in the beginning. I consider their ~100,000 pax/day estimate to be a little conservative. In 2016 Central and Futian CBDs will be some of the biggest and most prominent office districts in the world, fed by some of the busiest metro systems.

But here is a thought, the Guangzhou-Dougguang-Shenzhen RTS will initially end in Qinghai CBD with an option to extend to Futian CBD. What if you (literally) extend that idea further and interline that to the XRL, now Central, Qinghai, Nanshan, Shenwan and Futian CBDs will be connected. Now many +200m, Supertalls, Megatalls is that connecting?
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Old November 13th, 2013, 10:21 AM   #1651
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Originally Posted by saiho View Post
The MTR plans huge amount of shuttle service to the PRD. There will be a short haul train terminating at Shenzhen North every 15-minutes in the beginning.
Right now, Shenzhen-Guangzhou D train services get as frequent as 6 in rush ours (8:xx, 9:xx, 18:xx). Longua-Guangzhou South go up to 4 (15:xx). But those services are badly irregular, e. g. the 15:xx trains to Guangzhou South are :00, :20, :35, :50 - no memorable pattern.
Quote:
Originally Posted by saiho View Post
But here is a thought, the Guangzhou-Dougguang-Shenzhen RTS will initially end in Qinghai CBD with an option to extend to Futian CBD. What if you (literally) extend that idea further and interline that to the XRL, now Central, Qinghai, Nanshan, Shenwan and Futian CBDs will be connected. Now many +200m, Supertalls, Megatalls is that connecting?
Good idea!

The problems with existing railways are:
Guangzhou South location sucks. It is in an empty southern suburb 21 km from Guangzhou and thus the old centre.
The 102 km Guangzhou-Longhua railway is, at 350 km/h, too fast. Making a stop takes a lot of time, and a stopping train would get in the way of a following nonstop one.
There are too few stations. Just 3 in these 102 km. Now Humen is important - it is the second biggest town. But Qingsheng is in the empty Nansha district. Compare Guangzhou-Zhuhai - there are 12 stations in 97 km between Guangzhou South and Tangjiawan, 97 km, and 13th is under construction.
For comparison, how about the Kowloon-Canton railway? 147 km. But for some reason, no train makes more than 4 stops there.
So how about CRH6 service connecting Hong Kong to either Kowloon-Canton railway or some new line, actually both would be needed, with actual frequent stops?
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Old November 14th, 2013, 10:31 PM   #1652
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Quote:
Originally Posted by saiho View Post
I'm wondering perhaps it's better for MTR to use CRH6A's as short haul service. The trains are more suited towards shorter haul and dwell situations and the MTR380 can't even max out on speed in the HK-SZ tunnels while the CRH6 is just right.
MTR can certainly buy some CRH6 to run those shuttles, it's designed to tolerate the wear and tear associated with frequent stop and go service, and the extra door will allow faster boarding and disembarking speed. The MTR380 can still be used on longer routes that extend farther outside HK.
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Old November 14th, 2013, 11:09 PM   #1653
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Originally Posted by hmmwv View Post
MTR can certainly buy some CRH6 to run those shuttles, it's designed to tolerate the wear and tear associated with frequent stop and go service, and the extra door will allow faster boarding and disembarking speed. The MTR380 can still be used on longer routes that extend farther outside HK.
Can CRH6 travel beyond Longhua towards Guangzhou South?

CRH6 has a lower top speed. Sure, the CRH6 can accelerate faster than MTR380 towards Humen, but its top speed is just 220 km/h. Whereas MTR380 accelerating slower can continue to the 300 km/h top speed of Shenzhen-Beijing high speed railway - and then the CRH6 gets in the way.

On the other hand - Longhua-Xiamen high speed railway is limited to 200 km/h. Shall there be commuter services from Kowloon West that reverse at Longhua towards Huizhou?
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Old November 15th, 2013, 12:04 AM   #1654
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It sure can, but then we lose the advantage of having a two tiered train system. I think CRH6 should stay on the Shenzhen-Hong Kong line for shuttle service, while MTR380 is used for travel beyong Shenzhen.
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Old November 15th, 2013, 12:22 AM   #1655
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Originally Posted by hmmwv View Post
It sure can, but then we lose the advantage of having a two tiered train system. I think CRH6 should stay on the Shenzhen-Hong Kong line for shuttle service,
But then we lose the advantage of having CRH6 and its high acceleration.
Towards Guangzhou North, the distances are:
Futian - 31 - total 31
Longhua - 8 - 39
Guangming - 17 - 56
Humen - 36 - 92
Qingsheng - 19 - 111
Guangzhou South - 31 - 142
Guangzhou North - 45 - 187

The stations from Longhua towards Xiamen start:
Pingshan
Huizhou South
Huidong
Houmen
Shanwei

Now Shanwei is clearly outside Pearl river delta. But what types of trains should carry commuter services like Hong Kong-Guangming or Hong Kong-Huidong?
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Old November 15th, 2013, 01:15 AM   #1656
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Originally Posted by chornedsnorkack View Post
Shall there be commuter services from Kowloon West that reverse at Longhua towards Huizhou?
Not while I'm Minister of Railways.
If it's a "commuter"/"shuttle" service then people can just get off one train, cross to the other side of the platform and get on another train going someplace else. That's how commuter/metro systems usually work. And if it's HSR that's more reason to be careful about track layout at junction stations.
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Old November 19th, 2013, 12:19 PM   #1657
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I guess CRH6F is designed for commuter rails

Quote:
Chengdu commuter rail Line 18 will use CRH6F

Proposed Line 18: Chengdu South Railway Station to new airport
58 km (23 km underground), 8 stations, 160 kmph



by 高铁见闻
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Old November 19th, 2013, 12:56 PM   #1658
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I guess CRH6F is designed for commuter rails
Which trains shall serve Chengdu-Mianyang-Leshan and Chengdu-Pujiang high speed railways?
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Old November 19th, 2013, 01:27 PM   #1659
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CRH6F comes in two versions, for commuter service (160kph top speed) and for high-speed lines (220kph top speed).
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Old November 19th, 2013, 05:37 PM   #1660
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I guess CRH6F is designed for commuter rails
The entire CRH6 series is more or less designed for commuter/regional service. the CRH6A, CRH6F, CRH6S are all for commuter type applications with CRHA doing serving Express/Non-Stop/Regional Rail roles and the CRH6F performing Local/All Stop roles. CRH6S is for urban rail/shuttle service
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