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Old April 15th, 2011, 01:48 AM   #1961
foxmulder
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Quote:
Originally Posted by fragel View Post
if there is any safety issue, it is more likely the safety of the minister's position and profit of the airlines.
good one...
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Old April 15th, 2011, 02:39 AM   #1962
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main difference from a 300 to a 380km/h is energy consumption. At those speeds, friction with rails and cantenary problems are less important than air resistance itself.

If you had sub-spec construction, that speed reduction won't do any good in terms of preventing a catastrophic failure.
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Old April 15th, 2011, 02:55 AM   #1963
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Those 80kmh are equivalent to 60% more energy if it hit a track fault, probably almost as catastrophic as those speeds anyway but think about the extra energys wear on the trackbed that would cause a fault to develop in the firstplace.
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Old April 15th, 2011, 03:49 AM   #1964
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Those 80kmh are equivalent to 60% more energy if it hit a track fault, probably almost as catastrophic as those speeds anyway but think about the extra energys wear on the trackbed that would cause a fault to develop in the firstplace.
I don't know details about specs, but the force of attrition wheel-rail doesn't increase that much after 200km/h-250km/h. Air resistance is the culprit for the extra energy required.

Momentum is not that relevant for wear and tear of rail infrastructure at those speeds anyway.
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Old April 15th, 2011, 04:04 AM   #1965
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Quote:
Originally Posted by Suburbanist View Post
I don't know details about specs, but the force of attrition wheel-rail doesn't increase that much after 200km/h-250km/h. Air resistance is the culprit for the extra energy required.

Momentum is not that relevant for wear and tear of rail infrastructure at those speeds anyway.
You do understand the concept of F=ma don't you.(Newton's law of motions)
I also believe you understand the concept of law of the conservation of energy.
How does trains obtain motion?
By applying the third law, the mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction in relation between trains and tracks you get your answer.
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Old April 15th, 2011, 04:41 AM   #1966
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Originally Posted by SamuraiBlue View Post
You do understand the concept of F=ma don't you.(Newton's law of motions)
I also believe you understand the concept of law of the conservation of energy.
How does trains obtain motion?
By applying the third law, the mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction in relation between trains and tracks you get your answer.
I do understand that, but wear and tear is a bit more complicated. Wear and tear are caused by different forces experienced by the trackbed: repeated compression, vibrations, resonance, attrition-heat etc.
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Old April 15th, 2011, 04:46 AM   #1967
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Quote:
Originally Posted by Suburbanist View Post
I do understand that, but wear and tear is a bit more complicated. Wear and tear are caused by different forces experienced by the trackbed: repeated compression, vibrations, resonance, attrition-heat etc.
All those forces you mentioned are attributed to acceleration returning to my earlier post.
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Old April 15th, 2011, 04:51 AM   #1968
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don't tempt me to get started on physics... i could type an essay on that crap right now....specific values, equations, and all that good stuff....
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Old April 15th, 2011, 05:09 AM   #1969
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So could anyone provide us with at least some rough estimates of how much extra energy is needed to run at 350km/h and 380km/h compared to 300km/h?

Last edited by Pansori; April 15th, 2011 at 05:27 AM.
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Old April 15th, 2011, 05:22 AM   #1970
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So could anyone provide us with at least some rough estimates of how much extra energy is needed to run ar 350km/h and 380km/h compared to 300km/h?
well... given that you can find the mass of the train.. use the formula:

Kinetic Energy = 1/2(mass)(velocity^2)

for each speed. (use kg for mass and m/s for velocity)

the answer will provide the amount of energy in joules that the train has at each respective speed... in ideal conditions.

obviously friction and air resistance will add a lot to the energy, but this is what you can get for the average base energy. seeing as the velocity term is squared, it gives you a rough estimate of how much more energy you would need to move an object at faster speeds.
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Old April 15th, 2011, 11:06 AM   #1971
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Quote:
Originally Posted by BarbaricManchurian View Post
RIP HSR in China, 2008-2011. It was a good 3 years, indeed. No more grandiose plans of a line to Europe. No plans of a line to Singapore. No more pushing the limits of speed and what transportation and engineering can accomplish. All over some petty intraparty feud.
Looks like China Daily says otherwise about the plans to Europe. Although it doesn't say anything about HSR, this is still positive for the Chinese rail industry

China planning New Silk Road to Europe
Quote:
09:25, April 15, 2011

China is planning a "New Silk Road" that will run through Central Asia and continue into Europe facilitating improved transport and trade.

The road will complement a planned "Silk Track" railway that will also boost connections with Europe and the countries in between, officials and experts have confirmed.

Sources with the Xinjiang highway administration said construction will soon start on a 213-km expressway between Kashgar and Erkeshtam. The road is expected to be put into use in September 2013.

The project, which is likely to cost 4.3 billion yuan ($660 million), is being described as the first expressway to cross the Pamirs Plateau and offers access to Central Asia.

Ju Chengzhi, director of the international affairs department at the Ministry of Transport, told China Daily the soon-to-be-built Kashgar-Erkeshtam expressway is a section of the proposed new link between Asia and Europe.

He said the route within China will start in Lianyungang, in East China's Jiangsu province, and travel through Xi'an, in Northwest China's Shaanxi province, before reaching the Xinjiang Uygur autonomous region.

The proposed route will continue through Kyrgyzstan, Uzbekistan, Tajikistan, Turkmenistan, Iran and Turkey, before heading into Europe, he added.

"The route will link China with major countries in Central Asia, Western Asia and Europe. It will pass these countries' administrative centers, major cities and resource-producing areas," he said.

According to Ju, China has also proposed two other road connections between China and Europe -- one going via Kazakhstan and Russia and the other going through Kazakhstan and via the Caspian Sea.

Experts said barriers -- including technical ones and issues connected to taxation and customs -- are the reason why almost all of China's exported goods to Europe are transported by sea. Even goods from Xinjiang, Gansu and Inner Mongolia are currently sent east by rail to China's ports before they are shipped to Europe.

China's trade with Central Asian countries has grown nearly 50 times in the 17 years between 1992 and 2008, according to a report by Xinhua News Agency in 2009.

The report said the trading turnover between China and the five Central Asian countries was $527 million back in 1992 but had increased to $25.2 billion by 2008.

To facilitate communications and trade, China is also advocating a rail link that would start from the Xinjiang Uygur autonomous region in China and pass through Tajikistan, Kyrgyzstan and Afghanistan before arriving in Iran, according to Iranian former Foreign Minister Manouchehr Mottaki on Nov 15.

The railway would then be divided into two routes -- one of which would lead to Turkey and Europe.

Source: China Daily
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Old April 15th, 2011, 11:19 AM   #1972
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Quote:
Originally Posted by Fan Railer View Post

the answer will provide the amount of energy in joules that the train has at each respective speed... in ideal conditions.

obviously friction and air resistance will add a lot to the energy, but this is what you can get for the average base energy. seeing as the velocity term is squared, it gives you a rough estimate of how much more energy you would need to move an object at faster speeds.
Yes, but over long distances, friction and air resistance is much more important than instant energy.
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Old April 15th, 2011, 05:48 PM   #1973
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FT is the ultimate anti-China panphlet.

Should I believe the reasons FT suggests for this downgrade in terms of speed?

Isn't it logic enough the simple reason of making the system more cost-efficient and carry more people consuming less energy?

Are there official explanations?
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Old April 15th, 2011, 06:04 PM   #1974
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take a shower in Beijing West Railway Station.

http://www.tudou.com/programs/view/BrgWHoBvwl8/
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Old April 15th, 2011, 06:38 PM   #1975
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Quote:
Originally Posted by Luli Pop View Post

Should I believe the reasons FT suggests for this downgrade in terms of speed?

Isn't it logic enough the simple reason of making the system more cost-efficient and carry more people consuming less energy?

Are there official explanations?
Yes, there are:
Quote:
Originally Posted by Sheng Guangzu, China’s new railway minister
“This will offer more safety,” Mr Sheng was quoted as saying in the official Communist party mouthpiece, People’s Daily. “At the same time, this will allow more variation in ticket prices based on market principles.”
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Old April 15th, 2011, 06:46 PM   #1976
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Guys, some of you are over-analyzing the situation. I think this is mostly a political move. Their aim suppose to be cheaper tickets but still it looks purely political to me. When another set of political figures replaces these people, we might see an increase in speed. So only time will tell...
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Old April 15th, 2011, 06:49 PM   #1977
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The safety concerns are completely unfounded. Lowering the speed doesn't offer an increase in safety at all (in fact, with more different speed services, it's more dangerous), it's just a believable excuse that some will believe.
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Old April 15th, 2011, 07:40 PM   #1978
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Quote:
Their aim suppose to be cheaper tickets but still it looks purely political to me. When another set of political figures replaces these people, we might see an increase in speed. So only time will tell...
So are cheaper tickets forthcoming?

The next thing announced to get actually done is requiring ID for all high-speed tickets from 1st of June. How shall it work out?
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Old April 15th, 2011, 07:49 PM   #1979
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This seems to be a recreation of the halt of rapid airport expansion occurred in the early part of the last decade. I for one think in a year or two there will be findings suggesting there is no safety concerns about the system and the speed will be back. China operates as a single corporation, internal competition between railway and airlines are red hot and causing problems. They need to cap the growth of HSR a little bit so that domestic air travel don't get killed, thus also help create demand for the forthcoming domestic passenger jets (ARJ21, C919, etc). We all want China to have the best and fastest, but at the end of the day if it can't bring in money then China will be the loser in the long run.
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Old April 15th, 2011, 09:10 PM   #1980
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I have a question: In which dialect are the announcements at the railway stations in the south of China, Mandarin or local?
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