為什么不建一座美國到中國的橋梁呢

2019-10-23 14:20:33 | 來源: | 參與: 0

  Why don't we build a bridge from the US to China?

  我們為什么不建一座美國到中國的橋梁呢?

  以下是Quora讀者的評論:

  Michael Feely, Architecture : I practice it.

  Problem 1: Your assumption about the cost and survivability of a 5,000 mile long bridge across the entire pacific is wildly optimistic. To put it in context, Donald Trump’s border wall with Mexico is estimated to cost $21 billion. And that's for an object 25% the length, that can be built on solid ground, that doesn't need a 10 lane highway on top, and that need not fear hurricane damage. Using other mega-bridge projects as a model we get costs between 25 and 100 times greater than the $20 billion estimate you have (Call it $500billion to $2 trillion. And count on $2 trillion being closer to correct)

  Problem 2: A bridge implies a single start point and an end point. Presumably Shanghai to Long Beach or so. But what happens to cargo from Hong Komg to San Francisco. Does it have to go up the coast, to the bridge, and then up the coast again?

  Problem 3: To the extent that this bridge gets used, it basically is a target for half the people in the Pacific with an economic grudge. Security is going to be a headache.

  Problem 4: Why just the US and China. Why doesn't Japan get an off-ramp? How about South Korea?

  問題1:你對橫跨整個太平洋、5000英里長的橋梁的成本和耐用性過于樂觀了。相比之下,唐納德·特朗普擬建的墨西哥邊境墻估計耗資210億美元。長度只是這座橋的25%,可以建在堅實的地面上,不需要10車道,也不需要擔心颶風的破壞。以其他的特大橋項目為模型,我們得到的成本是你估計的200億美元的25到100倍(5000億到2萬億美元)。2萬億美元更準確。

  問題2:橋得有起點和終點。假定是從上海到長灘吧。那么從香港到舊金山的貨物怎么辦?它必須沿海岸向上,上橋,再沿海岸繼續向上?

  問題3:就這座橋的使用程度而言,它會是太平洋地區一半對經濟不滿的人的攻擊目標。安全問題將令人頭痛。

  問題4:為什么只提到美國和中國?日本不能搞個出口匝道?韓國呢?

  Problem 5: Now for the kicker. Average freight costs per ton-mile run about 15 cents for trucking, 5 cents for railroads- and about 3 cents for trans-oceanic container ships. Assuming you have a railroad on this bridge and a modest toll to pay for the original construction cost of the bridge, it would likely run about 6 cents per ton-mile to ship on. So there will be no payback, because there are already cheaper modes of transportation available. In theory, it will attract some cargo away from ships because it will be faster - container ships run around 37–46 km/h, whereas you could probably double that speed with rail freight on this giant bridge. But that’s about it for potential users.

  問題5:現在挑刺的人要跳出來了。貨運每噸英里的平均運費為15美分,鐵路為5美分,跨洋集裝箱船為3美分。假設你在這座橋上鋪設一條鐵路,每噸英里的運輸費用大概是6美分。所以得不償失,因為已經有更便宜的交通方式了。從理論上講,它能吸引一些貨運,因為它的速度會更快—集裝箱船運行約37-46公里/小時,而通過這座橋梁運輸,速度可以加倍。但只針對潛在用戶的。

  Nischal Ranjinath Muniandy, studied at KDU University College

  The answer is essentially down to a few core reasons.

  It cost a lot more than $4 million/mile for one thing. You would have to get tonnes of machinery, material and personnel thousands of kilometers into the open ocean. If we based this theoretical bridge on the Danyang-Kunshan Grand Bridge, it would cost at least $415 billion dollars and that’s mainly an overland viaduct. Basing it on the Dubai Floating Bridge would net us a cost of 2.125 trillion dollars. And this is not including the cost of maintenance.

  And not to mention that this bridge would have to withstand any extreme weather events and be tall enough to avoid ships crashing into it.

  But let’s just say for the sake of argument, this bridge was complete and is 5,000 miles from end to end. How will people get across? By road? Going at 100 mph, it would take 50 hours of non-stop driving to get from one end to another. And that would necessitate having a lot of amenities for drivers. Rest stops, gas stations, emergency services and perhaps even hotels. That would only add to the initial cost of construction and the cost of maintenance, but now you have a large labour cost as well. If someone is going to work in the literal middle of nowhere that’s a day’s drive from anywhere else, you bet they’d want to be paid and housed decently.

  答案基本上可以歸結為幾個核心原因。

  每英里的成本遠遠超過400萬美元。你不得不把成噸的機器、材料和人員運到幾千公里外的公海。如果我們把這座理論上的橋建在丹陽-昆山大橋上,它將花費至少4150億美元,主要是陸上高架橋。將它建在迪拜浮橋上將為我們帶來2.125萬億美元的凈成本。還不包括維護費用。

  更不用提這座橋還需承受任何極端天氣事件,還要足夠高以避免船只撞到橋上。

  但是為了方便討論,我們只說這座橋從一端到另一端長達5000英里。人們要如何通行?通過公路嗎?以每小時100英里的速度行駛,需要連續行駛50個小時。這就需要為司機提供很多便利設施。休息站,加油站,緊急服務,甚至酒店。這只會增加最初的建設成本和維護成本,但現在勞動力成本都極高。

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