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