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I had this idea the other day just for the heck of debating about if it would be feasible to build a bridge that crosses North Atlantic Ocean from Canada to Spain.

I mean from St-John's (Newfoundland, Canada) to Costa Da Morte (Spain). The bridge should be strong enough to survive the harsh weather conditions, salt water, time, tsunamis, etc. for a long period of time. Could it be a floating bridge or a floating tunnel with train tracks and or high-speed Maglev?

I calculated that the "bridge" is 3396 Km long (2110 miles) including the earth's curvature from the two countries.

Google Map visual presentation

Would it be feasible from an engineering stand point? Would it also be good for the economy from all the trades between the North-American continent and Europe with this high speed transport?

Could it also be too expensive and not financially viable even if all countries pitch in like we did with the international space station?

Cheers!

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    $\begingroup$ Don't forget to take plate tectonics into account. $\endgroup$
    – mouviciel
    Nov 5, 2014 at 16:06
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    $\begingroup$ What type of traffic are you intending for this bridge? Is this people or cargo or both? A high speed light rail 'bridge' is a different topic than a heavy industrial rail. I'm kinda curious if it'd be possible to have the bridge underwater...kinda a suspended underwater bridge...not quite at the bottom, but far enough below the surface to avoid weather and waves. $\endgroup$
    – Twelfth
    Nov 5, 2014 at 20:15
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    $\begingroup$ And one other question...is newfoundland to spain the closest route for North America - Europe...or would over the north pole be a shorter distance? $\endgroup$
    – Twelfth
    Nov 5, 2014 at 20:55
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    $\begingroup$ I know this is a little old as there's no accepted answer maybe you're still thinking about it. As bridge complexity scales faster than linearly with length, maybe you'd be better off going Canada-Greenland-Iceland-UK. Without a globe handy (or the right map projection) it looks like the total sea crossing is less, certainly it's in much shorter segments. Even a single link from Newfoundland to Ireland may be shorter. $\endgroup$
    – Chris H
    Feb 16, 2015 at 11:00
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    $\begingroup$ I know you just came up with this for discussion. But if you wanted a story about a trans-Atlantic bridge, you could have it built by someone who doesn't care about cost-efficiency--a grandiose dictator or billionaire, say, who is doing it out of ego. $\endgroup$
    – user14951
    Nov 1, 2015 at 21:11

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If someone wanted to build such a thing, it would almost certainly be a pontoon bridge composed of floating sections joined together. The average depth of the Atlantic is about 3300 m so I doubt it would be feasible or cost-effective to drive supports into the ocean floor. (OTOH an artifical island on the mid-Atlantic ridge might be a useful anchor point.)

The other advantage of a pontoon bridge is that its sections could be decoupled during severe storms -- effectively they would become ships which could ride out the storm, with passengers and vehicles on board, and then be joined back together.

The world's longest pontoon bridge is the Evergreen Point bridge, the floating section of which is 2310 m long. You are proposing a bridge approximately 1000 times longer.

Evergreen Point cost at least \$127 million at today's prices. So simplistically, an Atlantic bridge would cost \$127 billion. In practice it would be much more, because of the need to make it sturdy enough to withstand the weather in the open sea and decouple if necessary. If we multiply the cost by 10 to be safe, that is $1.27 trillion. There might also be difficulties with sourcing enough metal and other materials to build the bridge.

As it happens, \$100 billion is the approximate cost of the International Space Station. For the higher figure, the estimated cost of the 2003-14 Iraq war was $2 trillion. So given a large enough effort, the construction could probably be financed.

Would it be cost effective? Almost certainly not, unless something happened to radically change our economy and/or technology. For comparison, the world's container ship fleet numbers more than 6800 vessels, averaging 500 m in length. Simplistically, you could just string together almost all of the world's commercial shipping to build your bridge. But it's really a lot more useful to sail the ships around separately, to load and unload cargo at different ports around the world, instead of having a single (probably overcrowded) span from Canada to Spain.

As mentioned in the original question, a Transatlantic Tunnel, either floating beneath the surface or resting on the seabed, is another possibility. It would avoid problems with weather, and possibly be easier to find materials for, but it would still be a massive engineering task and astronomically expensive.

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    $\begingroup$ To add to this, it is faster to fly from any major city in North America to Europe than it is to drive from Halifax to Sydney, take the ferry from Sydney to Port aux Basques, and then drive to St John's. Let alone drive another 33 hours across the Atlantic. Let alone from any other city. Heck, the drive across the Atlantic is slightly longer than New York to Houston. You'd need to break up the drive into 5 or more shifts to even drive it safely. $\endgroup$
    – user772
    Nov 5, 2014 at 15:55
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    $\begingroup$ Fuel costs should be considered as well. I don't have the numbers but container ships are orders of magnitude more fuel efficient than a semi or even a train. Not to mention driving a semi on a wave riding pontoon bridge would be a seriously dicey little adventure. $\endgroup$
    – James
    Nov 5, 2014 at 16:23
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    $\begingroup$ A tunnel adds on the requirement of air circulation for thousands of miles...very hard. $\endgroup$
    – Oldcat
    Feb 20, 2015 at 0:44
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    $\begingroup$ The mention of an artificial island as an anchor point makes me think of the Öresund bridge between southern Sweden and Denmark. That bridge, however, only stretches for just under 8 km, and the total cost for the project was approximately 40 billion SEK (around 5 billion USD). $\endgroup$
    – user
    Aug 7, 2015 at 13:35
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    $\begingroup$ Now that the Evergreen Bridge has been replaced by a longer, more modern version, we can see the projected cost would be even higher. 4.56B for the new bridge x1000 suggests 4.56T at the low end, plus the significantly greater chance of construction problems and difficulties building far out from shore. $\endgroup$
    – Troyen
    Oct 3, 2017 at 8:31
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@James, et al

The Channel Tunnel between Britain and France is probably the closest actually completed project. They were smart enough to use electric trains. Avoids stop and go traffic, exhaust ventilation, and probably more fuel efficient as well.

I could see mag-lev trains with space for cars eventually competing with airlines/interstates. You don't have to drive, it's easy to schedule a stop every 1000 miles, you have your car when you get to your destination. Space and service on airplanes is getting steadily worse, imagine a train where you could walk around (listen to music in your parked car), stops every 8 hours at the equivalent of a highway rest area, your trip takes twice as long as by plane, but no luggage to deal with (stays in your trunk), no TSA, you can get a good night's sleep instead of arriving blurry eyed and jetlagged.

Now, could such service ever run across, or under, the Atlantic? I think the biggest issue might indeed be the seismic faults. You might have to construct some part of the tunnel on the sea floor, probably modular, of 20" thick steel tube sections, but the rest of it could be cut through bedrock, avoiding volcanic hotspots if possible.

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  • $\begingroup$ Welcome to the site. Odds are the expense to create and maintain this are not feasible but that's (as you point out) not to say its impossible. If you have questions about the site check out the help center and once you hit 20 rep (you're halfway there!) feel free to visit Worldbuilding Chat $\endgroup$
    – James
    Jun 8, 2016 at 20:36
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A bridge wouldnt be feasible. First there is the difficulty in constructing it, which has been discussed.

How would you get across it? There are no gas stations. You could not carry enough gas to get from one end to the other.

What if there was an accident or other emergency? A traffic jam would put traffic to a standstill - possibly for days or weeks. Not only that, there would be no way to get to the accident site.

Simply put, large ships (boats) are the most efficient method of transporting large amounts of cargo from one continent to another.

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There are any number of arguments against it.

1) We don't have materials strong enough. Either it must rest on the ocean floor, or it must float. Since the North Atlantic can be as much as 5 km deep, we're talking the mother of all pier systems, and the piers must operate in salt water. If it floats, as in a pontoon system, it will undergo fabulous stresses. The Gulf Stream crosses the proposed line of travel. This will provide a noticeable sideways thrust over hundreds of miles. Unless the bridge is conceived of as having considerable slack, the total sideways thrust is amplified by a factor of 1/(1 - cos $\Theta$), where $\Theta$ is the angle of deviation from a straight line. For instance, if the bridge only deviates by 3 degrees, the tension on the bridge will be the total sideways force multiplied by 730. (This overstates the effect, since the bridge will form a curve, but it illustrates the principle)

2) The bridge has to be made with variable length. The proposed path crosses the Mid-Atlantic Ridge, and the distance between the two ends increases by about an inch per year.

3) In summer, the bridge is subject to collisions with icebergs.

4) If the bridge is on the surface, the forces exerted by the North Atlantic Drift will be increased by major wind forces every time a hurricane heads up the US coast and then out into the North Atlantic. Again, respectable forces per unit length multiplied by hundreds of miles. Sea state will also cause the bridge to flex continuously, and that can't be good for reliability.

4) The bridge will isolate France, Great Britain, Germany and Scandinavia from the rest of the world by sea, unless they are willing to take the northern route, which isn't exactly feasible during winter.

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The average depth of the Atlantic is 3339 meters. The tallest manmade structure is 830 meters (the Burj Khalifa). This suggests that a bridge verges on the impossible. Then you would have to defend many hundreds of bridge piers against crazy people who might want to take over a large cargo ship and steer it into a pier.

What might be slightly more posible is a bouyant tube tethered under the ocean. Shipping could sail over it. If tethered considerably deeper than the tallest waves then storms would not bother it.

But one is still looking at something akin to constructing a submarine thousands of kilometers long! It's very hard to see how it could be economically viable. It would also need very many heavy doors so a breach would sink only one section not the whole tunnel.

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Constructing such a bridge would pose a lot of challenges in terms of costs, resources and technology needed to accomplish the task. Considering the distance and the depth of the intended bridge it would require massive resources in terms of metals to finish.

Another challenge comes on whether the bridge should be constructed to float on water or made to be a sub-sea bridge. A floating bridge would interrupt the normal movement of ships across the Atlantic ocean. Also considering the strength of sea waves, tides and tsunamis, the bridge would have to be strong enough to withstand such natural forces.

Cost-wise, it seems uneconomical at the moment to construct the bridge since ship constructing companies have done a great job in constructing massive ships that carry wide loads to various destinations (read Flexibility). Airlines have also done a great job to cover the need the need for speed across these continents. I would only conclude that it is illogical and uneconomical to construct the bridge at the moment.

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For a different spin on this idea see Harry Harrison's novel, "A Trans-Atlantic Tunnel, Hurray!" originally serialized in Analog.

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