# Where's all the submerged bridges? **URL:** \ **Category:** Factual Questions\ **Created:** [January 20, 2007, 1:36pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704 "2007-01-20T13:36:07Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [January 21, 2007, 7:51am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/21 "2007-01-21T07:51:41Z")
Don’t toss around distances like “100 ft” so lightly. 100 ft of horizontal distance is a trivial construction effort. a 100ft vertical habitation is almost as easy, today, but was a world-class construction effort not much more than century or so ago, when the definition of “skyscraper” was set at 5 stories. 100 feet down underwater? There are only a handful of permanent fixed 1 atm “shirtsleeve environment” habitable structures at 100 or 200 feet in the world. The Aquarius underwater coral research lab in the Florida Keys National Preserve is only at 62 ft depth, airlocked and sealed at substantially less than ambient water pressure, but a return to the surface still requires 17 hours of decompression. At 100-200 feet, you’re pretty much talking about a) submarines (pricey and nowhere near the size of a tunnel); b) structures sealed in bulk concrete, like tunnels; and c) structures like submarines and underwater habitats that require medical vetting to enter, monitoring to remain in, and decompression to safely exit 100 ft down can easily kill an experienced diver in full scuba gear, if s/he doesn’t follow all the rules – and the main danger lies in the effects of pressurization, not the water ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [January 21, 2007, 8:12am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/22 "2007-01-21T08:12:55Z")
Okay, well to go off into lala land, but how about a waterproof train that followed a tether through the water? Wings to keep it upright, etc. Price? Feasibility versus a chunnel connecting Russia and Alaska? ---
**Author:** ![Seven](https://avatars.discourse-cdn.com/v4/letter/s/3d9bf3/32.png) [@Seven](https://boards.straightdope.com/u/Seven)\ **Post date:** [January 21, 2007, 9:56am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/23 "2007-01-21T09:56:36Z")
[QUOTE=Sage Rat] Even Seattle has a floating bridge. [/QUOTE] Which one? The one that sank or the one they have to close in high winds? ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [January 21, 2007, 10:10am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/24 "2007-01-21T10:10:50Z")
[QUOTE=Seven] Which one? The one that sank or the one they have to close in high winds? [/QUOTE] That people will build wierd stuff just for the coolness factor was pretty much my point. ---
**Author:** ![Antonius\_Block](https://avatars.discourse-cdn.com/v4/letter/a/51bf81/32.png) [@Antonius\_Block](https://boards.straightdope.com/u/Antonius_Block)\ **Post date:** [January 21, 2007, 11:13am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/25 "2007-01-21T11:13:23Z")
[QUOTE=Sage Rat] Price? Feasibility versus a chunnel connecting Russia and Alaska? [/QUOTE] Actually, there’s nothing particularly infeasible about a [Bering Strait bridge](http://en.wikipedia.org/wiki/Bering_Strait_bridge) or [tunnel](http://news.bbc.co.uk/2/hi/europe/1099304.stm). The _problem_ is that each side of such an entity would be about 2000 miles from the nearest usable railhead, through extremely inhospitable landscapes. Even the US / Canada highway system falls several hundred miles short of Nome, and there’s nowhere near the capacity on that to make a trans-Bering link viable. Between North America and the Far East, it’s much more cost-effective and time-effective to transport bulk goods via ship, and people via plane. The Folkestone-Calais Chunnel links two densely-populated countries with appropriate infrastructure (well, at least once the UK side has the high-speed link to London in operation); a trans-Bering structure would start in the middle of nowhere, and end in the middle of nowhere, 50 miles – and a continent – away. The very epitome of a white elephant. ---
**Author:** ![SmackFu](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@SmackFu](https://boards.straightdope.com/u/SmackFu)\ **Post date:** [January 21, 2007, 5:15pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/26 "2007-01-21T17:15:29Z")
Not quite the same, but too cool not to mention: at either end of the Corinth Canal in Greece, there are bridges that sink under the water to let ships pass. > **[Submersible bridge](https://en.wikipedia.org/wiki/Submersible_bridge)** > > A submersible bridge is a type of movable bridge that lowers the bridge deck below the water level to permit waterborne traffic to use the waterway. This differs from a lift bridge or table bridge, which operate by raising the roadway. Two submersible bridges exist across the Corinth Canal in Greece, one at each end, in Isthmia and Corinth. They lower the centre span to 8 metres below water level when they give way to ships crossing the channel. > The submersible bridge's primary advantage over th... ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 22, 2007, 1:46am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/27 "2007-01-22T01:46:35Z")
[QUOTE=Sage Rat] It seems like it shouldn’t be all that much more difficult a task to build a submerged bridge that is partially buoyant. … If you set it to float 50 feet under water… [/QUOTE] Apart from that I just don’t understand why an underwater bridge would be useful, it sounds like you’re saying ‘partial buoyancy’ is some state in which a body will just hover at some point under the surface of the water, neither sinking or floating. This is really hard to achieve in laboratory conditions - in an ocean, it would be impossible and would be really susceptible to perturbation anyway. ---
**Author:** ![Will\_Repair](https://avatars.discourse-cdn.com/v4/letter/w/a698b9/32.png) [@Will\_Repair](https://boards.straightdope.com/u/Will_Repair)\ **Post date:** [January 23, 2007, 12:10am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/28 "2007-01-23T00:10:15Z")
[Chesapeake Bay Bridge-Tunnel](http://www.cbbt.com/) ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [January 23, 2007, 4:09am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/29 "2007-01-23T04:09:57Z")
[QUOTE=Will Repair] [Chesapeake Bay Bridge-Tunnel](http://www.cbbt.com/) [/QUOTE] As pointed out more than once already in the thread, this is not what the OP is discussing. 🙂 ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [January 23, 2007, 4:33am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/30 "2007-01-23T04:33:25Z")
[QUOTE=DSYoungEsq] this is not what the OP is discussing [/QUOTE] True, but it does demonstrate that there’s no big problem in designing a tunnel that withstands the pressure of something like 50’ of water above it. Of course, this tunnel is buried, and doesn’t need to meet the constraints (e.g. low weight) of one that might be designed to float. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [January 23, 2007, 6:14am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/31 "2007-01-23T06:14:23Z")
[QUOTE=Sage Rat] Okay, well to go off into lala land, but how about a waterproof train that followed a tether through the water? Wings to keep it upright, etc. Price? Feasibility versus a chunnel connecting Russia and Alaska? [/QUOTE] How would this be advantageous to a submarine? You’d be putting a LOT of force on the teather, if that was the sole means of guidance. Since this means you’re going to have to put a means of turning this thing to keep the forces from snapping the teather, it might as well be designed to not use one. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [January 23, 2007, 1:37pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/32 "2007-01-23T13:37:08Z")
[QUOTE=Pygmy Rugger] How would this be advantageous to a submarine? You’d be putting a LOT of force on the teather, if that was the sole means of guidance. Since this means you’re going to have to put a means of turning this thing to keep the forces from snapping the teather, it might as well be designed to not use one. [/QUOTE] I guess the potential advantage is that you are not carrying the power source (or at least the fuel) with you. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [January 23, 2007, 2:26pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/33 "2007-01-23T14:26:02Z")
[QUOTE=Sapo] I guess the potential advantage is that you are not carrying the power source (or at least the fuel) with you. [/QUOTE] Are you implying that the teather would be somehow powering the vessel, similar to a cable-car? That seems even less viable, having an electrically powered cable underwater. Unless I misunderstood your statement? ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [January 23, 2007, 2:27pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/34 "2007-01-23T14:27:49Z")
[QUOTE=Sage Rat] Watertight of course… And as said, it has the advantage of having a stable environment surrounding it. Or theoretically at least. I’m not arguing for it, it just seems like something someone would have done at least once in the last few millenia. [/QUOTE] If it’s watertight, wouldn’t it be a tunnel? ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [January 23, 2007, 2:45pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/35 "2007-01-23T14:45:29Z")
[QUOTE=Pygmy Rugger] Are you implying that the teather would be somehow powering the vessel, similar to a cable-car? That seems even less viable, having an electrically powered cable underwater. Unless I misunderstood your statement? [/QUOTE] no misunderstanding at all. You captured the full stupidity of it. 🙂 ---
**Author:** ![FordPrefect](https://avatars.discourse-cdn.com/v4/letter/f/e99b99/32.png) [@FordPrefect](https://boards.straightdope.com/u/FordPrefect)\ **Post date:** [January 23, 2007, 4:44pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/36 "2007-01-23T16:44:14Z")
[QUOTE=KP] Don’t toss around distances like “100 ft” so lightly. […] 100 ft down can easily kill an experienced diver in full scuba gear, if s/he doesn’t follow all the rules – and the main danger lies in the effects of pressurization, not the water [/QUOTE] Yet South African gold miners can descend 3.3 km into the earth’s crust. And the Chunnel is on average 150 feet below the sea bed: [Chunnel](http://www.raileurope.com/us/rail/eurostar/channel_tunnel.htm) I don’t see why a floating “tunnel”, or a submerged and embedded tunnel would be any different since both ends would be exposed to the surface air pressure. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [January 23, 2007, 8:11pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/37 "2007-01-23T20:11:05Z")
This would not allow ships to pass over it, but floating bridges already exist. They sometimes allow submarines to pass under them however 😉 ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [January 23, 2007, 9:14pm UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/38 "2007-01-23T21:14:57Z")
[QUOTE=Sapo] no misunderstanding at all. You captured the full stupidity of it. 🙂 [/QUOTE] Woosh! To me! See what I get, for posting before 8 AM local time?! ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [January 24, 2007, 1:59am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/39 "2007-01-24T01:59:33Z")
[QUOTE=Pygmy Rugger] How would this be advantageous to a submarine? You’d be putting a LOT of force on the teather, if that was the sole means of guidance. Since this means you’re going to have to put a means of turning this thing to keep the forces from snapping the teather, it might as well be designed to not use one. [/QUOTE] Well I posted it just to consider six minutes later, “Oh yeah, well that will fine up to the point where you run into a whale.” :smack: But I imagine that the advantage of a tether would be that you could make the craft longer. It would also be a chance to test out some materials for the space elevator and whatnot (assuming you consider that as being an advantage.) ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [January 24, 2007, 2:04am UTC](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704/40 "2007-01-24T02:04:52Z")
**Sage Rat** , I refuse to be whooshed twice in the same thread! 😉 [Previous page](https://boards.straightdope.com/t/wheres-all-the-submerged-bridges/388704.md?page=1)