how about floating roads instead of bridges?

Discussion in 'Boat Design' started by Squidly-Diddly, Oct 20, 2019.

  1. Squidly-Diddly
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    Squidly-Diddly Senior Member

    lower case "qualified" as in know to be able to produce similar projects as opposed to upper case "Qualified" as in have current forms on file with local govts and local fees paid.
    one of the best arguments for Floating Bridge, especially after Bay Bridge (still unfolding, like a slow motion train wreck) disaster is you don't need to rely on some "lengthy and convoluted" vetting, which turns out to be a major "single point failure" in itself. No one component is that big a deal, and if someone screws up the fix is doable, and everything will be out in the open.

    Instead of taking a Leap Of Faith that some previously unknown foreign firm's "vetting" means anything, and a guess no one really knows anything until after its all build (and paid for), a (mega)Floating Bridge would be several diff contractors producing easy to inspect/replace units, and they could even "spy" on each other to weed out any lacking units.

    Swinging a section of pontoons open and closed would require a bit more than just hitting the up/down buttons, but not too much more since it would only be done in safe weather and everything pre-engineered and just a few anchored cables and winches. Worst case, it doesn't come back together for safe traffic, so a bunch of drivers make U-turn to their old bridges, and you gotta call out the real Operators.
     
  2. gonzo
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    gonzo Senior Member

    Unless the contractor is "Qualified" as you put it, the contractor can not bid on a bridge. If someone screws up, people die. I don't understand how you come up with foreign firms vetting anything, do you have any evidence? I am a bridge inspector and also inspect highway construction. It takes several years for any project to be proposed, designed and approved. The process is not haphazard like you describe it. Also, if a bridge can only be opened in good weather, ships could not enter port in a storm and commerce would be severely limited. As for firms "spying" on each other, that is a crime.
     
  3. dinoa
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    dinoa Senior Member

  4. JosephT
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    JosephT Senior Member

    For busy harbors like San Francisco Bay, a floating bridge will always pose a problem for passing vessels. They're a temporary workaround when an earthquake or something else damages the Bay or Golden Gate bridge. The military cold deploy a floating bridge like this or just ramp up the use of ferry boats & trains as a workaround until the bridge is repaired.

     
  5. Ike
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    Ike Senior Member

    I don't know much about the second sinking but the first was caused by the bridge management. There was a gale with 80+ mph winds directly from the south on the canal which has about a 100 mile fetch. So the wind and waves plus tides alarmed the bridge operators. They mistakenly thought they could relieve the pressure on the bridge by opening it. Big mistake. It actually increased the stresses and the pontoons began breaking away and sinking. Hood Canal Bridge - Wikipedia https://en.wikipedia.org/wiki/Hood_Canal_Bridge
    The sinking of the old Lake Washington Floating Bridge was the result of mistakes made by the contractors who were working on it.
    In both cases it was not the fault of the design or construction of the bridges.
    I have used all three of the floating bridges literally thousands of crossings. They are actually more stable than a lot of suspension bridges. Galloping Gertie (the old Tacoma Narrows bridge) fell during a wind storm, and its replacement can get pretty scary. It fell because it was a faulty design (too light for the wind conditions and they didn't consider harmonics.) I have crossed a lot of suspension bridges, and thank you but I'll trust a floating bridge first. However, I don't know how appropriate that would be for the shallow waters of the south end of SF Bay let alone mud flats. Besides you already have four bridges across the bay. Why another?

    And large Navy ships have no problem getting through the Hood Canal Bridge on the way to Bangor Naval Base, including Trident Subs and large ammo ships. I've even seen aircraft carriers transit Hood Canal.
     
  6. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Seems like reasonable design for the location. I guess the big ramps are needed because it connects directly to land, and need to adjust for tides. A Swing-Away section in the middle of a longer Pontoon Bridge (such as would be deployed to cross SF Bay) wouldn't need such big ramps to handle in diff in height. Just about 2' of overlap out of 1/2" steel would be plenty.

    Didn't say what is used to swing, but just use a few anchors, cables and winches. Part of a good major roadway floater would be modular design, so the roadway could be widened as needed, and done so a whole lot cheaper, faster and less disruptive than any land road widening.
     
  7. dinoa
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    dinoa Senior Member

    It pivots on a pile dolphin fccbea2710135cde06add09658362ddb.jpg

    and stops on another near the opposite shore shown on the right of the transiting boat istockphoto-819595820-170667a.jpg

    images.jpg

    cables pull it into position. It handily survived a medcane last year
     
    Last edited: Oct 25, 2019
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  8. gonzo
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    gonzo Senior Member

    That is a very cavalier attitude towards bridge design.
     
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  9. JosephT
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    JosephT Senior Member

    Very interesting to see all of the portable bridge designs. As long as they do the job safely and the taxpayers are content with their investment...that's what matters most. On the topic of bridges & boats, this video is one of my favorites. And no need to move the bridge!

     
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  10. Barry
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    Barry Senior Member

  11. Squidly-Diddly
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    Squidly-Diddly Senior Member

    A Floater precludes all the normal risks of bridge design. Its so safe you can't even kill yourself by jumping off. lol. Golden Gate Bridge suicide barrier starting to take shape https://www.mercurynews.com/2019/02/17/golden-gate-bridge-suicide-barrier-starting-to-take-shape/ $200 MILLION, and what if they jump off the bridge, onto the safety net, then looks like easy climb to edge of net??? And even if it "works"(by injuring the jumper so staff can do something) wont they just find another way? $250 million was the original price to build the whole new Eastern half of new Bay Bridge.

    World's top professional bridge management in action at the World's Greatest Bridge. About 300,000 people showed up and no crowd control or limits, going well past any design specs and bending the bridge down in middle as had never been seen before, and odd swaying motion never known before. Pure dumb luck, calm weather and 1930s over-engineering that those people weren't all killed, plus no one realized what danger they were in so no panic rush made any sudden stress changes. But hey, its a PARTY! Nothing cavalier about that. A Floater will let you know when you start overloading it. No Inspectors or second-guessers required.

    The current Western half of Bay Bridge is still double decker. The upper deck falling at the Eastern half was what killed all those people in 1989, and put the bridge out of action for years. They knew it would likely happen in a big quake, and knew they didn't really know what a quake could do, and still don't. That seems pretty cavalier IMO. Generally its not a good idea to have heavy objects suspended over your head in an unstable environment. Supposedly one top Bay Bridge official moved across the bay so his family wouldn't need to take the NEW section, which some claim is also likely to go down suddenly in big quake. These design defects were brought up, as was near certainty of massive runaway cost increases, but They went ahead, mostly because someone liked how the new design looked, and it wasn't their money, and they weren't going to be taking the bridge.

    Here is another one of few new bridges recently built. Its a public college so its safe to say the event was literally crawling with fully certified Bridge Inspectors. While not a bridge over water it high-lights the inherent dangers of wide span engineering.Report: Flawed load-bearing design likely contributed to FIU bridge collapse https://therealdeal.com/miami/2018/06/17/report-flawed-load-bearing-design-likely-contributed-to-fiu-bridge-collapse/
    As I see it, the problem stems from the traffic design and the unused lane (with big white chevons). If they had a normal turn lane it would've allowed a nice big support in the center of the bridge that would also serve as a traffic separator and "safety island" for pedestrians who ain't up for climbing several stories of stairs just to cross a wide road. But some sharpie got hold of some big shot at the college and sold him on some "visionary"/"your legacy" etc hence the unnecessarily wide span. Oh, I guess it was going to have center tower/support, but for some reason it was Full Span during construction.

    In contrast, when a Floater sinks, it will sink in a storm, with nothing but lots and lots of warnings at each step. But we don't get real storms on SF Bay, and its mostly very shallow, so even if a Floater somehow sinks it would be easy to re-float. The best thing about a Floater is it can be moved, opened and closed with just a few anchors, cables and winches, and how fast that needs to happen can depend on how much you want to pay, but even most expensive gear still cheap.. It also occurs to me that if cables, anchors and winches are problematic a Floater's swing-section could be moved with an engine and propeller.

    Another important safety feature of Floaters is emergency access. IIRC one of the few spots our local "Life Flight" helicopter ambulance can't reach within few minutes anywhere in SF Bay area is....you guessed it....big suspension bridges due to all the cables. Not an issue with a Floater, just keep the street light poles far enough apart. Since a Floater is just a few feet above water, emergency access from water is also possible, even if a bomb or something completely blows up a section and no road access possible.
     
  12. Squidly-Diddly
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    Squidly-Diddly Senior Member

     
  13. gonzo
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    gonzo Senior Member

    On one hand you claim a few chains and anchors is all that is needed. On the other, praise what you consider "overengineering in the 1930s". Both statements are incorrect. Some bridges from the 1930s were not properly engineered by modern standards. For example the Tacoma Narrows and the Silver bridges. There were fewer standards and engineering background for many designs that failed. For example, all the fracture critical structures. They are all being replaced and are in a short regular inspection schedule. Further, you make claims of a bridge being overloaded. Where do you get the data from? Deflection is not and indication of overloading. All bridges deflect and vibrate. You are probably used to crossing them in a car. When you are climbing on them and walking through for inspection, there is always a lot of movement. Random claims are not a proper way of supporting your opinions.
     
  14. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Those pile dolphins and swinger look like perfect solution for shallow water such as most of SF Bay. I'm thinking for an SF Floater the Swing would be at least a few hundred yards out, because for the first few hundred yards SF Bay is about 2ft deep at low tide, and bottomless soft black mud after that, so for even small keel boats to pass the opening needs to be a ways out on the water, so the Swing would ride the tide at same level as rest of roadway so no big draw-bridge needed. I'm guess 10% of that bridge is the big floating block and pile, and the other 90% is those massive draw bridges.
     

  15. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Here is one route for cross SF Bay Floater, about 1/2 way between Bay and San Mateo Bridges. Chosen because both sides have close landing to major freeway and both landing sites have current occupants that wouldn't get all NIMBY about anything. West side is some Bio-tech firm with a few big vacant semi-waste land lots next door (squiggles are for new cloverleaf since butts directly into 101. East side curves to stay clear of end of Oakland International Airport, and runs onto major surface street dead ending into Bay Floater.png industrial zone with Sewage Treatment Plant, dirt lot "staging area" and some metal foundry nearby, and they ain't gonna care.

    Hunter's Point to Bay Farm Island would be a couple miles shorter, but don't have good access to major highway, and would have NIMBY issues with traffic increase. Those issues would far outweigh the cost of a couple extra miles of pontoons and decking, once ball get rolling and system standardized.

    Only ships that would need to be let through are the small bulk freighters that take on loads of gypsum at Port of Redwood City and maybe the Salt Evaporators in Newark but I think thats all rail. That only happens every few weeks at best. Have a couple of smaller faster gates for sailboats with scheduled hourly openings on weekends, and off peak openings during week. Those little orange "pills" to right of Hunter's Point are ships, and that is where they hang out, and there is room for 100x as many in that same deep water zone.

    Biggest NIMBY worry is current slip-holders with sailboats at Brisbane and other marinas, since they might have "connections". Shouldn't be a deal killer. RIP Pete's Harbor in RWC to build yet another stack of condos. Offer current slip holders TWO new slips of 2x size of old slips on either side of Floater.
     
    Last edited: Oct 27, 2019
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