Bathysphere Details

* See also TechnicalDrawings
* See also Bathysphere O rama
* See also Bathyspheres
* See also Transportation_Systems
* See also Real_Physics
* See also Maps
A vehicle with a Spherical 'Shell' Structure used to resist the pressures of Ocean Water
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When were Rapture's Bathyspheres Developed ? :
Trains were used in Rapture from the early construction days when workers and large amounts of materials had to be moved about the City.
Small submarines were used as control cabs for large sea-construction equipment used to construct the city and move materials and personnel about.
A cabled Bathysphere looks to have been the main path from the Lighthouse, and was used extensively to bring down the 20000+ immigrants and their luggage/lighter possessions, though some tracked cargo capsule system could also have been used ( all their furniture/worldly possessions ).
The Rapture Transit System, consolidated by Anton Kinkaide, used Bathyspheres for its First Class transit ( versus the Trolley/Tram components of the system ) using Cable Ways to systematically move along a network of fixed routes.  Earlier there likely were local routes/systems run by separate companies - Those all had been consolidated/standardized into one Metro Transit system.
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BATHYSPHERE - NOTE : WRONG TERM :
A "BATHYSCAPHE" is a free-diving self-propelled deep-sea submersible like what the things in Rapture should really be called ), consisting of a thick-walled metal crew cabin similar to a real cable-hanging Bathysphere, but suspended below a Float ( creating Neutral Buoyancy ), rather than hanging from a ( real ) bathysphere's surface cable. ( AGAIN -- > Real "Bathysphere" is NOT self propelled ).
Perhaps they did not think 'bathyscaphe' could be pronounced or even recognized by the Players ( or the writers were themselves ignorant ). BATHYSCAPHE > BATHYSPHERE SO Who knows why the gamemakers picked to have this term used INCORRECTLY ??? 
We Should have some character in the MMORPG game explaining this : 
:::"WHAT IDIOT CALLED THEM THAT ??? THAT ISN'T WHAT THAT WORD MEANS."
:::Suchong : IDIOT!! YOU NOT KNOW BATHYSPHERE FROM BATHYSCAPHE.
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Costs :
Independent (self-guided) Bathysphere (submarines) would be developed for personal use for those who could afford them, AND also the expensive facilities required to dock/maintain them. 
SORRY : Submarines are NOT like and CANNOT be like Automobiles in our world. They are more like our current small airplanes in complexity and costs. SO what is presented "Bathysphere Craze" ( mentioned by Prentice_Mill in BS2 ), implying use of them as private transport, simply would NOT be enuf use to put the AE out of business ).
(( NOTE : The game's pretending something supposedly NOT FANTASY which works other than it does in Our World is plain bad writing. ADAM was supposed to be the one 'different' element - THE SHOCK - and even that can be halfway plausibly explained )).
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Structure and Mechanisms :
A Spherical Shellhttps://www.atlasobscura.com/articles/bathysphere which holds out the external water pressure force by diverting the forces into opposition around its curved surface ( somewhat like an Arch does for a building ). Any systems within the shell/hull which act externally ( like drive engines or actuators of control surfaces ... ) must penetrate through the hull and thus must be carefully handled.
A Rapture Bathysphere's Hull would be at leastEngineering Rule of Redundancy and Overdesign usually has a critical component have a 300% margin of capability to handle contingencies. an inch thickness of steel ( to handle water pressure at Rapture's depth ). That Splicer who tried to cut it open when you first arrive wasn't quite insane enough to keep trying despite it being impossible ( It is not built just of Thick Foil like the Apollo Lunar Lander was ).   Activating the Door Emergency Open switch on the outside might have been more productive ( But then, you (the Player) would probably be dead before the story really began ).   It might have been even more scary for that to have happened, but with the Security Flybot showing up to "save the day" seconds before you were disemboweled .
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The Rapture Book (Novel) mentions repairs to the Cable system for lowering the Bathysphere down from the Lighthouse, and I have previously decided in MY design that most Rapture 'Bathyspheres' ( that word actually IS defined as a cable driven system, versus a Submarine/'Bathyscaphe' which ARE self-powered and free-floating ) work on drag-cables for their ordinary propulsion between stations (like 'Cable-Cars').  A cable is much more reliable than a self piloting vehicle (especially for something that is to be used as public transit - particularly by the more affluent folk) -- the system is actually a double cable for added reliability.  The discrepancy between the arrival animation (invisible cable) and what's mentioned in the Novel would be resolved.  ( Various game concept art SHOWED 'Bathyspheres' on cables. )
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Those big Hatches we see in the Bathysphere Dock at the Welcome Center ( the one we arrive through is open and the other closed ), should really only be used for emergency closures.  There should be sets of Airlock doors below (in the water tube) which the Bathysphere passes through for normal transit ( operating with a much faster/simpler sliding mechanism ).  The big 'hatches' ( not the greatest design - and is missing the huge actuators ) would be a redundant system normally left open.  The other dock there appears to be damaged, so that hatch is closed.   We didn't see a second approach path parallel to the way we came into the building from the Ocean ( there should have been a second one to have the whole second mechanism to handle the traffic and for the Cableway system to be more failure resistant ).
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The Bathyspheres are not very large (~ 12 ft across) and (all the ones we saw) look to be outfitted for passengers. Immigrant's luggage and possessions would come down from the ships some other way.  A freight dock at the Lighthouse would be logical to handle all of it, and likely ship it down another route ( an AE Train Station ?? and a descending track, or another CableWay ? ) directly to a warehouse complex, where the stuff would wait until the immigrants arranged their Rapture residences/businesses to ship it all to.  It is likely this freight would be prepackaged/containerized before the ships left port to simplify operations on arriving at Rapture.
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Metro Bathysphere (Breathing) Air System :
The DLC stuff about air scrubbers and Winter Blast Plasmid to fix its overheating ...
'What A Load of BS ... ( down the usual poor DLC road ... )
Humans breathe/consume on average about 16 cubic feet of air per hour.  The typical 12 foot 'sphere has at least 500 cubic feet of air in its cabin.  That is about 30 man-hours of air.  The longest uninterrupted trips in the Metro Transit routes take about 20 minutes ( with Express Non-Stop Routing through Hubs ).  Air is systematically cleared/renewed in the cabin at every dock stop (fans).   In the standard Bathysphere,  you have space for 8 passengers sitting ( several more potentially if there are 'strap-hangers - which would be atypical on a 'First Class' operation ).  So say 12 people times a trip of 20 minutes equals 4 man hours used, which leaves quite a large margin for safety and potential delays, without need to artificially adjust the O2/CO2 content.  A backup system would be in place to stretch that significantly  ( CO2 scrubber (Soda Lime) redundant cartridges and bottled O2 ) - normally sealed/inactive and only used for emergencies.
Personal use 'Submarine' Bathyspheres would have much more extensive ( normal-use CO2 scrubbers and O2 feeds ) systems for extended, many-hour trips, and thus require much more complexity, maintenance and greater expense.
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Those Huge Bathysphere Stations in the Game : 
Would be even Bigger if they ALL have multiple 'Docks' to support a fraction of the traffic flow they would have to allow -- Especially IF they are the primary passenger transport in Rapture ( which they really cannot be ). Even so to function there would be far more to them.
You might think they would be the perfect place for LOTS of advertisement billboards and such. First : Being Premium/Deluxe transport, the people using them would prefer NOT to have that clutter ( some nice decorative themes would continue to make sense ). Second : Not so many people would go through those stations compared to the AE and Trolley stations ( which would have transported the bulk of the Transit traffic ). So common advertisements wouldn't pay in the Bathyspheres venue. If there, they probably would be small and tasteful, and for more luxury/upscale products/services. 
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A 'Transfer' Bathysphere Station :
Low pressure ( Rapture Normal, sea-level pressure ) water tunnels can connect a Primary Bathysphere Cableway Station with Satellite secondary 'transfer' Stations.  ( I've done this on a number of my City level Maps ). 
The 'Transfer' Station, has a simple lift, with no complex high-pressure airlocks being required ( a great cost savings when there are multiple 'Stations' across a cluster of buildings ).  Being largely Tunnel excavation in the seabed would minimize structural expense. Bathyspheres coming into (fed to) the Primary Hub Station can move under their own power ( and/or a simple mechanical tow system ) to dispersed Transfer Stations at different points around a City cluster, so to conveniently minimized the Travelers walking longer distances to/from the centralized 'Hub' Station.  The premium prices of the Bathysphere service pays for this convenience for their customers.  ( The 'lesser' stratum of Trolley passengers have to walk alot more. )
Due to the extensive nature of this 'transfer' system, it would have likely been built into the original cluster building plans (before Construction). 
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Do 'Shock Treatments' Give You Fantasy Dreams ?? - THE Bathysphere Reality :
Scene in BS1 : Whole bunch of Bathyspheres surface next to an American Navy Submarine and Splicers climb out and start to kill the crew and to seize the submarine for Evil Jack ( not Sparrow, but maybe now 'Captain' ) ... fade out. A dramatic scene, but not exactly possible ( elsewhere is a separate explanation of why that Submarine would NOT possibly be there ). Unfortunately, the way the Metro Bathyspheres are designed, for a Bathysphere sitting on the surface, as the doors are opened the water will flood in and the Bathysphere will immediately sink rapidly beneath the surface taking the Splicer occupants on a one-way trip to 'Davy Jone's Locker'. To work, the hatch would have to be ONTOP of the Bathysphere, to have any chance of letting anyone climb out of them successfully when floating on the surface. In the Metro stations, something must lift the Bathysphere out of the water to clear its hatch to be opened for passengers to get in and out - a lift underneath or a crane from above.
It is all a simple matter of Buoyancy, where the Sub, to be able to submerge/go down, has to be HEAVIER than the water it displaces (its volume). To raise a large part of the vehicle above the water surface, the lower submerged part ( still in the water ) has to displace enough water volume by itself to hold the weight of both the lower and upper parts ( now much LIGHTER then that water it displaced before ).
The 12 foot-wide sphere displaces approximately 28 tons of water. If the Metro Bathysphere is to ride on the water high enough to clear the door, then 2/3rds of it MUST be lifted above the water level. The bottom 1/3 then has to by itself displace enough water to lift most of Bathysphere's weight/volume out of the water -- Which obviously is NOT enough in that design ( when at the same time the entire spherical hull must ALSO displace less than its weight to be able to sink/move Underwater ).SO yes, Levine and his Writers were Techo-Idiots and just did things that could not work to look good. With Fantasy stupidity like thgat we could had far more interesting and fun things - Ocean-going Balrogs and such ... Really not that much more fantastical than the game suggested Bathysphere mechanism that defines the Normal Laws of Physics - and no magical quantumz to cover the 'cuz' factor here. Pathetic and Sad. 
Other Possibilities :
What if the Bathysphere's trim was altered so it tipped back to raise the hatch out of the water ( not exactly what it was designed for, but for the sake of explaining this ) ??? How much structure ( small bit that a ballast tank could account for ) MUST be above the water for enough clearance to not flood the inside from the smallest waves when the hatch is opened. Would not that balance/trim alter as a Splicer climbed up one side of the hull - causing a rolling action and a fatal flooding of the interior ?? Tricky operation for half insane Splicers ?? ( Tricky even for an expert in a vehicle specially designed for it ).
Maybe if you had a bunch of flotation balloons around the top of the sphere ( like a US space capsule after a water landing ) ? Maybe a waterproof curtail wall to hold out the slopping water ?? ( History - all the Amphibious "DD" Sherman Tanks that sank in the waves off Omaha beach in WW2 - a Sherman tank weighs about 33 tons, close to the weight of Metro Bathyspheres ). Of course, balloons are fragile and must be deflated - complexity that does not have bustnmess. SO - BAD IDEA.
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Back to the odd 'dream' : More likely that some other vehicle would have had to be used to get all those Splicers to the Surface ( to attack the sub that shouldn't be there ) and they would have to climb out of it/them from hatches ontop ( like from a real Sub ) - NOT so easy to 'pour out' that way. 
Imagine cramming dozens of half-insane Splicers into a Fishing Sub designed for only a handful of crew ...
Or maybe best explanation is this scene is just a hallucination that Jack ( recently cranked up by huge quantities of ADAM Plasmids/tonics ) is having, while he is being deprogrammed by his Biological father ( special Flybots having been employed to shoot darts into Jack full of Horse tranquilizers, to capture him right after he killed Fontaine ). Ryan NOT being dead after the little plot "Twist" he pulled on Fontaine/Atlas -- Faking 'his' own death Ryan would then be able to give a proper lesson to his Son about REAL 'will' and "WINNING".
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Metro System Bathysphere Cables :
* The Bathyspheres of the Metro system 'grab' a moving Cable and are then towed to the destination ( sometimes releasing the cable and grabbing a different one at a 'switch' to go a different routing direction ).
* The Cables are plastic ( to resist sea water corrosion ) with a metal wire-rope core.
* The cables run in a continuous loop powered by winches at either end of the line (like cable cars are).
* When rebuilding Metro lines the cable will have to be repaired and restrung and the winches made to operate. This will require the use of a Submarine and Diving suits
* The Bathyspheres when the automatic controls are not working will have to be 'switched' manually ( actuating the grip to select the correct cable for the intended destination ). On arrival at a station the cable is auto released and the 'Sphere is guided by rollers thru the airlocks and the docking bays and any storage hangars if used.
* Maintenance Daddies and Humans in the diving Suits can use a 'grab' device and use the Metro CableWays to be transported about the City.
* Some cableways go upward a great distance. Many Metro stations are at 'Street' level which can be hundreds of feet over the seabed. Some private branches go up to Penthouses on buildings and some public Metroways to stations on the roofs of buildings.
* A network of Metro paths criss-cross the city ( converge on 'hubs' at the main stations )
* There are numerous 'switch' locations for divergent paths. ( ie- a private branch would have a switch off a main cableway )
* Broken/worn cables can be spliced with new cable sections stored at various maintenance locations in Rapture.
* Metro Stations require an operator for departures, but arrivals are designed to work automatically for safety reasons.
* Metro tow-cables act as antennas/wave-guides allowing good radio communications with the city system.
* The Metro system was designed with your safety in mind. Please keep your hands inside the sphere at all times.
NOTE - Raptures 'Cables', are largely point to point STRAIGHT LINES - unlike terrestrial old 'Cable Cars' which had to follow winding streets, the METRO Bathysphere cables have far less complicated mechanisms involved ( first of which was the expensive slot vaulting underneath and having to cross other cable car systems in cities ). Cable cars all but disappeared in the 1890 because Electric Trolleys were the FAR superior AFFORDABLE solution in most places.
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Cable Is As Cable Does :
The Bathyspheres, being on a Cable : It probably was (should be at minimum) for the travel up to the Lighthouse ( First as Immigrant Transport, then as a Tourist thing ), which was later curtailed (Though getting up there really didn't do alot of good for anyone trying to escape because where would you THEN go ?? But that didn't stop people from trying.)
More important was : The LightHouse Bathysphere in the early days being a 'much used' path, should have a dedicated system to 'speed up' the travel 'turn around'. ( Likewise, have the Rapture Station being directly below to eliminate all that unneeded bending path ( in-game there had just for 'Reveal' scene ) which meant a significant delay to get passengers down -- The trip being twice as long as it really needed to be. The people there should have already been quite aware of what Rapture was - to be ready to spend the rest of their lives there ...
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No Ashtrays in the Bathyspheres :
I saw this lack ... Its a Very terrible imposition to force people to collect their own ashes and butts on the 10 minute trips  across Rapture.
And since there is no NO SMOKING sign anywhere, at least they haven't denied the passengers ( who are paying a 'premium rate' for the Deluxe service ) the ability to smoke during the trip.  Possibly the 'steward' would  make one available.
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Rapture Bathysphere's Round Shape And Size : 
Things existing in computer games don't actually have "To Work"/be functional, which can lead to many unrealist designs for things/props. That pretty (Art Deco-ish) streamlined bronze ball shape just doesn't physically work. (( Sorry No Magic Quantumz here in Sci-Fi-based Rapture )) 
Particularly obvious when the exterior size largely matches most of its spacious interior space. A real submarines Pressure Hull is crammed full of machinery, leaving little space for the crew/passengers. They are also terribly complicated/constant maintenance headaches - usually most of the machinery is left exposed allowing easy access. 
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Reality is a Bitch - But the MMORPG is Trying To NOT Be Fantasy :
A REAL submarine requires ALOT of stuff outside the Pressure Hull ( ie - parts of the propulsion mechanism, steering/control, ballast tanks/pumps/air reservoirs ) and the complementary components inside. 
Having a huge interior bubble of air also makes those BioShock 'Bathyspheres' buoyancy ability and center-of-gravity contradictory to what the game has these vehicles do ( They CANNOT POSSIBLY FLOAT HIGH ENOUGH IN THE WATER TO ALLOW ENTRY WITH THAT DOOR ).
USN World War II Balao class Fleet submarines, had a maximum design depth of 600 feet
So the Rapture technology wasn't 'absurd' ... Of course permanent buildings built to withstand that pressure is a separate (but related) problem. But then, submarines can't have 7 foot thick rebar-reinforced concrete walls on their hull ( except maybe in Infinite BS for Fink's 'one-way-death traps' ).
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Sphere-o-Rama :
Most of a Bathysphere's interior being airspace for the passenger compartment, there must be some parts of the structure many times as dense as water built into the vehicle to compensate. A thick steel hull ( Steel weighs about 8 X as much as water ) and maybe some Lead weights ( Lead has a density 11 times as heavy as water ) and machinery/batteries, need to offset the empty space.
A ballast tank is used to adjust buoyancy ( balance of weight vs displacement ) is usually a small internal tank that can have the water forced from it (with compressed air) to shift the internal weight. It must be small or there will be no space inside the sphere for passengers. A hull strong enough to hold back the typical Rapture depth water pressure would be about an inch thick steel -- a 12 foot spherical steel shell that thick would weigh about 9.25 tons -- the rest would be machinery/batteries/tanks/ballast.
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The Man From R.Y.A.N. Takeoff of 'Man From U. N. C. L . E. A early 60s TV show :
Realtime Yachtman Advisor Network
The Thinker ( or rather a predecessor computer ) could do navigation problems quite fast, and moreso track positions to guide around known obstacles ( the system maintained detailed maps ) - very important to avoid Sub collisions with buildings.
Of course you really cannot fit such a necessarily huge computer on a vehicle like a Flybot or Bathysphere ( This is NOT Infinite Harry-Potterland ), so the analysis/calculation was done 'remote'.
Encoded signals were sent using sonic transponders ( Radio Waves go through water very poorly ).
Earlier there were loud Sonar beacons used by earlier navigation aids (ie- for the Fishing Sub Fleets), but they were judged by Ryan as being too risky - likely to eventually give away Rapture's position ( He had his spies on The Surface tracking various 'navy' technologies ).
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Stress Failure on Bathyspheres : 
Constant transitions from 280+ PSI while out in the ocean (600 ft depth level) to the Metro station docks (at 1 atm = 14 PSI) caused hull failures as the hulls were repeatedly compressed/decompressed. Several fatal incidents forced the Metro company to fix the problem or face bankruptcy from lack of ridership. Designs had to be modified and the hulls assembly joints strengthened to withstand this constant source of stress and resultant metal fatigue. The most successful design simply used a greatly over-engineered hull that was stiff enough to withstand the changes in pressure ( and made the Bathyspheres mass close to the 30 ton range, which forced operational/equipment changes to safely decelerate that mass ).
Bathyspheres come back into use (operated by the City), but are limited because of the damage and lack of maintenance.
The AE Trains make similar transitions and would have similar structural issues.
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Rapture - Submarines (Including 'Bathyspheres') Not Being "Automobiles" :
Reality Check
Some/Many (real) Art Deco buildings were designed for the new American Automobile culture (~1925). Unfortunately, with the game writer's 'vision' and their idea of 'Bathyspheres', Rapture is NOT/CANNOT BE an 'automobile' culture ( was a piss poor mimicking nostalgia nonsense that would've been better leaving out ).
Private subs owned by rich people ( that's "rich" in Rapture, which according to the story is elevated from what's considered "rich" in the Surface World ) aren't common enough in Rapture for many of those external advertisements ( you see out in the ocean ) to be worth paying for. People just don't go by them in the water all that much. They might as well be crowded around/within view of the building windows, directly outside, rather than 100+ feet away, obscured through the dark and murky water.
See Transportation In Rapture
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Car Parks/Parking Lots (Or Would That Be Sub Parks ?? ) :
One of the problems with Submarines type transport in Rapture is that they require alot more infrastructure/care than your Surface World Automobile.  If the infrastructure fails, you are crushed/drowned to death in seconds instead of inconveniently being stuck at 'the side of the road'.  So they have to be built much more robustly/fail-proof ( besides likely weighing 7+ times More than your ordinary car ).  The Parking spots likewise are more complicated as they need to transition between that high water pressure of Rapture's depth to the ordinary sea-level pressure you walk out into in Rapture's interior.  So, expense suddenly goes way up, even for mechanically 'advanced' Rapture, fewer people will own 'sub' cars -- even less than they do in a city like New York, where even in that era cars were less common.  Public transit was much more commonly used - it had to be.
You would have to be fairly rich to have a private 'garage' (sub bay/dock) attached onto your house/apartmentVERY 'pedestrian' to have a 'shared' sub dock - Something just not done by the 'Affluents' - Exclusivity you see is part of their 'gig'.  
Upscale Apartment complexes may have a 'parking structure' where the machinery/safeguards required could be shared, thus lowering expenses somewhat.  Still this would be many times more costly than we have up here for cars.   Maintenance/repair for the 'Subs' also would add substantial expenses for their owners.
A complementary problem would be the need for adequate parking garages at all the destinations people would want to get to.  Places frequented by the rich would not be a problem, but for everywhere else.  Shared complexes like shopping malls would likely have some parking facilities for Sub using customers.  Without sufficient destinations, the sub's utility becomes fairly low.
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 "Without Safety There Are No Profits" - Kinkaide :
I'm still trying to figure out how you could have lights embedded/attached to the Bathysphere cables. Designed to not foul the Bathysphere's clamps and the Station cable capstans ( have to be small/low profile ) and have to work with very low maintenance ( changing batteries by someone out in a Diving suit is a bit much for overhead cost ). Since the cables keep moving, maybe they can have little propellers/impellers turning a small generator ( and Rapture bioluminescent tech low power lights ).
It will make an interesting sight -- a string of lights (every 100 feet) disappearing off into the gloom along the Metro CableWays feeding in and out of the various City centers. Submarine traffic requires the cables be well lit for safety ( like they do on power lines in our world ). You can't have Bathyspheres and Subs colliding and customers plunging into the darkness screaming as they are crushed to death by water pressure -- it is bad for business.
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Metro Stations/System :
* Metro' "Grand Central Station" should NOT be a single Metro dock
** Multiple loading bays (3? 4?) and multiple airlock queues ( at least 2 -- one in/one out )
** Usually with 'ready' waiting positions used by empty excess 'spheres' ( Rush Hour maximum 'spheres in motion )
* Automatics - destination board in Bathysphere (bubble taxi) with all 'safe' destinations listed
** Semi-intelligent routing system to handle offset arrival vs departure loads ( likely human controlled/directed ).
** Manual control (usually locked out) overrides automatics - allows control guidance for non-standard destinations
* Station Schedule boards working again ( not just saying 'Cancelled' or 'Out of Service' -- now regular  departure/arrivals again )
* Docking of small 'subs' ( we saw one same sized as Bathysphere in BS1 - the one Atlas' "family" was allegedly blown up in to Fool the Player)
* Remote Metro stations - many still not working, some repaired others again have working automatics
* Many MetroWays are still choked with debris/overgrown Sea Life ( a good project for one YOU want to use alot in future )
* MetroWays - like People Mover at Disneyland? ..... no.
** Metro Bathyspheres don't seem to be submarines ( which are self-powered, free to move anywhere )
** The hull thickness required for ~800 foot depth ( allowance well beyond Raptures 600 foot baseline ) is about 1 inch steel plate (which takes up ~8 times its volume of air to have neutral buoyancy) leaving the remainder volume to offset other contents including payload. Preferably heavy items  in the lowest part of the sphere to act as ballast to maintain proper orientation. Adjustable ballast tanks required to  balance against varying loads [compressed air applied at stations after loading is simplest]
** Real Bathyspheres are lowered on cables, so Rapture's have something external dragging along paths.
** A Track system with moving cable like a 'Cable Car' is used for its simplicity (a powered roller system like the  Disney People Mover is many times as complicated and subject to more maintenance and failures - Rollers would only be  used in stations because of their versatility and control-ability). Cables could haul 'spheres with neutral buoyancy  across wide open spaces with little intervening structures needed ( actually like the old Skyway at Disneyland ).
** With multiple possible destinations, some way of switching paths required in the mechanism.
** Powered continuous cable winches are needed and the 'sphere has a "grip" to fasten to the cable and to grab an  alternate cable at a 'switch' ( like when branch off to a private Metro station or a Building with its own station )
** The MetroWays would be dual-laned ( one for each direction ) so that many spheres could be in motion along the same  paths ( certainly needed by a city system with major traffic loads at rush hour ).
* 'Sphere human capacity looks like 6 sitting and maybe 6 more 'strap-hangers'.
* Believe it or not, the displacement (12 foot sphere) is about 25 tons which means one 'sphere can carry an awful lot of  cargo weight and might normally need ALOT of ballast weight to achieve neutral buoyancy when almost empty ( and then  ballast tanks to offset greater loads ).
* Metro Stations are usually bulky space-wise, with the visible surface docks being only a portion of the whole mechanism  ( guideways, pumps, triple pressure doors, winch systems, emergency reservoirs )
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==Diagrams==
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* Bathyspheres are talked of like they were Automobiles ( Accu-Vox Audio Diary by Prentice_Mill (in BS2)) -- So there must (by extrapolation) have been more (affordable) miniature subs in Rapture to qualify that talk ( saw an add for a 'luxury' sub somewhere ) -- And still the problem would be the facilities the subs require ( which are not that simple or flexible -- NOT like a 'curbside' stop anywhere in a real city ). It would be logical that the Subs be able to share the same 'Metro' docking systems as the Bathyspheres.
* Bathyspheres would have some limited maneuvering ability ( to facilitate docking at stations ). But mainly they would use the moving cables to travel long distances along the MetroWays ( fixed paths more like Real World Cablecar routes ), and thus could dedicate more of their volume to 'cargo'. They thus travel 'station to station' ( locations which we assume are all over the City for them to have been 'convenient' or useful ).
* The Bathysphere's "Grip" mechanism must engage the constantly moving cable and is designed with a 'clutch' system to grab onto a cable as it constantly moves at the main traveling rate (?? 20 35 mph ??) and allows gradual acceleration. The Bathyspheres have neutral buoyancy but still mass something like 28+ tons -- which means alot of force to suddenly jerk it into the travelling velocity. Hence the gradual friction engagement of the grip.
* A second grip on a second parallel cable (upper/lower) would engage as a redundancy ( transit system safety requires more FailSafes than most people realize ). The second grip could 'partially grip, slipping on its built-in rollers with no friction ( but still retain its being anchored to the cable ).
* The Bathyspheres do not/cannot 'float' on the surface high enough to clear that doorway ( there is a reason real submarine have hatches that open upward from their decks ). No mechanism would work as you would have to have ballast tanks equal in volume to most of the inside of the sphere to adjust the buoyancy enough to allow them to float with only 1/3 the volume in the water ( and then later sink into the water completely ). So the Bathysphere must be externally lifted high enough out of the water for boarding ( either a crane from above or a lift deck underneath -- both robust enough to lift >28 tons of weight ).
* For convenience ('snappy service') the docking process should be fairly quick ( clearing whatever safeguards needed for Pressure Safety -- double airlocks/etc ... ) Pressure equalization water-to-water doesn't require pumping water/air ( just opening/closing doors ) and then just a final lift out of the water. Airlock type adapters on that forward facing doorway could be used optionally ( maybe at smaller 'private'/maintenance installations ) but are usually more time consuming ( with the required safety checks and the spacecraft-like 'docking approach', etc ... )
* Parking spaces would be provided at destinations for 'private' Bathyspheres and Submarines ( public units could just be sent on a return trip or forwarded onto a next destination ). Bathyspheres should sit flat on flat surface for when they are 'parked' out of the water ( and sitting when on the 'lift' ).
* Switching stations where the Bathysphere switches (engages/disengages) between different cables (to alternate destinations) has to be foolproof for both automatic and manual operations. They also have to be relatively simple to minimize maintenance. There would be guideways in the 'stations' while floating free (and decelerating) and changing directions and reengaging a different cable ( along with options like passing thru on the original cable, etc... ). The Rapture Lore says the Bathyspheres were largely 'automatic'. I suppose if we can have Flybots which mostly can 'fly about' successfully, a similar mechanism could be used for the limited 'off the cable' maneuverings ( once that technology is rebuilt for each Bathysphere ). Lining up (maneuvering) to grab the correct cable is facilitated by guides and simple sensors - nothing a Flybot's insect brain couldn't process.
* 4-Way intersections ( 2 lines crossing with switching between them freely ) would get too elaborate and are better replaced by 2 "T" (3-way) intersections). Likely there would be a minimum number of ANY remote 'switching' stations, rather switching between MetroWay cable paths would be mostly done at the large Metro stations where maintenance is simpler and the required mechanisms shared. The remote 'switches' would be mostly for Private 'Branch' lines would be costly and likely only be affordable by the Elite or by large companies. ( Dedicated branch lines can also be made with a single bi-directional cable to simplify the mechanism -- and be more like the old Skyway at Disneyland ).
* Ballast and trim tanks - the Bathysphere has to be able to adjust its weight to handle changes in cargo weight (like 8+ passengers) so requires ballast tanks to be variably filled with water/air to maintain the required neutral buoyancy. Trim tanks would adjust the weight distribution to maintain proper orientation. Both these systems would be external to the spherical passenger compartment ( else it would take up too much of the 'cargo' space ). Permanent ballast (lead/steel blocks below the deck) would adjust the mass to have neutral buoyancy at its empty weight ( and ballast tanks all full of water ).
* The Cable needs to be large enough (cable diameter) for a good non-destructive friction grip, and be strong enough to tow multiples of the 28+ ton Bathyspheres around easily ( or many at once in both directions ). The cable should be light as possible so that its weight doesn't strain when it is thousand(s) of feet long. The material has to resist corrosion and be something producible in 'self-sufficient' Rapture. Plastic wrapped steel wire cable would work. The Cable needs to be splicable for repairs and for the initial forming of the continuous loop. Semi-Temporary 'joiners' would be used for fast repairs ( simple enough for a Maintenance Daddy to employ ) until a Cable Maintenance cycle could do the permanent reweaving or cable replacement ( It is likely many of the still operating/recently used cables have ALOT of temp joiners along their lengths as system maintenance was disrupted since Rapture's %27civil war%27 (terrorism) times. ) Storage space for spare cables in the METRO stations - another part of the facilities required...
* Problem - Bathyspheres are supposed to be 'fast' transit, and need to accelerate quickly ( the bane of commuting systems everywhere ) and the vehicle weighs something over 28 tons of mass. How do you get that mass moving without destroying the mechanism, and more important - stop it at the "end of the line" ?? Solution Idea : a 2-speed dual cable system. Cable One runs at full speed and Cable Two at half speed. Bathysphere Grip engages low speed first then switches to the second 'fast' cable (second Grip) to go up to full speed ( the clutch in the grip allows varying friction to allow the change of speed when the cables are moving at a constant rate ). The reverse would be done to decelerate - first engaging only the slow cable using the clutch as a brake and then finally slipping BOTH cables to let water resistance ( that blunt front has to cause alot of water friction/resistance ) slow the Bathysphere a good distance away from the 'stop' point ( assisted by the maneuvering propellers for fine speed control ). The dual-speed Cable System is still redundant ( 2 cables held onto ) for safety -- either speed line can still get you to the destination if the other fails. If both fail, then neutral buoyancy allows rescue ( it doesn't sink or rise to surface ) and the onboard maneuvering propulsion may have more than enough range to slowly get to a safe destination. A few rescue units with airlock adapters and submarines to tow the Bathysphere to a station would be the final safety measures.
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Stations :
* Bathysphere stations are generally quite large ( alot of facilities/mechanisms/equipment to make them operate -- you don't just wheel around the 28+ ton Bathyspheres or wave a wand to change the pressure from 1 atmosphere to 19+ atmospheres @ 600 ft depth ). And all of it has to be done with safety and speed.
** The large sliding airlock door mechanisms take up alot of space, along with the volume of the airlocks built to pass the 12-foot sized Bathyspheres ( which are actually alot bigger than 12 x 12 x 12 feet ... ).
** The cable drive mechanisms ( like a SF Cable Car ) and pumping units take up an appreciable space.
** Likewise parking space for Subs/Bathyspheres add additional space usage ( plus overhead crane with access to parking and all the 'lifts' ).
** The usual passenger 'station' waiting/loading area, ticket booths, monumental decorations, etc ...
** Fortunately the Station is split-level with the lower 'water' level and the upper 'air' level.
** Various maintenance and servicing facilities would be required.
** Even outside the building, the 'guide cages' ( which protect/direct the cable on/off transitions ) stick out 60 feet ( remember that first approach to the Welcome Center from the Lighthouse ?? ).
** Small single line (termination) stations still require the double airlocks the larger stations use ( maybe not a dual in/out set that facilitates operating a busy station ).
* It is physically impossible for the Bathyspheres in BioShock to raise high enough from the water by themselves ( has to do with 'displacement' buoyancy and being able to submerge using ballast tanks and floating high enough to clear the door ). So Hydraulic elevator Lifts in each 'bay' would raise the Bathyspheres/Subs up out of the water for convenient 'front' loading ( as seen in the BS1/BS2 game ). The overhead crane can lift and move each (28+ ton) vehicle to a 'parking spot' when needed.
* Larger stations that handle multiple routes have more irregular shapes -- dependent on the cable route directions. They can share airlocks sets between several routes and all feed in to the loading bays. Speed is the essence for a 'transit' system, and getting the passengers moving is all important. Combined route stations make for more convenience (with less walking) than the single destination 'Metro' stations we saw in BS1.
* Working Destination & Schedule Boards -- yet another detail to implement for the MMORPG.
* An interesting phenomenon with fish being attracted to lights ( and bigger fish to the smaller fish ) -- How to keep the Sea_Life out of the Airlocks and 'Water Level' of the Metro stations. In BS1/BS2 we actually could have seen Splicers fishing in the Metro station pools.
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Mini-Subs :
* Airlock docking (docking at an airlock while submerged) is a slower alternate option ( docking and clamping ). All Bathyspheres can use the Mark 2 passenger door sized Open Airlocks ( a useful 'rescue' system ). This option is usually used for maintenance and other numerous locations where the much smaller Airlock units will fit and normal passenger traffic doesn't go.
* The 9-Foot Mini-Sub ( seen in BS2 hanging outside near 'The Journey to the Surface' ) uses the older Mark 1 Open Airlocks.
** They were used extensively in Rapture's construction and doubled as control 'cabs' for the various City construction equipment ( somebody had to haul those millions of tons of concrete and rock filler and pre-built building components around) .
** No doubt they also were used for/controlled fishing rigs to tow and manage fishnets and catch transfers.
** The Mini-Subs can also enter the Metro Stations, as can the 12-foot 'normal' subs ( larger subs use the docks at 'Port of Rapture' and at Neptunes Bounty and various private docks ).
* Sub seen in Smugglers Den/Hideout - should have a much smaller propeller and second contra-rotating propeller to keep that small sub from rotating/corkscrewing by a single propellers action ( you can see all its details if you use the cheats 'ghost'/'fly' ).
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Some of the diagrams show simplified iconic graphics of various Rapture elements which would be similar (pixel sprites) to what you would see in the 'retro' styled Tablet/Palmtop Mini-Games -- including some Quest/Mission based activities that introduce the Player (if they wish) to the basic operations of the City infrastructure.
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DLC 'Bathysphere' : At least in the original game the designer had a sense that deep water equals high pressure. Now the bathysphere has a mere shower door ( insufficient even for one of our automobiles ) presented in this model to be between the occupant and the crushing watery death.
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Porter and Tenenbaum walk off into the sunset. I do wonder who then found that Bathysphere before its 28 tons sank into the sand ( however it got that high up the beach ). Big Sisters didn't stick around, but this is a little more solid evidence. 
(NOTE - They actually would have waded in from much further out ( after the thing flooded when they opened the door ), as you could NOT possibly get the Bathysphere to float up this far in the surf with 3/4 of it underwater like shown in the pix above, and its shown right there with water AT the high tide mark).
If you were rich enough, and wanted to show off, you could have a Bathysphere with an interior like this -- a SQUARE gold plated "bathysphere".
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The Cable Systems the Bathyspheres would have to use would have Cable Hubs something like this. Continuous moving cable the 'Bathyspheres' latch onto and are thereby TOWED to a similar station on the other end ( what I would define Raptures Metro to actually be ).
That is FAR safer and simpler than the 'Bathyspheres being free moving 'submarines' -- PARTICULARLY for something which is supposed to be (Metro) Public Transit and an automatic system.
 
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Austen Bathysphere Co. (Map in Metro Exiting Arcadia - Shows Bathysphere Stations)
* Was there more than one Metro (transit) company ?? Cities often had competing lines.
* There are many private stations ( like the one seen in the MP residence ... single dock ).
* Since we don't have 'trucks', Bathyspheres for Freight operations would be a logical use to transport to buildings/factories/industrial sites ( A bigger system of Trolleys is far better ). .
* Just big enough to move your Hotdog Vending Cart to another part of Rapture ( wheel barrows fit easily ). Not very useful for anything much bigger.
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SONAR used on Bathyspheres for Safety :
The Bathyspheres had roller grips for the cables they traveled along, which allowed friction clutches to be used to smooth acceleration ( and prevent cable wear ) -- instead of suddenly grabbing the moving cables solidly and yanking the entire vehicle. Things could still go wrong and a Bathysphere could stall in front of another. A forward pointing SONAR sensor would, on detecting something (like a Bathysphere) too close directly ahead, activate a safety sequence un-tighten/loosening the grip on the cable ( while still fastened to it ) and apply reversed propeller thrust (bthe Bathyspheres did have maneuvering thrust capabilityb) to slow down and try to prevent collision. Deaths of passengers was always something to be avoided by the Austen Bathysphere Company.
Its not plain that the Bathyspheres had/required a human pilot ( who could do the same safety maneuver ), but a simple sensor system would greatly improve the passenger safety, when thousands of daily routine trips are made.
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Bathyspheres - You Can't Just Pull Up to a Curb and Get Out of Your Car :
Another strike against Bathyspheres being the normal everyday person's Transit in Rapture : Every destination HAS to have a Dock ( one of those things seen in the game - big even if cut down to minimal required systems, AND expensive to build and retrofit for a private Citizen ). Remember, you don't see a fraction of what the actual dock facility HAS to be. Otherwise, you have to rely on Public Bathysphere Facilities. How many would you need to have to be sufficiently convenient ?? SO NO, its not at all like an American Automobile.
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Joe Friday : Just The Air Seals Ma'am, Only the Air Seals :
The Bathyspheres have that front door ( and various access panels to the mechanism guts too ). With hat main door used for a 'transit system' vehicle, it opens and closes MANY times a day, and must work perfectly used routinely. This is NOT like some NASA spacecraft - with 10 technicians to quadruple check, and astronauts ready to die for their mission IF something went wrong. This is a system which has to maintain safely even when common stupidity occurs. 
This is just one component system - and again for a whole mechanism more complex than any automobile. Private Submarines and the AE trains would be similar, as would be the Dock facility mechanisms.
Such systems take time to perfect. So Rapture's Bathyspheres were very likely designed and developed long before Rapture existed ( definitinely if they were expected to be used when the City started in earnest with lots of citizens arriving ).
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Bathyspheres Would Have a Buoyancy 'Trim' System to Maintain Hull Orientation :
* That Spherical design causes easy tipping when the craft's load weights are out of balance, or when passengers move inside.
* Heavy ballast in the lowest section ( batteries, air tanks, etc ... ) still isn't enough to prevent/dampen tipping.
* A (relatively) simple automatic system of Trim Tanks and Pumps (the simple 'brains' being Mercury tilt switches) would adjust trim to keep the 'sphere level.
* Stabilization fins can assist to dampen minor shifting
* Thinking again : That a 12 foot sphere displaces about 30 tons of water, so to achieve neutral buoyancy the whole contents has to weigh that much ( and with a large open space inside ). A spherical hull of 1 inch steel plate weighs about 9 tons. Subtract whatever the batteries, various machinery and additional structure weighs and what's left would have to be filled out with ballast (lead or iron weights put at the lowest point inside/outside the sphere). If you add cargo or passengers you would have to take off the equivalent weight of ballast (impractical). Alternately you would have external ballast tanks you fill with air to offset the weight of cargo ( roughly 30 cubic feet of water replaced by air for every ton of cargo - can be adjusted with compressed air at the Metro station when the cargo is loaded ).
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I Don't remember seeing this in the game - a fan artists idea ??? Still the same old problem - It cannot float high enuf on the water to have a door on a side usable without flooding and sinking ( and when did you last see a car with the door on its TOP ?? ) At least it has some control surfaces for steering.
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Concept Art indicating this artist realized that 'Bathyspheres' are actually non-self-propelled conveyances, and should be moved via a Cable System ( Note - in BioShock, the stations seem to be labeled with only a single destination ... )
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Ignore the BaSx DLC plot rubbish "Scrubber" and 'overheating' in Fontaine's unlikely new 'Bathyspheres' :
Simple Anti-freeze in the Bathysphere ? Ocean water temps outside are near freezing much of the time in the North Atlantic
The Ocean water does moderate the temperature, but the systems would need to withstand a constant near freezing temp, with all the typical technological means to handle that environment.
A HEATER in a Bathysphere is far more important than any CO2 Scrubber, which the 20 minute (max) trips in such a closed interior volume might require ONLY FOR EMERGENCIES.
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Bathysphere Stations with Arrival and Departure Schedule Signs - Illogical :
And these capsules holding only about 8 people depart for hundreds of different places on a schedule ?
'Schedule' usually means that the unit will go whether there is anyone on board or not - on to its next specifically scheduled Stop, so that it is 'On Schedule', needed there to then transit on to its further destination (so empty units cant simply be 'cancelled').
These Stations mostly have only one hole (docking spot) which one Bathysphere fits in at a time ( a pretty significant choke-point to all operations if you consider it ).  Loading time - likely doesn't need to be more that a few minutes and with some additional time to clear the tunnel out into the Ocean -- before the next capsule can dock.  But scheduled things NORMALLY do not leave ahead of schedule, so they must sit there and wait - extra time monopolizing the loading area ) or requiring a tight juggling act to try to get them in and out as quickly as possible, making any delays a significant problem).  It adds upto an awful lot of overhead time wasted if nobody onboard is going to get-on or get-off a capsule ( but that time IS required by the scheduling system ).  Late capsules interfere with smooth operations of other scheduled runs.
If you have fewer destinations (string them as routes) then there are still the Stops along those routes to get to any possible destination and lots of wasted time consumed on average to get anywhere.
A subway train can arrive, stop in seconds, take whatever time unloading and loading, and then doors close and it is gone in a few seconds. A bus can do similar, their stopping time can be minimal.  Not so with the Bathyspheres we see.  These Bathyspheres stops are nowhere near that fast -- there are airlocks below that have to be guided through at relatively slow speed, and stopped for and then exited.  Lifts to raise the capsule above the water. It all takes quite a bit of time.   Meanwhile that one dock is being monopolized. 
Scheduling - How much time passenger waits for another one going same direction/to their destination ( if you miss the one you wanted ).  To get people to where they need to go, the routes criss-cross Rapture and potentially many 'transfers' are needed to get to a specific destination ( taking up even more time ).
* There need to be more holes (docks) - even the small stations should have at least 2 just for simple redundancy, should one have some problem.  Typical passenger throughput must be increased ( this is a City  ain't it ??  LOTS of people need to conveniently get around. )
* ALOT more holes/docks at main Stations - a need to increase capacity of people throughput the system handles at these key 'transfer' points.   Even if the Bathysphere system is more 'exclusive' (as I propose) it still needs more capacity that the pathetic showing we see in the game.  
* Ditch the Schedule system and have the Bathyspheres go where the customers need them too. Often, there simply are NOT 8 people all going to the same place ( or place along a route ), so these capsule on average will only carry a handful of passengers.  Much better if they go DIRECT to the passengers destination, bypassing stops they don't need to make.  No point in having so many traversing the ocean carrying no one or stopping at stops which are not needed, or waiting when they don't need to.  A supply of ready empty capsules is needed for an 'on-demand' system ( and a system of sending empty ones where needed with minimum  delay ).   The 'RODIN' computer system could handle such allocations, and adjust for customer destinations flow  and loading.   'Phoning ahead' might be encouraged to allow pre-staging the empty capsules.
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Arrival and Departure Schedule Signs - I saw one laying on the ground in the Station in Point Prometheus :
Station     Arrive    Depart
.............02:00     03:45
.............11:30     05:00
.............04:10     06:25
.............09:40     11:05
.............10:30     08:15
.............12:20     02:35
Hopefully those are semi-randomized numbers (barely), otherwise the times with different overlap between different 'scheduled runs' being in-station will overlap (a physical impossibility).
* No 'AM' or 'PM' indicator - very sloppy... ( or did they only operate that 12 morning hours a day ?? Sure that explains it ...  NOT !!. ).
* So few listed.  Really? That few people moved around a busy city ?   Yet more evidence of much less use than implied of the Bathysphere system and reliance on the Trolley to actually move the larger number of citizens about the city.
* A proper sign might be more like this  - even if the system is 'on-demand', customers need to easily tell them where to board (which dock) for their trip.
TIME   DOCK   DESTINATION
Where TIME is Departure, Arrival isn't that important.
There should be many more DOCKs now, and the passengers need to know which one they will board at.
DESTINATION is the next stop along a route. This might instead be a 'party' name if the Bathyspheres are operated On-Demand like Taxis ( a more logical system ) and in that case would be the leftmost column.
With those fancy huge interior of the stations you might expect Station personnel to actually organize activities in the Station with more organized service than the self-serve methods used with Trolleys.
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Another Goody for Small Submarine Design :
How easily Submarines can be off balance by the shifting of weight inside ( which has to be compensated for ) ... passengers, who I doubt would be tied down securely. On BIG submarines there is more inertia/dampening and less leverage for a human shifting their weight, but a small one can rock like a slow motion rowboat.
So if you have all the passengers sitting on the left ... Now your Bathysphere weighs over 29 tons, but shifting center of gravity will still cause it to tilt 'roll' some. ( Front to Back 'pitch' likewise )
Automatic mechanisms can compensate and maintain reasonable balance ( small electric pumps and trim tanks and level sensor feed back control ). Not horribly complex, and can be done without electronics. BUT require constant maintenance and tuning - adding to the general expenses of 'Bathyspheres'.
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Freight 'Container' Modules For Metro Cableways :
A method to make use of (pay for) those expensive cable systems the Metro Bathyspheres use.
Small (~ 1 ton, little over a cubic yard) Freight 'Containers' moved station to station, 'clipped' onto the moving cable and pulled off at the other end. Automatic systems to get the Containers on and off the cable and thru an airlock were added but constantly required manual assistance, increasing the cost. The Trolley freight system was more flexible and proved the better solution for cargoes of this size.
Pressurized Containers subjected to something around ~280 psi while in the Ocean - Spherical shape to minimize container structure ( a mass of thick steel ). The cargo containers are loaded inside at 1 atmosphere and remain sealed at that pressure so as not to suffer damage.
Container Buoyancy - not required to have neutral buoyancy ( system would complicate the Container with ballast tanks or require loading/matching ballast weights ). Containers are lighter than the water they displace and hang upwards from the cable fastener - the cargo is turned over and bounced around in-transit ( typical 'fragile' handling... ), but is no worse than what the Pneumo does to packages.
A portable Cable system like this was used for one of the quarries and used to move rock to build the City foundations. It was somewhat simpler as it did not need to move its cargo inside-to-outside-to-inside.
Another system was once installed between the Lighthouse 'island' ( actually before the Lighthouse was built ) and Port Rapture, to efficiently ferry thousands of shiploads of bulk construction materials down to the City.
Yet more Objects to be seen lying about the seafloor or inside being used for other purposes ( 4 foot wide half inch thick steel hemisphere - probably would make a good start for an armored turret ), highest concentration near Metro stations ( but they could be carried to just about anywhere in Rapture by now ).
Some bright person suggested that these containers be used as inexpensive one-man Bathyspheres, but that talk soon ended after it was suggested that the designer personally be the one to test the idea.
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Water Tunnelways Used For Bathysphere Operations :
* Sea Pressure Tunnels :
** The Standard Cable system towing Bathyspheres thru long tunnels.
** Some Bathysphere cable lines tunnel thru ridges instead of over them and a few of the Metro stations are 'underground'.
** The one that exits the Lighthouse travels a ways thru a tunnel ( thru the mass of rock below the Lighthouse ).
** Some are short extensions of the Metro Stations to clear obstructions (like buildings) to get a clear cable line to the destination station.
* Rapture Pressure tunnels (Metro extension water tunnels within nearby building structures) :
** Used for a few larger Metro stations to distribute the boarding facilities (lifts) across a larger area ( Premium passengers don't like extra walking ... )
** Maintained at 1 Atmosphere of pressure ( does not connect directly with sea ). That cuts down the number of duplicate airlock systems required for the Metro station's facilities.
** Overhead guide system used to keep Bathyspheres from bumping into tunnel walls.
* One architect was contracted to design one of the 'Plazas' be a 'Venice of Rapture' with numerous canals thru which Bathyspheres could move about as if they were streets ( unfortunately the heavy Bathyspheres still needed 'lifts' at strategic points to raise out of water for boarding ). Actually the surface boats (gondola styled) used for local traffic on the canals were more popular and useful. Like the real Venice, measures to keep the canals from smelling like sewers was a significant problem.
--- --- ---
Not Quite A Skyline in Rapture :
(Note to Self - add 'Skyway' to BioShock Rapture MMORPG ???)
* Bathysphere system is sortof a Skyway ( with the neutral buoyancy and the cable tow line ... and 'grip' )
* Construction cargoes can be moved using Metro cable ways ( of course they only run certain places )
* Maintenance Daddies can use Metro Cableways for transport ( they have a 'cable grip' as part of their equipment )
* Sorry, no 'Tears' in this MMORPG game.
In Buried at Sea (DLC) they thought about adding some dim mechanism to travel the Pneumo system the way you did Skylines in Columbia ( very sloppy, half-baked and rushed idea -- and has nothing to do with anything we saw in original Rapture ).
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Microgears/Turbines/Rods/Levers made out of Ryanium (sub-nanotech) - ?? This MMORPG isn't Steam Punk/Clock Punk (Its Gene-o-Punk) :
Use mechanical computer (WW2 tech) shit for Bathysphere Auto-Nav unit ??? A real one STILL weighs a ton (literally), and doesn't fit in the Bathysphere's interior space. Miniature clockwork computers really just don't work.
Bathyspheres allegedly replaced the AE Train system around 1952 ?? At that time there was no significant ADAM tech yet, Vacuum Tubes/early expensive Transistors were still in use for computers. ( No Thinker ). SO a Cable Tow system ( point to point like the Skyway at Disneyland(was) ) really is the most practical way it could work for an automatic/reliable/safe 'Transit System'. A number of the game concept pictures do show a Bathysphere on a cableway.
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Carwash for Bathyspheres/Subs :
Don't want any barnacles building up that cause unneeded drag and an unsightly look for something that's supposed to be a 'deluxe' service. Keep em 'shiny and polished''shiny and polished' - rusty, encrusted and smelly would NOT be so glamorous to those paying a premium price to use the Bathyspheres, so that the passengers can think they are special ( and willing to pay those premium rates ). The Bathyspheres we saw were pretty run down and grungy inside, compared to what they were like when in operation before the so-called %27civil war%27. Keep the windows clean and the seaweed from fouling the maneuvering propeller jets. Change the air filters regularly and empty the ashtrays. Thermostat set to a comfortable temperature -- much more pleasant than being in a subway in NYC when it is 100 degrees and 90% humidity.
--- --- ---
Fuel Cell Technology ( Solutions To Power Submarines ) :
Fuel Cells usually operate at 200 F. Bulky, caustic fluids... ( not practical for lightweight/compact/portable power units ... ), Heavy - so we won't see them powering Fly-bots ...
So, it is back to lightweight batteries, internal combustion engines and compressed gas.
- There cannot be any gas byproduct release
--- --- --- 
Anybody Ever Thought : What if We Put big Hydraulic Legs and Arms on one of those Metro Bathyspheres ???
* MECHS !!!! Maybe some of these are lying around somewhere leftover from the building phase of Rapture.
* Stability of walking on the seabed has its advantages for many operations.
* The Novel book talked about Subs used for construction which had 'arms' to manipulate large structural components.
* Sounds useful, and ugly enough to scare a Big Daddy (in the water anyway).
* Would they work outside the water ??? Hope the Splicers don't get some of them ... ( Rumor for quest to investigate ... )
* Appropriate for the Next Game where Rapture invades Columbia ...
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