Vac Trains
Beneath the surface of the Graham Sea on Pacifica runs the Liberty-Florida Island vac-tube;
the tube is supported by its own buoyancy and is anchored to the ocean floor safely below the shipping lanes
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Vac TrainsBeneath the surface of the Graham Sea on Pacifica runs the Liberty-Florida Island vac-tube; the tube is supported by its own buoyancy and is anchored to the ocean floor safely below the shipping lanes |
Magnetic levitation based
transportation system used to
provide rapid mass transit across a wide range of habitats from
planetary
surfaces to megastructural
constructs.
Vac Trains are built upon basic concepts predating
the
Information
Age although they are often associated with such
Information Age thinkers
as Gerard K. O’Neill and Paul Birch.
They make use of magnetically levitated cars operating in
an evacuated
chamber to provide transportation systems capable of approaching or
sometimes
even exceeding orbital or interplanetary transit velocities.
Transit tubes may be built on, above,
or below the surface
of a planet or habitat, suspended under water at a depth below that
used by
shipping or affected by storms, or attached to the outer hulls of space
habitats and megastructures. On
tectonically active worlds, the transit tube is often suspended inside
a larger
bracing tube filled with shock absorbing smart matter.
Some worlds even have free-fall vac trains,
where the train is accelerated into an orbit within the planet itself,
following an elliptical path for part of the journey.
Passengers briefly experience microgravity
conditions during such transits.
A short range vac train system, such as might be
used to
provide transportation between nearby communities on a planetary
surface, will
usually accelerate its cars at a steady but fairly gradual rate until
they
reach some predetermined velocity designed to provide a reasonable
transit time
to the destination (generally no more than a thousand kilometers per
hour),
then let the cars coast until they near the destination, whereupon they
are
gradually decelerated to a stop.
For longer range travel, either on a
planetary surface or
space habitat, the transit cars are often accelerated gradually but
continuously (half a standard gravity is a common acceleration) for
half of the
journey and then decelerated for the other half.
Such a system can cross significant planetary
or habitat distances in a matter of minutes and even Banks
Orbital
scale
constructions can be circumnavigated in less than 48 hours. Such high speed
transit systems must be built
to minimize tube curvature due to the velocities involved and may
appear almost
mathematically straight when observed from close range.
Note that passengers must be accommodated safely when accelerating in this fashion. Some trains have rotating sections to maintain vertical orientation for travelers during the acceleration and deceleration phases while others employ dedicated utility fog or plasm based seating which conforms to the passenger and maintains the desired orientation.
At the largest scales, mass stream technology may be used to provide motive power to the transit cars, which magnetically couple to a network of mass beams, specialized for the purpose. Such systems are employed in the Kiyoshi complex and similar structures and permit travel to any point on a given dyson component in less than a standard day. For transit between components, travel times are generally measured in days or weeks but the distances covered are several orders of magnitude larger and the high efficiency and energy conservative nature of the transport web makes it the preferred method of travel for anything other than emergency transit conditions.
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