Probably cheaper to deploy, but the capacity will always be low and speed slow.
I'm not one for an "either or" generally, but I really have a hard time seeing the benefit of blimps beyond "this is neat and kinda fun".
Most of the population of the world lives on 2 contiguous land masses. Flights to bridge the masses is fine but would represent a small fraction of the transport needed.
Rail doesn't have to solve all problems. It's a good solution to most problems.
But back to the blimp proposals, I can't see how a blimp would be a better option vs a boat. (Traditional flight is probably better than either).
Imagine a hexagonal grid of these between continents, with aqua-farms, data-centers, resorts, casinos, floating cities/solar/wind sprinkled in between. Err... Aqua-Loop?
Maybe 'grow' them 'in-situ' like corals, funghi, sponges, seaweed, algae, bamboo, whatever, by means of genetic manipulation.
edit: Not to forget, conduits for HVDC, ZBLAN, and all sorts of pipelinable stuff for the global super smart grid.
FUCK YEAH!
edding: Icebergs, yes, yes, Gridguards no less!
How can you build a railroad across an ocean?
One of the reasons why air travel is practical, and rail isn't, is because you don't need to build any infrastructure between airports. The other reason is because you can adjust flights between airports without needing to adjust infrastructure.
edding: Also imagine something like really long freight trains, a mile or so, double stacked, only running at something like 200 mph. And compare the capacity with any freight plane in use, vs. the speed of container ships. Also the possibility for pipelines right next to it. Conduits for energy and data. On and on and on...
edding: In case you havn't noticed, linking myself, elsethreads:
New rail will be very expensive to install and politicians are afraid of saying "we may need taxes to cover this".