A transportation concept or implementation that is touted as futuristic or innovative, but in execution turns out to be more expensive and less feasible than traditional means, outweighing their usefulness. Examples include but are not limited to Monorails (most often cited example)
Personal Rapid Transit, Maglev, etc, versus traditional means generally referring to rail, subway, and road infrastructure
The term generally carries a negative connotation, in that the solutions may be seen as an expensive 'white
elephant' in the truest sense: more difficult and more expensive to maintain and
add to without any perceived benefit other than looking cool
References:
Wiktionary, gadgetbahn
Wikipedia, White
Elephant disambiguation
Walt Disney World can't afford to expand their monorail, it costs a million dollars a mile for new
track, and with the
money it would take to expand that gadgetbahn they could buy a whole fleet of buses that
fit their existing needs