"Derek Lyons" wrote in message
...
"Kevin Brooks" wrote:

(large suspension bridges are a real bear to try and
destroy with conventional demo)

Seems to me that a largish FLSC (Flexible Linear Shaped Charge) would
do to sever one or both of the main suspension lines.

Not really. Take a gander at the size of the suspension cables for a large
bridge--they can be up to around three or more feet in diameter (the Golden
Gate is a bit over 36 inches). Take a gander at what kind of shaped charge
liner it would take to penetrate what is essentially 18 inches of steel, and
how much explosive is required to back it. Then imagine how massive that
puppy would have to be to get around that three foot cable. When we were
taught bridge demo, the large suspension bridge was not even really
addressed (I can recall an instructor flippantly remarking that it would
probably be best to just park a couple of fuel trucks under the cable at its
lowest point and light them off and hope that the thermal loading degraded
the strength enough to drop it). Given *lot's* of prep time you could make
it work, but you'd probably have to resort to precutting the cable part way
with a torch. I can recall an old Alistair MacLean novel where the bad guys
were going to drop the Golden Gate with "beehive" charges--but imagine the
efffect if you did wrap a ring of maybe the standard 40 pound chaped charges
around one of those cables. You'd end up with a few small diameter holes
penetrating most if not all of the way to the center, but you'd only be
taking out maybe 15 percent of the cross sectional area, which is unlikely
to do anything other than weaken the structure.

Brooks

D.
--
Touch-twice life. Eat. Drink. Laugh.