On Wed, 04 Jun 2008 21:27:45 -0500, "Martin H. Eastburn"
wrote:

Building trades need the skill for frames and such.
Sheet metal guys need it for that Cone to pipe at 48 degrees with a branch .....
Draw that out in a sheet to cut out then bend up right.

Lots of algebra is done everyday just thinking.

Then the engineering trades - lots of math.

When not addressed, a sky bridge falls or a boiler blows...

Sorry, but you have a huge error there - The Skybridge in the Kansas
City (Marriott?) was designed just fine. It failed because the
contractor did not build to the print as designed, and did not think
through the effects of the design changes he made or get them approved
by the architect and structural engineers.

The original design had multiple hanger rods going to the roof, one
for supporting each layer separately from the rest, and a specifically
designed saddle to hang them from.

The builder used one rod to hang the top bridge, then a second rod
from the top bridge down to the second, and then another from second
to third. And he modified the mounting method so one set of rods and
nuts on the top level was carrying the entire load of all three
levels. A disaster waiting to happen.

-- Bruce --