[TowerTalk] Self Supporting Tower Install

[jimlux]

On 5/11/17 8:33 PM, Lee K. Brown MD via TowerTalk wrote:
> I recently moved my US Tower crank-up from my old QTH to my new QTH,
> While the tower had been originally installed with the usual
> rectangular concrete base specified by the P.E. that US Tower used to
> wet stamp the plans for me, the P.E. that I engaged for the
> re-install locally specified a cylinder of concrete. Apparently not
> unusual at all.
>
there's a well developed process for drilling round holes (caissons) for
supports for things like traffic lights, etc. A machine comes out and
drills a 3-4 foot diameter hole, you drop the rebar cage in, fill with
concrete, etc.

Works nicely in places without a lot of room (e.g. a sidewalk), if you 
make the column deep, it can support an enormous moment (there's several 
traffic signals spanning 3-4 lanes near my house doing this, the 
cantilever loads must be huge with a fairly heavy left turn signal 
hanging out 4 lanes in)