On 10/7/19 7:05 am, 'Brent Efford' via TramsDownUnder wrote:
> Modern practice is to have the overhead support structure in two
> parts: a foundation of reinforced concrete with a flange connection at
> ground level and a galvanised steel mast bolted to it, generally well
> after the foundation is created. That is the design used for new
> railway electrification construction in Auckland and the current
> renewal programme in Wellington – and I am sure elsewhere.
This depends on the engineer in charge. Directly concreted in place
poles are still commonly installed too. I think it's one of those things
that are like fashion, comes in waves.
Really I don't think it makes much difference either way for the life of
the installation if done properly.
I've even seen video in the UK of them using a machine to directly auger
the pole into place. The pole is fabricated with a screw on the base and
the machine simply twists it into the ground.