On Thu, 12 Dec 2013 19:12:58 +0000
mogga wrote:

We're getting some new street lights and have noticed they have little
antennas on the top.

What is it for? They look like they have a light detetctor same as the
old ones too.

Where I lived in the States, they were so that a speeding Police
Cruiser or Fire Engine could signal them on approach to turn green in
its favour.
Or it could be some remote control, allowing individual shut-off,
instead of block by block.
Or, if you see black helicopters marked 'GCHQ' hanging around, they
could be something else entirely.......

There was also a local experiment in the US to provide WiFi for
residents, and they used street light poles to hold the antennae, but
the whole scheme foundered and died. The equipment is probably still
there, if anybody wants it.

--
Davey.