Most of us who live on small city lots seem to couple a pair of
diametrically-opposed words together when we consider 80M vertical
antennas. The two words are "efficient (or effective)" and "small".
The only somewhat serious antenna thought I had a while back was to put
up a quarter-wave 80M vertical right at the edge of my front sidewalk.
It would probably have a top hat and a small coil somewhere in the
middle. And, it would be installed during a contest or to chase a
DX-pedition, but other times it would be stored along side the house -
and that would be most of the time.
Insofar as radials are concerned, some would certainly be run back
towards the house and along either side of the house. BUT, if I drilled
through the curb and ran a copper pipe under the sidewalk and connected
it to the vertical "base" (likely a pipe in the ground), I could then
run radials down, across and along the street - just nail them down to
the street and pour tar over the radial wires (I know from experience
the time to do install radials like this would be in the middle of the
night when no neighbors are out and about (they could be named
"stradials", an acronym for "street radials").
When operating it would likely be necessary to put some of those orange
traffic cones out in order to meet (or at least approach) the FCC's
"radiation rules", and maybe I might have to dump some dirt on the
sidewalk so as to justify the orange traffic cones when my neighbors see
them in the morning. And then ...
Amazing what hams who live on city lots spend their waking hours
thinking about, isn't it?