I've mentioned it before, if the hedge isn't overhanging the pavement
you could probably put up railings. If it is overhanging then cut it
back. I get a bit peaved when I have to step into the road to avoid
walking into peoples hedges.

That's not a fair point when you don't know the situation. Yes, of
course, the hedge grows outwards over the pavement but only by a few
inches. I don't see how I could ensure that it didn't encroach at all
without destroying the hedge myself. The key point is that the pavement
is wide (at least 10 feet), and there is no unreasonable encroachment,
and certainly not enough to justify pushing each other into it. Even if
it was cut back a few inches, I don't see why that would make the kids
want to stop doing it.