Lights in the US have buttons that you can press. But they don't always work. There's one light in Cambrige, MA, that, as far as I could tell, never ever said WALK.
https://www.google.com/maps?ll=41.869753,-87.648017&spn=...
It turns red immediately when you press the button. When I was in college, I would entertain myself between classes by going over, pressing the button just as the upstream light turned green and cars began accelerating, and then not crossing the street.
This, incidentally, is probably why most lights don't change immediately.
Not everyone understands that you need to keep standing on the pad, or that the bike crossing doesn’t last long enough to walk all the way across.