The flashing “DON’T WALK” or upraised hand is a warning to people who have not yet entered the intersection. It means that it is too late to start to cross the street before the traffic signal changes and allows cars to proceed. Signals are timed to allow plenty of time for people who have already started walking to safely cross the street.
What does the countdown timer tell me?
The countdown timer counts down the number of seconds that the flashing "Upraised Hand" will be on. This gives the pedestrian that has already started to cross the street a feel for the amount of time they have left to complete their crossing before the signal changes.
Do the push buttons really work?
Yes, the buttons really work but they work more like pushing a button for an elevator than flipping a light switch. When pushing the button for an elevator, you expect to wait until the elevator gets to the floor you are on before the doors open. A pedestrian push button works much the same way. Motor vehicles have to be given enough notice to allow them to stop safely before you can safely cross the roadway much like waiting for the elevator to get to your floor before the doors open.