What number can those countdown peds start counting from?

Well, the display supports up to 99 seconds but I'm not sure if the controller can.

I don't think 99 seconds is practical either. i meant is there a standard # of seconds that is used? Or does is the setting random?

I've noticed here the clearance int. is usually 10-15s for city streets and residential areas, and 20-30s for suburban arterial roads.

To answer your guys questions. The controller can time the clearance cycle from 0-999 seconds. If I was to put in a 120 second clearance interval, the countdown unit will remain at 99 until it hit 98 seconds and then resume counting.

There was once a method to the madness as far as timing the flashing dont walk. It was a formula involving 4 feet/second and the length of the crosswalk. Now its based more on the lines of how often the crosswalk is used, by older or younger people, plus the length of it. Average counting lengths are 18 for more roads. Sometimes as high as 35 for pretimed intersections or as low as 8 if the signal is allowed to rest in walk until side street movement.