Greatest Traffic Invention Ever

Once again I'm left wondering, why didn't I come up with this idea?  That's what occurs to me nearly every time I approach an intersection in downtown Cedar Rapids with the countdown walk sign.  I'm a huge fan of football and basketball, both home to a play clock and shot clock, respectively.  That's why I can't figure out why a "traffic shot clock" didn't occur to me.  What a brilliant idea.  Remember when you used to approach an intersection behind the wheel, or on foot, and the Don't Walk was flashing red?  That only told us we were close to the end, but how close?  I need specifics.  Thankfully, now I know...if I'm within a block with 10 seconds to go on the "traffic shot clock," I'll make it.  Anything less, it's not gonna happen because I'd never speed up to make a light.  No, never would any of us do that.  So to whoever created them, thank you for the "traffic shot clock."