two questions:

1. at what distance can you see the time left?

2. this still does not solve for calculating the speed necessary (for which to utilize as a benchmark if you're actually going to make it through the light).

in pedestrian crosswalk signals, ability to accelerate is probably an order of magnitude greater -- you go from walking to running to beat the signal.

not so with traffic lights, even if you have a visible countdown timer (and as i mentioned above, how will a human calculate the baseline speed at which it is necessary to drive in order to be able to safely cross).