Concept Traffic Light Shows How Much Time Is Left Through A Sand Glass

You ever find yourself stuck at a traffic light that'll just never turn green? Doesn't it feel like forever? If traffic lights used  this concept LED Sand Glass, you'll know exactly how much time is left. Here's how it works:
It's an incredibly simple idea: LED lights trickle down in a virtual sand glass that countdowns how much more Red and Green there will be. When it approaches 3 seconds left, the LEDs switch to yellow and give you an exact count on what's left.

Could it work? Maybe. But how it turns yellow before it turns green AND red could be a little confusing !