We've all been there. You're sitting at a stoplight, patiently waiting to make your turn. An approaching car has its turn signal on, so you begin to pull out, only to realize the approaching car isn't slowing or turning at all. Hard braking, horn honks, and possibly rude gestures are soon to follow. (This is why I don't trust turn signals until the car actually begins to make the turn.)
What if the approaching car had a brake light on the front? You would've known it wasn't slowing down despite the errant turn signal and waited to see what it did. Similarly, if you saw both the turn signal and a front brake light, you could be even more confident that the car was really going to slow down and turn. A recent study by the Technical University in Graz, Austria, suggests that front-facing brake lights could benefit everyone.
Of course, a bright red light on the front of a car is illegal for many good reasons. Red is reserved for the back of the car, and forward-facing red lights could also be confused with emergency vehicles. That's why the study proposes a green front brake light instead. A brake light that isn't red may seem counterintuitive, but when you're facing of the braking car, it's giving you a green light that it's safe to proceed because it's slowing down.
To determine how much front brake lights might help, researchers studied data from 200 car crashes that occurred at Austrian intersections, then ran computer simulations of what would happen if drivers had the extra warning that front brake lights would have provided in those situations. They simulated reaction times of 0.5 seconds (a perfect drag race reaction time), one second (average), and 1.5 seconds (someone with slower reflexes or who may not have been paying close attention).
The simulations showed that 7.5% of these crashes could have been avoided completely with the slowest reaction time, and 17% with the fastest reaction. Additionally, 25.5% of these crashes still would have occurred, but at a significantly lower impact speed, reducing injuries and vehicle damage. You can't always prevent a crash, even with automated emergency braking systems, but reducing the severity of a crash is always helpful. Of course, testing this outside a computer simulation would be necessary to gather real-world data.
There are certainly obstacles to implementing front brake lights. Cars would have to be redesigned to include them. People, not just drivers, would have to be taught how they work. The biggest obstacle would probably be changing existing laws prohibiting front brake lights. Only white and amber front lights are legal in the U.S., so green would have to be added to the list. Considering how long it took for adaptive headlights to become legal, this could take a while.