This is a huge undertaking but would be an awesome feature. Waze would have the ability to know when traffic signals are red and green based on Wazers. It can detect a Wazer ahead is stopped at an intersection, and can warn others behind that the signal is Red. This may also impact ETAs as well. In high volume cities like LA, this would be a feasible idea especially during rush hour. However, it may not be realistic at times of lower volume. This could save time, allow for smarter decisions, save gas, and be greener for the entire world!