Have you ever wondered what the blinking or steady white light is on top of some stop lights? It is one part of the emergency vehicle traffic signal preemption system, that emergency responders and even some train or transit bus services use to change the light to give them the right away through intersections so they can arrive to their call both quicker and safer. It is also a tool you can use as a driver as another way to know that an emergency vehicle is possibly coming and also from what direction that emergency vehicle could be coming.
For example, if you see the white light on top of the stop light blinking, you know that the emergency vehicle will be coming from the left or right. If that white light on top of the stop light is a steady white light, you know that the emergency vehicle will be coming from either behind or in front of you. You will oftentimes see these signals begin to alert for the incoming threat well before you ever hear or see the emergency vehicle.
Knowing what the lights mean is only half the battle though, once you know what the light means, you next need to know what to do if this occurs. If the light is steady, make sure to check your mirrors, to ensure you don't need to pull to the right side of the road. Always pull to the right side of the road when an emergency vehicle is coming. If you are coming up to a light that is green and you see it start to blink, slow down and prepare to stop as that likely means the light is going to quickly change from green to red from an incoming emergency vehicle.