Final answer:
The correct action for drivers when an emergency vehicle approaches with activated sirens and lights is to pull over to the side of the road and stop, allowing the emergency vehicle to pass. The Doppler effect allows observers to discern the approach and passing of the vehicle.
Step-by-step explanation:
When approaching a very busy intersection in an emergency vehicle with your sirens and lights activated, the correct action is not explicitly mentioned in the reference information provided. However, the best practice for drivers who are not in the emergency vehicle is to pull over to the side of the road and stop to allow the emergency vehicle to pass safely. The presence of a siren, often accompanied by the Doppler effect, signifies the urgency of the vehicle's mission and indicates that other drivers should immediately yield the right of way. If one is standing on a sidewalk, the frequency of the siren observed will most closely match the actual frequency when the ambulance is directly in front of you, as there is no relative motion to cause a shift in pitch. Emergency vehicles typically have the right of way in traffic, and their ability to navigate intersections safely and quickly can be a matter of life and death.