Final answer:
The safe following distance behind an emergency vehicle like a fire apparatus is often 500 feet. You must pull over and become stationary when you hear an ambulance's siren, to let it pass safely. Safe crossing distance behind a car varies, but maintaining several car-lengths is usually recommended.
Step-by-step explanation:
The question pertains to the safe following distance that a vehicle must maintain from fire apparatus in an emergency situation. The law varies by jurisdiction, but a common stipulated safe distance is often at least 500 feet. When you hear the Doppler shift in an ambulance's siren, indicating it is approaching, it is crucial to pull over to the side of the road and stop, thus becoming stationary to let it pass safely. It is inappropriate to run toward or alongside the ambulance, as these actions can compromise safety. Regarding how far away a car must be before crossing, it may depend on visibility and speed, but ensuring a safe number of car-lengths distance, typically equating to several seconds behind the vehicle, is a sound practice.