Under normal driving conditions, what is the recommended minimum following distance at 55 MPH on the expressway?

The recommended minimum following distance at 55 MPH on the expressway is indeed 3 seconds. This is a guideline based on the principle that it provides enough time for a driver to react in case of sudden stops or emergencies without increasing the risk of a rear-end collision.

The 3-second rule is particularly important because it helps account for various factors like vehicle reaction time, road conditions, and potential distractions. When driving at higher speeds, such as on an expressway, having this space allows for adequate reaction time to maintain safety, especially considering that it takes time for a driver to perceive a hazard and then respond appropriately.

In different conditions, the following distance may need to be adjusted (for instance, in inclement weather or heavy traffic), but under normal circumstances, 3 seconds strikes a balance between maintaining efficiency and ensuring safety on the road.