What is the heavy vehicle formula for timed interval following distance under 40 MPH?

The correct answer is based on the safe following distance guidelines for heavy vehicles traveling at speeds under 40 MPH. To ensure adequate stopping time and maintain a safe distance from the vehicle ahead, the formula recommends one second of following distance for every 10 feet of vehicle length. For example, if you are driving a truck that is 50 feet long, you would need a following distance of 5 seconds to provide sufficient reaction time in case the vehicle in front of you suddenly stops or slows down. This formula is particularly important for heavy vehicles because they require more time and distance to stop compared to lighter vehicles.

The other choices reflect different distances that are not suitable for heavy vehicles, which have unique handling and stopping characteristics. Using a following distance based on incorrect measurements could compromise safety on the road. Therefore, the guideline of one second for every 10 feet of vehicle length is crucial for safe operation, especially given the longer stopping distances required by large trucks and buses.