Commercial Driver License (CDL) Class B Practice Test

How do you determine the seconds of following distance needed for your vehicle?

1. One second for every 10 feet of vehicle length under 40 mph, add a second over 40 mph

2. Two seconds for every 20 feet of vehicle length

3. Three seconds at all speeds

4. One second regardless of vehicle length

The correct answer is: One second for every 10 feet of vehicle length under 40 mph, add a second over 40 mph

The correct approach to determining the following distance needed for your vehicle is based on the vehicle's length and speed. When you are driving at speeds under 40 mph, the rule is to maintain one second of following distance for every 10 feet of your vehicle's length. When you are traveling over 40 mph, it is important to add an additional second. This practice accounts for longer stopping distances at higher speeds and ensures that you have enough reaction time to prevent a collision or maintain safe control of your vehicle. Following this rule promotes safer driving conditions by allowing for a buffer that corresponds to both the vehicle size and the speed at which it is traveling. This method reflects sound defensive driving techniques, emphasizing the importance of adapting following distance based on both speed and vehicle size for optimal safety on the road.