What is vehicle platoon dispersion and why does it matter?

• A. The clustering of vehicles into dense groups at stop lines; affects safety margins.
• B. The spreading of a group of vehicles as they travel; affects capacity and LOS.
• C. The random fluctuations in vehicle speeds due to driver error.
• D. The variation in vehicle types within a platoon.

Answer: (B)

Vehicle platoon dispersion is the spreading of a group of vehicles as they travel, caused by small differences in speeds, accelerations, braking, and driver reaction times. As the platoon moves, these tiny variations accumulate, so gaps between vehicles grow and the group becomes less tightly packed. This matters because highway capacity depends on keeping vehicles closely spaced at a given speed. When dispersion increases, average headways rise, reducing the number of vehicles that can pass a point per hour and lowering the level of service. In coordinated platoons with precise speed control, dispersion can be minimized to preserve higher capacity. The other ideas describe different phenomena—stoppage clustering, random speed fluctuations, or vehicle-type variation—not the traveling spread of a platoon.