These decisions are being made for reasons largely unrelated to automation. Rather they are associated with reduced energy consumption, simplification of vehicle design, enhanced ease of vehicle assembly, improved ability to adjust performance to match driver preferences, and cost savings compared to traditional direct mechanical control devices. Roadside computers are better suited for traffic management, setting the target speed for each segment and lane of roadway, and allocating vehicles to different lanes of a multilane automated facility. The aim is to maintain balanced flow among the lanes and to avoid obstacles or incidents that might block a lane. The vehicle's onboard computers are better suited to handling decisions about exactly when and where to change lanes to avoid interference with other vehicles.
Some additional functions have no direct counterpart in today's driving.
Most important, wireless communication technology makes it possible for each automated vehicle's computer to talk continuously to its counterparts in adjoining vehicles. This capability enables vehicles to follow each other with high accuracy and safety, even at very close spacings, and to negotiate cooperative maneuvers such as lane changes to increase system efficiency and safety. Any failure on a vehicle can be instantly known to its neighbors, so that they can respond appropriately to avoid possible collisions. At check-in stations, wireless communication between vehicles and roadside would verify that the vehicle is in proper operating condition prior to its entry to the automated lane. Similarly, the check-out system would seek assurance of the driver's readiness to resume control at the exit.