Today - Before CAV Systems (BCS) - CAVs from different vendors do not normally “think alike.” Common protocols will change that by making CAV actions predictable. Without common protocols, my CAV might behave differently from yours; mine might preserve the spacing between it and the CAV in front, yours might close that gap. Since neither CAV could predict the speed or spacing of the other, safety could be compromised.
Therefore, in a CAV System, each CAV will observe the same protocols, to maintain speed and spacing and to select or change lanes. A lane change by one CAV would not endanger nearby CAVs maintaining authorized speeds and spacing.
Common CAV Protocols (for CAVWAY with Local Lane and Express Lane)
A CAV might choose to be in the Local Lane if and only if its route called for it to exit at the next node and to be in the Express Lane otherwise.
A CAV might stay in the current lane unless a lane change was in order according to the Lane Selection protocol.
A CAV might change lanes if the Lane Selection protocol called for it to do so, but only when it sensed that it was safe (to an open space in the adjacent lane).
Constant speeds and spacing
Each CAV in the Local Lane might observe the Local-Lane speed. Each CAV in the Express Lane might observe the Express-Lane speed. The Express-Lane speed could be higher than the Local-Lane speed to enable lane changes and long-distance efficiency.
Common CAVWAY Protocols
The load-monitoring protocol might require that CC at each node monitor a small number of upstream spaces (boxes) at regular intervals to determine how many were open and how many CAVs could enter the traffic flow during that interval.
The access-control protocol might require that each CC check each CAV registration and then, to prevent overloading, grant CAVWAY access to only the number of registered CAVs authorized by the load-monitoring protocol.