Comment Re:Probably not as useful. (Score 2) 96
I disagree. The measure of highway utilization for a single vehicle is not just the amount of space it uses (length plus front separation). It's that space multiplied by the amount of time it needs that space. If everyone is supposed to maintain X seconds of separation (I've been told 3) between their vehicle and the one in front, then additional speed won't change the total utilization. Except for one thing: as speed approaches infinity, the portion of utilization that the vehicle length contributes shrinks to zero. Therefore, the faster vehicles travel, the less capacity they use.
Of course, that assumes that everyone drives perfectly, which is the real problem: even something as simple as an unexpected lane change can trigger slow downs in an at-capacity roadway that ripple throughout the following traffic, breaking the flow and potentially causing a cascade down to stop-and-go.