The newest twist is the variable toll charge as now exists in northern Virginia on top of HOV regs. Not quite clear as to how the rates are determined but apparently the required EZ pass just pulls it quietly out your wallet. An infinitely variable form of taxation granted to a government agency.
Ah, for the days of the open roads of the Defense Highway System of Eisenhower.
The variable toll charge is on express lanes that run parallel to the free lanes on I-95 and I-495. The tolls go up and down depending on how congested the free lanes are, in order to keep the express lanes free-flowing. A driver with two or more passengers (HOV-3) can take them for free, as long as he has an EZ-Pass Flex transponder switched to the carpool (free) setting.