Registered carpools with 3 or more passengers are allowed to use the lanes free of charge, as are motorcycles, public transit vehicles (including taxies), approved clean energy fuel vehicles, and emergency vehicles responding to an active emergency (i.e. with lights and sirens activated). All other vehicles are charged an all-electronic toll to use the lanes, and the fees vary depending on traffic conditions both in the express lanes and the general purpose lanes.
The Miami ETL has a similar purpose to a similarly designed tollway in Baltimore - however thus far the ETL has become gridlocked at times in addition to the general purpose lanes, and therefore hasn’t really served its full purpose. Highway officials have been working on solutions to prevent double tolling for vehicles that get caught in a gridlock and are stopped underneath a toll gantry, and are also working to figure out how to make the lanes function better to actually relieve congestion on the highway.
Currently, non-exempt vehicles using the lanes must have a SunPass transponder or another valid compatible equivalent. However, there are future plans to enable “Pay-by-Plate” tolling in the express lanes for non-SunPass users, although this feature is not currently available.